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Ultrasound imaging as an instrument for measuring tissue elasticity: “Shear-wave Elastography” VS. “Strain-Imaging”

Posted in Bio Instrumentation in Experimental Life Sciences Research, Biomarkers & Medical Diagnostics, CANCER BIOLOGY & Innovations in Cancer Therapy, Imaging-based Cancer Patient Management, Medical Devices R&D Investment, Medical Imaging Technology, Image Processing/Computing, MRI, CT, Nuclear Medicine, Ultra Sound, tagged Cancer - General, cancer management, Clinical trial, elastography, Georg Salomon, guided biopsy, imaging, innovations in cancer management, malignant lesions, Medical imaging, Personalized medicine, Prostate cancer, screening, screening for cancer, shear-wave elastography, strain imaging, tissue elasticity, Transrectal ultrasonography, ultrasound imaging, ultrasound technology on June 6, 2013| 4 Comments »

Ultrasound imaging as an instrument for measuring tissue elasticity: “Shear-wave Elastography” VS. “Strain-Imaging”

Writer and curator: Dror Nir, PhD

In the context of cancer-management, imaging is pivotal. For decades, ultrasound is used by clinicians to support every step in cancer pathways. Its popularity within clinicians is steadily increasing despite the perception of it being less accurate and less informative than CT and MRI. This is not only because ultrasound is easily accessible and relatively low cost, but also because advances in ultrasound technology, mainly the conversion into PC-based modalities allows better, more reproducible, imaging and more importantly; clinically-effective image interpretation.

The idea to rely on ultrasound’s physics in order to measure the stiffness of tissue lesions is not new. The motivation for such measurement has to do with the fact that many times malignant lesions are stiffer than non-malignant lesions.

The article I bring below; http://digital.studio-web.be/digitalMagazine?issue_id=254 by Dr. Georg Salomon and his colleagues, is written for lay-readers. I found it on one of the many portals that are bringing quasi-professional and usually industry-sponsored information on health issues; http://www.dieurope.com/ – The European Portal for Diagnostic Imaging. Note, that when it comes to using ultrasound as a diagnostic aid in urology, Dr. Georg Salomon is known to be one of the early adopters for new technologies and an established opinion leader who published many peer-review, frequently quoted, papers on Elastography.

The important take-away I would like to highlight for the reader: Quantified measure of tissue’s elasticity (doesn’t matter if is done by ShearWave or another “Elastography” measure implementation) is information that has real clinical value for the urologists who needs to decide on the right pathway for his patient!

Note: the highlights in the article below are added by me for the benefit of the reader.

Improvement in the visualization of prostate cancer through the use of ShearWave Elastography

by:

Dr Georg Salomon¹ Dr Lars Budaeus¹, Dr L Durner²& Dr K Boe¹

1. Martini-Clinic — Prostate Cancer Center University Hospital Hamburg Eppendorf Martinistrasse 52, 20253 Hamburg, Germany

2. Urologische Kilnik Dr. Castringius Munchen-Planegg Germeringer Str. 32, 82152 Planegg, Germany

Corresponding author; PD Dr. Georg Salomon

Associate Professor of Urology

Martini Clinic

Tel: 0049 40 7410 51300

gsalornon@uke.de

Prostate cancer is the most common cancer in males with more than 910,000 annual cases worldwide. With early detection, excellent cure rates can be achieved. Today, prostate cancer is diagnosed by a randomized transrectal ultrasound guided biopsy. However, such randomized “blind” biopsies can miss cancer because of the inability of conventional TRUS to visualize small cancerous spots in most cases.

Elastography has been shown to improve visualization of prostate cancer.

The innovative ShearWave Elastography technique is an automated, user-friendly and quantifiable method for the determination of prostatic tissue stiffness.

The detection of prostate cancer (PCA) has become easier thanks to Prostate Specific Antigen (PSA) testing; the diagnosis of PCA has been shifted towards an earlier stage of the disease.

Prostate cancer is, in more than 80 % of the cases, a heterogeneous and multifocal tumor. Conventional ultrasound has limitations to accurately define tumor foci within the prostate. This is due to the fact that most PCA foci are isoechogenic, so in these cases there is no differentiation of benign and malignant tissue. Because of this, a randomized biopsy is performed under ultrasound guidance with at least 10 to 12 biopsy cores, which should represent all areas of the prostate. Tumors, however, can be missed by this biopsy regimen since it is not a lesion-targeted biopsy. When PSA is rising — which usually occurs in most men — the originally negative biopsy has to be repeated.

