Virginia Research Day 2025

Medical Student Research Clinical

03 Comparative Analysis of Methods for Obtaining Median Nerve Cross Sectional Area Using Ultrasound

Onyeukwu, C.; Toncich, R.; Saggar, R.; Fowler, Dr. J. Corresponding author: rtoncich@vcom.edu

University of Pittsburgh Medical Center (UPMC) Orthopaedics

82.4%). The resident showed significantly higher reliability with the Trace method compared to the A-B method (p = 0.03), while the experienced surgeon showed no significant differences between methods. Conclusion: All three ultrasound methods demonstrated high reliability in measuring median nerve CSA, with the Trace method showing some advantages in accuracy and precision. The choice of method may be influenced by operator experience, with less experienced operators potentially benefiting more from the Trace method.

Background: Ultrasound measurement of median nerve cross-sectional area (CSA) is widely used in carpal tunnel syndrome (CTS) diagnosis. This study compared three common measurement methods: A-B, Ellipse, and Trace to evaluate their reliability and accuracy. Methods: Ten patients with suspected CTS underwent ultrasound examination. Two observers (an experienced hand surgeon and an orthopaedic surgery resident) measured median nerve CSA using three methods in both standard and zoom-enhanced views. Measurements were compared to ImageJ software as the gold standard. Intra-rater and inter-rater reliability, accuracy, and measurement error were assessed using intraclass correlation coefficients (ICC), Bland Altman analysis, and Standard Detectable Difference (SDD).

Results: All methods showed high reliability (ICC range: 0.940-0.994) but consistently underestimated CSA compared to ImageJ (12.154 ± 5.134 mm²). Significant differences were found between ImageJ and the Ellipse method (p = .015) and between ImageJ and the AB method (p = .05), but not between ImageJ and the Trace method (p = .078). Mean differences (95% limits of agreement) were: A-B method -1.46 mm² (-4.76 to 1.87 mm²), Ellipse method -1.96 mm² (-5.09 to 1.17 mm²), and Trace method -1.26 mm² (-4.11 to 1.59 mm²). SDDs were 2.06 mm², 2.69 mm², and 1.57 mm² for A-B, Ellipse, and Trace methods, respectively. Accuracy was highest for the Trace method both with zoom (84.2%) and without zoom (85.5%), followed by A-B (zoom: 82.1%, no-zoom: 83.6%) and Ellipse methods (zoom: 81.0%, no-zoom:

Protocol Number: STUDY20070308

131 2025 Research Recognition Day