Cinematic study of temporomandibular joint motion using ultra-fast magnetic resonance imaging.

Magnetic Resonance Images (MRI) of the temporomandibular joint (TMJ) are usually performed to study the opening/closing movements of the mandible and have up to now been pseudodynamic step-by-step images simulating condylar motion by post-processing reconstruction. The aim of this study was: 1. to optimize a TMJ cine-imaging method to give a better clinical result than the step-by-step methods; 2. to develop an ultra-fast MRI Gradient Echo (GE) sequence for this purpose; and 3. to analyze condylar movements in the sagittal, coronal and para-axial planes during border mandibular displacements and chewing. Both TM joints were studied in six asymptomatic volunteers. The method involved a compromise between in-plane resolution, slice thickness, signal-to-noise ratio and time resolution. Routine clinical use was found to be a GE pulse sequence providing three images per second with an isometric voxel resolution of approximately two millimeters in ridge. This did not allow visualization of the disk. Using this sequence enabled real and simultaneous condylar displacement observation in the three planes of space and therefore contributed to a better functional diagnosis of pathologic TMJ motions.

Evaluation of a fast pseudo-cinematic method for magnetic resonance imaging of the temporomandibular joint.

A pseudo-cinematic magnetic resonance imaging study of the temporomandibular joint (TMJ) was undertaken with the aim of reconciling image quality with the shortest possible examination time. Two receivers were compared, a surface coil and a circularly polarized head coil, and the latter was found to be superior. Using a gradient echo sequence, repetition time and flip angle were optimized by visual assessment of the images and by measuring the contrast-to-noise ratio. A mechanical device was used to control opening and closing. The technique has been used on a series of 75 subjects, 60 of whom had TMJ dysfunction. Total acquisition time was 7 min. The results confirmed that it is possible to obtain pseudo-cinematic TMJ images suitable for clinical diagnosis by optimizing the choice of receiver and capture parameters.

Parasagittal magnetic resonance imaging of the lateral pterygoid muscle: a preliminary study.

Ten anatomic territories, including both lateral pterygoid muscle and temporomandibular joint heads, were explored with magnetic resonance imaging in subjects with no dysfunctional disorders. The sequence used was one of inversion-recovery, supplemented with image contrast reversal for better visualization. The muscles were observed in the resting position and in dynamic relation. Slice plane definition provided information on the anatomic variations of the superior head and on the muscle-articular junction, in particular on the fascicular aspect of the superior lateral pterygoid muscle and on the differentiation between condyle insertions under effort. The choice of technique and the results are discussed. Avenues are opened for the exploration of muscles utilizing magnetic resonance imaging.

Multivariate analysis of craniomandibular disorders.

This article presents the clinical application of a special statistical method, the Multiple Correspondence Analysis (MCA), derived from data analysis and particularly suited to study a restricted population (here, 202 patients with temporomandibular joint [TMJ] disorders) whose characteristics are defined by a large number of modalities (140). Processing of a Burt-type data table, or Complete Disjunctive Table (CDT), provided a geometrical visualization of information, and permitted determination of the prevalent factor axes. Results showed a significant relationship between all the articular disorders, either peripheral or focal (TMJ), thus revealing the possibility of a yet, little known morphogenic influence on the genesis of TMJ disorders.

Magnetic resonance imaging of the TMJ: identification of anatomic elements by controlled movement and application to normal and pathologic clinical situations.

Magnetic resonance imaging of the temporomandibular joint is evaluated by an ex vivo model, in normal patients, and in those with TMJ dysfunctions. Adaptation of MRI techniques for very thin articular elements is discussed.