What urologists expect from imaging and biopsy procedures is the detection of prostate cancer at an early stage and an accurate description of all foci within the prostate with different (Gleason) grades of differentiation for best treatment options.

In the past 10 years a couple of new innovative ultrasound techniques (computerized, contrast enhanced and real time elastography) have been introduced to the market and their impact on the detection of early prostate cancer has been evaluated. The major benefit of elastography compared to the other techniques is its ability to provide visualization of suspicious areas and to guide the biopsy needle, in real time, to the suspicious and potentially malignant area.

Ultrasound-based elastography has been investigated over the years and has had a lot of success for increasing the detection rate of prostate cancer or reducing the number of biopsy samples required. [1-3]. Different companies have used different approaches to the ultrasound elastography technique (strain elastography vs. shear wave elastography). Medical centers have seen an evolution in better image quality with more stable and reproducible results from these techniques.

One drawback of real time strain elastography is that there is a significant learning curve to be climbed before reproducible elastograms can be generated. The technique has to be performed by compressing and then decompressing the ultrasound probe to derive a measurement of tissue displacement.

Today there are ultrasound scanners on the market, which have the ability to produce elastograms without this “manual” assistance: this technique is called shear-wave elastography. While the ultrasound probe is being inserted transrectally, the “elastograms” are generated automatically by the calculation of shear wave velocity as the waves travel through the tissue being examined, thus providing measurements of tissue stiffness and not displacement measurements.

There are several different techniques for this type of elastography. The FibroScan system, which is not an ultrasound unit, uses shear waves (transient elastography) to evaluate the advancement of the stiffness of the liver. Another technique is Acoustic Radiation Force Impulse or ARF1 technique, also used for the liver. These non-real-time techniques only provide a shear wave velocity estimation for a single region of interest and are not currently used in prostate imaging.

A shear wave technology that provides specific quantification of tissue elasticity in real-time is ShearWave Elastography, developed by Super-Sonic Imagine. This technique measures elasticity in kilopascals and can provide visual representation of tissue stiffness over the entire region of interest in a color-coded map on the ultrasound screen. On a split screen the investigator can see the conventional ultrasound B-mode image and the color-coded elastogram at the same time. This enables an anatomical view of the prostate along with the elasticity image of the tissue to guide the biopsy needle.

In short, ShearWave Elastography (SWE) is a different elastography technique that can be used for several applications. It automatically generates a real-time, reproducible, fully quantifiable color-coded image of tissue elasticity.

QUANTIFICATION OF TISSUE STIFFNESS Such quantification can help to increase the chance that a targeted biopsy is positive for cancer.

It has been shown that elastography-targeted biopsies have an up to 4.7 times higher chance to be positive for cancer than a randomized biopsy [4J. Shear-Wave Elastography can not only visualize the tissue stiffness in color but also quantify (in kPa) the stiffness in real time, for several organs including the prostate. Correas et al, reported that with tissue stiffness higher than 45 to 50 kPa the chance of prostate cancer is very high in patients undergoing a prostate biopsy. The data from Gorreas et al showed a sensitivity of 80 % and a high negative predictive value of up to 9096. Another group (Barr et A) achieved a negative predictive value of up to 99.6% with a sensitivity of 96.2% and specificity of 962%. With a cut-off of 4D kPa the positive biopsy rate for the ShearWave Elastography targeted biopsy was 50%, whereas for randomized biopsy it was 20.8 95. In total 53 men were enrolled in this study.

Our group used SWE prior to radical prostatectomy to determine if the Shear-Wave Elastography threshold had a high accuracy using a cutoff >55 kPa. (Fig 1)

We then compared the ShearWave results with the final histopathological results. [Figure I], Our results showed the accuracy was around 78 % for all tumor foci We were also able to verify that ShearWave Elastography targeted biopsies were more likely to be positive compared to randomized biopsies. [Figures 2, 3]

CONCLUSION

SWE is a non-invasive method to visualize prostate cancer foci with high accuracy, in a user-friendly way. As Steven Kaplan puts it in an editorial comment in the Journal of Urology 2013: “Obviously, large-scale studies with multicenter corroboration need to be performed. Nevertheless, SWE is a potentially promising modality to increase our efficiency in evaluating prostate diseases:’

