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Posts Tagged ‘MRI – US image fusion’


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

Reporter: Dror Nir, PhD

This year’s AUA takes place in San Diego, USA.

Wednesday, May 08, 2013 10:30 AM-12:30 PM
SDCC: Room 8
Prostate Cancer: Detection & Screening (V)
Moderated Poster
Funding: none
2209: “Histoscanning”- aided template biopsies for patients with previous negative TRUS biopsies.
Oleg Apolikhin; Andrey Sivkov; Gennady Efremov; Nikolay Keshishev; Oleg Zhukov; Andrey Koryakin

Abstract: 2209
Introduction and Objectives
One of the biggest problems in the diagnosis of prostate cancer (PCa), which distinguishes it from many other solid tumors, is the difficulty of tumor imaging by means of standard visualization techniques. A transrectal ultrasound (TRUS) biopsy is mostly performed on the basis of risen PSA and is often blind – tissue specimens are taken from standard zones. Biopsy under MRI control is technically and logistically complicated and expensive, while TRUS can`t always differentiate the suspicious areas. A TRUS-based innovative technique, “Histoscanningâ€� is used in our centre for PCa identification and targeted biopsy.

Methods
Prior to template biopsy we have performed Histoscanning to 31 patients, with previous one to six negative TRUS biopsies and persistent clinical suspicion of PCa (elevated PSA, high-grade prostatic intraepithelial neoplasia (HPIN) in 4 cores or suspicious TRUS findings). Age range was 51 – 75, with PSA values 3,8 – 14,3 ng/ml. Prostate size range 22-67cc. Most of the patients (n-26) from this group received therapy with 5α-reductase inhibitors for 6 months or more. Depending on the gland size, 10-14 standardized cores were taken + 4 additional cores from the suspicious zones marked on Histoscanning report.

Results
Histopathology identified PCa in 13 out of 31 patients , adenocarcinomas with Gleason score ranging 6-8. In 11 patients with no signs of PCa we found HPIN or low-grade PIN. Comparing histology reports with Histoscanning mapping, in 8 PCa cases we found high correlation of this method with histopathological study on the amount and location of tumor lesions and in 5 cases Histoscanning showed greater spread of lesions, with good correlation of the tumor location.

Conclusions
Due to the effectiveness, ease of use and the short time required for data processing, Histoscanning is a promising method for more effective targeted biopsy of the prostate.

As a result of ongoing research, we aim to evaluate sensitivity and specificity of the method, fuse it with MRI, to create a 3D model for biopsy or surgery. In the future, this data could be used for decision making on the nerve-sparing prostatectomy and minimally invasive focal treatments such as cryoablation, high-intensity focused ultrasound, radiofrequency or laser ablation.

Date & Time: May 8, 2013 10:30 AM
Session Title: Prostate Cancer: Detection & Screening (V)
Sources of Funding: none

Personal note:

On the authors’ intention to fuse HistoScanning with MRI: The authors report a very compelling clinical benefit just from using HistoScanning for guiding their biopsies. HistoScanning itself results in a 3D mapping of the prostate and the suspicious locations inside.

3D mapping of the prostate by HistoScanning analysis following motorised TRUS. the colored locations represents tissue suspicious for being cancer.

3D mapping of the prostate by HistoScanning analysis following motorised TRUS. the colored locations represents tissue suspicious for being cancer.

Fusing ultrasound & MRI images is prone to image-registration errors (e.g. due to differences in the prostate’s shape-distortion by the probe) which are larger than the accuracy sought for when performing biopsy or nerve-sparing surgery. I recommend anyone who wishes to guide biopsies and treatment based on MRI and therefore is in need for good level of localized-MRI interpretation, to rely on dedicated MRI interpretation applications and not intra-modalities image fusion.

In addition, major benefits of using HistoScanning for managing prostate cancer patients are the accessibility; A urologist can perform himself, at any time he chooses and at any place, simplicity; it only requires routine TRUS, patient-friendly; it lasts less than a minute and does not require anesthesia and low-cost; it’s ultrasound! Mixing HistoScanning with MRI will certainly eliminate these.

