High resolution MRI for quantitative assessment of inferior alveolar nerve impairment in course of mandible fractures: an imaging feasibility study

Abstract

The purpose of this study was to evaluate a magnetic resonance imaging (MRI) protocol for direct visualization of the inferior alveolar nerve in the setting of mandibular fractures. Fifteen patients suffering from unilateral mandible fractures involving the inferior alveolar nerve (15 affected IAN and 15 unaffected IAN from contralateral side) were examined on a 3 T scanner (Elition, Philips Healthcare, Best, the Netherlands) and compared with 15 healthy volunteers (30 IAN in total). The sequence protocol consisted of a 3D STIR, 3D DESS and 3D T1 FFE sequence. Apparent nerve-muscle contrast-to-noise ratio (aNMCNR), apparent signal-to-noise ratio (aSNR), nerve diameter and fracture dislocation were evaluated by two radiologists and correlated with nerve impairment. Furthermore, dislocation as depicted by MRI was compared to computed tomography (CT) images. Patients with clinically evident nerve impairment showed a significant increase of aNMCNR, aSNR and nerve diameter compared to healthy controls and to the contralateral side (p < 0.05). Furthermore, the T1 FFE sequence allowed dislocation depiction comparable to CT. This prospective study provides a rapid imaging protocol using the 3D STIR and 3D T1 FFE sequence that can directly assess both mandible fractures and IAN damage. In patients with hypoesthesia following mandibular fractures, increased aNMCNR, aSNR and nerve diameter on MRI imaging may help identify patients with a risk of prolonged or permanent hypoesthesia at an early time.

Ultrashort echo time Cones double echo steady state (UTE‐Cones‐DESS) for rapid morphological imaging of short T2 tissues

“…1 In DESS, an SSFP signal is separated into two components, free induction decay (FID)-like signal (S + ) and echo-like signal (S − ), by using an extended and unbalanced readout gradient between two consecutive RF pulses. 2 DESS has been widely used for clinical applications in musculoskeletal (MSK) [3][4][5][6][7][8][9][10] and neuroimaging [11][12][13][14][15][16] due to its flexible tissue contrast involving T 1 , T 2 , and diffusion weighting. In DESS imaging, fat signal commonly appears with high signal intensity due to its high T 2 over T 1 ratio, a signal which typically needs to be suppressed when attempting to image non-lipid tissues with specificity.…”

Magnetic Resonance Imaging Finding of Periodontal and Inferior Alveolar Nerve Inflammation in a Subject With Trigeminal Neuralgia

“…Conclusions: Imaging of the inferior alveolar nerve is challenging 1 . In this case, post‐contrast T1 SPIR MRI allowed visualization of inferior alveolar nerve and its inflammation and led to the final diagnosis.…”

Mandibular Third Molar Surgery: Intraosseous Localization of the Inferior Alveolar Nerve Using 3D Double-Echo Steady-State MRI (3D-DESS)

“…A variety of MRI studies investigated the visualization of the IAN, with several reports achieving promising results of direct visualization in preoperative imaging of impacted third molars [ 20 , 21 ]. Data generated by the recently introduced 3D double-echo steady-state with water excitation MRI sequence provided excellent results regarding visualization of the IAN [ 19 , 23 , 24 , 25 , 30 ]. The results achieved in this study confirm the previous reports about the feasibility and accuracy of the IAN’s direct precise displaying by the 3D-DESS protocol [ 23 ] ( Figure 7 ).…”

“…Since the IAN’s intraosseous course cannot be displayed by conventional radiographic assessment, an increasing number of MRI studies have investigated its direct visualization, with only a few studies achieving promising reliable results in the context of third molar surgery [ 20 , 21 ]. Excellent visualization of the IAN was enabled by applying the recently introduced 3D double-echo steady-state (3D-DESS) with water excitation MRI sequence [ 22 , 23 , 24 , 25 ]. Previous reports documenting the IAN’s intraosseous course had various significant limitations, such as using CBCT imaging displaying only the nerve canal [ 26 ] or skull studies using cadavers not allowing for generalized information or having edentulous mandibles [ 27 , 28 ].…”