Abstract
Internal derangements of the temporomandibular joint (TMJ) are a major cause of jaw pain and dysfunction as well as other related clinical symptoms.
TMJ diagnosis is the abnormal position and appearance of the disk.Most X-ray-based methods arc useful for evaluating bony abnormalities, but their reduced soft-tissue contrast often makes the diagnostic evaluation of TMJ disorders difficult.Magnetic resonance (MR) imaging is a very recent addition to the medical diagnostic of TMJ diseases.MR imaging can produce high-quality tomograhpic images of greater soft-tissue contrast without ionizing radiation or known biological hazards.
MR system was circular type Simens Magnetom1.5tesla.Display matrix was 256×256.
A Modulated Helmholtz type coil of17cm in diameter was developed in Kameda General Hospital in order to increase signal to noise ratio in the area of bilateral TMJs.The distance between two coils was16-20cm.The head was placed in supine position in the center of two surface coils.
A Modulated Helmholtz type coil:
1. Modulated Helmholtz type coil was used as an emitter and a receiver.
2.Modulated Helmholtz type coil had a pair of17cm coils, which were movable according to head width of each patient.
3. MR imaging of bilateral TMJs was taken at once because of no necessity to reset a surfacecoil.
4. It was easy to set the positioing of the head.
