Figure 2.

Diagrams of pathologic sectioning protocol overlaid on a coronal (a) and axial (b) T₂w image. After placing the prostate in the sectioning box, the first cut made is approximately 0.6 mm from the apex of the gland to create the apical section, with successive axial cuts 3mm apart moving towards the base. The axial cross-sections are designated by letters “A”, “B”, “C”, etc., depending on the size of the prostate, with “A” being the most apical slice. Slices are divided into four quarters (b). Each quarter is labeled based on the letter of the slice from which it comes and its position in the slice (e.g. anterior/posterior = A/P and right/left = R/L). After removal from the box, the apical portion is sectioned in 2mm intervals with parallel cuts emanating from the urethra. The sections near the urethra are labeled “RDUMA” (right distal urethral margin A) and “LDUMA” (left distal urethral margin A). The next two sections from the center are then labeled “RDUMB” and “LDUMB”, etc. This process continues out to the lateral margins of the apical section. Each slice section is then embedded in a paraffin block and one 4-micrometer H&E-stained slide is prepared from each section and digitized. A pathologist then digitally annotates the prostate capsule (red contour) and cancer regions (brown contour) on each slide (c). Slides from a complete axial slice are then manually assembled into a PWM by aligning the capsule annotations of the quartered pathology sections to form a continuous capsule while minimizing the overlap of tissues between the combined sections (d).