Optimizing Contrast‐Enhanced Magnetic Resonance Neurography of the Brachial Plexus With Delayed Scanning

Abstract

ABSTRACT Background Contrast‐enhanced magnetic resonance neurography (ceMRN) can enhance brachial plexus visualization and quality of imaging. However, the interval between contrast injection and scanning that provides the highest‐quality images is not known. Methods Fifteen patients underwent brachial plexus imaging using the 3D T2‐NerveView sequence with a scanning duration of 5 min. A consecutive six‐phase scan was initiated immediately at the start of contrast agent injection. Subsequently, all patients' images were classified into six groups according to the phases: group A (phase 1, delay 0 min), group B (phase 2, delay 5 min), group C (phase 3, delay 10 min), group D (phase 4, delay 15 min), group E (phase 5, delay 20 min), and group F (phase 6, delay 25 min). The image quality in each group was assessed based on nerve signal (signalnerve), muscle signal (signalmuscle), lymph node signal (signallymph node), background noise (BN), signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and subjective score. Results Signalnerve, signalmuscle, BN, and SNR did not significantly differ among the six groups (p > 0.05). However, significant differences (p < 0.05) were observed in signallymph node (F = 16.067), CNR (F = 9.495), and subjective score (χ2 = 23.586). As the scanning delay increased, signallymph node intensity gradually increased whereas the CNR gradually decreased. The subjective score was significantly higher in groups B (4.83 ± 0.24), C (4.90 ± 0.21), D (4.87 ± 0.30), E (4.83 ± 0.31), and F (4.83 ± 0.31) than in group A (4.47 ± 0.30). Conclusion We recommend performing brachial plexus ceMRN 5 min after contrast injection. With this delay, the brachial plexus can be visualized optimally with minimal interference from background signals.

Keywords

• brachial plexus
• compressed sensing
• delayed scanning
• image quality
• magnetic resonance neurography