1991 Volume 37 Issue 2 Pages 294-313
The T1 and T2 relaxation times of the phantom were measured in the magnetic resonance imaging (MRI) using the headcoil and the surface coil for the temporomandibular joint (TMJ). The purpose of this study on the phantom was to investigate the feature of the surface coil for TMJ (TMJ-coil). Two spin echo (TR=2, 000 msec, TE=30 msec and TR=2, 000 msec, TE=80 msec) and one inversion recovery (TR=2, 000 msec, TI=-500 msec) pulse sequence with a 256×256 matrix and two excitations were used, and the T1 and T2 values were obtained by the ROI (region of interest) in the maps of T1 and T2. As a result of the phantom study, I acquired the knowledge that I have to set an object on the center of the TMJ-coil with a distance more than 3 cm.
With the TMJ-coil, measurements of T1and T2 relaxation times of meniscus and lateral pterygoid muscle were performed on 30 normal volunteers and 30 patients who had been diagnosed internal derangement of the TMJ. The 30 patients were classified into two groups; one composed of 15 patients diagnosed meniscal displacement with reduction (goup MDWR) and the other was of 15 patients diagnosed meniscal displacement without reduction (group MDWOR).
Between the volunteers and patients, there was a significant decrease in T1 and T2 relaxation times of meniscus and Ti relaxation times of lateral pterygoid muscle. There was no significant difference between group NIDWR and group MDWOR. There was no significant difference in sex or age, either. The more long-term the patients were, the more the T1 relaxation times decreased. The decrease in T1 and T2 relaxation times of meniscus probably represented water loss.
The decrease in T1 and T2 relaxation times of lateral pterygoid muscle was slight compared with that of meniscus.
