Osteometry of the mandible performed using dental MR imaging

BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identi fy the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal, Dental MR images are c omparable to dental CT scans, which directly show the IANB; however, measur ements of length may not be reliable owing to susceptibility artifacts and held inhomogeneities in the oral cavity, Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry. METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradie nt-echo sequence and dental CT were performed in six anatomic specimens, Th e axial scans were reformatted as panoramic and cross-sectional reconstruct ions on a workstation and characteristic cross sections were obtained from all mandibles, The longest axis in the bucco lingual and apico-basal direct ions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of t he mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with me asurements on corresponding MR and CT reformatted images. RESULTS: The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar rid ge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods. CONCLUSION: The accuracy of length measurements in the jaw bones obtained u sing dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternativ e to CT for dental imaging.