Short MRI Protocol Could Be Alternative for Prostate Cancer Follow-Up

Using a short, bi-parametric MRI protocol without contrast can help radiologists detect twice as many clinically significant prostate cancers as prostate-specific antigen (PSA) testing.

In a study published Feb. 11 in JAMA Oncology, investigators from Imperial College London in the United Kingdom pointed to the potential of bi-parametric MRI as another imaging option for population-based prostate-cancer screening.

“These findings suggest that a short, non-contrast MRI may have favorable performance characteristics as a community-based screening test,” said the team led by David Eldred-Evans, MBBS, from the Imperial College London department of surgery and cancer.

Men who have elevated PSA frequently require additional imaging, such as a multi-parametric MRI scan that offers high accuracy for prostate cancer detection. But, the scans can take between 30 minutes-to-40 minutes. Alternatively, bi-parametric MRI (bpMRI) protocols do not use contrast, and it can truncate the scan to roughly 15 minutes. Alongside the shorter scan time, bpMRI also eliminates the need to expose patients to gadolinium, the team said.

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To explore the feasibility and efficacy of bpMRI – and the use of ultrasound for prostate cancer screening – Eldred-Evans’ team pulled data from the Imperial Prostate 1 Prostate Cancer Screening Trial (IP1 PROSTAGRAM) and used it to compare the effectiveness of bpMRI and ultrasound to PSA testing. Trial data came from seven primary care practices and two imaging centers throughout the United Kingdom and included 408 men who underwent prostate cancer screening between October 2018 and May 2019.

As part of the trial, men were screened with a PSA test, a B-mode and shear-wave elastography ultrasound, and a 15-minute non-contrast bpMRI. Researchers identified prostate test scores of at least 3μg/L as positive, and bpMRI scores of 3-to-5 (on a 5-point scale) and ultrasound scores of 4-to-5 were also considered positive. They conducted biopsies on all positive results, giving clinically significant cancers a Gleason score of 7 or more.

Based on this analysis, the team discovered both bpMRI and ultrasound produced clinically significant outcomes. Exams using bpMRI with 3-to-5 scores resulted in more positive results than did PSA testing – 72 to 40, respectively. Ultrasound exams performed similarly, resulting in 96 positive results compared to PSA’s 40. However, the results of these tests with 4-to-5 scores were not statistically significant when compared to PSA. Those bpMRI and ultrasound studies produced roughly an equivalent number of positive exams – 43 to 40 for MRI and 42 to 40 for ultrasound.

Ultimately, the team said, mpMRI exams that had 3-to-5 scores and 4-to-5 scores detected twice as many clinically significant cancers as did PSA screening. When looking at over-diagnosis, the rate of identification for insignificant cancers was comparable between MRI and PSA, but the rate for ultrasound was nearly double.

In an accompanying editorial, experts from Massachusetts General Hospital said these results set the stage for additional investigations on how imaging can be used for population-based prostate cancer screenings. The findings indicate that MRI will play an important role, said Susanna Lee, M.D., Ph.D., associate professor of radiology, and Aileen O’Shea, MBBCh BAO, clinical fellow in radiology.

“[The team’s] findings clearly point to prostate MRI as a promising screening test. Future trials should be designed to include MRI in the prostate cancer screening strategy with image acquisition and interpretation protocols that are widely accessible, well tolerated, and readily generalizable,” they said. “In the long run, if successful, prostate MRI will be able to join mammography and low-dose computed tomography of the thorax as an imaging screening test that saves lives and improves the health of the general population.”

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