PREVALENCE OF BONE-MARROW SIGNAL ABNORMALITIES OBSERVED IN THE TEMPOROMANDIBULAR-JOINT USING MAGNETIC-RESONANCE-IMAGING

Purpose: The purpose of this investigation was to determine the preval ence of bone marrow signal abnormalities in patients referred for temp eromandibular joint (TMJ) magnetic resonance imaging (MRI). This inves tigation was done because of prior studies suggesting that condylar ma rrow signal abnormalities indicate avascular necrosis. Subjects and Me thods: Retrospective review was done of 449 consecutive TMJ MR examina tions in 415 patients from 1991 to 1994. Examinations were obtained wi th a surface coil at 1.5 T with routine T1, T2, and T2 images. Condyl ar marrow signal abnormalities were reviewed and classified into eithe r a bone marrow edema pattern (hypointense T1, hyperintense T2) or a s clerosis pattern (hypointense T1 and hypointense T2), Patients with ty pical findings of osteoarthritis were excluded from the sclerosis cate gory. Results: Condylar marrow signal abnormalities were present in 37 patients (9%), Twenty-six patients (6%) had the edema pattern, 14 pat ients (3%) had the sclerosis pattern, and 3 patients had both. Two pat ients with the edema pattern had a history of surgery; five patients w ith the sclerosis pattern had a history of surgery. The only follow-up MRIs obtained in the 37 patients were on one patient with edema at 8 months and on one patient with sclerosis at 10 months, MRI demonstrate d a stable appearance of these patterns. Conclusion: It was concluded that condylar marrow signal abnormalities are not rare in patients ref erred for TMJ MRI. The clinical significance of the changes is uncerta in.