Detection and localization of prostate cancer with the targeted biopsy strategy based on ADC Map: A prospective large-scale cohort study

The Ideal Biopsy protocol to perform to detect all, or at least the majority of, prostate cancers has been a controversial topic, and subject to considerable change in the modern biopsy era. Ultrasound-guided prostate biopsies to take six cores were first recommended. Since the late 1990s, this recommendation was changed to 10–12 cores, on the basis of data showing that the more-extensive biopsies resulted in the detection of 30 % more cancers than the conventional sextant biopsy (1, 2). Saturation biopsies might be advised in patients with repeated negative results from standard biopsies and for whom persistent suspicion of prostate cancer exists on the basis of PSA level (1). Correlation studies comparing biopsy results to those obtained from radical prostatectomy specimens (3, 4) or autopsied material (5, 6) have raised main issues that cancers are frequently missed on initial biopsy and are mischaracterized in terms of size, location and grade. Anterior portion seems to be very special in the detection of cancer, because anterior portion cancers could be missed by standard peripheral zone biopsies (7) and require additional sets of biopsies before detection (8). Together with the aid of novel imaging technique, suspicious foci could be sampled through targeted prostate biopsies, which could increase cancer detection rate and improve characterization. MR imaging of the prostate gland with endorectal coil or pelvic phased array coil has been widely used to detect and localize malignant lesions which mainly occurs in the peripheral zone (9, 10). Although some studies demonstrated the added value of T2-weighted MR imaging and MR spectroscopy in localizing prostate cancer compared with endorectal ultrasonography (10, 11), MR imaging has been generally considered inadequate for use in the evaluation of transition zone cancers because of heterogeneous T2 signal intensity in the normal transition zone(12). Recently, several investigators have reported the potential usefulness of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) map for detecting prostate cancer, which shows lower ADC than a normal peripheral zone and a nonmalignant transition zone (13–15). In this prospective large-scale cohort study, we aimed to present the usefulness of targeted biopsy strategy based on ADC maps in the detection and localization of prostate cancer.