Evaluation of TargetScan® Device in Prostate Cancer Detection

Introduction:

The Envisioneering TargetScan^® is a novel transrectal ultrasound (TRUS) device that uses a flexible needle to biopsy the prostate in a template fashion. First a computer algorithm identifies an ideal biopsy scheme using the measured dimensions of the prostate. The system then uses a fixed template that allows the physician to biopsy the prostate at specific locations and to target the same region of the prostate in the future if needed.

Methods:

We simulated the TargetScan® biopsy on 20 men who underwent radical prostatectomy for localized prostate cancer. The height, longitudinal length and transverse width of the specimen were measured. Using these dimensions, a computerized algorithm generated specific coordinates at which to biopsy the specimen. The specimen was then placed in the model and 12 cores were taken from the gland based on the template. In 14 specimens two separate surgeons biopsied the prostate at the same coordinates, for a total of 24 cores per gland. All TargetScan® biopsy specimens were sent to one pathologist (DGB) for review. The whole prostate specimen was step-sectioned to identify the locations of the cancer. The preoperative clinical biopsy data, TargetScan® biopsy data and final pathology data were compared. A Mann-Whitney rank sum test was used to compare the differences between two groups.

Results:

Table 1a: Quadrant detection analysis Number of quadrants with cancer 64/80 (80.0%) Number of quadrants TargetScan® detected cancer 31/64 (48.4%) Table 1b: Repeat Biopsy analysis Total number of cores biopsied by each surgeon 168 Total number of cores that contained cancer 38 Number of cores that matched on pathologic analysis 143/168 (85.1%) Number of cancer cores that matched on pathologic analysis 25/38 (65.8%)

The TargetScan® device detected prostate cancer in 16 and high grade PIN in an additional 2. Among the 4 patients whose cancer was not found on TargetScan® biopsy, 2 had cancer in less than 1% of the prostate. Figure 4 compares the mean number of positive biopsies on the TargetScan^® and clinical biopsies. Figure 5 shows the percent of cases that were up-graded, down-graded or were unchanged on final pathology using the TargetScan^® and clinical biopsies. Table 1 shows the reproducibility of the TargetScan® biopsy when more than 1 surgeon simulated it.

Conclusion:

The TargetScan^® device is a novel method for performing a template-guided transrectal prostate biopsy. The device better predicts final Gleason score when compared to conventional biopsy techniques and is reproducible. These findings suggest that the TargetScan® may allow more accurate identification and characterization of cancer (in terms of grade, location and size) than non-template clinical biopsies.