Figure 6a. Carpal tunnel syndrome in a 40-year-old woman with a large intramuscular hemangioma extending through the flexor muscles of the forearm down to the carpal tunnel. The patient underwent release of the retinaculum 6 months earlier. (a, b) Longitudinal (a) and transverse (b) 5-13-MHz color Doppler US scans of the proximal carpal tunnel show an enlarged median nerve (arrows) containing abnormal vessels. FT = flexor tendon. (c) Coronal T2-weighted MR image (repetition time msec/echo time msec = 2,000/72) of the forearm shows the hemangioma (arrowheads) as a large hyperintense lesion involving the ventral aspect of the forearm, as well as the carpal tunnel. (d, e) Axial T2-weighted (d) and fat-suppressed T2-weighted (e) MR images (1,920/72) of the wrist show increased signal intensity in the epineurium surrounding the fascicles of the median nerve (arrow). This appearance is due to the presence of abnormal vessels within the nerve substance.