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FIG 3. A, Cross-sectional reconstruction of a mandible derived from an axial CT scan with an effective section thickness of 1 mm. Localization of the mandibular canal (arrowheads) was not possible with certainty on this section. A comparison with adjacent sections was necessary to determine the exact location of the mandibular canal for the measurements.
B, Cross-sectional reconstruction of the same mandible as in A, in the same location, derived from an axial T1-weighted (6.2/20) MR image (31° flip angle and an effective section thickness of 0.5 mm). The mandibular neurovascular bundle (arrowheads) is easily distinguished on this single section as a moderately hyperintense structure. No additional technique was required for its localization.
C, Cross section for direct osteometry corresponding to cross-sectional reconstructions in A and B. The contents of the mandibular canal were colored with enamel. The location of the mandibular canal (dark area) is the same as that identified on the dental MR cross section. Note that the transition from cortical to spongy bone is not as clear-cut as the reformatted MR and CT images suggest.
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