Multi-modal volume registration of the Temporo-mandibular joint by using MRI- and CT-imagery

The treatment of orofacial pain and temporo-mandibular disorders (TMD) has evolved into a multidisciplinary approach. Studies have demonstrated that MRI of the TMJ is the most accurate concerning disk position. CT is considered to be the most accurate for osseous changes. Being able to register these two modalities allows to transfer the coordinates of computerized axiography and scelettal analyses on the base of a lateral cephalometric radiograph for anatomical reference and for disk displacement. Material and methods: In order to display TMJ images as a dynamic study has been affected by using MAGNETOM SP 63, Siemens and C 100 XL, Imatron. To facilitate this procedure a modified BURNETT-device was developed to passivily open the patient's mouth. Results: The tomograms have a ACR Nemo-format and were transferred in PCX-format for using surface-based methods to register CT- and MRI-imagery. The transfer of the original geometry in a CAD-model is concluded. The 3D-models of the TMJ are creating by using a five-axio CNC-milling machine and laser lithography. Conclusion: An initial comparison of the 3D-models of the TMJ's vs anatomic structures showed a good correlation with respect to the axiographpyprotocol While this approach based on aligment of surfaces, this technique ist depend on the a priori quality of the available segmentations. Alternativly, intensity-based technique can work directly with the volumetric data and must be relied on some what ad hoc assumptions about the nature of the signals involved. Adjustment of the relative position and orientation is needed until the mutual information between images and computerized axiography is maximized. Keywords: TMJ, MRI, CT, 3D model, 3D reconstruction, axiography, lateral X-ray, laser lithography modelling