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New development in measuring mechanical properties of tissue
Author – Writer: Dror Nir, PhD
Article 11.5.4 New development in measuring mechanical properties of tissue
Measuring the effects induced onto imaging by the mechanical properties of tissue is a common approach to differentiate tissue abnormalities. In previous posts I discussed the applicability of imaging applications that visualize variations in tissue stiffness; e.g. ultrasound-elastography and MRI-elastography as aid in the diagnosis workflow of cancer. Today, I would like to report on a recent publication made in SPIE Newsroom describing an optical-imaging system to measure tissue stiffness at high resolution. I think that such emerging technologies should be followed up as they bear promise to bridge deficiencies of the traditional modalities currently in use.
Reporting on:Optical elastography probes mechanical properties of tissue at high resolution
By: David Sampson, Kelsey Kennedy, Robert McLaughlin and Brendan Kennedy
Information published at:SPIE Newsroom – Biomedical Optics & Medical Imaging
Probing the micro-mechanical properties of tissue using optical imaging might offer new surgical tools that enable improved differentiation of tissue pathologies, such as cancer or atherosclerosis.
11 January 2013, SPIE Newsroom. DOI: 10.1117/2.1201212.004605
Elastography is an emerging branch of medical imaging that uses mechanical contrast to better characterize tissue pathology than can be achieved with structural imaging alone. It achieves this by imaging a tissue’s response to mechanical loading. Although commercial products based on ultrasonography and magnetic resonance imaging (MRI) have been available for several years, these new modalities offer superior tissue differentiation deep in the human body. However, elastography is limited by its low resolution compared with the length scales relevant to many diseases. Increasing the resolution with optical techniques might offer new opportunities for elastography in medical imaging and surgical guidance.
An elastography system requires a means of loading the tissue to cause deformation and an imaging system with sufficient sensitivity and range to capture this deformation. Implicit in these requirements is access to the tissue of interest. Optical elastography has previously been largely based on schemes that suit small tissue samples rather than intact tissue in living humans. Additionally, such schemes have not had the sensitivity or range to produce high-fidelity images of mechanical properties. We have addressed both these issues in our recent work, developing the means to access tissues in vivo and improve the sensitivity and range of optical elastography using phase-sensitive optical coherence tomography as the underlying modality. The use of optical coherence tomography to perform elastography has come to be referred to as optical coherence elastography.1
To make optical coherence elastography on human subjects feasible, we designed an annular piezoelectric loading transducer (see Figure 1), through which we could simultaneously image, enabling the first in vivo dynamic optical coherence elastography on human subjects.2 We were subsequently able to extend this to three dimensions (see Figure 2), in collaboration with Stephen Boppart’s group at the University of Illinois at Urbana-Champaign.3 This extension took advantage of the high speed of spectral-domain optical coherence tomography, and the maturity of phase-sensitive detection techniques originally developed for Doppler flowmetry and microangiography.
Figure 1. Schematic (left) and photograph (right) of the annular load transducer and imaging optics for in vivo optical coherence elastography.
Figure 2. 2D images of in vivo human skin selected from 3D stacks. (a) Optical coherence tomography image and (b) the same image overlaid by the 2D dynamic elastogram recorded at 125Hz load frequency, highlighting the greater strain in the epidermis. Reprinted in modified form with permission.3
For general access to tissues in the body, optical coherence elastography faces two basic limitations. The free-space probe requires miniaturization for versatile access to tissue in confined or convoluted geometries. We addressed this in studies of the elastic properties of human airways using catheter-based anatomical optical coherence tomography.4
Figure 3. (a) Schematic diagram of needle optical coherence elastography. The phase difference Δφ=φ1– φ2 determines the displacement, d, when scaled by the wavelength, λ, and refractive index, n. (b) Needle and pig trachea. (c) Local displacement versus distance, with tissue boundaries indicated by red stars. (d) Representative histology. Reprinted in modified form with permission.6
More fundamentally, optical coherence tomography can only penetrate, at best, 1–2mm into most tissues, limiting it to superficial applications. To address this issue, we combined optical coherence elastography with needle probes, an active research area in our group (see Figure 3).5 We conveniently use the needle probe itself to deform the tissue during insertion.6 The deformation ahead of the needle tip depends on the mechanical properties of the tissue encountered, as well as on the nearby tissue environment, particularly on any interfaces ahead of it. We measure the local sub-micrometer displacement of the tissue between two positions of the moving needle probe. We plot this displacement versus distance ahead of the probe: see Figure 3(c). The slope of the displacement at location z is a measure of the local strain. A change in slope signifies a change in tissue stiffness; the steeper the slope, the softer the tissue (other things being equal). Figure 3 highlights this effect in a layered sample of pig trachea. The positions of the changes in slope correlate well with the tissue interfaces shown in the accompanying histology: see Figure 3(d).
The other key area of improvement we have focused on is lowering the optical coherence elastography noise floor by increasing the detection sensitivity, which is vital to make clinical imaging practical. We firstly showed that Gaussian-smoothed, weighted-least squares strain estimation improved the sensitivity of estimates by up to 12dB over conventional finite-difference methods.7 Next, we showed that performance could be further improved at low optical coherence tomo- graphy signal-to-noise ratios (and, therefore, at greater depths in tissue) by employing a 2D Fourier transform technique.8Combined with other system refinements, these improvements have enabled us to reach a displacement sensitivity of 300pm for typical optical coherence tomography signal-to-noise ratios in tissue, with room for improvement.
The Young’s modulus of soft tissue varies from kPa to tens of MPa, whereas the scattering coefficient of such tissues—which is largely responsible for determining the contrast of optical coherence tomography—is typically in the range 2–20mm−1. This apparent native advantage in mechanical over optical contrast (see the example in Figure 4), combined with the maturation of optical coherence elastography methods, bodes well for the future. In our group, we are pursuing tumor-margin identification using elastography; others have begun to consider corneal elastography,9, 10 and still others are examining shear wave schemes with the aim of probing Young’s modulus much deeper in tissues.11,12
Figure 4. Optical coherence tomography (a) and optical coherence elastography (b) images of the same phantom with two inclusions visible, showing enhanced mechanical over scattering contrast.
Optical elastography currently sits at a similar stage of development as ultrasound elastography did in 1999. Based on a similar trajectory, this field will rapidly expand over the next decade. Our recent results point to the first convincing applications of optical elastography being just around the corner.
We acknowledge funding for this work from Perpetual Trustees, the Raine Medical Research Foundation, the Cancer Council of Western Australia, the Australian Research Council, the National Health and Medical Research Council (Australia), and the National Breast Cancer Foundation (Australia).
David Sampson
Optical+Biomedical Engineering Laboratory School of Electrical, Electronic and Computer Engineering
and Centre for Microscopy, Characterisation and Analysis The University of Western Australia
Perth, Australia
Kelsey Kennedy, Robert McLaughlin, Brendan Kennedy
Optical+Biomedical Engineering Laboratory School of Electrical, Electronic and Computer Engineering The University of Western Australia
Perth, Australia
References:
1. J. Schmitt, OCT elastography: imaging microscopic deformation and strain of tissue, Opt. Express 3(6), p. 199-211, 1998.doi:10.1364/OE.3.000199
2. B. F. Kennedy, T. R. Hillman, R. A. McLaughlin, B. C. Quirk, D. D. Sampson, In vivo dynamic optical coherence elastography using a ring actuator, Opt. Express 17(24), p. 21762-21772, 2009.doi:10.1364/OE.17.021762
3. B. F. Kennedy, X. Liang, S. G. Adie, D. K. Gerstmann, B. C. Quirk, S. A. Boppart, D. D. Sampson, In vivo three-dimensional optical coherence elastography, Opt. Express 19(7), p. 6623-6634, 2011.doi:10.1364/OE.19.006623
4. J. P. Williamson, R. A. McLaughlin, W. J. Noffsingerl, A. L. James, V. A. Baker, A. Curatolo, J. J. Armstrong, Elastic properties of the central airways in obstructive lung diseases measured using anatomical optical coherence tomography, Am. J. Resp. Crit. Care 183(5), p. 612-619, 2011.doi:10.1164/rccm.201002-0178OC
5. R. A. McLaughlin, B. C. Quirk, A. Curatolo, R. W. Kirk, L. Scolaro, D. Lorenser, P. D. Robbins, B. A. Wood, C. M. Saunders, D. D. Sampson, Imaging of breast cancer with optical coherence tomography needle probes: Feasibility and initial results, IEEE J. Sel. Topics Quantum Electron. 18(3), p. 1184-1191, 2012. doi:10.1109/JSTQE.2011.2166757
6. K. M. Kennedy, B. F. Kennedy, R. A. McLaughlin, D. D. Sampson, Needle optical coherence elastography for tissue boundary detection, Opt. Lett. 37(12), p. 2310-2312, 2012. doi:10.1364/OL.37.002310
7. B. F. Kennedy, S. H. Koh, R. A. McLaughlin, K. M. Kennedy, P. R. T. Munro, D. D. Sampson, Strain estimation in phase-sensitive optical coherence elastography, Biomed. Opt. Express 3(8), p. 1865-1879, 2012.doi:10.1364/BOE.3.001865
8. B. F. Kennedy, M. Wojtkowski, M. Szkulmowski, K. M. Kennedy, K. Karnowski, D. D. Sampson, Improved measurement of vibration amplitude in dynamic optical coherence elastography, Biomed. Opt. Express 3(12), p. 3138-3152, 2012. doi:10.1364/BOE.3.003138
9. R. K. Manapuram, S. R. Aglyamov, F. M. Monediado, M. Mashiatulla, J. Li, S. Y. Emelianov, K. V. Larin, In vivo estimation of elastic wave parameters using phase-stabilized swept source optical coherence elastography, J. Biomed. Opt. 17(10), p. 100501, 2012.doi:10.1117/1.JBO.17.10.100501
10. W. Qi, R. Chen, L. Chou, G. Liu, J. Zhang, Q. Zhou, Z. Chen, Phase-resolved acoustic radiation force optical coherence elastography, J. Biomed. Opt. 17(11), p. 110505, 2012. doi:10.1117/1.JBO.17.11.110505
11. C. Li, G. Guan, S. Li, Z. Huang, R. K. Wang, Evaluating elastic properties of heterogeneous soft tissue by surface acoustic waves detected by phase-sensitive optical coherence tomography, J. Biomed. Opt. 17(5), p. 057002, 2012. doi:10.1117/1.JBO.17.5.057002
12. M. Razani, A. Mariampillai, C. Sun, T. W. H. Luk, V. X. D. Yang, M. C. Kolios, Feasibility of optical coherence elastography measurements of shear wave propagation in homogeneous tissue equivalent phantoms,Biomed. Opt. Express 3(5), p. 972-980, 2012. doi:10.1364/BOE.3.00097
I have mentioned HistoScanning (ultrasound-based tissue characterization technology which I have invented and developed to a medical device) in many of my previous posts. HistoScanning for prostate is a specific HistoScanning application that is applied to the ultrasound’s raw signal (not the image) following a comprehensive scan of the prostate capturing its entire volume. The whole process takes about ten minutes and the output is a digital 3D map of the prostate gland where locations suspicious of presenting with prostate cancer are indicated.
HistoScanning report with 2, bilateral, basal lesions.
The urologist translates such map into a “prostate regional biopsy scheme” when planning his biopsies and direct the needle, under ultrasound guidance, to these predefined suspicious locations.
The systematic biopsy patterns targeted 7 sectors bilaterally: transition zone, apex, center, and base, each medially and laterally.
