[Comparison of magnetic resonance images of the temporomandibular joint using different coils]

Objective: To explore and compare the clinical application value of 8-channel head phased-array coil, an 8-channel temporomandibular joint (TMJ)-specific surface coil, and a single-channel surface coil in TMJ MRI examinations. Methods: A total of 600 temporomandibular disorders (TMD) patients (1 200 joints) who underwent TMJ MRI examination in the First People's Hospital of Jinzhong from June 2020 to January 2025 were retrospectively screened. Based on inclusion/exclusion criteria, 120 TMD patients (240 joints) with closed-mouth oblique sagittal proton density weighted imaging (OSag PDWI), coronal T2 fat-suppression weighted imaging (OCor fs T2WI) and open-mouth oblique sagittal proton density weighted imaging (OSag PDWI) were included. Patients were divided into groups A, B, and C, with 40 cases in each group. Group A (31female, 9male, median age 24 years old), underwent 8-channel head phased-array coil imaging. Group B (29 female, 11male, median age 23.5 years old) underwent TMJ imaging with an 8-channel surface coil. Group C (29 female, 11male, median age 22.5 years old) underwent single-channel surface coil imaging. There were no significant differences in age, gender, type or disease types among groups (P>0.05). Six healthy volunteers without TMD (4 female, 2 male, range 19 to 45 years old) underwent imaging with all three coils as self-control. The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and image quality were compared for five regions of interest (ROI) in both patients and volunteers. Results: Under the same sequence and the same parameters, SNR and CNR in group B were higher than those in group A, and SNR and CNR in group C were also higher than those in group A, the differences were statistically significant (P<0.05). However, there were significant differences in SNR and CNR between group B and group C in the closed and open positions of ROI1, the open positions of ROI3 and the open positions of ROI5 (P<0.05), and there were no significant differences in other positions (P>0.05). Group B had the best image quality, followed by group C and group A had the worst image quality. There were significant differences in the visualization of OSag PDWI in the closed mouth position, OCor T2WI in the coronal position, and OSag PDWI in the open mouth position, such as condyle, anterior attachment, joint disc, double lamina area, joint cavity and lateral pterygoid muscle (P<0.05). There were significant differences between group B and group C in showing the joint cavity in the closed mouth position and showing the structure of the bilaminar area in the open mouth position (P<0.05). There was no significant difference in other regions of interest (P>0.05). The subjective scores of condyle, anterior attachment, articular disc, bilaminar area, articular cavity, lateral pterygos muscle and other structures were medium to high in group A, high in group B, and high or high in group C by two radiologists independently. In the five rois, the 8-channel TMJ surface coil showed more details, especially in the articular disc, condyle and lateral pterygoid muscle regions, and had more advantages in both volunteers and patients. Conclusions: The 8-channel TMJ-specific surface coil provides significantly clearer visualization of critical anatomical details within the ROIs, demonstrating the highest clinical application value and is recommended as the preferred choice.