Three-dimensional imaging and display of the temporomandibular joint.

Despite recent advances in diagnostic radiology, current techniques for radiographic evaluation of the temporomandibular joint continue to present the clinician with difficult problems in interpretation and diagnosis. The use of three-dimensional images reconstructed from computed tomographic (CT) data improves the diagnostic value of conventional CT at no additional risk to the patient and may provide new insights into this complex anatomic structure. A sequence of 1.5 mm CT sections is made with a slice-to-slice spacing of 1.0 mm. These are used to construct a new sequence of slices by mathematical interpolation in which the new slice spacing equals the size of the pixels. Structures to be imaged separately are then masked in the interpolated sections prior to "windowing" for the appropriate tissue density. A special algorithm detects the boundary surface of the selected structure. The surface pixels are assigned gray levels on the basis of their distance and attitude from the observer. When displayed, this produces a simulated three-dimensional image. The image can be rotated and sectioned. Rotations permit otherwise hidden surfaces to be examined. Images of a human temporomandibular joint in vitro are presented to demonstrate (1) the bony components of the joint and their relationships within the joint; (2) the bony components separated to display hidden surfaces; and (3) the joint meniscus in situ and as a separate component.