In that sense, the workflow is similar to using MRI for tumor detection and creating a tumor map for targeting the biopsy.
As reasoning for conducting the study the investigators argue that: “Exact staging of prostate cancer before treatment is essential for relevant therapeutic decision making. Current procedures, such as nerve-sparing prostatectomy and brachytherapy, as well as active surveillance and future focal treatment options, depend on the reliable identification of cancerous lesions within the prostate. Systematic prostate biopsies with at least 10 to 12 cores are the current standard method to detect and locate significant prostate cancer, as scientific evidence during the last decades has shown. Nevertheless, there are no homogeneous data concerning the required number of cores and the technical approach of prostate biopsy procedures. The unstable histologic results on active surveillance and the well-known discrepancy between transrectal diagnostics and radical prostatectomy specimens underline the necessity to develop reliable diagnostic tools for precise detection and localization of prostate cancer. Recent data on HistoScanning computer-aided ultra-sonography have shown favorable results. To generate a greater diagnostic yield than systematic needle biopsies, we integrated HistoScanning-guided targeted biopsies in our general prostate biopsy regimen. We report the cancer detection rate in a prospective series of 80 patients.”
The study’s objective was: “To define potential improvement in prostate cancer detection by application of a computer-aided, targeted, biopsy regimen using HistoScanning.”
Materials and Methods: “The data were collected prospectively from 80 men who consecutively underwent a systematic 14-core prostate biopsy supplemented by targeted transrectal and perineal ultrasound-guided biopsies. All biopsies were performed between March 2011 and September 2011. Indications for prostate biopsy were suspicious findings at the digital rectal examination (DRE), or serum prostate-specific antigen (PSA) level >10 ng/mL, or both. In case of elevated serum PSA levels >4 ng/mL a PSA-velocity of >0.75 ng/mL p.a. and free-to-total PSA ratio <15% were seen as the indication for prostate biopsies. Thirty-six patients had undergone a previous transrectal prostate biopsy. All patients were informed of the mode of the extended prostate biopsy scheme and its potential complications. All patients provided written informed consent for the procedure.After indication and before starting the biopsy procedure, all patients underwent a standardized 3-dimensional (3D) transrectal ultrasound (TRUS) with an end-fire array of a BK 8818 probe. Computer-aided analysis of the raw (radio-frequency) back-scatter data was performed by using the Conformite Europeene-marked and commercially available HistoScanning device, admitted for medical use in the European Union (software version 2.1, Advanced Medical Diagnostics, Belgium).”
“Each patient was diagnosed preoperatively by HistoScanning, defining a maximum of 3 suspicious areas. These areas were biopsied, both transrectally and via the perineum, with a maximum of 3 cores per location.”
Results: “We detected prostatitis in 30 patients (37.5%), premalignant lesions in 10 (12.5%), and prostate cancer in 28 (35%). The transrectal technique was used to detect 78.6% of all cancers using 14 cores by systematic biopsy. With a maximum of 9 targeted cores, 82.1% of all cancers were detected with the targeted perineal approach and 53.6% were detected with the targeted transrectal approach. Although our data did not show significant difference in the performance of targeted transperineal compared with systematic transrectal biopsies, the detection rate of targeted transrectal biopsies was significantly lower.”
Conclusion: “The presented targeted biopsy scheme achieved an overall detection rate of 85% of prostate-specific antigen–relevant pathologic lesions within the prostate. Thus, the presented procedure shows an improved detection rate compared with standard systematic prostate biopsies, and the number of cores required is reduced. Furthermore, the perineal HistoScanning-aided approach seems to be superior to the transrectal approach with respect to the prostate cancer detection rate. The presented procedure might be a step toward reliable ultrasound-based tissue characterization and toward fulfilling the requirements of novel therapeutic strategies.”
The authors’ included an elaborated discussion on the background to their study and its results. This discussion is important for understanding the limitation of the study results and for putting the authors conclusion into balanced context: “When other solid-organ cancer guidelines are compared with prostate cancer guidelines, the common methods of prostate cancer detection are unmasked as an outmoded concept because cancer detection is based on chance as a result of a blinded, subjective examination. A systematic biopsy with at least 10 to 12 cores is considered the standard procedure in prostate cancer diagnostics to date. 1,2 The continuous increase in the number of biopsy cores taken over the last years has predictably improved the detection rate, but several studies report detection rates of only 30% to 40% even in repeated biopsies. 5,9 It is noteworthy that the recommendations must be seen as a compromise bbetween the cancer detection rate and the invasiveness of the surgical procedure. Modern diagnostic procedures, including magnetic resonance imaging, elastography, computerized analysis of TRUS/artificial neuronal network analysis, and HistoScanning, try to overcome this principle of approach.7,10,11 The current therapeutic concepts and further currently evolving therapy strategies depend on sophisticated prostate cancer diagnostics. It is more important than ever to look for ways to detect and locate the cancer before subjecting patients to more or less invasive procedures as the indication for surgical treatment or prostate-preserving (focal) tumor therapy. The results of magnetic resonance imaging for prostate cancer detection are very promising so far and show a sensitivity of up to 80%. Elastography has also shown promising capabilities for cancer detection, with a recent review article reporting that several studies show 74% to 75% sensitivity.11 HistoScanning has shown 93% sensitivity in detecting and locating prostate cancer. 12 As a matter of principle, our study is unable to report on the accuracy or sensitivity of prostate cancer detection because the exact number of cancer lesions in our patients collective remains incomputable. Integration of HistoScanning for guided, targeted biopsies helped us achieve a prostate cancer detection rate of 35%. These data are lower than results from current publications on initial prostate biopsies but higher than those of repeated biopsy protocols.4,5,13 Given that tumors looked for during initial biopsies are usually large and easy to detect, we believe that this finding is caused by the smaller overall risk of cancer in a repeated biopsy setting, as was the case in 37.5% of our patients (0.61 biopsies per patient). Overall, HistoScanning seems to improve selective targeting of suspicious prostate lesions. Taking into account all malignant, premalignant, and atypical histologic findings, including prostate cancer, atypical small acinar proliferations, and high-grade prostatic intraepithelial eoplasia, the detection rate of relevant prostatic lesions by specimens from perineal-targeted biopsies rises to 47.5% and 85%, including prostatitis, respectively. Apart from the high quality of the HistoScanning tissue analysis, we believe in a significant effect of the technical approach used to perform the biopsy. As our data show, prostate cancer detection rates from specimens obtained from perineal-targeted biopsies differed significantly from the transrectal-targeted biopsy regimen, a difference that occurred independently from previous tissue analysis because both targeted approaches are aligned to the same scanning process. Compared with the transrectal approach, the perineal biopsy technique might reduce variables that can influence the needle placement. Furthermore, longitudinal biopsy punches following the axis of the prostate seem to allow more accurate sampling of the anterior part. Theoretically, because previous studies reported inhomogeneous results comparing transrectal and transperineal prostate biopsies.3,4,13 The use of a 14-gauge needle in perineal biopsies might be responsible for a systematic bias because it possibly yields more tissue than transrectal cores. Despite this potential advantage, systematic transrectal biopsies do not reflect a significant difference in the detection rate. Nevertheless, due to the individual setting, our study is unable to report standardized results on the accuracy of comparing transrectal and transperineal needle placement. Template-guided mapping biopsies have recently attracted attention because of the high rate of cancer detection as initial (75%) and even repeat biopsy procedures (46%). 14 It notably increases the ability to locate and differentiate cancer foci within the prostatic gland, implicating mapping biopsies for active surveillance or focal treatment purposes regardless of the considerable surgical trauma generated by the use of extended biopsy protocols. A reduction of tissue trauma by generating a greater diagnostic yield would be a favorable methodologic aspect as initiated by our study. Regarding cancer detection, the presented data show no significant differences between the perineal-targeted and transrectal-targeted systematic biopsy regimen, but even though considerably fewer tissue samples (14 vs 9 cores; -35%) were taken from selected prostate areas, we detected no significant limitations by the perineal approach. These data are even more encouraging when bearing in mind that the number of samples represents a crucial factor in prostate cancer detection rates, as recently reported. A critical issue in the present study is in the implementation of the modified biopsy procedures. Although the surgeons at our center are experienced in using TRUS, our data show a learning curve during the first 80 procedures. In addition, the overlaying of the HistoScanning image analysis to the B-mode grey-scale live ultrasound picture is done by the surgeon performing the biopsy. This process implies a bias in individual interpretation of the TRUS picture and manual needle guidance. The online fusion of HistoScanning with the ultrasound image presumably would increase the handling accuracy. Further methodologic limitations lie in the heterogeneous and small collective of patients that were included in the study. With regard to the reasonably high number of previous negative biopsy specimens, patient selection can affect the hit rate of positive biopsy specimens. This circumstance might make the cancer detection frequency with HistoScanning look relatively small in this particular study compared with other diagnostic methods in patients undergoing an initial biopsy, but this is due to the daily routine in an academic referral center.
For completeness of this reporting and before stating my own conclusion I bring here below two comments that were made, one by Dr. Stephen Jones of Glickman Urological and Kidney Institute, Cleveland, Ohio and the reply by the first author:
COMMENT
The promise of image-guided diagnosis and management of prostate cancer has been frustratingly elusive. Early pioneers of prostate ultrasound imaging reported that hyperechoic lesionswere indicative of malignancy, but it rapidly became clear that the opposite was actually more realistic. Even so, these hypoechoic lesions were soon shown to be poor indicators of prostate cancer. Thus, the value of visual abnormalities on grey-scale prostate ultrasound imaging remains essentially negligible with current technology. As a result, a number of alternative imaging modalities have been developed and introduced with great excitement. Typically, images in the publications showcase an apparently obvious cancer standing out in contrast to adjacent benign tissues. Unfortunately, the data still reveal minimal value from most of these technologies, and those reported in this article are similarly disappointing. HistoScanning demonstrated interesting color images, but coupled with a transperineal-targeted biopsy found exactly one more case of prostate cancer than did the current standard of care—the 14-core extended transrectal biopsy. This “difference” is actually statistically identical (P >.99). Exactly the same number of patients (n¼ 4) was found exclusively by both transperineal HistoScan-targeted biopsy as with standard transrectal biopsy, and when targeted using the transrectal approach, the technology actually missed almost half of the cancers that were identified overall. Furthermore, these data do not support the suggestion that 9 cores are less morbid or traumatic than 14 cores, and the literature is replete with reports demonstrating this is simply not true. This is especially misleading when those 9 cores come at the cost, morbidity, time, and complexity of an operation such as this performed under general anesthesia. So the real question remains whether HistoScanning or any emerging technology to image the prostate—improves visualization of prostate cancer. Although magnetic resonance imaging is beginning to show notable promise, the clinical value of most other modalities remains mostly anecdotal. As one whose desire for a solution remains frustratingly unfulfilled, I hope that some imaging technique will demonstrate clinical value during my career.J. Stephen Jones, M.D., Department of Regional Urology, Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, Ohio
REPLY
In accordance with your comprehensive notes, we have to search for diagnostic improvement and underline the need further investigations in the field of prostate cancer diagnostics and staging. Minimally invasive techniques, focal and targeted therapy modalities, and low-risk cancer surveillance probably are future treatment modalities for prostate malignancies that progressively challenge common diagnostic pathways. Sophisticated therapy strategies will require reliable staging results. The constant increase of cores taken during systematic prostate biopsy apparently will not overcome the well-known diagnostic uncertainties. Consequently, imaging techniques and methods of biopsy targeting will gain in importance. Clearly, the presented data do not show significant improvement in the overall detection rate of prostate cancer in our patient cohort. Further, the maximum number of 9 biopsy cores must be attributed to the initial study design and will undergo further investigation; however, the results rather support the study approach than reduce its validity. Considering the indeterminate number of cancers, the proof of superiority remains incomputable. Compared with the current standard of care of 12 to 14 cores, we detected no significant limitations, although perineal-targeted biopsies took significantly fewer cores (3-9 cores [35%]). Maintaining the detection rate unchanged and focusing on 1 to 3 preselected suspicious index lesions display a proof of principle rather than disappointing results. In line with future treatment options mentioned above, any less invasive, focused diagnostic procedure represents an encouraging advance compared with the common and recommended practice of a nonselective, systematic biopsy of the prostate to harbor cancerous tissue.Moritz F. Hamann, M.D., Department of Urology and Pediatric Urology, University of SchleswigeHolstein, Campus Kiel, Kiel, Germany
As mentioned by the authors, further improvement of the outcome of HistoScanning-based targeted biopsies of prostate is expected when an implementation of image-fusion application between the “off-line” generated 3D tumor map and the real-time ultrasound guiding the needle will be available; similar to the results presented already when using ultrasound-MRI image fusion applications for prostate biopsy. Of course, the ultimate biopsy workflow (which I am currently engaged in developing) that urologist are asking for is the one comprised of real-time ultrasound-based tissue characterization and real-time ultrasound guidance of the needle to the lesion.