REFERENCES

Pallweln, L. et al-. Sonoelastography of the prostate: comparison with systematic biopsy findings in 492 patients. European journal of radiology, 2008. 65(2): p. 304-10.
Pallwein, L., et al., Comparison of sono-elastography guided biopsy with systematic biopsy: Impact on prostate cancer detecton. European radiology, 2007_ 17.(9) p. 2278-85.
Salomon, G., et al., Evaluation of prostate can cer detection with ultrasound real-time elas-tographyl a companion with step section pathological analysis after radical prostatectomy. European urology, 2008. 5446): p. 135462-
Aigner, F., at al., Value of real-time elastography targeted biopsy for prostate cancer detection in men with prostate specific antigen 125 ng/mi or greater and 4-00 ng/ml or Lass. The Journal of urology, 2010. 184{3): p. 813.7,

Other research papers related to the management of Prostate cancer and Elastography were published on this Scientific Web site:

Imaging: seeing or imagining? (Part 1)

Early Detection of Prostate Cancer: American Urological Association (AUA) Guideline

Today’s fundamental challenge in Prostate cancer screening

State of the art in oncologic imaging of Prostate.

From AUA2013: “HistoScanning”- aided template biopsies for patients with previous negative TRUS biopsies

On the road to improve prostate biopsy

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The unfortunate ending of the Tower of Babel construction project and its effect on modern imaging-based cancer patients’ management

Posted in Imaging-based Cancer Patient Management, tagged biopsies, brain lesion, breast biopsies, breast biopsy, breast cancer, breast cancer mortality, breast cancer screening, breast screening, CANCER BIOLOGY & Innovations in Cancer Therapy, cancer patient management, Clinical trial, cost efficient cancer diagnosis, cost efficient cancer treatment, cost efficient solution, CT scans, directed biopsies, DW MRI, efficient business, european congress of radiology, evidence based medicine, free hand biopsies, guided biopsies, hands on appoach, health, healthcare, healthcare business, imaging guided biopsies, imaging in cancer, Imaging-based Cancer Patient Management, Imaging-based Cancer Patient Management | Tagged biopsies, innovation in health, innovation in healthcare, Magnetic resonance imaging, magnetic resonance imaging mri, magnetic tracking, mammography, Medical Devices R&D Investment, medicine, MRI, MRI imaging, multi-functional MRI, mutation, open mri systems, personalised medicine, prostat cancer screening, Prostate, Prostate biopsy, Prostate cancer, prostate guided biopsies, prostate hisoscanning, Prostate-specific antigen, radiographically dense breasts, research, science, tagged biopsy needles, tagged cancer, tracking, Transrectal ultrasonography, Triple-negative breast cancer, TRUS, ultrasound guided breast biopsy breast biopsy, ultrasound imaging, ultrasound imaging Bio Instrumentation in Experimental Life Sciences Research on October 22, 2012| 4 Comments »

The unfortunate ending of the Tower of Babel construction project and its effect on modern imaging-based cancer patients’ management

Curator: Dror Nir, PhD

The story of the city of Babel is recorded in the book of Genesis 11 1-9. At that time, everyone on earth spoke the same language.

Picture: Pieter Bruegel the Elder: The Tower of Babel_(Vienna)

It is probably safe to assume that medical practitioners at that time were reporting the status of their patients in a standard manner. Although not mentioned, one might imagine that, at that time, ultrasound or MRI scans were also reported in a standard and transferrable manner. The people of Babel noticed the potential in uniform communication and tried to build a tower so high that it would reach the gods. Unfortunately, God did not like that, so he went down (in person) and confounded people’s speech, so that they could not understand each another. Genesis 11:7–8.

This must be the explanation for our inability to come to a consensus on reporting of patients’ imaging-outcome. Progress in development of efficient imaging protocols and in clinical management of patients is withheld due to high variability and subjectivity of clinicians’ approach to this issue.

Clearly, a justification could be found for not reaching a consensus on imaging protocols: since the way imaging is performed affects the outcome, (i.e. the image and its interpretation) it takes a long process of trial-and-error to come up with the best protocol. But, one might wonder, wouldn’t the search for the ultimate protocol converge faster if all practitioners around the world, who are conducting hundreds of clinical studies related to imaging-based management of cancer patients, report their results in a standardized and comparable manner?

