Invited Review: A neuromuscular clinician's guide to magnetic resonance neurography-Link to Article

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Magnetic resonance neurography (MRN) is increasingly used in clinical practice to assess peripheral nerve disorders. This technology optimizes MR imaging to enhance visibility of nerve anatomy and pathology. The primary MRN sequence features a high-resolution, heavily T2-weighted fluid-sensitive approach on a 3.0 Tesla magnet system, which effectively highlights nerve structures against surrounding tissues. Additional techniques like diffusion-weighted imaging (DWI) may be employed for specific disease characterization, while gadolinium-based contrast can be used for image enhancement and better disease evaluation.<br /><br />On fluid-sensitive sequences, a normal peripheral nerve displays an iso- to slightly hyperintense signal compared to skeletal muscle, retaining a consistent trajectory and architecture. Peripheral nerve abnormalities show variations in signal, size, and architecture, which provide insights into different underlying conditions. Although some MRN findings like nerve hyperintensity are nonspecific, certain diagnoses such as benign peripheral nerve tumors or high-grade nerve injuries can be determined with high certainty based on MRN imaging.<br /><br />Peripheral nerve imaging with MRN relies on high spatial resolution and soft tissue contrast, favoring 3 Tesla systems for enhanced results. Normal peripheral nerves show distinct fascicular architecture and course with minimal fat within the epineurium. Skeletal muscles can also be evaluated for changes indicative of denervation, presenting as altered signal intensities.<br /><br />MRN offers significant advantages for noninvasive assessment of nerve conditions, but it does have limitations, such as high costs and inability to distinguish certain nerve pathologies from one another. A systematic approach to MRN can enhance diagnostic accuracy and patient care by clearly identifying structural causes of neuropathy and effectively differentiating tumor types in peripheral nerve tumors. However, improvements are still needed for better characterization of long-segment nerve abnormalities.

Keywords

Magnetic resonance neurography

Peripheral nerve disorders

MR imaging

T2-weighted

Diffusion-weighted imaging

Gadolinium-based contrast

3 Tesla magnet

Nerve abnormalities

Noninvasive assessment

Diagnostic accuracy