Magnetic Resonance Neurography: Improved Diagnosis of Peripheral Neuropathies

Abstract

Peripheral neuropathies account for the most frequent disorders seen by neurologists, and causes are manifold. The traditional diagnostic gold-standard consists of clinical neurologic examinations supplemented by nerve conduction studies. Due to well-known limitations of standard diagnostics and atypical clinical presentations, establishing the correct diagnosis can be challenging but is critical for appropriate therapies. Magnetic resonance neurography (MRN) is a relatively novel technique that was developed for the high-resolution imaging of the peripheral nervous system. In focal neuropathies, whether traumatic or due to nerve entrapment, MRN has improved the diagnostic accuracy by directly visualizing underlying nerve lesions and providing information on the exact lesion localization, extension, and spatial distribution, thereby assisting surgical planning. Notably, the differentiation between distally located, complete cross-sectional nerve lesions, and more proximally located lesions involving only certain fascicles within a nerve can hold difficulties that MRN can overcome, when basic technical requirements to achieve sufficient spatial resolution are implemented. Typical MRN-specific pitfalls are essential to understand in order to prevent overdiagnosing neuropathies. Heavily T2-weighted sequences with fat saturation are the most established sequences for MRN. Newer techniques, such as T2-relaxometry, magnetization transfer contrast imaging, and diffusion tensor imaging, allow the quantification of nerve lesions and have become increasingly important, especially when evaluating diffuse, non-focal neuropathies. Innovative studies in hereditary, metabolic or inflammatory polyneuropathies, and motor neuron diseases have contributed to a better understanding of the underlying pathomechanism. New imaging biomarkers might be used for an earlier diagnosis and monitoring of structural nerve injury under causative treatments in the future.

Quantitative magnetic resonance neurographic characterization of peripheral nerve involvement in manifest and pre‐ataxic spinocerebellar ataxia type 3

“…Tibial fascicles of the left sciatic nerve and their distal continuation as tibial nerve with coverage from the proximal thigh down to the distal ankle were segmented on 140 axial slices/ participant generated by sequence (2) by one neuroradiologist (J.K.) blinded to clinical data. To exclude significant side differences, the tibial nerve was additionally segmented on 35 axial slices at the right mid to distal thigh, a region where previous studies predominantly identified nerve lesions in different neuropathies [7,[14][15][16].…”

Diffusion Tensor Imaging Evaluates Effects of Acupoint Injection at Zusanli (ST36) for Type 2 Diabetic Peripheral Neuropathy

“…MRN technology can evaluate peripheral nerves with a diameter of 2 mm and above and identify the fine structure of peripheral nerves [ 7 ]. Among the sequences, DTI is a noninvasive functional MR technology developed on the basis of diffusion-weighted imaging to display the fine structure of tissues [ 23 ].…”

“…Magnetic resonance neuroimaging (MRN) can obtain high-resolution 3-dimensional images of nerve fibers, which can provide a basis for the diagnosis of peripheral neuropathy [ 7 ]. Traditional neuro-electromyography has poor diagnosis efficiency of nerve lesions and is highly subjective.…”

Magnetic resonance tractography of the brachial plexus: step-by-step

“…Also, the MRN method provides an excellent and accurate 3D anatomy of the peripheral nerves. However, MRN is challenging due to various factors such as insufficient suppression of vascular signals, spatial resolution, subject motion, insufficient fat-signal suppression and surrounding structures involved in the quality of the acquired data ( 44 , 45 ). With respect to this, the conventional 3D-T2-STIR MRN cannot visualize the neighboring vessels and therefore it cannot assess their involvement in brachial plexopathy.…”