Neuropathy Score Reporting and Data System (NS-RADS): A Practical Review of MRI-Based Peripheral Neuropathy Assessment

Imaging of Peripheral Nerves: AJR Expert Panel Narrative Review

Peripheral nerve imaging provides information that can be critical to the diagnosis, staging, and management of peripheral neuropathies. MRI and ultrasound are the imaging modalities of choice for clinical evaluation of the peripheral nerves given their high soft-tissue contrast and high resolution, respectively. This AJR Expert Panel Narrative Review describes MRI- and ultrasound-based techniques for peripheral nerve imaging; highlights considerations for imaging in the settings of trauma, entrapment syndromes, diffuse inflammatory neuropathies, and tumor; and discusses image-guided nerve interventions, focusing on nerve blocks and ablation.

A Practical Approach to Diagnosing Peripheral Neuropathies

Polyneuropathies are common, with the incidence increasing with older age. The causes of polyneuropathies are diverse and numerous, and it can be challenging for clinicians to determine the etiology of a particular patient's neuropathy. In this article, we systematically detail a practical approach to polyneuropathies, beginning with the most important aspects of the workup, the history and physical. We then discuss the limited diagnostic approach required for patients who present with a distal symmetric polyneuropathy and the more comprehensive approach for patients who present with other neuropathy subtypes.

Contrast-enhanced magnetic resonance neurography for diagnosing brachial plexopathy: improved visualization and additional imaging features

Contrast-enhanced magnetic resonance neurography (CE-MRN) holds promise for diagnosing brachial plexopathy by enhancing nerve visualization and revealing additional imaging features in various lesions. This study aims to validate CE-MRN's efficacy in improving brachial plexus (BP) imaging across different patient cohorts. Seventy-one subjects, including 19 volunteers and 52 patients with BP compression/entrapment, injury, and neoplasms, underwent both CE-MRN and plain MRN. Two radiologists assessed nerve visibility, with inter-reader agreement evaluated. Quantitative parameters such as signal intensity (SI), contrast-to-noise ratio (CNR), and contrast ratio (CR) of the C7 nerve were measured. Both qualitative scoring and quantitative metrics were compared between CE-MRN and plain MRN within each patient group. Patient classification followed the Neuropathy Score Reporting and Data System (NS-RADS), summarizing additional imaging features for each brachial plexopathy type. Inter-reader agreement for qualitative assessment was strong. CE-MRN significantly enhanced BP visualization and nerve-tissue contrast across all cohorts, particularly in volunteers and patients with injuries. It also uncovered additional imaging features such as hypointense signals in ganglia, compressed nerve sites, and neoplastic enhancements. CE-MRN effectively mitigated muscle edema and vascular contamination, enabling precise classification of BP injuries. Overall, CE-MRN consistently enhances BP visualization and provides valuable imaging features for accurate diagnosis.

MRI-based Neuropathy Score Reporting And Data System (NS-RADS): multi-institutional wider-experience usability study of peripheral neuropathy conditions among 32 radiology readers

OBJECTIVE

To determine the inter-reader reliability and diagnostic performance of classification and severity scales of Neuropathy Score Reporting And Data System (NS-RADS) among readers of differing experience levels after limited teaching of the scoring system.

METHODS

This is a multi-institutional, cross-sectional, retrospective study of MRI cases of proven peripheral neuropathy (PN) conditions. Thirty-two radiology readers with varying experience levels were recruited from different institutions. Each reader attended and received a structured presentation that described the NS-RADS classification system containing examples and reviewed published articles on this subject. The readers were then asked to perform NS-RADS scoring with recording of category, subcategory, and most likely diagnosis. Inter-reader agreements were evaluated by Conger's kappa and diagnostic accuracy was calculated for each reader as percent correct diagnosis. A linear mixed model was used to estimate and compare accuracy between trainees and attendings.

RESULTS

Across all readers, agreement was good for NS-RADS category and moderate for subcategory. Inter-reader agreement of trainees was comparable to attendings (0.65 vs 0.65). Reader accuracy for attendings was 75% (95% CI 73%, 77%), slightly higher than for trainees (71% (69%, 72%), p = 0.0006) for nerves and comparable for muscles (attendings, 87.5% (95% CI 86.1-88.8%) and trainees, 86.6% (95% CI 85.2-87.9%), p = 0.4). NS-RADS accuracy was also higher than average accuracy for the most plausible diagnosis for attending radiologists at 67% (95% CI 63%, 71%) and for trainees at 65% (95% CI 60%, 69%) (p = 0.036).

CONCLUSION

Non-expert radiologists interpreted PN conditions with good accuracy and moderate-to-good inter-reader reliability using the NS-RADS scoring system.

CLINICAL RELEVANCE STATEMENT

The Neuropathy Score Reporting And Data System (NS-RADS) is an accurate and reliable MRI-based image scoring system for practical use for the diagnosis and grading of severity of peripheral neuromuscular disorders by both experienced and general radiologists.

KEY POINTS

• The Neuropathy Score Reporting And Data System (NS-RADS) can be used effectively by non-expert radiologists to categorize peripheral neuropathy. • Across 32 different experience-level readers, the agreement was good for NS-RADS category and moderate for NS-RADS subcategory. • NS-RADS accuracy was higher than the average accuracy for the most plausible diagnosis for both attending radiologists and trainees (at 75%, 71% and 65%, 65%, respectively).