Regional Collagen Fiber Network in the Articular Disc of the Human Temporomandibular Joint: Biochemical 3-Tesla Quantitative Magnetic Resonance Imaging Compared to Quantitative Histologic Analysis of Fiber Arrangement

Aims: To evaluate the regional collagen fiber network in the human temporomandibular joint (TMJ) disc by using biochemical magnetic resonance imaging (MRI) and quantitative histology. Methods: MRI of 5 heads (10 TMJ discs) obtained from partially dentate or edentulous cadavers was performed at 3-Tesla MRI by using a flexible, 8-channel transmit-receive coil. After MRI, all 10 discs were processed histologically. Percentages of coronal, sagittal, and transverse collagen fibers were assessed stereologically for the anterior, central, and posterior parts of the disc. An anisotropy index was calculated for collagen fiber arrangement in all three regions of interest. Results: In the central part of the TMJ disc, collagen fibers were arranged anisotropically with a preferentially sagittal direction. In the anterior and posterior parts, evidence for fibers being arranged isotropically (randomly) without preferred direction was found. Mean MRI T2 values appeared to be correlated with the anisotropy index of collagen fibers (r = -0.45; P .05). When tested individually, T2 values of the isotropic anterior and posterior disc regions showed a partial but significant correlation with the anisotropy index of collagen fibers (r = -0.54; P .05), whereas the anisotropic central part did not (P > .05). Conclusion: This study has provided the first systematic comparison of quantitative data on collagen fiber isotropy and anisotropy assessed in histologic sections with biochemical quantitative MRI for human TMJ fibrous cartilage. Keywords: comparison of MRI and histology, fibrocartilage, MRI, temporomandibular joint, 3 Tesla