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Singapore, Singapore

Mat Jais I.S.,Wrist Analysis Research Laboratory | Liu X.,Wrist Analysis Research Laboratory | Liu X.,National University of Singapore | An K.-N.,Rochester College | Tay S.C.,Wrist Analysis Research Laboratory
Medical Engineering and Physics | Year: 2014

Introduction: Carpal bones motions exhibit hysteresis that is dependent on the direction of wrist motion, which can be seen during 4-dimensional (3D plus time) imaging of the wrist. In vitro studies have demonstrated the phenomenon of carpal hysteresis and have reported that hysteresis area increases with carpal instabilities. However, their techniques required implantation of bone markers and thus cannot be used clinically. The objective of this study is to use noninvasive 4-dimensional computed tomography (4DCT) technique to quantify carpal hysteresis, and to determine the reliability of this method. Method: A cadaveric wrist mounted on a custom motion simulator was imaged using a dual-source CT scanner while undergoing periodic radioulnar deviation. Ten image phases of this motion was reconstructed through retrospective cardiac gating. The rotational angles of scaphoid, lunate and triquetrum in each phase were derived through manual registration using Matlab after segmenting the bones in Analyze 8.1. These angles were then plotted against global wrist positional angles to produce the hysteresis curves and the area was calculated. The image segmentation and measurements were repeated by 2 raters to derive intra- and inter-rater reliability assessments. Results: The hysteresis area was found to be larger in the lunate (96.5deg2) followed by triquetrum (92.3deg2) and scaphoid (67.5deg2). The measurement of the total hysteresis area of the scaphoid had the highest reliability with intra- and inter-rater reliability of 95.5% and 95.4% respectively. Discussion: We have demonstrated that our approach of using 4DCT imaging can be used to assess and quantify the hysteresis of the carpal motion with good reliability. © 2014 IPEM. Source


Neo P.Y.,Wrist Analysis Research Laboratory | Mat Jais I.S.,Wrist Analysis Research Laboratory | Panknin C.,Siemens AG | Lau C.C.,Wrist Analysis Research Laboratory | And 3 more authors.
Medical Engineering and Physics | Year: 2013

Objective: Dynamic Computed Tomography (CT) promises insights into the pathophysiology of carpal instability by recording images of the carpus while it is in motion. The purpose of this study was to investigate the effect of motion velocity on image quality for dynamic carpal imaging applications using a clinical dual-source CT (DSCT) scanner. Methods: A phantom with targets in the axial, coronal and sagittal planes was attached to a motion simulator and imaged using a 64-slice DSCT scanner. Data was acquired when the phantom was stationary and during periodic linear motion. Spatial resolution, motion artifacts and banding artifacts were assessed. Results: Mean spatial resolution was 0.82. mm at 36. mm/s and 0.79. mm at 18. mm/s. Banding artifacts were mild at 36. mm/s and minimal at 18. mm/s. Motion artifacts were minimal at motion velocity of up to 36. mm/s in both the coronal and sagittal planes. Axial plane motion artifacts were moderate at 36. mm/s and mild at 18. mm/s. Discussion: Sub-millimeter resolution is achievable with commercially available DSCT scanners with mild to moderate amounts of motion artifacts at velocities of 18. mm/s and 36. mm/s respectively. © 2013 IPEM. Source

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