References
1. Heidenreich A, Bellmunt J, Bolla M, et al. EAU guidelines on prostate cancer. Part 1: screening, diagnosis, and treatment of clinically localised disease. Eur Urol. 2011;59:61-71.
2. National Comprehensive Cancer Network. Clinical Practice Guidelines in Oncology: Prostate Cancer Early Detection. Available at http://www.nccn.org 2011 Accessed May 2011.
3. Abdollah F, Novara G, Briganti A, et al. Trans-rectal versus transperineal saturation re-biopsy of the prostate: is there a difference in cancer detection rate? Urology. 2011;77:921-925.
4. Hara R, Yoshimasa J, Tomohiro F, et al. Optimal approach for prostate cancer detection as initial biopsy: prospective randomized study comparing transperineal versus transrectal systematic 12-core biopsy. Urology. 2008;71:191-195.
5. Patel AR, Jones JS. Optimal biopsy strategies for the diagnosis and staging of prostate cancer. Curr Opin Urol. 2009;19:232-237.
6. Al Otaibi M, Ross P, Fahmy N, et al. Role of repeated biopsy of the prostate in predicting disease progression in patients with prostate cancer on active surveillance. Cancer. 2008;113:286-292.
7. Braeckman J, Autier P, Garbar C, et al. Computer-aided ultrasonography (HistoScanning): a novel technology for locating and characterizing prostate cancer. BJU Int. 2008;101:293-298.
8. Braeckman J, Autier P, Soviany C, et al. The accuracy of transrectal ultrasonography supplemented with computer-aided ultrasonography for detecting small prostate cancers. BJU Int. 2008;102:1560-1565.
9. Presti JC Jr, O’Dowd G, Miller C, et al. Extended peripheral zone biopsy schemes increase cancer detection rates and minimize variance in prostate specific antigen and age related cancer rates: results of a community multi-practice study. J Urol. 2003;169:125-129.
10. Turkbey B, Mani H, Shah V, et al. Multiparametric 3T prostate magnetic resonance imaging to detect cancer: histopathological correlation using prostatectomy specimens processed in customized magnetic resonance imaging based molds. J Urol. 2011;186: 1818-1824.
11. Trabulsi EJ, Sackett D, Gomella L, et al. Enhanced transrectal ultrasound modalities in the diagnosis of prostate cancer. Urology. 2010;76:1025-1033.
12. Simmons LA, Autier P, Zat_ura F, et al. Detection, localisation and characterisation of prostate cancer by Prostate HistoScanning. BJU Int. 2012;110:28-35.
13. Emiliozzi P, Corsetti A, Tassi B, et al. Best approach for prostate cancer detection: a prospective study on transperineal versus transrectal six-core prostate biopsy. Urology. 2003;61:961-966.
14. Taira AV, Merrick GS, Galbreath RW, et al. Performance of transperineal template-guided mapping biopsy in detecting prostate cancer in the initial and repeat biopsy setting. Prostate Cancer Prostatic Dis. 2010;13:71-77.
Other research papers related to the management of Prostate cancer were published on this Scientific Web site:
A new etiology for Prostate Cancer based on Integrative Genomic Analyses reveals difference in Pathomechanism between Early onset and and Non-Early onset was reported this week in Cancer Cell, Volume 23, Issue 2, 159-170, 11 February 2013
Early Onset: Androgen-Driven Somatic Alteration Landscape in Early-Onset Prostate Cancer
Median age of 47: EO-PCAs harbored a prevalence of balanced SRs, with a specific abundance of androgen-regulated ETS gene fusions including TMPRSS2:ERG
Non Early onset:
Around 65 years of age at onset: elderly-onset PCAs displayed primarily non-androgen-associated structural rearrangement (SR) formations.
Treatment Comparison for Clinically Localized Primary Prostate Cancer Therapies
2-3 day hospital stay, catheter for 2-3 weeks for open surgery; shorter
hospitalization and fewer postoperative complications for laparoscopic procedure
Data presented are for clinically localized, low-high risk primary prostate cancer. The information provided in the chart is therapy and not device specific and may not include all potential risks, recovery and outcome information. For further information please see references.
The Sonablate® 500 is approved for investigational use within the U.S. and is being studied for the treatment of prostate cancer in clinical trials in the U.S. The FDA has made no decision as to the safety or efficacy of the Sonablate® 500 for the treatment of prostate cancer. Currently, the device is available for the treatment of prostate cancer outside the U.S. in more than 30 countries.
Early detection of prostate cancer increased dramatically the five-year survival of patients. “This study demonstrates for the first time that it is possible to generate medicines with both targeted and programmable properties that can concentrate the therapeutic effect directly at the site of disease, potentially revolutionizing how complex diseases such as cancer are treated”. The Phase I clinical trial is still ongoing and continued dose escalation is underway; BIND Biosciences is now planning Phase II trials, which will further investigate the treatment’s effectiveness in a larger number of patients.
BIND-014 is a programmable nanomedicine that combines a targeting ligandand a therapeutic nanoparticle. BIND-014 contains docetaxel, a proven cancer drug which is approved in major cancer indications including breast, prostate and lung, encapsulated in FDA-approved biocompatible and biodegradable polymers. BIND-014 is targeted to prostate specific membrane antigen (PSMA), a cell surface antigen abundantly expressed on the surface of cancer cells and on new blood vessels that feed a wide array of solid tumors. In preclinical cancer models, BIND-014 was shown to deliver up to ten-fold more docetaxel to tumors than an equivalent dose of conventional docetaxel. The increased accumulation of docetaxel at the site of disease translated to marked improvements in antitumor activity and tolerability. BIND-014 is currently in Phase 1 human clinical testing in cancer patients with advanced or metastatic solid tumor cancers (NCT01300533). The early development of BIND-014 was funded in part by the National Cancer Institute and the U.S. National Institutes of Standards and Technology (NIST) under its Advanced Technology Program (ATP).
In regards to treatment choice: “active surveillance, focal therapy, radical prostatectomy, and radiation therapy represent a range of treatments with varying degrees of invasiveness for men with different disease grades and stages. Active surveillance and focal therapy, which are relatively new options, are promising but are complicated by uncertainties in risk stratification that affect treatment decision-making, as well as by uncertainties regarding the definition of appropriate outcome measures. Biopsy, which leaves the possibility of under sampling, is not sufficient to resolve these uncertainties. Novel biomarkers and modern imaging are expected to play increasingly important roles in facilitating broader acceptance of both active surveillance and focal therapy. Further research, particularly involving prospective validation, is needed to facilitate standardization and establish the roles of advanced imaging tools in routine prostate cancer management.”
My summary: Prostate cancer is a disease managed by urologists, not radiologists. This disease’s multi-choice of pathways is “craving” for tissue characterization. Nothing could fit the urologist’s work-flow better than ultrasound-based tissue characterization!
Median age of 47: EO-PCAs harbored a prevalence of balanced SRs, with a specific abundance of androgen-regulated ETS gene fusions including TMPRSS2:ERG,
Non Early onset:
Around 65 years of age at onset: elderly-onset PCAs displayed primarily non-androgen-associated SRs.
Integrative Genomic Analyses Reveal an Androgen-Driven Somatic Alteration Landscape in Early-Onset Prostate Cancer
Genome sequencing revealed age-related genetic alterations in PCA
Early-onset PCAs display a specific abundance of androgen-driven rearrangements
These age-linked alterations coincide with activity levels of the androgen receptor
This is an observation of age-specific DNA alterations in a common cancer
Summary
Early-onset prostate cancer (EO-PCA) represents the earliest clinical manifestation of prostate cancer. To compare the genomic alteration landscapes of EO-PCA with “classical” (elderly-onset) PCA, we performed deep sequencing-based genomics analyses in 11 tumors diagnosed at young age, and pursued comparative assessments with seven elderly-onset PCA genomes. Remarkable age-related differences in structural rearrangement (SR) formation became evident, suggesting distinct disease pathomechanisms. Whereas EO-PCAs harbored a prevalence of balanced SRs, with a specific abundance of androgen-regulated ETS gene fusions includingTMPRSS2:ERG, elderly-onset PCAs displayed primarily non-androgen-associated SRs. Data from a validation cohort of > 10,000 patients showed age-dependent androgen receptor levels and a prevalence of SRs affecting androgen-regulated genes, further substantiating the activity of a characteristic “androgen-type” pathomechanism in EO-PCA.
Early onset prostate cancer tumors tend to have a propensity for containing balanced structural rearrangements, particularly involving genes regulated by the androgen hormone, according to a study in Cancer Cell. As part of the International Cancer Genome Project’s Early-Onset Prostate Cancer project, researchers from Germany and the UK performed whole-genome sequencing on tumor and matched normal samples from 11 individuals who were surgically treated for prostate cancer at a median age of 47 years old. The tumors were also subjected to transcriptome and methylome sequencing.
When they compared sequences from these tumors with sequences from a previously described set of samples taken from seven individuals diagnosed with prostate cancer at around 65 years of age, investigators saw a rise in gene fusion-producing structural changes in the early onset samples.
Those fusions often affected ETS family genes and other genes prone to androgen-related regulation, researchers reported. In contrast, tumors from individuals whose prostate cancer appeared later in life were more apt to contain structural rearrangements affecting genes without any androgen ties.
Follow-up tests using samples from more than 10,000 other patients seemed to support this link between age at prostate cancer diagnosis and androgen receptor rearrangement, study authors said, pointing to a distinct, androgen-driven “pathomechanism” in early-onset forms of the disease.
Uchida T, Ohkusa H, Nagata Y, Hyodo T, Satoh T, Irie A. Treatment of localized prostate cancer using high-intensity focused ultrasound. BJU international 2006;97:56-61.
Uchida T, Ohkusa H, Yamashita H, et al. Five years experience of transrectal high-intensity focused ultrasound using the Sonablate device in the treatment of localized prostate cancer. International journal of urology : official journal of the Japanese Urological Association 2006;13:228-33.