Is there a reason for not reaching a consensus on imaging reporting? And I’m not referring only to intra-modality consensus, e.g. standardizing all MRI reports. I’m referring also to inter-modality consensus to enable comparison and matching of reports generated from scans of the same organ by different modalities, e.g. MRI, CT and ultrasound.

As developer of new imaging-based technologies, my personal contribution to promoting standardized and objective reporting was the implementation of preset reporting as part of the prostate-HistoScanning product design. For use-cases, as demonstrated below, in which prostate cancer patients were also scanned by MRI a dedicated reporting scheme enabled matching of the HistoScanning scan results with the prostate’s MRI results.

The MRI reporting scheme used as a reference is one of the schemes offered in a report by Miss Louise Dickinson on the following European consensus meeting : Magnetic Resonance Imaging for the Detection, Localisation, and Characterisation of Prostate Cancer: Recommendations from a European Consensus Meeting, Louise Dickinson ^a,b,c,*, Hashim U. Ahmed^a,b, Clare Allen^d, Jelle O. Barentsz^e, Brendan Carey^f, Jurgen J. Futterer^e, Stijn W. Heijmink^e, Peter J. Hoskin^g, Alex Kirkham^d, Anwar R. Padhani h, Raj Persadⁱ, Philippe Puech ^j, Shonit Punwani^d, Aslam S. Sohaib^k, Bertrand Tombal^l,Arnauld Villers^m, Jan van der Meulen^c,n, Mark Emberton a,b,c,

http://www.europeanurology.com/article/S0302-2838(10)01187-5

Image of MRI reporting scheme taken from the report by Miss Louise Dickinson

The corresponding HistoScanning report is following the same prostate segmentation and the same analysis plans:

Preset reporting enabling matching of HistoScanning and MRI reporting of the same case.

It is my wish that already in the near-future, the main radiology societies (RSNA, ESR, etc..) will join together to build the clinical Imaging’s “Tower of Babel” to effectively address the issue of standardizing reporting of imaging procedures. This time it will not be destroyed…:-)

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Knowing the tumor’s size and location, could we target treatment to THE ROI by applying imaging-guided intervention?

Posted in CANCER BIOLOGY & Innovations in Cancer Therapy, Imaging-based Cancer Patient Management, tagged biopsies, brain lesion, breast biopsies, breast biopsy, breast cancer, breast cancer mortality, breast cancer screening, breast screening, Cancer - General, CANCER BIOLOGY & Innovations in Cancer Therapy, cancer patient management, Clinical trial, cost efficient cancer diagnosis, cost efficient cancer treatment, cost efficient solution, CT scans, directed biopsies, DW MRI, efficient business, european congress of radiology, evidence based medicine, free hand biopsies, guided biopsies, hands on appoach, health, healthcare, healthcare business, imaging guided biopsies, imaging in cancer, Imaging-based Cancer Patient Management, Imaging-based Cancer Patient Management | Tagged biopsies, innovation in health, innovation in healthcare, Magnetic resonance imaging, magnetic resonance imaging mri, magnetic tracking, mammography, Medical Devices R&D Investment, medicine, MRI, MRI imaging, multi-functional MRI, mutation, open mri systems, personalised medicine, prostat cancer screening, Prostate, Prostate biopsy, Prostate cancer, prostate guided biopsies, prostate hisoscanning, Prostate-specific antigen, radiographically dense breasts, research, science, tagged biopsy needles, tracking, Transrectal ultrasonography, Triple-negative breast cancer, TRUS, ultrasound guided breast biopsy breast biopsy, ultrasound imaging, ultrasound imaging Bio Instrumentation in Experimental Life Sciences Research on October 16, 2012| 25 Comments »

Knowing the tumor’s size and location, could we target treatment to THE ROI by applying imaging-guided intervention?

Author: Dror Nir, PhD

Advances in techniques for cancer lesions’ detection and localisation [1-6] opened the road to methods of localised (“focused”) cancer treatment [7-10]. An obvious challenge on the road is reassuring that the imaging-guided treatment device indeed treats the region of interest and preferably, only it.

A step in that direction was taken by a group of investigators from Sunnybrook Health Sciences Centre, University of Toronto, Ontario, Canada who evaluate the feasibility and safety of magnetic resonance (MR) imaging–controlled transurethral ultrasound therapy for prostate cancer in humans [7]. Their study’s objective was to prove that using real-time MRI guidance of HIFU treatment is possible and it guarantees that the location of ablated tissue indeed corresponds to the locations planned for treatment. Eight eligible patients were recruited.

