By using MRI scans in addition to CT scans, radiation oncologists can identify the blood vessels that control erectile function and plan treatment to target the prostate more precisely, sparing those nearby vessels.

"As we treat younger men, erectile function is an important concern. We're often treating men in their 50s, and this is a very important issue for them. Most of the men I see are going to be cured. Once you start curing cancers at an extremely high rate, then the focus moves to quality of life,” says Patrick W. McLaughlin, M.D., clinical professor of Radiation Oncology at the University of Michigan Medical School.

The erectile dysfunction is most commonly caused by a problem in the blood vessels, and doctors know that radiation causes obstruction of the vessels that fall within the treatment area. Using that as a starting point, the team began investigating radiation-related erectile dysfunction as a blood vessel problem.

Typically, radiation oncologists rely on a CT scan to identify the prostate and plan treatment. But because of limitations in the CT scan, the images do not show the bottom of the prostate. Doctors instead estimate where the prostate ends, based on average distance from identifiable structures.

By using more precise MRI images, the team was able to plan treatment more accurately. Preliminary results suggest that avoiding the vessels prevents erectile dysfunction.

"Because we can't see any detail of this area on CT scans, we just assume if we treat below the prostate it's no big deal. But it is a big deal. There is no cancer below the prostate, but there are critical structures related to erectile function as well as urine sphincter function. Treating below the prostate may result in needless problems,” McLaughlin says. "I don't have much doubt from what I've seen that this approach is likely to have huge impact.”; Source: University of Michigan Health System