Very-High-Resolution Sonography Of Median Nerve : A Comparative Study Vs High-Resolution Sonography In Healthy Subjects

The use of ultrasound in the study of peripheral nerves dates back to the late 80s [1]; the first ultrasound studies of the median nerve (MN) affected by carpal tunnel syndrome (CTS) date back to the 90s [2]. Since then, ultrasound has been increasingly used in the study of peripheral nerves becoming the main morphological examination to be combined with functional electrodiagnostic tests [3]. The MN, due to the high prevalence of CTS, is the most commonly studied nerve with ultrasound, using probes with a frequency varying between 12 and 20 MHz. According to the guidelines, ultrasound has a primary role in the diagnosis of CTS [3]. Since 2016, a very-high-resolution ultrasonography (VHRUS) equipment is available for clinical use which incorporates transducers with upper frequencies of 48 MHz (pixel resolution 50 µm, depth 2.3 cm) and 70 MHz (pixel resolution 30 µm, depth 1cm) (fig. 1). The aim of this work is to compare VHRUS and traditional high-resolution ultrasonography (HRUS) in order to validate this new equipment in the evaluation of the MN in healthy subjects by comparing the cross-section areas (CSA) and the perimeters, measured on images obtained at the wrist and forearm level