The setup

Treatment protocol

The result

“There was excellent agreement between the zone targeted for treatment and the zone of thermal injury, with a targeting accuracy of ±2.6 mm. In addition, the temporal evolution of heating was very consistent across all patients, in part because of the ability of the system to adapt to changes in perfusion or absorption properties according to the temperature measurements along the target boundary.”

Technological problems to be resolved in the future:

“Future device designs could incorporate urinary drainage during the procedure, given the accumulation of urine in the bladder during treatment.”

“Sufficient temperature resolution could be achieved only by using 10-mm-thick sections. Our numeric studies suggest that 5-mm-thick sections are necessary for optimal three-dimensional conformal heating and are achievable by using endorectal imaging coils or by performing the treatment with a 3.0-T platform.”

Major limitation: “One of the limitations of the study was the inability to evaluate the efficacy of this treatment; however, because this represents, to our knowledge, the first use of this technology in human prostate, feasibility and safety were emphasized. In addition, the ability to target the entire prostate gland was not assessed, again for safety considerations. We have not attempted to evaluate the effectiveness of this treatment for eradicating cancer or achieving durable biochemical non-evidence of disease status.”

References

SIMMONS (L.A.M.), AUTIER (P.), ZATURA (F.), BRAECKMAN (J.G.), PELTIER (A.), ROMICS (I.), STENZL (A.), TREURNICHT (K.), WALKER (T.), NIR (D.), MOORE (C.M.), EMBERTON (M.). Detection, localisation and characterisation of prostate cancer by Prostate HistoScanning.. British Journal of Urology International (BJUI). Issue 1 (July). Vol. 110, Page(s): 28-35
WILKINSON (L.S.), COLEMAN (C.), SKIPPAGE (P.), GIVEN-WILSON (R.), THOMAS (V.). Breast HistoScanning: The development of a novel technique to improve tissue characterization during breast ultrasound. European Congress of Radiology (ECR), A.4030, C-0596, 03-07/03/2011.
Hebert Alberto Vargas, MD, Tobias Franiel, MD,Yousef Mazaheri, PhD, Junting Zheng, MS, Chaya Moskowitz, PhD, Kazuma Udo, MD, James Eastham, MD and Hedvig Hricak, MD, PhD, Dr(hc) Diffusion-weighted Endorectal MR Imaging at 3 T for Prostate Cancer: Tumor Detection and Assessment of Aggressiveness. June 2011 Radiology, 259,775-784.
Wendie A. Berg, Kathleen S. Madsen, Kathy Schilling, Marie Tartar, Etta D. Pisano, Linda Hovanessian Larsen, Deepa Narayanan, Al Ozonoff, Joel P. Miller, and Judith E. Kalinyak Breast Cancer: Comparative Effectiveness of Positron Emission Mammography and MR Imaging in Presurgical Planning for the Ipsilateral Breast Radiology January 2011 258:1 59-72.
Anwar R. Padhani, Dow-Mu Koh, and David J. Collins Reviews and Commentary – State of the Art: Whole-Body Diffusion-weighted MR Imaging in Cancer: Current Status and Research Directions Radiology December 2011 261:3 700-718
Eggener S, Salomon G, Scardino PT, De la Rosette J, Polascik TJ, Brewster S. Focal therapy for prostate cancer: possibilities and limitations. Eur Urol 2010;58(1):57–64).
Rajiv Chopra, PhD, Alexandra Colquhoun, MD, Mathieu Burtnyk, PhD, William A. N’djin, PhD, Ilya Kobelevskiy, MSc, Aaron Boyes, BSc, Kashif Siddiqui, MD, Harry Foster, MD, Linda Sugar, MD, Masoom A. Haider, MD, Michael Bronskill, PhD and Laurence Klotz, MD. MR Imaging–controlled Transurethral Ultrasound Therapy for Conformal Treatment of Prostate Tissue: Initial Feasibility in Humans. October 2012 Radiology, 265,303-313.
Black, Peter McL. M.D., Ph.D.; Alexander, Eben III M.D.; Martin, Claudia M.D.; Moriarty, Thomas M.D., Ph.D.; Nabavi, Arya M.D.; Wong, Terence Z. M.D., Ph.D.; Schwartz, Richard B. M.D., Ph.D.; Jolesz, Ferenc M.D. Craniotomy for Tumor Treatment in an Intraoperative Magnetic Resonance Imaging Unit. Neurosurgery: September 1999 – Volume 45 – Issue 3 – p 423
Medel, Ricky MD, Monteith, Stephen J. MD, Elias, W. Jeffrey MD, Eames, Matthew PhD, Snell, John PhD, Sheehan, Jason P. MD, PhD, Wintermark, Max MD, MAS, Jolesz, Ferenc A. MD, Kassell, Neal F. MD. Neurosurgery: Magnetic Resonance–Guided Focused Ultrasound Surgery: Part 2: A Review of Current and Future Applications. October 2012 – Volume 71 – Issue 4 – p 755–763
Bruno Quesson PhD, Jacco A. de Zwart PhD, Chrit T.W. Moonen PhD. Magnetic resonance temperature imaging for guidance of thermotherapy. Journal of Magnetic Resonance Imaging, Special Issue: Interventional MRI, Part 1, Volume 12, Issue 4, pages 525–533, October 2000

