Three-dimensional computer reconstruction of prostate cancer from radical prostatectomy specimens: evaluation of the model by core biopsy simulation.

OBJECTIVES

A technique was developed for three-dimensional (3D) modeling of prostate cancer and transrectal biopsies. To test the model, the cancer yield of a simulated 10-biopsy protocol was compared with a simulated sextant protocol and with preoperative biopsies regarding cancer detection and correlation with tumor volume.

METHODS

Transrectal ultrasound-guided core biopsies were taken from 81 men according to a standardized 10-biopsy protocol that included sextant biopsies. The patients underwent radical prostatectomy and specimens were step-sectioned and whole-mounted. Cancer and the prostate capsule were outlined on the slides and the regions transferred to a computer software program developed by our group. A 3D volume of each prostate was reconstructed from the sections. Virtual core biopsy needles imitating the positions of the real biopsies were inserted into the prostate and the cancer yield was calculated. Only the standardized positions were considered in this study (ie, additional biopsies from hypoechoic foci were not accounted for).

RESULTS

Of the cancers detected with 10 standardized virtual biopsies, 24% would have remained undetected with sextant biopsies. The cancer yield of 10 virtual biopsies correlated with the preoperative biopsies (r = 0.64) and with the tumor volume (r = 0.56). A multiple regression analysis showed that the cancer yield of a simulation of 10 biopsies correlated better with tumor volume than did a simulation of sextant biopsies (P = 0.02).

CONCLUSIONS

We conclude that computer-assisted 3D reconstruction of prostate cancer can be used as a model for evaluation and optimization of biopsy protocols.