A Pilot Trial of Sonoelastography for Planning Tumor-targeted Prostate Biopsy

Overview

Prostate cancer is the most common cancer and the second-leading cause of cancer death amongst men in the United States. Sonoelastography is an imaging technology predicated on reproducible differences in the backscattered ultrasound signal produced by compression of tissues of varying stiffness. It permits measurement of the elastic properties of tissue. These measurements can be transposed onto conventional anatomic ultrasound images, producing a colorized overlay that allows direct visualization of the anatomic distribution of tissue stiffness. In this study, we aim to determine whether prostate biopsies planned with sonoelastographic guidance would be more likely than random prostate biopsies to intersect with foci of carcinoma in the prostate gland, and to determine whether prostate biopsies planned with sonoelastographic guidance would be more likely than random prostate biopsies to yield histopathology representative of the final Gleason Score obtained at pathologic assessment of the resected prostate.

Background and Significance Prostate cancer is the most common cancer and the second-leading cause of cancer death amongst men in the United States. Initially, tumors biopsy guided by detected by conventional B-mode transrectal ultrasound (TRUS). Unfortunately, prostate cancer had a highly variable ultrasound echo pattern and may be indistinguishable from normal prostate, and the sonographic appearance of BPH overlaps with that of prostatic carcinoma, which limited the accuracy of conventional ultrasound, producing sensitivity and specificity for prostate carcinoma of only 40-50%. There is therefore an urgent need for better localization and more accurate biopsy of prostate cancer. Sonoelastography is an imaging technology predicated on reproducible differences in the backscattered ultrasound signal produced by compression of tissues of varying stiffness. It permits measurement of the elastic properties of tissue. These measurements can be transposed onto conventional anatomic ultrasound images, producing a colorized overlay that allows direct visualization of the anatomic distribution of tissue stiffness. Previously, several studies have reported that the feasibility of sonoelastography to distinguish between benign and malignant nodules and thereby guide biopsy. These assessments were based on the change in anatomic appearance of nodules after compression with a transrectal ultrasound probe. However, these reports did not specify the criteria used to determine that lesions seen by elastography were the same lesions seen by histopathology, did not assess whether biopsies planned with the assistance of sonoelastography would have intersected with the foci of prostate cancer, and did not address the histopathologic characteristics of areas of the prostate that were falsely positive at sonoelastography. If sonoelastography were to more accurately delineate foci of tumor in the prostate than B mode ultrasound, and it could be used to guide biopsy, then there would be fewer missed cancers at biopsy. In addition, sonoelastography-guided biopsies may be more representative of the ultimate Gleason Score of the tumor. Specific Aims: Aim 1: To determine whether prostate biopsies planned with sonoelastographic guidance would be more likely than random prostate biopsies to intersect with foci of carcinoma in the prostate gland. Aim 2: To determine whether prostate biopsies planned with sonoelastographic guidance would be more likely than random prostate biopsies to yield histopathology representative of the final Gleason Score obtained at pathologic assessment of the resected prostate.