Writer: Dror Nir, PhD

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Introducing smart-imaging into radiologists’ daily practice.

Posted in Imaging-based Cancer Patient Management, tagged biopsies, brain lesion, breast biopsies, breast biopsy, breast cancer, breast cancer mortality, breast cancer screening, breast screening, Cancer - General, CANCER BIOLOGY & Innovations in Cancer Therapy, cancer patient management, Clinical trial, cost efficient cancer diagnosis, cost efficient cancer treatment, cost efficient solution, CT scans, directed biopsies, DW MRI, efficient business, european congress of radiology, evidence based medicine, free hand biopsies, guided biopsies, hands on appoach, health, healthcare, healthcare business, imaging guided biopsies, imaging in cancer, Imaging-based Cancer Patient Management, innovation in health, innovation in healthcare, Magnetic resonance imaging, magnetic resonance imaging mri, magnetic tracking, mammography, Medical Devices R&D Investment, medicine, MRI, MRI imaging, multi-functional MRI, mutation, open mri systems, personalised medicine, prostat cancer screening, Prostate, Prostate biopsy, Prostate cancer, prostate guided biopsies, prostate hisoscanning, Prostate-specific antigen, radiographically dense breasts, science, tagged biopsy needles, tracking, Transrectal ultrasonography, Triple-negative breast cancer, TRUS, ultrasound guided breast biopsy breast biopsy, ultrasound imaging Bio Instrumentation in Experimental Life Sciences Research on October 9, 2012| 6 Comments »

Introducing smart-imaging into radiologists’ daily practice.

Author and Curator: Dror Nir, PhD

Radiology congresses are all about imaging in medicine. Interestingly, radiology originates from radiation. It was the discovery of X-ray radiation at the beginning of the 20^th century that opened the road to “seeing” the inside of the human body without harming it (at that time that meant cutting into the body).

Radiology meetings are about sharing experience and knowhow on imaging-based management patients. The main topic is always image-interpretation: the bottom line of clinical radiology! This year’s European Congress of Radiology (ECR) dedicated few of its sessions to recent developments in image-interpretation tools. I chose to discuss the one that I consider contributing the most to the future of cancer patients’ management.

In the refresher course dedicated to computer application the discussion was aimed at understanding the question “How do image processing and CAD impact radiological daily practice?” Experts’ reviews gave the audience some background information on the following subjects:

A. The link between image reconstruction and image analysis.
B. Semantic web technologies for sharing and reusing imaging-related information
C. Image processing and CAD: workflow in clinical practice.

I find item A to be a fundamental education item. Not once did I hear a radiologist saying: “I know this is the lesion because it’s different on the image”. Being aware of the computational concepts behind image rendering, even if it is at a very high level and lacking deep understanding of the computational processes, will contribute to more balanced interpretations.

Item B is addressing the dream of investigators worldwide. Imagine that we could perform a web search and find educating, curated materials linking visuals and related clinical information, including standardized pathology reporting. We would only need to remember that search engines used certain search methods and agree, worldwide, on the method and language to be used when describing things. Having such tools is a pre-requisite to successful pharmaceutical and bio-tech development.

