Sampling Prostate Cancer Tissue for Biobanking: An MRI-guided Targeted Technique to Remove Biopsy Punches from Fresh Tumor Tissue

After the specimen has been collected, sterilize the laminar flow hood and prostate-slicing apparatus with 70% ethanol, and weigh the prostate on a standard scale in grams. Then, paint the right side with blue ink and the left side of the specimen with black ink, covering the full capsule and seminal vesicles with ink to allow discrimination of the surgical margins.

To slice the prostate, place the tissue with the base and apex facing opposite walls of the apparatus with the posterior side down and the anterior side up. Place gold pins around the tissue specimen, pushing the prostate inward slightly, if necessary, to achieve a snug fit, and measure the prostate length from the base to the apex to compare this measurement to the prostate length as measured by MRI.

If the prostate has shrunk, adjust the anticipated slicing position by the appropriate percentage of the reduction. Next, measure from the base to the desired transverse slice and select the pin that sits closest to this measurement to slice around. Wearing chainmail gloves to prevent injury, place the blades of the slicing device on either side of the identified pin, and use the spacer to keep the blades 5 millimeters apart.

To acquire the slice, use long strokes to slowly but firmly move the blades downward, forward, and backward, confirming by feel that a full slice has been separated before disassembling the apparatus. Then, remove the walls and pins, and use gloves to carefully transfer the slice onto a sterile piece of corkboard.

After acquiring the specimen, visually inspect the transverse slice for comparison with the axial MRI image. In some cases, the tumor area may appear paler than the surrounding tissue. Palpate the transverse slice gently. The tumor may feel firmer than the surrounding tissue. Using the axial MRI image as a guide, select one or more areas for sampling, and use a 6-millimeter punch to push down on the tissue area of interest.

Twist the tissue punch on the spot and down against the cork to ensure a full separation, using a sharp scalpel to separate the biopsy sample from the specimen as necessary. When the sample has been acquired, remove the punch and use the plunger to eject the sample into the appropriate container for the subsequent downstream analysis.