MR Neurography of Fine-Caliber Nerves: Technical Considerations and Practical Applications.

MR neurography (MRN) is a powerful tool for evaluating peripheral nerve disorders, traditionally focused on larger nerves like the sciatic nerve, lumbosacral plexus, and brachial plexus. With advances in hardware and software and improved vascular signal suppression, MRN enables reliable assessment of fine-caliber nerves-defined as those with a diameter of up to 6 mm. The small size, variable anatomy, and proximity to vessels and soft-tissue lesions make imaging of such nerves particularly challenging at routine MRI. The authors focus on MRN of fine-caliber nerves throughout the body, offering technical guidance and case-based examples for practical applications. The MRN protocol should include high-resolution two-dimensional and three-dimensional (3D) isotropic acquisitions, with a tailored field of view and appropriate coil selection. Vascular signal suppression is critical and can be achieved using noncontrast or contrast-enhanced techniques, such as postcontrast short τ inversion-recovery (STIR) or steady-state sequences. Sequence optimization, considering parameters like echo time, fat suppression, spatial resolution, and echo train length, is essential to improve nerve conspicuity. A structured approach to imaging and reporting the most clinically relevant fine-caliber peripheral nerves is presented, highlighting protocol suggestions, key anatomic landmarks, and common lesion sites. By applying dedicated imaging protocols with advanced 3D techniques, radiologists can enhance detection of fine-caliber nerve lesions and provide more confident imaging guidance for clinical decision making and treatment planning. ©RSNA, 2026 Supplemental material is available for this article.