Shift to bp-MRI Cuts Exam Time and Increases Access, Enhances Patient Safety
A streamlined, contrast-free MRI approach boosts efficiency while preserving PI-RADS categorization
Prostate MRI plays a key role in assessing clinically significant prostate cancer, with radiologists assigning PI-RADS categories to convey the likelihood of clinically significant cancer.
Researchers at Dalhousie University in Halifax, Nova Scotia, Canada, implemented a change to the institution’s MRI protocol for assessing prostate cancer.
They moved from using a contrast-enhanced multiparametric MRI (mp-MRI) protocol to a non-contrast biparametric MRI (bp-MRI) protocol with defined recall criteria for intravenous (IV) gadolinium contrast.
“This decision was based on growing evidence that bp-MRI performs comparably to mp-MRI, given that IV contrast is only clinically significant for upgrading peripheral-zone PI-RADS 3 lesions to PI-RADS 4 when dynamic enhancement is present,” said John-David Brown, MD, from the Department of Diagnostic Radiology at Dalhousie. “The main driver of this institutional change was to improve access, a benefit highlighted in a recent study by Rehman et al. The primary goals of our study were to determine the recall rate of this new protocol and assess whether PI-RADS distribution changed.”
Removing IV contrast from the default protocol can enable faster exams that can be performed in more settings and with less dependence on the availability of an onsite radiologist, according to Dr. Brown.
At the same time, it reduces contrast-related risks and potentially lowers system costs while maintaining an accurate level of PI-RADS categorization.
Assessing the Impact of a bp-MRI Protocol Change
In the first part of their study, Dr. Brown and colleagues retrospectively reviewed consecutive 3T prostate bp-MRIs performed after the protocol change between April 2023 and May 2024.
“Of 554 exams, 547 met inclusion criteria,” he explained. “Thirty-six patients (6.6%) were recalled for IV contrast, and 91.7% (33/36) of those recalls were for PI-RADS 3 reassessment.”
Nearly half of the recalled PI-RADS 3 lesions (48.5%, 16/33) were upgraded to PI-RADS 4. The median time to recall was 35 days.
“Our findings add further support for adopting a prostate bp-MRI protocol with a recall system as a practical, patient-centered alternative to routine mp-MRI.”
— JOHN-DAVID BROWN, MD
In the second part of the study, the investigators compared 225 consecutive pre-implementation mp-MRI exams with 225 consecutive post-implementation bp-MRI exams. “We found no statistically significant difference in PI-RADS distribution before versus after implementation of the bp-MRI protocol with recall system,” Dr. Brown said.
This suggests that selective contrast recall can clarify equivocal lesions without changing overall risk stratification.
Because PI-RADS categorization remained stable after the switch, the team could shorten exams and simplify scheduling without sacrificing quality. This combination, and not the protocol change alone, is what ultimately expanded patient access by allowing more efficient use of scanner time and staff resources.
The need for contrast in routine prostate MRI is limited, Dr. Brown asserted. “In our study, 93.4% of patients (511/547) were spared IV contrast entirely.”
These findings are consistent with existing bp-MRI literature. “Replacing mp-MRI with bp-MRI did not shift PI-RADS distribution,” he confirmed.
Dr. Brown and his colleagues encourage other institutions to make the same change.
“Our findings add further support for adopting a prostate bp-MRI protocol with a recall system as a practical, patient-centered alternative to routine mp-MRI,” he said. “For patients, the advantages are clear: less contrast exposure, shorter appointments and improved access while maintaining PI-RADS categorization comparable to mp-MRI.”
For More Information
Access the Abdominal Imaging study, “Implementation of a biparametric prostate MRI protocol with a recall system for intravenous contrast: an analysis of recall rates and comparison of PI-RADS category distribution.”
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