MRI alone versus MRI-CBCT registered images to evaluate temporomandibular joint internal derangement

Objective To evaluate the effect of magnetic resonance imaging–cone beam computed tomography (MRI-CBCT) image registration on inter- and intraexaminer consistency when evaluating temporomandibular joint (TMJ) internal derangement compared to MRI alone. Methods MRI and CBCT images of 25 patients (50 TMJs) were obtained and coregistered using mutual-information rigid image registration via Mirada XD software. Two experienced radiologists independently and blindly evaluated two types of images (MRI alone and MRI-CBCT registered images) at two different times (T1 and T2) for TMJ internal derangement, based on sagittal and coronal articular disc position in relation to the head of the condyle and the posterior slope of the articular eminence. Results The intraexaminer consistency with MRI alone (examiner 1 = 0.85 [0.74-0.92]; examiner 2 = 0.91 [0.84-0.95]) was lower than for the MRI-CBCT registered images (examiner 1 = 0.95 [0.91-0.97]; examiner 2 = 0.97 [0.96-0.99]). The interexaminer consistency of evaluating internal derangement with MRI alone (0.52 [0.18-0.73] at T1; 0.71 [0.45-0.84] at T2) was lower than for the MRI-CBCT registered images (0.97 [0.95-0.98] at T1; 0.98 [0.96-0.99] at T2). When disc position classification was dichotomized to normal versus anteriorly displaced, intraexaminer agreement for the two examiners was 0.52 and 0.63 for MRI alone, but was 0.91 and 0.92 for MRI-CBCT registered images. Interexaminer agreement for MRI alone was 0.29 at T1 and 0.42 at T2, but was 0.96 at both examination times for MRI-CBCT registered images. Conclusion The MRI-CBCT registered images improved intra- and interexaminer consistency in the evaluation of internal derangement of TMJ.