[To evaluate the disk position of the temporomandibular joint using calcium suppressed spectral-based CT images in the patients with temporomandibular disorder].

To evaluate the application of calcium suppressed (CaSupp) spectral CT technique in evaluating disk position and measuring the thickness of the posterior band of temporomandibular joint (TMJ). The twenty-three temporomandibular disorder patients [mean age 23(12~62) years, male/female=14/9] were performed with oblique sagittal and coronal proton density weighted imaging (PDWI) and spectral CT scans from February to July, 2019 in Department of Radiology, Hainan Hospital of General Hospital of Chinese PLA, and 45 TMJ joints were evaluated. The subjects were classified into two groups according to the scanning modalities: MRI measurement group and CaSupp spectral-based CT group. The CaSupp technique were applied with the spectral-based CT images and CaSupp images were generated. The oblique sagittal and coronal CaSupp imaged were reformatted by perpendicular to the long axis of the condyle. The TMJ disk positions were evaluated on oblique sagittal and coronal images, and the maximal disk thickness were measured on the oblique sagittal images. The joint position was basically consistent on MRI and CaSupp images for the 45 TMJ joints. The intra-class coefficient value was 0.843 (0.712, 0.914) for the measurement of the posterior band of the TMJ disk between MRI and CaSupp images. Bland-Altman presented that the [95.6% (43/45)] points with the difference located in the 95% agreement interval. Wilcoxon paired text demonstrated that there was no significant different for the thickness of the posterior band between MRI [2.57 (1.76, 3.65) mm] and CaSupp images [2.67 (1.74, 4.56) mm] (0.07). The CaSupp spectral-based CT could be used to evaluated the TMJ disk position and the thickness of the posterior band.