Magnetic Resonance Imaging Signal Intensities of the Temporomandibular Joint Articular Disc and Cortical Bone: Are These Measurements Valid for the Diagnosis of Temporomandibular Joint Disease?

Abstract

: The purpose of this study was to clarify the validity of measuring the signal intensities of cortical bone CB and temporomandibular joint TMJ discs on magnetic resonance MR images for the diagnosis of TMJ disease. Two investigations were performed. In the rst investigation, MR images of 13 TMJs of volunteers were obtained using a multi spin-echo sequence. Echo time TE was increased from 10 msec to 200 msec in steps of 10 msec. The signal intensities of the CB of the condylar head, and the anterior AD and posterior PD bands of the TMJ disc were measured, and their attenuation patterns were compared. In the second investigation, clinical MR images of 30 TMJs from patients with suspected TMJ disorders were selected. Proton density-weighted images PDWIs and T2-weighted images T2WIs were obtained at TEs of 14 and 85 msec, respectively, using a double-echo fast spin-echo sequence. The signal intensities of CB, AD, and PD were measured and compared with that of the external auditory meatus air using a Bonferroni test. AD and PD showed nearly identical signal intensity attenuation patterns. The signal intensities of AD and PD were lower than CB at TEs longer than 20 msec although they were higher at TEs shorter than 20 msec. Clinical PDWIs and T2WIs showed similar results. The signal intensities of CB, AD, and PD were signi cantly higher than the external auditory meatus air in both PDWIs and T2WIs. CB and TMJ discs show characteristic signal intensities, suggesting that the signal intensity measurement of these structures is valid.