I find item C strongly linked to A, as all methods for better image interpretation must fit into a workflow. This is a design goal that is not trivial to achieve. To understand what I mean by that, try to think about how you could integrate the following examples in your daily workflow: i.e. what kind of expertise is needed for execution, how much time it will take, do you have the infrastructure?

In the rest of this post, I would like to highlight, through examples that were discussed during ECR 2012, the aspect of improving cancer patients’ clinical assessment by using information fusion to support better image interpretation.

Adding up quantitative information from MR spectroscopy (quantifies biochemical property of a target lesion) and Dynamic Contrast Enhanced MR imaging (highlights lesion vasculature).

Image provided by: Dr. Pascal Baltzer, director of mammography at the centre for radiology at Friedrich Schiller University in Jena, Germany

Registration of images generated by different imaging modalities (Multi-modal imaging registration).

The following examples: Fig 2 demonstrates registration of a mammography image of a breast lesion to an MRI image of this lesion. Fig3 demonstrates registration of an ultrasound image of a breast lesion scanned by an Automatic Breast Ultrasound (ABUS) system and an MRI image of the same lesion.

Images provided by members of the HAMAM project (an EU, FP7 funded research project: Highly Accurate Breast Cancer Diagnosis through Integration of Biological Knowledge, Novel Imaging Modalities, and Modelling): http://www.hamam-project.org

Multi-modality image registration is usually based on the alignment of image-features apparent in the scanned regions. For ABUS-MRI matching these were: the location of the nipple and the breast thickness; the posterior of the nipple in both modalities; the medial-lateral distance of the nipple to the breast edge on ultrasound; and an approximation of the ribcage using a cylinder on the MRI. A mean accuracy of 14mm was achieved.

Also from the HAMAM project, registration of ABUS image to a mammography image:

registration of ABUS image to a mammography image, Image provided by members of the HAMAM project (an EU, FP7 funded research project: Highly Accurate Breast Cancer Diagnosis through Integration of Biological Knowledge, Novel Imaging Modalities, and Modelling): http://www.hamam-project.org

Automatic segmentation of suspicious regions of interest seen in breast MRI images

Segmentation of suspicious the lesions on the image is the preliminary step in tumor evaluation; e.g. finding its size and location. Since lesions have different signal/image characteristics to the rest of the breast tissue, it gives hope for the development of computerized segmentation techniques. If successful, such techniques bear the promise of enhancing standardization in the reporting of lesions size and location: Very important information for the success of the treatment step.

Roberta Fusco of the National Cancer Institute of Naples Pascal Foundation, Naples/IT suggested the following automatic method for suspicious ROI selection within the breast using dynamic-derived information from DCE-MRI data.

Automatic segmentation of suspicious ROI in breast MRI images, image provided by Roberta Fusco of the National Cancer Institute of Naples Pascal Foundation, Naples/IT

Her algorithm includes three steps (Figure 2): (i) breast mask extraction by means of automatic intensity threshold estimation (Otsu Thresh-holding) on the parametric map obtained through the sum of intensity differences (SOD) calculated pixel by pixel; (ii) hole-filling and leakage repair by means of morphological operators: closing is required to fill the holes on the boundaries of breast mask, filling is required to fill the holes within the breasts, erosion is required to reduce the dilation obtained by the closing operation; (iii) suspicious ROIs extraction: a pixel is assigned to a suspicious ROI if it satisfies two conditions: the maximum of its normalized time-intensity curve should be greater than 0.3 and the maximum signal intensity should be reached before the end of the scan time. The first condition assures that the pixels within the ROI have a significant contrast agent uptake (thus excluding type I and type II curves) and the second condition is required for the time-intensity pattern to be of type IV or V (thus excluding type III curves).

Written by: Dror Nir, PhD

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Imaging-guided biopsies: Is there a preferred strategy to choose?

Posted in Bio Instrumentation in Experimental Life Sciences Research, CANCER BIOLOGY & Innovations in Cancer Therapy, Imaging-based Cancer Patient Management, Medical Devices R&D Investment, tagged biopsy needles, brain lesion, breast biopsy, breast cancer, breast cancer screening, directed biopsies, guided biopsies, health, http www youtube, Magnetic resonance imaging, magnetic tracking, mammography, medicine, open mri systems, prostat cancer screening, Prostate, Prostate biopsy, Prostate cancer, prostate guided biopsies, prostate hisoscanning, Prostate-specific antigen, tracking, Transrectal ultrasonography, ultrasound guided breast biopsy on September 29, 2012| 7 Comments »

Imaging-guided biopsies: Is there a preferred strategy to choose?

