Image visibility of cancer to enhance targeting precision and spatial mapping biopsy for focal therapy of prostate cancer.

Abstract

To assess the advantages of cancer image visibility when using multiparametric transrectal ultrasonography (TRUS) in potential candidates for focal therapy for prostate cancer. A total of 93 potential candidates for focal cryotherapy underwent grey-scale and Doppler TRUS-guided biopsy. All real-time TRUS images were recorded, allowing subsequent reviewing for the planning of targeted focal cryotherapy, and/or follow-up targeted biopsy. The spatial mapping of TRUS-visible lesions and targeted sampling areas were individually documented in schematic anatomic drawings of the prostate. Data from the baseline imaging-targeted biopsies were compared with systematic (non-targeted) biopsies. Of the 93 patients, 73 patients with low- to intermediate-risk disease were eventually considered to be candidates for hemi-ablative focal cryosurgery, i.e. cryoablation of one lobe. Among the 93 patients, a total of 681 biopsy cores were available for analysis, including imaging-targeted (n = 256, 37.5%) and systematic (n = 425, 62.5%) cores. Of the 256 targeted biopsy cores, 65% (n = 167) were positive for cancer, compared with 6.2% (26/425) in systematic (non-targeted) cores (P < 0.001). A total of 88% (82/93) of the biopsy-proven cancer index lesions were TRUS-visible. When comparing TRUS-visible with image-invisible index lesions, the cancer-involved core length was 6.1 vs 1.5 mm (P < 0.001), respectively. Furthermore, the percent of core with involved cancer was 48 vs 16% (P < 0.001), and the mean Gleason score was 7.0 vs 6.2 (P < 0.001). With increasing TRUS-visible lesion size (<10, 11-15, 16-20, >20 mm), cancer-involved core length and percent of core with cancer also significantly increased (P = 0.009 and P = 0.008, respectively). TRUS-guided targeted biopsies significantly improved the detection and staging of higher grade and larger volume cancer, compared with image-blind (non-targeted systematic) biopsies. Image visibility enhanced the precise targeting and accurate spatial mapping of cancer to help identify more appropriate candidates for focal therapy.