High-resolution dental magnetic resonance imaging of inferior alveolar nerve responses to the extraction of third molars

Abstract

The objective of this study was to assess whether signal changes can be detected in the neurovascular bundle of the mandibular canal after the extraction of a third molar. We retrospectively analyzed MRI scans of 30 test subjects with healthy mandibles and 41 patients who had had a wisdom tooth extracted. Signal intensities were measured at particular sites in the neurovascular bundle, which were defined as regions of interest (ROI) in the sagittal T1-weighted images before and after intravenous administration of a paramagnetic contrast agent. On the basis of the signal intensity increases that were measured after contrast agent administration, we compared the signal increases obtained for the patients who had received surgical treatment with the results obtained for the population of test subjects with unremarkable mandibles ( t-test, P<0.05). Compared with the healthy test subjects, patients who had received surgical treatment showed significantly higher signal intensity increases at two measurement sites, i.e., the second molar and the second premolar ( P<0.05). We found no significant differences when the measurements were performed at the first molar ( P=0.06), the third molar ( P=0.47) and in the area of the ascending mandibular ramus ( P=0.79). Compared with a population of healthy test subjects, patients who had their third molars surgically removed show higher signal intensity increases in the neurovascular bundle after intravenous contrast agent administration. The underlying cause may be the higher blood flow in the arteries and veins and the perineural plexus, which may give evidence of the pathophysiological mechanism of nerve damage in the narrow canal as a result of osteotomy.

Diffusion tensor imaging of the inferior alveolar nerve using 3T MRI: a study for quantitative evaluation and fibre tracking

“…[7][8][9] While on the other hand, the IAN was evaluated quantitatively using DTI and was visualized three-dimensionally by tractography in the present study. DTI can provide quantitative data based on the diffusivity and anisotropy of microscopic water motion within nerve fibres, and the nerve fibres can be visualized three-dimensionally.…”

“…Recently, several studies have evaluated the mandibular canal using MRI. [7][8][9] Among these, some researchers reported that changes to the neurovascular bundle including IAN could be evaluated on the basis of T 1 -and T 2 -related signal intensities on high-quality MR images.…”

MRI volumetry for the preoperative diagnosis of trigeminal neuralgia

“…These highresolution magnetic resonance sequences make it possible to analyze cranial nerves quantitatively for the first time [14,15]. In contrast to patients with acute inflammatory diseases of the cranial nerves (facial and inferior alveolar nerves) [16,17], patients with trigeminal neuralgia show no contrast enhancement of the affected region prior to surgery. The significant volume difference that was preoperatively noted between the affected and the healthy side in patients with neuralgia is, however, indicative of nerve damage.…”

Assessment of Apical Periodontitis by MRI: A Feasibility Study

“…All data presented in this study were acquired on a high-field (3 T) whole-body clinical MR system. The likely drop in SNR may be addressed e. g. by usage of intraoral-coils [34], surface coils [37], or even dedicated dental phased-array coils [53]. The high imaging costs and long acquisition times still likely restrict the application of MRI to clinical research.…”