Muto S, Yoshii T, Saito K, Kamiyama Y, Ide H, Horie S. Focal therapy with high-intensity-focused ultrasound in the treatment of localized prostate cancer. Japanese journal of clinical oncology 2008;38:192-9.
Ahmed HU, Zacharakis E, Dudderidge T, et al. High-intensity-focused ultrasound in the treatment of primary prostate cancer: the first UK series. British journal of cancer 2009;101:19-26.
Inoue Y, Goto K, Hayashi T, Hayashi M. Transrectal high-intensity focused ultrasound for treatment of localized prostate cancer. International journal of urology : official journal of the Japanese Urological Association 2011;18:358-62.
Uchida T, Shoji S, Nakano M, et al. Transrectal high-intensity focused ultrasound for the treatment of localized prostate cancer: eight-year experience. International journal of urology : official journal of the Japanese Urological Association 2009;16:881-6.
Sumitomo M, Hayashi M, Watanabe T, et al. Efficacy of short-term androgen deprivation with high-intensity focused ultrasound in the treatment of prostate cancer in Japan. Urology 2008;72:1335-40.
Sumitomo M, Asakuma J, Yoshii H, et al. Anterior perirectal fat tissue thickness is a strong predictor of recurrence after high-intensity focused ultrasound for prostate cancer. International journal of urology : official journal of the Japanese Urological Association 2010;17:776-82.
Dudderidge T, Ahmed H, Emberton M. High-intensity focused ultrasound for localized prostate cancer: initial experience with a 2-year follow-up. BJU international 2009;104:1170-1; author reply 1.
Shelley M, Wilt TJ, Coles B, Mason MD. Cryotherapy for localised prostate cancer. Cochrane Database Syst Rev 2007:CD005010.
Cheetham P, Truesdale M, Chaudhury S, Wenske S, Hruby GW, Katz A. Long-term cancer-specific and overall survival for men followed more than 10 years after primary and salvage cryoablation of the prostate. Journal of endourology / Endourological Society 2010;24:1123-9.
Jones JS, Rewcastle JC, Donnelly BJ, Lugnani FM, Pisters LL, Katz AE. Whole gland primary prostate cryoablation: initial results from the cryo on-line data registry. The Journal of urology 2008;180:554-8.
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Williams SB, Prasad SM, Weinberg AC, et al. Trends in the care of radical prostatectomy in the United States from 2003 to 2006. BJU international 2011;108:49-55.
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The paper gives a fair description of the use of imaging in interventional oncology based on literature review of more than 200 peer-reviewed publications. In this post I summaries the chapter on imaging used in management of Lymphoma.
The traditional tasks of imaging in the management of lymphoma include: staging, assessing response to therapy and confirming it reaching an end-point and detecting recurrence. The leading imaging modality is PET/CT. In their literature review the authors include several references claiming that the clinical outcome of lymphoma patients has improved significantly due to better prognosis – largely related to better disease characterization and identification of prognostic markers in recent years. Adoption of functional imaging that improved pre-treatment staging and assessment of the response to treatment contributed as well to this outcome 178 .179 “Most of the recent progress in management of lymphoma occurred after the widespread introduction of [18F]FDG PET and PET/CT. Accordingly, [18F]FDG PET is now part of the revised lymphoma response criteria.180 “
A 46-year-old male with diffuse large B cell lymphoma, stage IV was studied. Baseline maximum intensity projection (MIP) positron emission tomography (PET) image with [18F]fluorodeoxyglucose ([18F]FDG) (A) shows widespread disease, which is essentially resolved on interim scan after 4 cycles of chemotherapy (B). The interim scan also shows increased [18F]FDG uptake in bone marrow related to administration of granulocyte colony-stimulating factor (GCSF). (C,D) Transaxial CT and PET/CT fusion images at baseline show abnormal [18F]FDG uptake in extensive mediastinal and hilar lymphadenopathy as well as in bone lesions in a right rib and the right scapula. On interim scan (E,F) abnormal [18F]FDG uptake at all of these sites has resolved although residual enlarged lymph nodes remain. The sites are better seen on a contrast-enhanced CT (G) and measure up to 5.3 cm × 3.6 cm. Chemotherapy was continued for a total of 8 cycles. At the time of writing, the patient remained disease-free after 9 years of follow-up.
Subsequent to their acknowledgment of PET/CT as the most promising imaging modality for management of Lymphoma, the authors focused their review to on its role in this disease pathway. It being well understood that the clinical utility of [18F]FDG PET in lymphoma “depends on the intensity of radiotracer uptake in disease sites, which will affect the test accuracy for staging and characterizing residual masses after completion of therapy, as well as the role of the test in response assessment. The intensity of [18F]FDG uptake in lymphoma is determined by tumor histology, grade (eg, indolent versus aggressive NHL)”,181, 182 At the end of their extensive review the authors do mention that PET/MRI might become an important player in the management of this disease, especially in pediatric cases.
Other research papers related to the management of Lymphoma were published on this Scientific Web site:
The paper gives a fair description of the use of imaging in interventional oncology based on literature review of more than 200 peer-reviewed publications. In this post I summaries the chapter on colorectal cancer imaging. It reviews current and developing radiologic practices in CRC with respect to screening, preoperative evaluation, surveillance, and post-treatment re-staging.
Colorectal cancer (CRC) is an example to successful imaging-based screening evident by noticeable reduction in mortality rates. The 5-year survival rate of CRC patients diagnosed at an early stage is 90%.1121 According to this review; “(CRC) is the third most common cancer worldwide and the second most frequent cause of cancer death in the United States. The American Cancer Society estimates that 143,460 new cases of CRC will be diagnosed and 51,690 deaths from CRC will occur in the United States in 2012.120 Because of screening and removal of premalignant polyps, incidence rates have declined over the last 3 decades.”
The authors found out that the increased use of CT in CRC screening has the potential of reducing its costs and associated tisks 122 In addition, use of DW-MRI enabled better outcomes of CRC liver metastasis treatment as it enables tailored localized treatment of such lesions.123124 Finally, the authors found that: “MRI for staging of rectal cancer has become standard practice and, in some instances, is performed in lieu of surgeon-performed endorectal US (ERUS), providing the radiologist with an even greater role in the management of patients with CRC.125 “
Screening
“CRC is a largely preventable disease, as the progression of the adenoma-carcinoma sequence of mutations is slow and leaves ample time to intervene. Nonetheless, approximately 41% of the population (in the USA) eligible for screening remains unscreened. 126 Most screening is performed using non-imaging tests”
Any of these screening strategies will reduce mortality from CRC.126, 127
Among imaging tests used for screening, barium enema has seen a continual decline in usage, at least in part due to the landmark study showing that this test detected only 39% of polyps identified at colonoscopy, including only 48% of those > 1 cm in size.131 The recent (and largest, with > 2500 patients) multicenter CT colonography (CTC, also known as virtual colonoscopy) screening study, performed by the American College of Radiology Imaging Network, found that CTC had sensitivity of 90% and similar specificity for polyps > 9 mm, and the number of centers using CTC has increased.122 Widespread deployment of CTC remains hindered, in part, by the 2009 decision of the Center for Medicare and Medicaid Service (CMS) to deny reimbursement based on 1) potential radiation risk, 2) impact of detection of extracolonic findings, and 3) efficacy in the 65 years and older age group of concern to CMS. Data from studies reported after this decision put CTC in a good position to be reconsidered for reimbursement. The median estimated effective dose is currently 5 to 6 mSv, a dose far less than that received from a standard CT exam and even comparable to or lower than that received from a barium enema examination. In fact, the radiation dose from CTC is equivalent to that received from cosmic radiation in a 1-year period.132 Extra-colonic findings occur in 7% to 11% of cases and lead to extra examinations in about 6% with a relevant new diagnosis made in 2.5%, according to the experience of the largest screening center in the United States.133 Furthermore, when detection of extracolonic cancers and aortoiliac aneurysms is included along with CRC screening, CT colonography (CTC) has been shown to be more clinically effective and more cost-effective than optical colonoscopy.134 In an observational study, CTC accuracy was maintained in patients aged 65 to 79 years, who were compared to the overall general population sample. In the older patients, CTC remained a safe and effective modality and program outcome measures, such as colonoscopy referral and extracolonic work-up rates, remained similar to those in other screened groups.135“
Detection and Characterization
“Diagnosis and clinical staging of primary colonic adenocarcinoma is most often accomplished by combining colonoscopy with biopsy and performing cross-sectional imaging to detect metastatic disease.
Although CT and MRI are widely used for preoperative whole-body staging, they are not recommended first-line methods for detection of primary lesions. In contradistinction, CTC has matured into an excellent diagnostic method for detection of CRC. Data drawn largely from screening studies tell us that its sensitivity for polyps > 10 mm is 90% or greater, and that it will detect nearly every cancer. In fact, a recent meta-analysis of more than 11,000 patients indicated that CTC had sensitivity of 96.1% (398 of 414) for CRC, and when cathartic cleansing and fecal tagging were used, no cancers were missed (Fig. 16).137 Detection of flat cancers remains a challenge with CTC as compared with endoscopic methods in which mucosal surface details are better appreciated. CTC not only detects CRC, but with its cross-sectional depiction also allows characterization of tumors using the TNM staging system138 with reasonable T- and N-stage accuracies of 83% and 80%, respectively.139 CTC is an operator-dependent technique that has shown great variability between radiologists with different degrees of training. Computer-aided detection (CAD) was developed for this reason and because 10,000 to 15,000 images must be scrutinized for each large adenoma detected. In a screening cohort of 3077 consecutive asymptomatic adults, stand-alone CAD had sensitivities of 97% and 100% for advanced neoplasia and cancer, respectively.140
Coronal reformatted CT scan of the abdomen and pelvis shows a left colon primary adenocarcinoma causing colonic obstruction.
Three-dimensional rendering from CT colonography shows a right colon adenocarcinoma which was stage T1N0.
With magnetic resonance colonography (MRC), detection of masses is limited because techniques employing air cause susceptibility artifacts, and those employing dark-lumen techniques with water-filling and intravenous gadolinium are under scrutiny because of concerns about the potential risk of nephrogenic systemic fibrosis. In addition, in the largest screening study, the sensitivity of MRC was only 70% in patients with colorectal lesions more than 10 mm in size.141
Imaging plays a critical role in detecting liver metastases in order to properly stage and treat the patient with colorectal cancer. NCCN guidelines recommend contrast-enhanced CT or MRI.142 “
MRI is the most promising imaging modality for management of rectal cancer.
Staging of this cancer is primarily accomplished with US, typically performed by surgeons. MRI using phased-array coils provides complete visualization of the pelvic anatomy and, especially, the circumferential resection margin, an important landmark for the standard total mesorectal excision.
In an MRI of rectal carcinoma, the T2-weighted axial image shows rectal mass penetrating the wall and extending to the left posterolateral mesorectal fascia (also known as the circumferential resection margin).
The MERCURY study125established the near equivalence of MRI to histopathology for identification of this margin, an important advantage of MRI over ERUS, with which the margin is not routinely visualized.147 T- and N- stage accuracies of MRI (87% and 74%, respectively) were similar to those of ERUS (82% and 74%, respectively).148 Accurate lymph node identification remains a problem for MRI. Toward this end, a new albumin-bound gadolinium agent has shown some promise, and further results are awaited.149”
Role of Imaging in Assessing Treatment Response
“Imaging plays a critical role in 1) determining response to systemic and loco-regional treatment of liver metastases, 2) assessing response to local treatment and restaging rectal cancer primary lesions, and 3) detecting and assessing the treatment response of extra-hepatic metastatic disease. Systemic treatment (and in some centers, hepatic artery infusion) of non-resectable liver metastases with chemotherapy aims at reduction of the metastatic burden, which, occasionally may allow attempts at curative liver resection.
