Four-dimensional CT Analysis of Wrist Kinematics during Radioulnar Deviation

Purpose To determine the technical feasibility of four-dimensional (4D) CT for analysis of the variation of radioscaphoid angle (RSA) and lunocapitate angle (LCA) during wrist radioulnar deviation. Materials and Methods In this prospective study, 37 participants suspected of having scapholunate instability were evaluated from January 2015 to December 2016 with 4D CT and CT arthrography (mean age ± standard deviation, 42.3 years ± 15; range, 21-75 years; 27 men [mean age, 44 years ± 15] and 10 women [mean age, 38 years ± 14]). Five angular parameters for RSA and LCA variation during radioulnar deviation were calculated by two independent readers. CT arthrography was used as the reference standard method for scapholunate ligament tear identification. Results In the control group (n = 23), the mean values for RSA were 103° ± 8 and 104° ± 9, whereas the mean values for LCA were 86° ± 9° and 90° ± 11° with a coefficient of variation of 11% and 13% for reader 1 and reader 2, respectively. The interobserver and intraobserver agreements were excellent for RSA and substantial to excellent for LCA. In the pathologic group (n = 14), LCA amplitude, standard deviation, and maximal angle were lower for both readers with respect to the control group, measuring 36% and 44% (P = .003), 37% and 44% (P = .002), and 13% and 19% (P = .003), respectively. RSA amplitude did not show statistically significant results in the pathologic group (P > .13). LCA yielded the highest sensitivity (71%-93%), whereas RSA yielded the highest specificity (87%-100%). Conclusion Semiautomatic four-dimensional CT analysis of the wrist during radioulnar deviation is technically feasible and reproducible for evaluation of carpal kinematic abnormalities. © RSNA, 2018 Online supplemental material is available for this article .