Detection of kinetic trajectory in the wrist during fingers motions using high-frequency ultrasound

Carpal tunnel syndrome (CTS), resulted from the compression of the median nerve traveling through the carpal tunnel of the hand, is commonly leading to intermittent numbness and pain of the finger. The diagnosis of CTS is usually performed by physical or nerve electricity examinations, and which still has significant false negative rate. To improve on the diagnostic technique, an attempt was carried out to image a local anatomical structure of the wrist using high-frequency ultrasound and to detect the kinetic trajectory of the median nerve following fingers motions. A 32 MHz ultrasound imaging system was employed on each right wrist of 14 healthy volunteer. Ultrasonic radio-frequency signals and images were collected corresponding to fingers movements from extension (0°) to flexion (90°) with an increment of 5°. The kinetic trajectory of the median nerve was detected by correlation coefficient-based motion tracking technique. To better improve the analysis efficiency of motion tracking, the tracking calculation was amenable to rapid execution on the current generation of graphics processor units. High-frequency ultrasound images could provide adequate resolution to readily discern the median nerve in the wrist. The median nerve moves toward to palmar and ulnar direction as the finger flex. The averaged resultant displacements for male and female were 3.74 and 2.04, respective, as the flexuous angle was 90°. The resultant displacements of median nerve for males were significant larger than those for females as the flexuous angles were larger than 35°. The tendency of resultant displacement of the median nerve is exponential rise in the ulna-palmar direction corresponding to the movement of fingers form 0°to 90°. This study has verified that the kinetic trajectory of median nerve may be useful as baseline data for future studies of the motion analysis on the CTS.