Quantitative Assessment of Peripheral Nerve Echogenicity in Children and Adolescents Aged 2-17 Years: A Retrospective...

Introduction/Aims: Quantitative analysis of nerve echogenicity can support the diagnosis of mono- and polyneuropathies, for instance by distinguishing inflammatory-demyelinating from axonal damage. However, echogenicity is mainly assessed qualitatively and examiner-dependently. This study aimed to establish quantitative reference data for grayscale values of peripheral nerves in the upper and lower extremities of healthy children and adolescents to provide a clinical benchmark. Methods: We retrospectively analyzed ultrasound data from 211 healthy children aged two to seventeen years who had undergone standardized examinations of 15 peripheral nerve sites. Grayscale analysis (0-255 levels per pixel) was performed within manually defined regions of interest (ROIs) using ImageJ (version 1.52). Echogenicity values were correlated with age, weight, height, and body mass index (BMI). Results: Echogenicity showed no significant overall association with biometric parameters. Mean grayscale values ranged from 85.23 ± 2.16 for the tibial nerve at the medial malleolus to 134.62 ± 2.69 for the sural nerve. Gain settings below 60 resulted in significantly lower grayscale values, whereas measurements with gain ≥ 60 were stable and comparable. Discussion: We propose reference grayscale ranges for peripheral nerves in healthy children and adolescents as a practical benchmark for clinical use and future studies. Due to technical constraints-particularly retrospective image processing and non-lossless data export-each laboratory should establish its own reference dataset, or multicentric parameters should be established. As our sample consisted predominantly of Caucasian participants, ethnic differences should be considered when applying these values to other populations.