THE MEASUREMENT OF THE GLENOID BONY DEFECT IN SHOULDER INSTABILITY WITH 3D CT AND MRI-A : A COMPARATIVE STUDY
Authors: C Jaspars; J Markenstein; S Rijkenberg; J Willems;
References: Presented at SECEC 2009
The purpose of this study was to investigate if MRI-arthro is as reliable as 3D CT technique in quantifying the glenoid bone loss in patients with anterior shoulder instability. We compared MR-arthro "en face view "images of the glenoid with three-dimensionally reconstructed computed tomography images.
Material and Methods
We included 35 patients with recurrent anterior shoulder instability. MR-arthro-images and 3D CT images were collected pre-operatively. Images were randomised and blinded for two observers. Each observer measured the series twice, with an appropriate interval of three weeks. The intra class correlation of intra- and inter observer reliability was determined, using SPSS® version 16.0.
The intra-observer reliability of observer A with 3D CT for the 1st and the 2nd measurement is. 953 (95% CI =.907-.976) and for MR-arthro. 713 (95% CI =.432 -.855). For observer B the intra-observer reliability is. 954 with 3D CT (95% CI =. 909-.977) and. 942 with MR-arthro (95% CI =.884-.970). The inter-observer reliability between the two observers for the 1st measurement of 3D CT images was. 845 (95% CI =. 694-.922) and for MR-arthro. 538 (95% CI =. 085-.767). Reviewing the 2nd measurements of 3D CT we found an inter-observer reliability : ICC. 915 (95% CI =.831-.957) and. 819 (95% CI =. 642-.909) (MRI images). When comparing 3D CT with MR-arthro, we found good results. For observer A : 1st measurement : ICC. 439 (95% CI = -.111-.717) and for the 2nd measurement : ICC. 765 (95% CI =. 538-.882). Observer B ICC (MRI vs. CT) :. 711 (95% CI =. 428-.854) and. 731 (2nd series) (95% CI =.467-.864).
This study shows that the method of MR-arthro is a promising method of pre-operative radiographic analysis in patients with recurrent shoulder instability. Both soft tissue lesions as bony glenoid lesions can be visualised. High intra and inter-observer correlations show that MRI-arthro is reliable and valid for measuring bony defects of the glenoid.