Transrectal ultrasound is a tool commonly used to guide the placement of the needle during prostate biopsies, but now there's a better way.

A biopsy, you will remember, is the procedure whereby your urologist gets a sample of your prostate tissue when he suspects you may have prostate cancer. It usually involves inserting a thin needle through your rectum, urethra or perineum.

The problem with ultrasound is that it cannot easily distinguish cancerous tissue from healthy tissue. In fact, needles guided by transrectal ultrasound miss potentially aggressive high-grade tumors a full 40 percent of the time.

Biomedical engineers have addressed this deficiency by adding high-resolution pictures of the prostate made by a newer technology called multi-parametric magnetic resonance imaging (MP-MRI) into the mix. Prostate tumors show up on MP-MRI as dark spots, and by adding MP-MRI images taken beforehand to the real-time ultrasound images, urologists can target suspicious regions of the gland while steering clear of healthy tissue. Engineers call this enhanced-tech procedure a “fusion-guided biopsy.” It was first written about extensively in the Journal of the American Medical Association (JAMA) in January of 2015.

To create an image of your prostate, you will be placed on an MRI table and a special device called a coil will be inserted into your rectum directly under the prostate.  A balloon tip on the coil will be inflated to hold the coil in place. A series of images will be taken of the prostate and surrounding area. Contrast, which is a special MRI dye, will be given by IV near the end of the exam. The exam takes about 45 minutes to an hour. After all of the images are acquired, the coil balloon will be deflated and removed.

A radiologist will review the images and construct a 3-dimensional picture of your prostate indicating where suspicious lesions for cancer may be. This image will then be over-layed upon the “live” transrectal ultrasound during the actual biopsy procedure.

In an editorial accompanying the JAMA article, Lawrence H. Schwartz, of the Columbia University College of Physicians and Surgeons, and Ethan Basch, a medical oncologist at the University of North Carolina and an associate editor of JAMA, wrote that fusion-guided biopsy promises “more appropriate treatment recommendations, such as higher-intensity treatment for high-risk disease and active surveillance for men with low-grade tumors.”