Objective: To determine the utility of intravenous contrast in magnetic resonance neurography (MRN).
Materials and methods: A search of our PACS for MRN studies performed in 2015 yielded 74 MRN exams, 57 of which included pre- and post-contrast images. All studies were independently reviewed by 3 musculoskeletal radiologists with peripheral nerve imaging experience for presence/absence of nerve pathology, presence/absence of muscle denervation, and contrast utility score based on a 4-point Likert scale. The medical record was reviewed for demographic and clinical data.
Results: The mean contrast utility score across all readers and all cases was 1.65, where a score of 1 indicated no additional information and a score of 2 indicated mild additional information/supports interpretation. The mean contrast utility score was slightly higher in cases with a clinical indication of amputation/stump neuroma or mass (2.3 and 2.1 respectively) and lower in cases with a clinical indication of trauma (1.5). The mean contrast utility score was lowest in patients undergoing MRN for pain, numbness, and/or weakness (1.2).
Conclusion: Intravenous contrast provides mild to no additional information for the majority of MRN exams. Given the invasive nature of contrast and recent concerns regarding previously unrecognized risks of repetitive contrast exposure, assessment of the necessity of intravenous contrast in MRN is important. Consensus evidence-based practice guidelines regarding intravenous contrast use in MRN are necessary.
Keywords: Intravenous contrast; MR neurography; MRI; Peripheral nerve.