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

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.

Inclusion Criteria:

1. Age 18 years of age or older.

2. Serum PSA between 4 and 10 ng/mL.

3. A diagnosis of prostate cancer based on extended (twelve core) random prostate biopsy
within three months prior to study entry.

4. Clinically localized prostate carcinoma i.e. TNM stage T2c or less.

5. The patient has elected to undergo radical prostatectomy to treat the prostate
carcinoma.

6. The patient consents to undergo a diagnostic transrectal ultrasound of the prostate
with elastography.

Exclusion Criteria:

1. Any contraindication to transrectal ultrasonography, including prior anorectal surgery,
inflammatory bowel disease, rectal fistula, or fissure-in-ano.