Diffusion tensor tractography for the inferior alveolar nerve (V3): initial experiment

ObjectiveThe inferior alveolar nerve is the third branch (V3) of the trigeminal nerve and one of the important nerves in dental treatment clinically. In particular, in the assessment of nerve invasion by malignant tumors of jaw bone, diagnostic imaging of the inferior alveolar nerve is essential. The purpose of this study was to evaluate the application of diffusion tensor tractography (DTT) in the mandible for the visualization of the inferior alveolar nerve as an initial experiment.Study designThe subjects were 10 healthy volunteers. Magnetic resonance (MR) imaging was performed using a 1.5-T MR unit (Intera Achiva; Philips Medical Systems). The raw data from the DTT sequence images were transferred to an off-line workstation, which used Philips Research Imaging Development Environment software for image registration and fiber tracking.ResultsBecause the signal-to-noise ratio in DTT of oral and maxillofacial structures was low, it was difficult to set regions of interest exactly on the inferior alveolar nerve, though this becomes easier by overlaying of T1-weighted images. Thus the inferior alveolar nerve was observed running inside of the mandible in all tested cases.ConclusionsIn conclusion, we successfully visualized the inferior alveolar nerve by the automatic fiber tracking method of DTT in normal volunteers. Further application and assessment will be necessary in pathologic states of the mandible.