Due to the limitations of CT with regard to soft tissue contrast and fatty liver. MRI has greater sensitivity for remaining (or new) lesions < 1.0 cm due to its superior soft tissue contrast. In a recent meta-analysis of 25 eligible studies, MRI showed higher sensitivity than CT on a per-patient basis (P = .05) and on a per-lesion basis as well (P = .0001). With its 81.1% sensitivity and 97.2% specificity, MRI is thus the preferred modality.151 Nonetheless, under the current NCCN guidelines, CT remains the preferred modality.142
Loco-regional (“liver-directed”) therapies include radiofrequency, microwave ablation, transarterial chemo- or particle embolization and irreversible electroporation. With these treatments, responding lesions can actually increase in size, and simple size criteria are no longer sufficient to determine response. The European Association for the Study of the Liver has issued new criteria to assess viability of remaining tumor based on enhancing residual volume by multiphase CT or MRI.152 However, the field is rapidly changing and there is no consensus on the optimal imaging strategy following loco-regional therapy.
Recent meta-analyses of randomized controlled trials comparing low-intensity and high-intensity surveillance programs have shown advantages for more intense follow-up in Stages I-III disease;170-173 however, controversies remain regarding the optimal surveillance strategy. “
Lymphoma Imaging
To be followed…
Other research papers related to the management of Colorectal cancer were published on this Scientific Web site:
The paper gives a fair description of the use of imaging in interventional oncology based on literature review of more than 200 peer-reviewed publications. In this post I summaries the chapter on prostate cancer imaging.
Prostate Cancer Imaging
Although ultrasound is the most frequently used imaging-device in prostate cancer management the authors did not review the related literature. Instead, they focused their review on MRI and PET imaging. To anyone who wishes to learn about ultrasound-imaging’s state of the art in prostate cancer I can offer reading some of my previous posts that are listed below.
My own interpretation (as stated in my summary-note) to the focus by the authors on MRI and PET imaging is that they were mainly looking to highlight the advances in those imaging modalities which provides tissue characterization! Although, this term is not explicitly mentioned by them.
The authors identifies correctly the main issues in Prostate cancer management:
It’s a frequent disease, but not an aggressive killer
It’s highly heterogeneous, therefore it is difficult to predict the clinical outcomes both before and after treatment.
“Although several predictive methods have been developed,72 the treatment decision-making process is complex and requires balancing clinical benefits, life expectancy, comorbidities and potential treatment-related side effects.”
The disease’s staging and related prognosis are determined during diagnosis based on PSA level and the Gleason score of biopsy’s samples. “Although prostate-specific antigen (PSA) screening hsis as resulted in the diagnosis of prostate cancer at earlier stages and with lower Gleason scores, it has also contributed to concerns about over-diagnosis, overtreatment of clinically insignificant disease, associated treatment-related toxicity, and escalating costs”
The following sections summarizes the latest advances in MRI and PET imaging methods for functional and metabolic assessment of prostate cancer.
Advances in MRI of Prostate Cancer
“MRI is potentially an ideal imaging modality for the local staging of prostate cancer, given its ability to depict the prostate and surrounding structures in exquisite detail. Recently, morphologic imaging with conventional MR imaging sequences has been supplemented by a multiparametric imaging approach using new functional and metabolic methods, namely diffusion waited MRI (DW-MRI); dynamic contrast-enhanced MRI (DCE-MRI), which probes tissue micro-vascular and perfusion properties; and MR spectroscopy (Fig. below).”
Representative images from a 3-T multiparametric MRI examination in a 57-year-old man with PSA level of 9.1 ng/mL and Gleason score 7 (3 + 4) prostate cancer (arrow) located in the right anterior prostate and involving the transition and peripheral zones: (A) transverse T2-weighted image, (B) transverse ADC map generated from DW-MRI images, (C) transverse DCE-MRI image, (D) volume transfer constant (Ktrans) parametric map from DCE-MRI overlaid on T2-weighted image.
Diffusion-Weighted MRI
“Because the diffusion of water molecules within tumors is more restricted than in normal tissue, ADCs calculated with DW-MRI tend to be lower in cancer than in normal tissue. A number of studies, using various image acquisition methods and reference standards, have reported the utility of DW-MRI in prostate cancer detection.74-79. More importantly, studies have indicated that the greatest value of DW-MRI as an addition to conventional MRI might lie in its potential to assess prostate cancer aggressiveness noninvasively, because ADC values have been shown to correlate significantly with tumor Gleason scores.77-79 “
“However, the clinical value of DW-MRI in predicting the surgical Gleason score needs to be further studied.”
Dynamic Contrast-Enhanced MRI
“DCE-MRI is based on the repeated acquisition of images of a region of interest during the passage of an intravenously administered contrast agent. DCE-MRI allows malignant tissue to be distinguished from benign tissue by exploiting differences in the distribution of the contrast agent between vascular and extravascular spaces over time. 80 Prostate cancer usually shows early, rapid, and intense enhancement with quick washout of contrast compared to noncancerous prostate tissue. Although DCE-MRI has shown potential in assessing prostate cancer in preliminary studies, further research is necessary to establish its clinical value and indications and address technical challenges, such as standardization of acquisition and analysis methods.”
MR Spectroscopy
“Commercially available acquisition and analysis software packages for MR spectroscopic imaging of the prostate produce 3-dimensional spectral data showing the relative concentrations of tissue metabolites within specified volumes of tissue. In the prostate, the metabolites of interest on in vivo MR spectroscopic imaging are citrate, creatine, choline, and polyamines.87, 88 (choline + creatine)/citrate ratio has traditionally been used to identify prostate cancer on MR spectroscopy. “
“Studies have indicated that MR spectroscopy might have potential for aiding cancer localization, estimating tumor volume, noninvasively assessing prostate cancer aggressiveness and predicting the probability of insignificant cancer.90-92”
the authors found that MRI, especially when acquired with multiparametric techniques (DW-MRI, DCE-MRI, and/or MR spectroscopy), has the potential to add value in prostate cancer diagnosis, eg, by guiding biopsy to the most suspicious areas and eventually reduce the number of systematic/random biopsies.108-110 A specific use-case for MRI guided biopsies is men with elevated PSA and negative systematic/random TRUS-guided biopsy where MRI is used for locating suspicious areas for targeted biopsies.111 MRI, “could potentially improve prostate cancer management especially in the intermediate- and high-risk groups.” 112 They also suggest to use MRI, especially when acquired with multiparametric techniques as a tool for choosing and managing active survailance and focal treatment. These two novel methods of treatment have immerged as an answer to unbearable overdiagnosis and overtreatment in prostate cancer management.113114
About active surveillance: “Given the risks of morbidity associated with radical treatment (eg, radical prostatectomy or radiation therapy), active surveillance (monitoring of PSA levels, periodic imaging and repeat biopsies) is gaining acceptance as an alternative initial management strategy for carefully selected men with low-risk prostate cancer.115 Active surveillance could be a considerably more cost-effective approach than immediate treatment for prostate cancer, as suggested in a theoretical cohort.116 Furthermore, by preserving quality of life and minimizing the harms from radical treatment of low-risk prostate cancer, active surveillance could mitigate the concerns regarding extensive screening, overdiagnosis, and overtreatment of prostate cancer. Ultimately questions about how to best practice active surveillance will need to be addressed in prospective studies. Currently, the main challenges in active surveillance of prostate cancer are adequate characterization of disease at diagnosis and determination of the risk of progression.”
About focal therapy:, sometime referred to as focused therapy. This approach is frequently used in other cancers; e.g. breast lumpectomies. The idea is to treat only the cancer lesion and preserve the rest of the organ. Such treatment has the potential of offering better quality of life for the patients. 117 An open clinical question in respect to focal treatments is related to the fact that prostate cancer is often multifocal. Some studies suggest that it is enough to treat the index tumor (tumor volume > 0.5 mL) in order to control the disease.118 To date, patients’ selection for focal treatment is based on multiparametric MRI techniques and prostate mapping biopsy (trans-perinea template biopsy) 119
Advances in PET Imaging of Prostate Cancer
The main application for [18F]FDG PET is in patients with aggressive, metastatic prostate cancer. For these patients it helps detecting metastasis, and assessment on response to treatment.93-97, The authors of this review did not find support to using it for the majority of prostate cancer patients who are diagnosed at early stage due to its low specificity in this population.
Representative images from 3-T MRI and [18F]FDG PET/CT examinations in a 70-year-old man with PSA level of 8.0 ng/mL and Gleason score of 8 (4 + 4) prostate cancer (arrow) located in the left posterolateral prostate within the peripheral zone: (A) transverse T2-weighted image, (B) transverse fused [18F]FDG PET/CT image, (C) transverse fused [18F]FDG PET/CT image overlaid on T2-weighted MRI.
Other tracers such as [11C]choline and radiolabeled acetate ([11C]acetate) have recently been evaluated in clinical studies and found to be more promising than [18F]FDG for prostate cancer assessment.93, 96, 98
“Currently, the major indication for choline PET/CT is the early localization of recurrence in patients with PSA relapse after primary radical treatment. Potentially, this test may also be useful in radiotherapy planning.99, 100 Acetate participates in cytoplasmic lipid synthesis, and an increased fatty acid synthesis is thought to occur in prostate cancer.101 Similarly to [11C]choline, radiolabeled acetate ([11C]acetate) appears to be more useful than [18F]FDG in the assessment of prostate cancer before and after treatment.102, 103 “
“In summary, the role of PET imaging in prostate cancer is still evolving, as new and promising tracers are under investigation. Rigorous clinical trials using these new tracers in specific clinical scenarios will be needed before they can be employed routinely.”
On expectations from future screening, diagnosis and pre-treatment staging the authors summarizes: “An imaging modality that could reliably assess prostate cancer would be of great help in selecting from the wide range of management options now available.” and;
“there is a pressing need to improve not only anatomical imaging for tumor detection, localization and staging, but also functional and metabolic imaging for characterization of tumor biology. “
In regards to treatment choice: “active surveillance, focal therapy, radical prostatectomy, and radiation therapy represent a range of treatments with varying degrees of invasiveness for men with different disease grades and stages. Active surveillance and focal therapy, which are relatively new options, are promising but are complicated by uncertainties in risk stratification that affect treatment decision-making, as well as by uncertainties regarding the definition of appropriate outcome measures. Biopsy, which leaves the possibility of under sampling, is not sufficient to resolve these uncertainties. Novel biomarkers and modern imaging are expected to play increasingly important roles in facilitating broader acceptance of both active surveillance and focal therapy. Further research, particularly involving prospective validation, is needed to facilitate standardization and establish the roles of advanced imaging tools in routine prostate cancer management.”
My summary: Prostate cancer is a disease managed by urologists, not radiologists. This disease’s multi-choice of pathways is “craving” for tissue characterization. Nothing could fit the urologist’s work-flow better than ultrasound-based tissue characterization!
Colorectal Cancers Imaging
To be followed…
Other research papers related to the management of Prostate cancer were published on this Scientific Web site:
The paper gives a fair description of the use of imaging in interventional oncology based on literature review of more than 200 peer-reviewed publications.
In this post I summaries the chapter on lung cancer imaging.
