Comparison of Different Sequences of Magnetic Resonance Imaging and Ultrasonography with Nerve Conduction Studies in Peripheral Neuropathies.

Background: Peripheral neuropathies refer to a group of disorders in which there is damage to the nerves of the peripheral nervous system. Electrophysiologic studies are the main stay for the diagnosis of peripheral neuropathies. However, direct visualization of the nerves is possible with exact localization of site of disease with high-resolution ultrasonography (USG) and 3-Tesla magnetic resonance imaging (MRI) scanner, and newer magnetic resonance (MR) sequences.
Methods: We performed a cross-sectional study including 55 patients and 64 nerves with upper limb peripheral neuropathies. All patients included underwent high-resolution focused USG of the nerves and MR neurography. A nerve conduction velocity study was performed for reference.
Results: The diagnostic confidence of the turbo spin echo T2-weighted (T2W) MR sequence was seen to be highest, with a sensitivity of 95.31%, whereas it was 81.25% for USG. Continuity of the nerve in patients with traumatic neuropathy was seen in 65.7% and 62.86% (22/35) nerves on MRI and USG, respectively. T1-weighted and T2W MR sequences were seen to be equally effective in establishing the continuity of the nerve. Increase in the caliber/thickening was seen in 77% of cases on MRI and 73.8% of cases on USG. Neuroma formation was seen equally on both MR and USG in 60.66%. We consistently found low fractional anisotropy (FA) values at the site of disease.
Conclusions: USG is a sensitive technique to diagnose peripheral neuropathies and it should be used as a screening modality for focused MR to be performed later. Turbo spin echo T2W fast spin has the highest sensitivity to identify nerve disease and is comparable with nerve conduction studies. Among the newer sequences, diffusion tensor imaging should be performed to increase diagnostic confidence.
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