Diffusion imaging zeroes in on specific prostate-cancer sections

The advanced diffusion-weighted imaging technique RSI, short for restriction-spectrum MRI (RSI-MRI), is able to detect variations in tumor grade with voxel-level precision—and so could aid in customizing treatment of prostate cancer patients whose disease is spreading faster in some tumor regions than others. 

Clinical Cancer Research published the research behind the conclusion June 1.

RSI-MRI can distinguish individual pools of water within tissue based on their inherent diffusion characteristics, which makes the technique a good choice for directly measuring tumor cells in vivo.

In the new study, Ghiam Yamin MD, PhD, of UC-San Diego and colleagues looked at 10 post-prostatectomy cases, homing in on regions of tumor as identified by a uropathologist.

Grading tile grids according to voxel dimensions, they calculated a RSI-MRI cellularity index based on presurgical prostate MR scans.

In all, the team analyzed 2,795 tiles and found that the RSI-MRI cellularity index successfully distinguished between prostate cancer and benign tumor.

More telling, they found significant differences between benign tissue and prostate cancer classified as low-grade or high-grade, while RSI-MRI similarly differentiated between low and high-grade prostate cancer.

The authors note that their current findings are consistent with previous RSI-MRI studies involving whole tumors.

They conclude that, because RSI-MRI can detect variations in tumor grade with a reliably high degree of granularity, the technique “may become an option for planning targeted procedures where identifying the area with the most aggressive disease is important.”