Lung Cancer Imaging
“Lung cancer remains the most common cause of death from cancer worldwide, having resulted in 1.38 million deaths (18.2% of all cancer deaths) in 2008.48 It also represents the leading cause of death in smokers and the leading cause of cancer mortality in men and women in the United States. In 2012, it was estimated that 226,160 new cases of lung cancer would be diagnosed (accounting for about 14% of cancer diagnoses) and that lung cancer would cause 160,340 deaths (about 29% of cancer deaths in men and 26% of cancer deaths in women) in the United States.1 The 1-year relative survival rate for the disease increased from 35% to 43% from 1975 through 1979 to 2003 through 2006.49 The 5-year survival rate is 53% for disease that is localized when first detected, but only 15% of lung cancers are diagnosed at this early stage.”
For cancer with such poor survival rates removal of the primary lesion by surgery at an early-stage disease is the best option. The current perception in regards to lung cancr is that patients may have subclinical disease for years before presentation. It is also known that early lung cancer lesions; adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are slow-growing, doubling time which can exceed 2 years.52 But, since at present, no lung cancer early-detection biomarker is clinically available, the diagnosis of this disease is primarily based on symptoms, and detection often occurs after curative intervention and when it’s already too late – see: Update on biomarkers for the detection of lung cancer and also Diagnosing lung cancer in exhaled breath using gold nanoparticles. Until biomarker is found, the burden of screening for this disease is on imaging.
“AIS and MIA generally appear as a single peripheral ground-glass nodule on CT. A small solid component may be present if areas of alveolar collapse or fibroblastic proliferation are present,50, 51 but any solid component should raise concern for a more invasive lesion (Fig. 8). Growth over time on imaging can often be difficult to assess due to the long doubling time of these AIS and MIA, which can exceed 2 years.52 However, indicators other than growth, such as air bronchograms, increasing density, and pleural retraction within a ground-glass nodule are suggestive of AIS or MIA.
CT image shows a ground glass nodule, which is the typical appearance of AIS, in the right upper lobe.
CT (A) demonstrated extensive consolidation with air bronchograms in the left upper lobe, which at surgical resection were found to represent adenocarcinoma of mixed subtype with predominate (70%) mucinous bronchioloalveolar subtype. PET imaging in the same patient (B) demonstrated uptake in the lingula higher than expected for bronchioloalveolar carcinoma and probably due to secondary inflammation/infection. CT (C) obtained 3 years after images (A) and (B) demonstrated biopsy-proven recurrent soft-tissue mass near surgical site. Fused FDG/PET images (D) demonstrate no uptake in the area. This finding is consistent with the decreased uptake usually seen in tumors of bronchioloalveolar histology (new terminology of MIA).
In August 2011 the results of the “National Lung Screening Trial “ which was funded by the National Cancer Institute (NCI) were published in NEJM; Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening. This randomized study results showed that with low-dose CT screening of high-risk persons, there was a significant reduction of 20% in the mortality rate from lung cancer as compared to chest radiographs screening.
Based on these results one can find the following information regarding Lung Cancer Screening on the NCI web-site:
“Three screening tests have been studied to see if they decrease the risk of dying from lung cancer.
The following screening tests have been studied to see if they decrease the risk of dying from lung cancer:
Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
Low-dosespiral CT scan (LDCT scan): A procedure that uses low-dose radiation to make a series of very detailed pictures of areas inside the body. It uses an x-ray machine that scans the body in a spiral path. The pictures are made by a computer linked to the x-ray machine. This procedure is also called a low-dose helical CT scan.
Screening with low-dose spiral CT scans has been shown to decrease the risk of dying from lung cancer in heavy smokers.
A lung cancer screening trial studied people aged 55 years to 74 years who had smoked at least 1 pack of cigarettes per day for 30 years or more. Heavy smokers who had quit smoking within the past 15 years were also studied. The trial used chest x-rays or low-dose spiral CT scans (LDCT) scans to check for signs of lung cancer.
LDCT scans were better than chest x-rays at finding early-stage lung cancer. Screening with LDCT also decreased the risk of dying from lung cancer in current and former heavy smokers.
A Guide is available for patients and doctors to learn more about the benefits and harms of low-dose helical CT screening for lung cancer.
Screening with chest x-rays or sputum cytology does not decrease the risk of dying from lung cancer.
Chest x-ray and sputum cytology are two screening tests that have been used to check for signs of lung cancer. Screening with chest x-ray, sputum cytology, or both of these tests does not decrease the risk of dying from lung cancer.”
The authors of Advances in oncologic imaging†‡ found out that for pre-treatment staging and post treatment follow-up of lung cancer patients mainly involves CT (preferably contrast enhanced, FDG PET and PET/CT. “Integrated PET/CT has been found to be more accurate than PET alone, CT alone, or visual correlation of PET and CT for staging NSCLC (Non-small-cell lung carcinoma).59 “
The standard treatment of choice for localized disease remains surgical resection with or without chemo-radiation therapy (stage dependant). “The current recommendations for routine follow-up after complete resection of NSCLC are as follows: for 2 years following surgery a contrast-enhanced chest CT scan every 4 to 6 months and then yearly non-contrast chest CT scans.62 Detection of recurrence on CT is the primary goal in the initial years, and therefore, optimally, a contrast-enhanced scan should be obtained to evaluate the mediastinum. In subsequent years, when identifying an early second primary lung cancer becomes of more clinical importance, a non-contrast CT chest scan suffices to evaluate the lung parenchyma.
CT (A) of 78-year-old male who was status post–left lobe lobectomy and left upper lobe wedge resection shows recurrent nodule at the surgical resection site. Fused PET/CT (B) demonstrates increased [18F]FDG uptake in the corresponding nodule at the surgical resection site consistent with recurrent tumor.
In patients undergoing chemotherapies: “ [18F]FDG PET response correlates with histologic response.63 [18F]FDG PET scan data can provide an early readout of response to chemotherapy in patients with advanced-stage lung cancer.64
In patients treated by recently developed “Targeted Therapies” such as Radiofrequency ablation (RFA) the authors found out that PET/CT is the preferred imaging modality for post treatment follow-up.
“ Most patients treated with pulmonary ablation will have had a pre-procedure CT or a fusion PET/CT scan, which allows more precise anatomic localization of abnormalities seen on PET. Generally, either CT or PET/CT is performed within a few weeks of the procedure to provide a new baseline to which future images can be compared to assess for changes in size, degree of enhancement or [18F]FDG avidity.67”
CT (A) demonstrates new left upper lobe mass representing new primary NSCLC in a patient who had a status post–right pneumonectomy for a prior NSCLC. CT (B) obtained in the same patient 2 weeks after radiofrequency ablation (RFA) demonstrates the postablation density in the left upper lobe. Fused PET/CT (C) obtained 4 months after RFA demonstrates mild [18F]FDG uptake at RFA site in the left upper lobe consistent with posttreatment inflammation. Fused PET/CT (D) obtained 7 months after RFA demonstrates new focal [18F]FDG uptake at post-RFA-opacity consistent with recurrent tumor.
Prostate Cancer Imaging
To be followed…
Other research papers related to the management of Lung cancer were published on this Scientific Web site:
The paper gives a fair description of the use of imaging in interventional oncology based on literature review of more than 200 peer-reviewed publications.
In this post I summaries the chapter on breast cancer imaging.
Breast Cancer Imaging
As a start the authors describes the evolution in the ACS imaging guidelines for breast cancer screening. Most interesting to learn is how age limits are changing. The most recent: “In 2010, the Society of Breast Imaging and the Breast Imaging Commission of the ACS issued recommendations for breast cancer screening to provide guidance in light of the controversies and emerging technologies.5 These recommendations were based on multiple prospective randomized trials as well as population-based experience.
Recommendations for screening with non-mammographic imaging are based not on evidence showing mortality reduction but largely on surrogate indicators, i.e., tumor size and nodal status, suggesting improved survival compared with women who are not screened.” I have referred to these guidelines in my recent post: Not applying evidence-based medicine drives up the costs of screening for breast-cancer in the USA.
As long as imaging interpretation is based mainly on observations related to lesion morphology:
“The imaging characteristics of malignant lesions are nonspecific and usually do not allow a definitive diagnosis. When a biopsy is recommended based on mammography, it has a 25% to 45% likelihood of resulting in a diagnosis of carcinoma.11 Similar positive predictive values are reported for biopsies recommended based on MRI.”
It is worthwhile noting that these results do not reflect purely the specificity of the imaging device but rather the specificity of the whole workflow; i.e imaging, biopsy and histopathology. All imaging techniques have false negatives: Mammography screening of general population misses approximately 20% of the cancers. This rate increases as breast density increases. MRI is not applied to general population. When applied to highly suspicious cases MRI misses ~10% of the invasive cancers. Although ultrasound has proven to be useful in detecting cancer especially in women with dense breasts: Automated Breast Ultrasound System (‘ABUS’) for full breast scanning: The beginning of structuring a solution for an acute need! Based on the literature reviewed by the authors of this paper they do not recommend routine sonography for these women.
For women with locally advanced breast cancer (Fig. 2) who undergo neoadjuvant therapy before breast surgery, the authors recommends post-treatment staging using MRI, which has been found to predict complete response with sensitivity above 60% and specificity as high as 90%.26
A 27-year-old female with locally advanced poorly differentiated invasive ductal carcinoma underwent evaluation of extent of disease before starting neoadjuvant chemotherapy. Sagittal fat-suppressed T1-weighted postcontrast MR images demonstrate an almost 6-cm heterogeneously enhancing mass (A) involving the skin of the lower breast (arrow) with (B) right axillary (arrow) and (C) right internal mammary adenopathy (arrow).
Same is recommended for women who have undergone lumpectomy if the surgical margins are positive. As post therapy follow-up, a new baseline mammogram of the treated breast is recommended followed by annual mammography.
Contrast-enhanced digital mammography – “involves the injection of iodinated contrast material, as is done for computed tomography (CT); this enables hypervascular lesions to be seen with modified mammography technology, potentially providing the same information obtained through MRI. Little has been published on the clinical application of this technology, but diagnostic accuracy better than that of mammography and approaching that of MRI has been reported.31, 32”
MR choline spectroscopy – has been shown to improve the positive predictive value of breast MRI and may be useful in reducing the number of lesions that require biopsy (Fig. 4).33 Studies of spectroscopy have reported sensitivities of 70% to 100% and specificities of 67% to 100% in the detection of breast cancer. Decreasing choline concentrations may also be a useful indication of tumor response to treatment before any change in tumor volume can be detected.34, 35 Technical factors have limited the use of spectroscopy to lesions 1 cm in size or larger.”
Sagittal fat-suppressed T1-weighted postcontrast MR image is shown (A) of the right breast of a 48-year-old female who was status post–contralateral mastectomy for DCIS with the spectroscopy voxel placed over an enhancing mass (arrow). The magnified spectrum (B) demonstrated no choline peak. Biopsy yielded fibroadenoma.
Diffusion-weighted MRI (DW-MRI) – “adding DW-MRI data to other imaging characteristics of lesions on breast MRI may increase the positive predictive value of the examination, in turn decreasing the number of benign lesions requiring biopsy for diagnosis.” See also Imaging: seeing or imagining? (Part 2).
Axial T1-weighted fat-suppressed postcontrast MR image is shown (A) of the left breast of a 42-year-old female with biopsy-proven contralateral cancer undergoing evaluation of disease extent. An enhancing mass (arrow) was seen in the left breast. This mass (arrow) was also demonstrated on the axial diffusion-weighted MR image (B). Biopsy yielded fibroadenoma with atypical ductal hyperplasia and lobular carcinoma in situ.
