Quantitative assessment of nerve echogenicity as an additional tool for evaluation of common fibular neuropathy

Abstract

Objective: Quantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods has shown promise in the assessment of ulnar neuropathy at the elbow. The purpose of this study was to determine the clinical usefulness of quantitative echogenicity measurement when using these three automatic thresholding methods in the evaluation of patients with common fibular (CF) neuropathy.

Methods: High-resolution ultrasonography (HRUS) images of the CF nerve from 45 patients with CF neuropathy were compared to 42 healthy controls.

Results: With all three methods patients with CF neuropathy had significantly higher mean hypoechoic fraction than healthy controls at the level of the fibular head (FH): MaxEntropy 87.4% versus 71.9% (p<0.001), RenyiEntropy 84.7% versus 68% (p<0.001) and Yen 87.6% versus 68.2% (p<0.001). Patients with CF neuropathy could be differentiated from healthy controls at a hypoechoic fraction cut-off point of 82% (MaxEntropy), 80% (RenyiEntropy) and 80% (Yen) with a sensitivity of 82%, 82% and 84% respectively, and a specificity of 93%, 95% and 83% respectively. Similar results were found for sonographic measurements above the FH.

Conclusion: Quantitative assessment of nerve echogenicity using the MaxEntropy, RenyiEntropy and Yen methods can be used to distinguish between patients with CF neuropathy and healthy controls with high sensitivity and specificity.

Significance: These three proven automatic thresholding methods can be used to assess nerve echogenicity in future studies. Quantitative echogenicity assessment with HRUS shows promise for the future as a potential diagnostic tool in daily clinical practice.

Keywords: Common fibular neuropathy; Echogenicity; High-resolution ultrasonography; Hypoechoic fraction; Peripheral nervous system; Quantitative assessment.