Individual flexor tendon identification within the carpal tunnel: A semi-automated analysis method for serial cross-section magnetic resonance images

Abstract

Nicole M Kunze1, Jessica E Goetz2, Daniel R Thedens3, Thomas E Baer2, Ericka A Lawler2, Thomas D Brown21Department of Biomedical Engineering, 2Department of Orthopaedics and Rehabilitation, 3Department of Radiology, University of Iowa, Iowa City, IA, USAAbstract: Carpal tunnel syndrome is commonly viewed as resulting from chronic mechanical insult of the median nerve by adjacent anatomical structures. Both the median nerve and its surrounding soft tissue structures are well visualized on magnetic resonance (MR) images of the wrist and hand. Addressing nerve damage from impingement of flexor digitorum tendons co-occupying the tunnel is attractive, but to date has been restricted by a lack of means for making individual identifications of the respective tendons. In this image analysis work, we have developed a region-growing method to positively identify each individual digital flexor tendon within the carpal tunnel by tracking it from a more distal MR section where the respective tendon identities are unambiguous. Illustratively, the new method was applied to MRI scans from four different subjects in a variety of hand poses. Conventional shape measures yielded less discriminatory information than did evaluations of individual tendon location and arrangement. This new method of rapid identification of individual tendons will facilitate analysis of tendon/nerve interactions within the tunnel, thereby providing better information about mechanical insult of the median nerve.Keywords: carpal tunnel syndrome, magnetic resonance imaging, region growing, digital flexor tendons