Shuai Leng PhD, Presenter: Nothing to Disclose

Kristin D. Zhao MA, Abstract Co-Author: Nothing to Disclose

Mingliang Qu MD, Abstract Co-Author: Nothing to Disclose

Kai-Nan An PhD, Abstract Co-Author: Nothing to Disclose

Richard Berger MD, Abstract Co-Author: Nothing to Disclose

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG

To use non-gated 4-dimensional (4D) CT to detect subtle dynamic joint instabilities, which can only be observed during joint motion.

A motion device was constructed to simulate radioulnar deviation of the wrist joint. A cadaveric forearm was mounted to this device, producing periodic radioulnar motion through a maximum arc of 30° (10° of radial deviation and 20° of ulnar deviation) at 30 cycles per minute, representing a typical wrist motion speed. The moving wrist was scanned using a dual-source CT system (Definition FLASH, Siemens Healthcare, Forchheim, Germany). A non-gated perfusion-like scan mode was used to acquire continuous projection data from each x-ray source for 2 seconds (one motion cycle) without translation of the patient table. Z-axis coverage for this mode was 38.4 mm, which fully encompassed the proximal carpal bones. Images were reconstructed using the commercial dual-source cardiac reconstruction algorithm with 75 ms temporal resolution. The wrist was scanned before and after cutting all three portions of the scapholunate ligament (simulating scapholunate instability).

Carpal bones, distal radius and ulna, and joint spaces were clearly delineated in the reconstructed 2D images and 3D VRT images. No motion blurring or banding artifacts were visible and image quality was considered to be excellent by an experienced hand surgeon. Motion of each carpal bone and the change in joint spaces and contact areas were clearly visualized throughout the motion cycle in the 4D movies generated from the 3D image series at each phase of motion. Subtle differences in joint motion were identified when 4DCT images of the intact wrist were compared with those acquired after the ligaments were cut, demonstrating the ability of our 4DCT technique to detect dynamic joint instability.

The non-gated 4DCT technique generated high spatial and high temporal resolution (75 ms) images of the moving wrist joint. Because this method does not require periodic motion, it provides a more robust method than retrospectively-gated techniques and may allow diagnosis of dynamic joint instabilities, which can only be detected during joint motion.

Non-gated 4DCT provides a method to diagnose dynamic joint instabilities at an early stage, allowing intervention to restore normal function before the onset of arthritis or static deformities.

Leng, S, Zhao, K, Qu, M, An, K, Berger, R, McCollough, C, High Spatial and Temporal Resolution 4D CT Imaging for Assessment of Musculoskeletal Joint Instability.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005339.html