Abstract
Background High-resolution ultrasound (HRUS) and magnetic resonance neurography (MRN) are considered
complementary to clinical and neurophysiological assessment for neuropathies.
Aims The aim of our study was to compare the accuracy of HRUS and MRN for detecting various
peripheral nerve pathologies, to choose the correct investigation to facilitate prompt
patient management.
Materials and Methods This prospective study was done using HRUS with 14 MHz linear-transducer and 3 or
1.5T MR in cases referred for the assessment of peripheral nerve pathologies. Image
interpretation was done using a scoring system (score 0–3 confidence level) to assess
for nerve continuity/discontinuity, increased nerve signal/edema, fascicular change,
caliber change, and neuroma/mass lesion. We determined the accuracy, sensitivity,
and specificity of these modalities compared with the diagnostic standard determined
by surgical and/or histopathological, if not performed then clinical and/or electrodiagnostic
evaluation.
Results The overall accuracy of MRN was 89.3% (specificity: 66.6%, sensitivity: 92.6%, negative
predictive value [NPV]: 57.1%, positive predictive value [PPV]: 95%) and that of HRUS
was 82.9% (specificity: 100%, sensitivity: 80.4%, NPV: 42.8, PPV: 100). The confidence
level for detecting nerve discontinuity and change in nerve caliber was found to be
higher on ultrasonography than magnetic resonance imaging (MRI) (100 vs. 70% and 100
vs. 50%, respectively). Pathology of submillimeter caliber nerves was accurately detected
by HRUS and these could not be well-visualized on MRI.
Conclusion HRUS is a powerful tool that may be used as the first-line imaging modality for the
evaluation of peripheral nerve pathologies, and a better means of evaluation of peripheral
nerves with submillimeter caliber.
Keywords
high-resolution - magnetic resonance - neurography - submillimeter - ultrasound