Ultrasound-elastography – “Ultrasound elastography has been reported to differentiate benign from malignant breast lesions with sensitivities of 78% to 100% and specificities of 21% to 98%.39 When added to other US techniques, it may improve radiologists’ performance in distinguishing malignant breast lesions.”
Positron emission tomography (PET) – “alone or combined with CT, allows noninvasive, quantitative assessment of biochemical and functional processes at the molecular level in the body. It is most often performed with the radiolabeled glucose analogue [18F] fluorodeoxyglucose ([18F]FDG) to detect the elevated glucose metabolism that is a hallmark of cancer. In breast cancer, its utility depends on the pretest probability for advanced disease, and thus the clinical stage.” The authors found that the use of [18F] FDG PET to patients with stage I and II disease is “limited”. Specifically, they claim that it is not sufficiently accurate for axillary nodal staging in this subset of patients.40 The did find enough evidence to recommend the use of FDG PET in patients with advanced disease: “where it accurately defines disease extent,41 and frequently eliminates the need for other imaging tests, and provides an early readout of treatment response as well as prognostic information.”
Combined PET/MRI is mentioned as a promising technology for predicting response to therapy “but this remains to be proven”.
Positron emission mammography (PEM) – “adapts full-body PET imaging to the breast. In a multicenter study, the interpretation of PEM in conjunction with mammographic and clinical findings yielded a sensitivity of 91% and a specificity of 93% for breast cancer.47 “. However, the authors mention that its use for screening (applying to healthy women) has been criticized because of the need to administer a radioactive tracer.
Lung Cancer Imaging
To be followed…
Other research papers related to the management of breast cancer were published on this Scientific Web site:
Ovarian Cancer and fluorescence-guided surgery: A report
Author, Editor: Tilda Barliya PhD
Article 11.4.6 Ovarian Cancer and fluorescence guided surgery A report
Surgery is being commonly used to diagnose, treat and even help prevent cancer. In which the surgeon will cut into the body to remove the cancer along with some surrounding healthy tissue to ensure that all of the cancer is removed. However distinguishing cancer cells from healthy ones during surgery can prove difficult, if not impossible. Sometimes lesions are detected only postoperatively, leading to more surgery down the line. Currently, surgeons rely on vision and touch to detect tumors during surgery but in many cases there is still no good way to determine a tumor’s margins.
In recent years, major progression has been made in imaging-guided surgery and doctors believe that use of fluorescent dye could boost survival rates by guiding them to tiny clusters of malignant cells.
The first fluorescence-guided surgery in ovarian cancer patients have yielded great results and are summarized herein.
Dr. Phillip Low, a Ralph C. Corely Distinguished Professor of Chemistry from Purdue University has invented a fluorescent imaging agent to a modified form of the vitamin folic acid, which acts as a “homing device” to seek out and attach to ovarian cancer cells (1)
” Of all gynecologic malignancies, epithelial ovarian cancer (EOC) is the most frequent cause of death, both in the United States and in Europe. The relative absence of a clear, distinctive clinical presentation in early stages, combined with the lack of a screening tool, often results in the disease being diagnosed only at more advanced stages. The overall 5-year survival rate is 45%, and for stages III and IV it is only 20–25%.” Cytoreduction surgery followed by chemotherapy is considereed the most effective treatment. Radiologic approaches such as X-ray, CT, MRI and ultrasound have been considered for use in assisting surgical procedures, but these are not tumor specific and generally are not useful for intraoperative applications. Therefore, a better tumor-specific detection strategy may drastically improve the patient survival.
The overexpression of folate receptor-α (FR-α) in 90–95% of epithelial ovarian cancers prompted the investigation of intraoperative tumor-specific fluorescence imaging in ovarian cancer surgery using an FR-α–targeted fluorescent agent. Moreover, the absence of FR-α on healthy cells leads to high tumor-to-normal ratios.
As a ligand of FR-α, folate has already been conjugated to DTPA for SPECT/CT imaging and to several PET tracers. It has also been linked to fluorescein for use in imaging metastatic disease in murine tumor models, although this was never tested in humans.
In this article, the authors have conjugated the folate to fluorescein isothiocyanate (FITC) for the use in surgery together with a real-time multispectral intraoperative fluorescence imaging system.
The authors have conducted the first clinical trial using the fluorescence-guided surgery in ovarian cancer patient. Described herein:
Tumor-specific fluorescent agent:
Targeting of the FR-α in ovarian cancer in patients, the imaging agent was produced at clinical grade according to GMP conditions by Endocyte Inc. Folate hapten (vitamin B9) was conjugated with fluorescein isothiocyanate (FITC), yielding folate-FITC (See Fitgure). Folate-FITC has an excitation wavelength of 495 nm and emits light at 520 nm. The conjugate has a very high sensitivity and clusters of cancer cells as small as one-tenth of a millimeter can be detected, as opposed to the earlier average minimal cluster size of 3 millimeters in diameter based on current methods of visual and tactile detection.
Folate-FITC was dissolved in 10 ml sterile normal saline and injected at a dose of 0.3 mg per kg body weight over a period of 10 min and was injected 2 hrs prior to the surgery.
Patients:
10 patients with different stages of the over cancer were recruited, The mean age of all patients was 61.2 ± 11.4 (mean ± s.d.). Four patients were diagnosed with a malignant epithelial ovarian tumor (two serous carcinomas, one undifferentiated carcinoma and one mucinous carcinoma) and one patient with a serous borderline tumor. Five patients were diagnosed with a benign ovarian tumor, as confirmed by histopathology: two fibrothecomas, one cellular fibroma, one cystic teratoma and one benign multicystic ischemic ovary.
Multispectral fluorescence camera system:
The camera system (developed by the Technical University Munich/Helmholtz Center) consists of a charge-coupled digital (EM-CCD) camera (Andor Technology) for sensitive fluorescence detection and two separate cameras for detection of intrinsic fluorescence and color (PCO AG). The system is controlled by a synchronized multi-CPU computer system (Dell Computer) for simultaneous processing of raw data and image registration and rendering. The system allows color imaging and simultaneous sensitive fluorescence detection in the visible light spectrum, as appropriate for FITC imaging. Surgery and imaging procedure are described in detail in the article (1). Shortly, a live imaging during surgery enabled the surgeon to locate the tumor and remove it, biopsy was taken for further histopathology.
Results:
Fluorescence was detectable intraoperatively in all patients with a malignant tumor and FR-αexpression but was absent in the patient with a malignant tumor but no FR-α expression and in those with benign tumors (Table 1)
Table 1: Demographics an individual data for patients
Study no.
Age (years)
Histopathology
FIGO stage
In vivofluorescence
IHC FR-α expression
FM FITC
n = 10 patients. ++, strong; +, moderate; 0, weak; −, absent; FIGO, International Federation of Gynecology and Obstetrics; IHC FR-α, immunohistochemistry folate-receptor alpha; FM FITC, fluorescence microscopy for folate-FITC; n.a., not applicable.
Malignant tumor
1
72
Serous ovarian carcinoma
III
++
++
++
7
76
Serous ovarian carcinoma
III
+
+
+
9
64
Undifferentiated carcinoma
III
–
–
–
10
61
Mucineus ovarian carcinoma
III
+
+
+
Borderline tumor
5
48
Serous borderline tumor
I
0
+
0/+
Benign tumor
2
59
Fibrothecoma
n.a.
–
–
–
3
74
Fibrothecoma
n.a.
–
–
–
4
53
Mature cystic teratoma
n.a.
–
–
–
6
64
Benign multicystic ischemic ovary
n.a.
–
–
–
8
41
Fibroma
n.a.
–
–
–
Healthy tissue did not show any fluorescence signal either in vivo, ex vivo or on histopathological validation. In two separate still images of patients with ovarian cancer, the mean tumor-to-background ratio (as compared to healthy peritoneal surface) for ten demarcated fluorescent tumor deposits in each still image was 3.1 (± 0.8 s.d.). In the patient with a high-grade serous carcinoma and extensive peritoneal disseminated disease (stage III, FR-α positive), widespread tumor-specific fluorescence (white spots) was present throughout the abdominal cavity, as confirmed by ex vivo histopathology. Real-time image-guided excision of fluorescent tumor deposits of size <1 mm was feasible.
Five surgeons independently identified tumor deposits on three separate color images (shown on a representative image in (Left) and on their corresponding fluorescence image of precisely the same area (Right).
The number of tumor deposits detected by surgeons when guided by tumor-specific fluorescence (median 34, range 8–81) was significantly higher than with visual observation alone (median 7, range 4–22, P < 0.001).
Summary:
In this limited series, the authored showed that the use of intraoperative tumor-specific fluorescence imaging of the systemically administered FR-α–targeted agent folate-FITC offers specific and sensitive real-time identification of tumor tissue during surgery in patients with ovarian cancer and the presence of FR-α–positive tumors. Nevertheless, one patient presented with a malignant tumor that did not express FR-α, and consequently, no fluorescence was detected.
A major advantage over current imaging modalities is that an intraoperative fluorescence imaging system offers a large field of view for inspection and staging. This, in turn, may permit future patient-tailored surgical interventions and may decrease the number of needless extensive surgical procedures and the associated morbidity.
The second major advantage of intraoperative imaging as compared to current standard techniques is that it may guide the surgeon in debulking efforts, thus contributing to more efficient cytoreduction and ultimately improving the effect of adjuvant chemotherapy in patients with reduced tumor load
Improving the detection of cancer deposits to submillimeter size might ultimately improve survival rates, but whether this is the case needs to established by additional clinical studies.
Advantages:
In ovarian cancer, the FR-α appears to constitute a good target because it is overexpressed in 90–95% of malignant tumors, especially serous carcinomas.
Targeting ligand, folate, is attractive as it is nontoxic, inexpensive and relatively easily conjugated to a fluorescent dye to create a tumor-specific fluorescent contrast agent.
Disadvantages:
Overexpression of FR-α varies strongly between different solid tumors originating from different organs, a characteristic that reduces the general applicability of folate-FITC in cancer.
Many organs have autofluorescence in the excitation and emission parameters of the FITC dye.
Development of new fluorescent agents in the near-infrared spectrum will allow for identification of more deeply seated tumors, based on the stronger penetration properties of near-infrared dyes with an excitation wavelength >700 nm compared to FITC.
This is the first in-human proof-of-principle and the potential benefit of intraoperative tumor-specific fluorescence imaging in staging and debulking surgery for ovarian cancer using the systemically administered targeted fluorescent agent folate-FITC. Larger international multicenter studies using standardized, uniformly calibrated multispectral fluorescence camera systems combined with folate-FITC are needed to confirm our data and further elucidate the diagnostic (accuracy, sensitivity and specificity) and therapeutic value of the reported approach in larger series of ovarian cancer patients.
Note: Other similar approaches have been explored for brain tumors (3a, 3b) in human clinical trials using 5-aminolevulinic acid (5-ALA). We will not address this trial in this discussion.
Ref:
1. Gooitzen M van Dam, George Themelis, Lucia M A Crane, Niels J Harlaar, Rick G Pleijhuis, Wendy Kelder, Athanasios Sarantopoulos, Johannes S de Jong, Henriette J G Arts, Ate G J van der Zee, Joost Bart, Philip S Low & Vasilis Ntziachristos. Intraoperative tumor-specific fluorescence imaging in ovarian cancer by folate receptor-αtargeting: first in-human results. Nature Medicine 17, 1315–1319 (2011). http://www.nature.com.rproxy.tau.ac.il/nm/journal/v17/n10/full/nm.2472.html
3a. Stummer W, Pichlmeier U, Meinel T, Wiestler OD, Zanella F, Reulen HJ; ALA-Glioma Study group. Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial. Lancet Oncol 2006 May;7(5):392-401.
