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

Abstract

Objective: To assess the advantages of cancer image visibility when using multiparametric transrectal ultrasonography (TRUS) in potential candidates for focal therapy for prostate cancer.

Patients and methods: 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.

Results: 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).

Conclusions: 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.