Determining the optimal magnetic resonance imaging sequences for the efficient diagnosis of temporomandibular joint disorders.

Abstract

To compare and analyze nine MRI sequences of the TMJ and determine the optimum sequence for the rapid diagnosis of TMDs so as to develop new clinical guidelines. Twenty young volunteers (a total of 40 joints) aged 22-26 years were recruited. Three basic sequences, T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), and proton density-weighted imaging (PDWI), together with three positions, oblique sagittal (OSag) with closed mouth, oblique coronal (OCor) with closed mouth, and OSag with opened mouth, were selected in combination for testing. In the OCor position, four regions of interest (ROIs), the condyle (C), the disc (D), the disc outside (DO), and fat (F), were analyzed. For the OSag with closed mouth position and the OSag with opened mouth position sequences, the four ROIs were the condyle (C), the disc (D), the disc ahead (DA), and the disc rear (DR). The signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and signal intensity ratio (SIR) were calculated and analyzed using independent sample t-tests and one-way analysis of variance. Two senior radiologists scored the images of the nine MRI sequences subjectively and selected three optimal sequences. Using the three selected sequences, 1479 patients with anterior disc displacement with reduction (ADDwR) or anterior disk displacement without reduction (ADDwoR) were evaluated by comparing the preoperative TMJ MRI with the outcomes of the maxillofacial arthroscopy or open surgery. The T1WI sequence showed the highest SNR while the T2WI group had the lowest SNR. The ROIs of the T2WI group had the highest CNR and SIR values in the OCor and OSag sequences. In the OCor sequence, the value for the SIR F/DO group was higher than the SIR C/D and SIR C/DO values. Using subjective analysis to evaluate the quality of the scans, the highest total scores were obtained for the OSag T2WI with opened mouth and OSag PDWI with closed mouth sequences. From the objective and subjective analysis, the three optimal sequences selected were OSag PDWI, OCor T2WI with closed mouth, and OSag T2WI with opened mouth. In patients with anterior disc displacement, the comparisons of the surgery and the selected MRI sequences indicated that the total diagnostic accuracy of the MRI was 96.3% (1,425/1,479 cases). For patients with ADDwoR, the diagnostic accuracy was 98.5% (1,372/1,393 cases), and for those with ADDwR it was 61.6% (53/86 cases). There were significant differences between the ADDwoR and ADDwR groups (χ2=312.92, P<0.01). The three optimal MRI sequences for the rapid and efficient diagnosis of TMD were determined to be OSag PDWI, OCor T2WI with closed mouth, and OSag T2WI with opened mouth.