Imaging Enhances Prostate Cancer Tumor Targeting

Restriction spectrum imaging distinguishes between different prostate cancer tumor grades.

The potential use of restriction spectrum imaging (RSI) as a biomarker may help enhance magnetic resonance imaging (MRI) to be able to distinguish between different prostate cancer tumor grades.

RSI-MRI works by correcting magnetic field distortions in other imaging techniques, reported the study published in Clinical Cancer Research. Water diffusion within tumor cells that have a high nuclear volume fraction is the primary focus, and allows for imaging to accurately plot tumor location and differentiate between tumor grades.

Researchers found that RSI-MRI can be used as a guide for treatments to help target tumors that are of the highest grade.

“Noninvasive imaging is used to detect disease, but RSI-MRI takes it a step further,” said senior study author David S. Karow, MD, PhD. “We can predict the grade of a tumor sometimes without a biopsy of the prostate tissue. This is taking all that's good about multi-parametric MRI and making it better.”

Since 2014, more than 1000 patients at UC San Diego Health have been imaged using the RSI-MRI. A subset has also undergone MR-fused ultrasound guided prostate biopsy.

“Previously, we relied completely on systematic, but random, biopsies of the prostate to diagnose cancer, which has been the standard practice in our field for years,” said study co-author J. Kellogg. “Now, we use RSI-MRI to precisely target specific areas of concern and enhance the accuracy of our diagnosis. Greater accuracy means improved care tailored to each individual patient. With RSI-MRI, we are better able to identify which cancers are more aggressive and require immediate treatment, and which ones are slow growing and can be safely observed as part of a program called active surveillance.”

The current study included 10 patients to evaluate more than 2700 discrete data points. The next step is to implement technology into other hospitals to determine if it can be used in isolation from other screening tools.

Prior studies by the study authors found that RSI-MRI increases the ability of detection and is more successful used in isolation compared with traditional multi-parametric MRI.

The findings suggest that RSI-MRI could eventually be used as a stand-alone, non-contrast screening tool. The approach would take only 15 minutes, compared with 40 to 60 minutes that normal contrast-enhanced exams take.

“What our evidence shows so far is the imaging benefit is coming from RSI-MRI,” said senior study author David S. Karow, MD, PhD. “I think this technique could become standard of care and mainstream for the vast majority of men who are at risk for prostate cancer. Full contrast MRI is expensive and risky for most men. This is the kind of exam that could be done on a routine clinical basis.”

This imaging technology was initially created to characterize aggressive brain tumors, but now RSI-MRI has the potential to change how physicians approach cancer biopsies and treatments.

“RSI-MRI could be a transformational imaging technology for oncologists in the same way CT scans altered the way effects of treatment are quantitated from plain X-rays,” said Jonathan W. Simons, MD, Prostate Cancer Foundation president and Chief Executive Officer. “Based on the investigations at UC San Diego, this is a particular promise that needs more validation. Now testable is the hypothesis that RSI-MRI could identify oligometastatic prostate cancer that became curable through its identification by RSI-MRI.”