Figure 4a. Biopsy-proved Gleason grade 8 adenocarcinoma in a 71-year-old man with a PSA level of 5.65 ng/mL. (a, b) T2-weighted axial MR image (a) and T2-weighted coronal MR image (b) show that the dominant tumor (T) within the left peripheral zone extends from the apex to the base. Obliteration of the left rectoprostatic angle (arrow in a) is indicative of extracapsular extension. (c) On the spectra from 1H MR spectroscopy, voxels marked with * show an increase in choline (Ch/Cr) and a marked decrease in or absence of citrate (Cit); these voxels correspond to the low-signal-intensity region on the axial MR image (a). The metabolic profile is indicative of a high-grade tumor. Findings at surgery and histopathologic examination helped confirm a large Gleason grade 8 tumor with extracapsular extension (stage T3a).