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Peripheral nerves in different body locations display different echotextures on ultrasound imaging, and knowledge of peripheral nerve echotexture is helpful for locating target nerves. However, the degree of echogenicity is often difficult to characterize. We aimed to define objectively the degree of echogenicity of peripheral nerves using grayscale measurements and compare nerve echotexture with matched histologic samples.Ultrasound images of peripheral nerves in 12 body locations were obtained in 20 healthy subjects using linear 8- to 12-MHz and curved 3- to 5-MHZ transducers. Corresponding nerve segments from 2 cadavers were imaged in vitro before they were sectioned for histologic examination. Nerve echogenicity was assessed by an objective grayscale (G) and a subjective echogenicity index (SEI) determined by experienced evaluators. The results of G and SEI in selected peripheral nerves were compared and correlated with histologic morphometry.There is a close correlation between SEI and G (P0.05). Mixed echogenicity was seen in 30% of the peripheral nerves; 25.4% were predominantly hypoechogenic, and 44.5% hyperechogenic. Nerves in the neck and upper arm are more frequently hypoechoic, whereas those in the leg are more frequently hyperechoic. Histologically, differences in echogenicity are dependent on fascicle diameter and on nerve fascicular pattern, that is, differing ratios of fascicle number to total nerve area.This study suggests that grayscales can be used to objectively determine echogenicity and shows that grayscale measurements match well with subjective visual grading. Histologic analysis showed that both ratio of total fascicular area to whole nerve area and fascicular pattern are important determinants of echogenicity.

A 79-year-old woman presented with an asymptomatic mass which had been growing slowly for the last five years. Physical examination showed a soft, mobile, spheroid, 1.2×1.2×1.2 cm sized subcutaneous nodule covered with normal skin in the left infraorbital area. The lesion was completely excised under a clinical suspicion of an epidermal cyst and there has been no recurrence since. Histologically, the mass was completely lying within an expanded vessel (figure 1). In the periphery of the lesion, there were small foci of diversely-branching vascular channels with the spindle cells in a fascicular pattern (figure 2). There was also proliferation of short oval-to-spindle cells with eosinophilic …