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Last week, I came across an interesting abstract related to work that is carried-out in UCLA for several years now by Prof. Lenny Marks. Lenny participated to the development of “Artemis”. Artemis is a system that is adjunct to ultrasound and performs 3D Imaging and Navigation for Prostate Biopsy by Eigen. I thought that this deserves a complementary post to Imaging-guided biopsies: Is there a preferred strategy to choose? which I posted few weeks ago

Artemis

When men present with risk parameters for harboring prostate cancer, they are advised to undergo a transrectal ultrasound guided prostate biopsy (TRUS biopsy). Over one million biopsies are carried out in the USA ever year.

The indications for a prostate biopsy in the USA are:

·         Raised PSA above 2.5ng/ml

·         Raised age-specific PSA

·         Family history of prostate cancer

·         High PSA density > 0.15ng/ml/cc

·         High PSA velocity> 0.75 ng/ml/year or doubling time ❤ years

·         Abnormal digital rectal examination

Overall, men undergoing systematic trans-rectal ultrasound (TRUS) guided biopsy of 12 cores of prostatic tissue have approximately 1 in 4 probability of being diagnosed with prostate cancer. Of these, about half are diagnosed with low risk disease. A known problem with the current practice of TRUS biopsy, is that it is performed blind – the operator does not know where the cancer is. Therefore, many low risk cancers that do not need treating are detected and many high risk cancers are missed or incorrectly classified.

The abstract below is reporting the results of a clinical study, aimed to evaluate the potential added value in using Artemis and ultrasound-MRI image fusion when performing TRUS biopsies, as a method and system to allow urologists to progress from blind biopsies to biopsies, which are mapped, targeted and tracked.

Image fusion is the process of combining multiple images from various sources into a single representative image. Ultrasound is the imaging modality used to guide Artemis in performing the biopsies. In this study MRI is used to overcome the “blindness” regarding tumor location. More on MRI’s cancer detection reliability  can be found in my posts Imaging-guided biopsies: Is there a preferred strategy to choose? and Today’s fundamental challenge in Prostate cancer screening.

Source

Curr Opin Urol. 2013 Jan;23(1):43-50. doi: 10.1097/MOU.0b013e32835ad3ee.

MRI-ultrasound fusion for guidance of targeted prostate biopsy.

Marks LYoung SNatarajan S.  Department of Urology, David Geffen School of Medicine bCenter for Advanced Surgical and Interventional Technology, University of California, Los Angeles, Los Angeles, California, USA.

Abstract

PURPOSE OF REVIEW:

Prostate cancer (CaP) may be detected on MRI. Fusion of MRI with ultrasound allows urologists to progress from blind, systematic biopsies to biopsies, which are mapped, targeted and tracked. We herein review the current status of prostate biopsy via MRI/ultrasound fusion.

RECENT FINDINGS:

Three methods of fusing MRI for targeted biopsy have been recently described: MRI-ultrasound fusion, MRI-MRI fusion (‘in-bore’ biopsy) and cognitive fusion. Supportive data are emerging for the fusion devices, two of which received US Food and Drug Administration approval in the past 5 years: Artemis (Eigen, USA) and Urostation (Koelis, France). Working with the Artemis device in more than 600 individuals, we found that targeted biopsies are two to three times more sensitive for detection of CaP than nontargeted systematic biopsies; nearly 40% of men with Gleason score of at least 7 CaP are diagnosed only by targeted biopsy; nearly 100% of men with highly suspicious MRI lesions are diagnosed with CaP; ability to return to a prior biopsy site is highly accurate (within 1.2 ± 1.1 mm); and targeted and systematic biopsies are twice as accurate as systematic biopsies alone in predicting whole-organ disease.

SUMMARY:

In the future, MRI-ultrasound fusion for lesion targeting is likely to result in fewer and more accurate prostate biopsies than the present use of systematic biopsies with ultrasound guidance alone.

Written by: Dror Nir, PhD.

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