Synthetic magnetic resonance imaging for quantitative parameter evaluation of temporomandibular joint disorders

Objective: This study investigated the usefulness of quantitative parameters [longitudinal relaxation (T1), transverse relaxation (T2), and proton density (PD)] obtained with synthetic magnetic resonance imaging (MRI) in assessing the progression of temporomandibular joint (TMJ) disorders. Methods: For individual TMJ disorder diagnoses, the presence of disc displacement in MRI and the osseous change in cone-beam CT were investigated. Joints were classified into three stages: (1) silent stage, no disc displacement or osseous change; (2) incipient stage, presence of disc displacement and absence of osseous change; and (3) progressed stage, both disc displacement and osseous change. In synthetic MRI, the T1, T2, and PD values of the condyle bone marrow were measured simultaneously. The median T1, T2, and PD values were analyzed according to disc displacement, osseous changes, and joint stage. Results: Significant differences were observed in the T1 and PD values of joints with disc displacement or condylar osseous change compared to normal joints. The T1 and PD values also differed between the silent and progressed stages. The PD value differed between the silent and incipient groups, while the T2 value did not differ significantly among the three groups. Conclusion: The PD and T1 values of condylar bone marrow obtained from synthetic MRI can be used as sensitive indicators of TMJ disorder progression. The PD value of the bone marrow showed potential as a useful biomarker for recognizing the initial stages of TMJ disorders. Synthetic MRI is useful for the simultaneous acquisition of effective MRI parameters for evaluating TMJ disorders.

Hyperostosis Frontalis Interna: Its Relationship to Cerebral Atrophy

In not a few of the recorded cases of hyperostosis frontalis interna there has been observed some degree of cortical atrophy, chiefly affecting the frontal poles, and its occurrence raises the question of its possible relationship to the osseous change.Three alternatives may be entertained: (1) Brain atrophy is caused by the encroachment and pressure of the hyperostotic area on the surface of the brain; (2) brain atrophy is primary, the shrinkage of the frontal convolutions in some way exciting a compensatory bony overgrowth ; (3) the two processes, osseous and neural, are entirely independent of each other.