Variability in the MR image of the temporomandibular joint

Although MR imaging typically shows the meniscus of the temporomandibular joint (TMJ) as a biconcave region of low signal within the joint space, there is a great deal of variability in the MR images of healthy and diseased joints. The authors examined surgically extirpated menisci (n=55), cadaver TMJs (n=16), normal volunteers (n=5), and symptomatic patients (n=25) to identify the important parameters affecting the MR image. The authors found the meniscus has a short T2 (<50 msec), which is shortened further with degenerative changes; short repetition time/echo time (TR/TE) spin-echo images depict morphology well while long TR/TE images provide more information concerning adaptive remodeling of the disc; joint space, disk and condyle relationships are most usefully demonstrated via direct sagittal images; for any given pulse sequence the histopathologic state of the joint is a key determinant of the MR image obtained