Were related to the benefit of better planning lumpectomies based on priory knowledge of the lesions’ size and location. The main challenge in using imaging as a tool for treatment planning is the devices’ specificity; i.e. the probability of identifying healthy tissue as malignant. The reason is the wish to avoid unnecessarily large excisions. When discussing the use of “popular” non-ionizing devises such as MRI in breast-imaging; e.g. my post introducing smart-imaging into radiologists’ daily practice I mentioned the low specificity of MRI in that respect. So, if one is reluctant to use ultrasound, for example due to its large inter observer variability and want to rely on the Mammography based work-flow, what new modalities are available?
Stereoscopic digital mammography
Stereoscopic digital mammography (SDM) uses a pair of digital mammograms, taken from slightly different angles and a stereo display workstation loaded with image-analysis software, to create a three-dimensional image of the internal structure of each breast. The resulting stereo image reveals more detail within the breast tissue than a standard two-dimensional mammogram.
Radiologist interacting with a stereo digital mammography workstation. (Credit: Image courtesy of Radiological Society of North America)
Purpose:To compare stereoscopic digital mammography (DM) with standard DM for the rate of patient recall and the detection of cancer in a screening population at elevated risk for breast cancer.
Materials and Methods:Starting in September 2004 and ending in December 2007, this prospective HIPAA-compliant, institutional review board–approved screening trial, with written informed consent, recruited female patients at elevated risk for breast cancer (eg, personal history of breast cancer or breast cancer in a close relative). A total of 1298 examinations from 779 patients (mean age, 58.6 years; range, 32–91 years) comprised the analyzable data set. A paired study design was used, with each enrolled patient serving as her own control. Patients underwent both DM and stereoscopic DM examinations in a single visit, findings of which were interpreted independently by two experienced radiologists, each using a Breast Imaging Reporting and Data System (BI-RADS) assessment (BI-RADS category 0, 1, or 2). All patients determined to have one or more findings with either or both modalities were recalled for standard diagnostic evaluation. The results of 1-year follow-up or biopsy were used to determine case truth.
Results:Compared with DM, stereoscopic DM showed significantly higher specificity (91.2% [1167 of 1279] vs 87.8% [1123 of 1279];P= .0024) and accuracy (90.9% [1180 of 1298] vs 87.4% [1135 of 1298];P= .0023) for detection of cancer. Sensitivity for detection of cancer was not significantly different for stereoscopic DM (68.4% [13 of 19]) compared with DM (63.2% [12 of 19],P.99). The recall rate for stereoscopic DM was 9.6% (125 of 1298) and that for DM was 12.9% (168 of 1298) (P= .0018).
Conclusion:Compared with DM, stereoscopic DM significantly improved specificity for detection of cancer, while maintaining comparable sensitivity. The recall rate was significantly reduced with stereoscopic DM compared with DM.
Digital Breast Tomosynthesis
Digital Breast Tomosynthesis (DBT) entered the Breast-Imaging field few years ago. Early 2011, a digital mammography device by Hologic aimed at improving the specificity of mammography was approved by the FDA as a tool that may improve cancer detection while reducing the number of patient recalls.
The DBT device takes 15 successive images, each at a slightly different angle along an arc across the breast. The concept is simple: What is hidden behind fibroglandular tissue in one image might be visible in another if the angle is slightly different (Figure bellow).
Figure. (a) A suspicious lesion seen on standard 2D digital mammography (far left). (b) After examining multiple slices generated using breast tomosynthesis (5 images), the lesion seen on 2D (far left) is determined to be a false positive. (Images courtesy of Hologic. Used with permission.)
Out of recent publications related to the incorporation of DBT in breast-cancer management I picked up the following two:
Purpose:To assess cancer detection rates, false-positive rates before arbitration, positive predictive values for women recalled after arbitration, and the type of cancers detected with use of digital mammography alone and combined with tomosynthesis in a large prospective screening trial.
Materials and Methods:A prospective, reader- and modality-balanced screening study of participants undergoing combined mammography plus tomosynthesis, the results of which were read independently by four different radiologists, is under way. The study was approved by a regional ethics committee, and all participants provided written informed consent. The authors performed a preplanned interim analysis of results from 12631 examinations interpreted by using mammography alone and mammography plus tomosynthesis from November 22, 2010, to December 31, 2011. Analyses were based on marginal log-linear models for binary data, accounting for correlated interpretations and adjusting for reader-specific performance levels by using a two-sided significance level of .0294.
Results:Detection rates, including those for invasive and in situ cancers, were 6.1 per 1000 examinations for mammography alone and 8.0 per 1000 examinations for mammography plus tomosynthesis (27% increase, adjusted for reader; P = .001). False-positive rates before arbitration were 61.1 per 1000 examinations with mammography alone and 53.1 per 1000 examinations with mammography plus tomosynthesis (15% decrease, adjusted for reader; P < .001). After arbitration, positive predictive values for recalled patients with cancers verified later were comparable (29.1% and 28.5%, respectively, with mammography alone and mammography plus tomosynthesis; P = .72). Twenty-five additional invasive cancers were detected with mammography plus tomosynthesis (40% increase, adjusted for reader; P < .001). The mean interpretation time was 45 seconds for mammography alone and 91 seconds for mammography plus tomosynthesis (P < .001).
Conclusion:The use of mammography plus tomosynthesis in a screening environment resulted in a significantly higher cancer detection rate and enabled the detection of more invasive cancers.
Twenty-five additional invasive cancers were detected with mammography plus tomosynthesis — a 40% increase.
Detection rates, including those for invasive and in situ cancers, were 6.1 per 1,000 examinations for mammography alone and eight per 1,000 examinations for mammography plus tomosynthesis — a 27% increase.
False-positive rates before arbitration were 61.1 per 1,000 examinations with mammography alone and 53.1 per 1,000 examinations with mammography plus tomosynthesis — a 15% decrease.
After arbitration, positive predictive values for recalled patients with cancers verified later were comparable (29.1% with mammography alone and 28.5% with mammography plus tomosynthesis).
Mean interpretation time was 45 seconds for mammography alone and 91 seconds for mammography plus tomosynthesis.
Purpose: To compare the diagnostic performance of breast tomosynthesis versus supplemental mammography views in classification of masses, distortions, and asymmetries.
Materials and Methods: Eight radiologists who specialized in breast imaging retrospectively reviewed 217 consecutively accrued lesions by using protocols that were HIPAA compliant and institutional review board approved in 182 patients aged 31–60 years (mean, 50 years) who underwent diagnostic mammography and tomosynthesis. The lesions in the cohort included 33% (72 of 217) cancers and 67% (145 of 217) benign lesions. Eighty-four percent (182 of 217) of the lesions were masses, 11% (25 of 217) were asymmetries, and 5% (10 of 217) were distortions that were initially detected at clinical examination in 8% (17 of 217), at mammography in 80% (173 of 217), at ultrasonography (US) in 11% (25 of 217), or at magnetic resonance imaging in 1% (2 of 217). Histopathologic examination established truth in 191 lesions, US revealed a cyst in 12 lesions, and 14 lesions had a normal follow-up. Each lesion was interpreted once with tomosynthesis and once with supplemental mammographic views; both modes included the mediolateral oblique and craniocaudal views in a fully crossed and balanced design by using a five-category Breast Imaging Reporting and Data System (BI-RADS) assessment and a probability-of-malignancy score. Differences between modes were analyzed with a generalized linear mixed model for BI-RADS–based sensitivity and specificity and with modified Obuchowski-Rockette approach for probability-of-malignancy–based area under the receiver operating characteristic (ROC) curve.
Results: Average probability-of-malignancy–based area under the ROC curve was 0.87 for tomosynthesis versus 0.83 for supplemental views (P < .001). With tomosynthesis, the false-positive rate decreased from 85% (989 of 1160) to 74% (864 of 1160) (P < .01) for cases that were rated BI-RADS category 3 or higher and from 57% (663 of 1160) to 48% (559 of 1160) for cases rated BI-RADS category 4 or 5 (P < .01), without a meaningful change in sensitivity. With tomosynthesis, more cancers were classified as BI-RADS category 5 (39% [226 of 576] vs 33% [188 of 576]; P = .017) without a decrease in specificity.
Conclusion: Tomosynthesis significantly improved diagnostic accuracy for noncalcified lesions compared with supplemental
,
![A 46-year-old male with diffuse large B cell lymphoma, stage IV was studied. Baseline maximum intensity projection (MIP) positron emission tomography (PET) image with [18F]fluorodeoxyglucose ([18F]FDG) (A) shows widespread disease, which is essentially resolved on interim scan after 4 cycles of chemotherapy (B). The interim scan also shows increased [18F]FDG uptake in bone marrow related to administration of granulocyte colony-stimulating factor (GCSF). (C,D) Transaxial CT and PET/CT fusion images at baseline show abnormal [18F]FDG uptake in extensive mediastinal and hilar lymphadenopathy as well as in bone lesions in a right rib and the right scapula. On interim scan (E,F) abnormal [18F]FDG uptake at all of these sites has resolved although residual enlarged lymph nodes remain. The sites are better seen on a contrast-enhanced CT (G) and measure up to 5.3 cm × 3.6 cm. Chemotherapy was continued for a total of 8 cycles. At the time of writing, the patient remained disease-free after 9 years of follow-up.](https://i0.wp.com/pharmaceuticalintelligence.com/wp-content/uploads/2013/02/nfig019.jpg)
![Representative images from 3-T MRI and [18F]FDG PET/CT examinations in a 70-year-old man with PSA level of 8.0 ng/mL and Gleason score of 8 (4 + 4) prostate cancer (arrow) located in the left posterolateral prostate within the peripheral zone: (A) transverse T2-weighted image, (B) transverse fused [18F]FDG PET/CT image, (C) transverse fused [18F]FDG PET/CT image overlaid on T2-weighted MRI.](https://i0.wp.com/pharmaceuticalintelligence.com/wp-content/uploads/2013/01/fig-13-prostate.jpg)
![CT (A) of 78-year-old male who was status post–left lobe lobectomy and left upper lobe wedge resection shows recurrent nodule at the surgical resection site. Fused PET/CT (B) demonstrates increased [18F]FDG uptake in the corresponding nodule at the surgical resection site consistent with recurrent tumor.](https://i0.wp.com/pharmaceuticalintelligence.com/wp-content/uploads/2013/01/fig-10-lung.jpg)
![CT (A) demonstrates new left upper lobe mass representing new primary NSCLC in a patient who had a status post–right pneumonectomy for a prior NSCLC. CT (B) obtained in the same patient 2 weeks after radiofrequency ablation (RFA) demonstrates the postablation density in the left upper lobe. Fused PET/CT (C) obtained 4 months after RFA demonstrates mild [18F]FDG uptake at RFA site in the left upper lobe consistent with posttreatment inflammation. Fused PET/CT (D) obtained 7 months after RFA demonstrates new focal [18F]FDG uptake at post-RFA-opacity consistent with recurrent tumor.](https://i0.wp.com/pharmaceuticalintelligence.com/wp-content/uploads/2013/01/fig-11-lung.jpg)
Intraoperative tumor-specific fluorescence imaging in ovarian cancer by folate receptor-α targeting (
2012pharmaceutical
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