Author: Dror Nir, PhD

The most stressful period in a cancer patients’ pathway is from the moment they fail a screening test or present with suspicious symptoms to the moment they are diagnosed. Today’s medical guidelines require histopathology findings as the only acceptable proof: positive results mean you are a cancer patient, negative results mean, well…maybe you are and maybe you are not. You now enter into what might be a very long period, sometime years, of uncertainty regarding your health and prospects. And why?

Because the substance for histopathology is acquired by biopsies, and biopsies are known to be inaccurate. For example, breast and prostate biopsies fail to find 25% to 35% of the cancer lesions at the first biopsy session.

Therefore, it is not surprising that from the beginning of this procedure, medical practitioners look for ways to incorporate imaging into the workflow. In the last decade, significant progress has been made in the introduction of imaging-guided biopsies. The most common modalities were ultrasound and CT/mammography. Recently, as the industry solved the issues of magnetic field compatibility for biopsy needles and the introduction of open MRI systems, MRI-guided biopsies were also made possible.

Ultrasound-guided biopsies are by far the most commonly used procedure. Why? Because they can be often performed as an office-based procedure. Here are some interesting links to YouTube videos describing such procedures:

Prostate

Prostate Ultrasound and Prostate Biopsy by Dr. Neil Baum

Transrectal ultrasound (Trus) Biopsy of the prostate

Breast

Ultrasound-Guided Breast Biopsy

Breast Tissue Biopsy

The main advantages: they are easily accessible, low cost and quick. The disadvantages of these procedures are that they are very much operator dependent, rather than standardized, and there are no quality assurance guidelines attached. Efforts to standardize ultrasound-based biopsies and increase their efficiency are evident by recent introductions of ultrasound systems into the market , which support real-time guided biopsies and ultrasound applications that perform real-time biopsy tracking. But these systems are still far from being widely available. I will touch on this issue in my upcoming posts as I am part of these efforts.

CT and Mammography guided biopsies require more sophisticated equipment and well-trained operators. As an example:

Breast Biopsy – What To Expect

The main advantage: if you return to the same operator, the process is likely to be reproducible. The disadvantages are identical to that of ultrasound-based biopsies. It is worthwhile to note that, recently, radiologists who perform biopsies are required to go through a certification process. Still, such certification demands vary between the various radiology societies.

MRI-guided biopsies are an even more sophisticate and complex procedure:

Prostate:

DynaTRIM Video

DynaTRIM Intervention

An interesting quote from Dr. Hashim U. Ahmed, M.D., MRCS, Division of Urology Department of Surgery, University College of London (https://mail.google.com/mail/u/1/?shva=1#label/Work%2FLinks%2FAuntMinnie/139d9c5bc6bda842): “Advocating the widespread use of MRI before biopsy in a population of men with risk parameters for harboring prostate cancer has a number of advantages, which might ultimately benefit the care these men undergo. Increasing the detection of prostate cancer that requires treatment while avoiding biopsy – and hence unnecessary treatment – in those with insignificant or no cancer are compelling arguments for this approach.”

Breast

MRI Breast Biopsy – Diagnostic and Biopsy Services for Breast Evaluation

I recommend reading the following article regarding the use of Open MRI to guide freehand biopsies of breast lesions. Especially interesting is the discussion where the authors give a good description of the difficulties in breast biopsies they are trying to overcome in order to achieve good lesion sampling.

MR-guided Freehand Biopsy of Breast Lesions in a 1.0-T Open MR Imager with a Near-Real-time Interactive Platform: Preliminary Experience Frank Fischbach, MD, et. al

http://radiology.rsna.org/content/early/2012/08/14/radiol.12110981.full?sid=bd45ceb4-9c8d-4ffc-b80b-0345ee679b4e

The question remains: which biopsy procedure is the best? And does this question have one coherent answer, i.e. one that will satisfy the patients, the doctors and the health-care insurers? Will the answer to this question remain the subject of endless uncoordinated clinical studies?

If anyone who reads this post knows on methodological scientific or regulatory initiatives aimed at answering this question on a level of global guide lines I would appreciate his comment.

Written by: Dror Nir, PhD.