Preoperative visualization of the lingual nerve by 3D double-echo steady-state MRI in surgical third molar extraction treatment

Abstract

Objectives To assess the lingual nerve (LN) visualization using a 3D double-echo steady-state MRI sequence (3D-DESS). Materials and methods Three readers prospectively evaluated the LN for its continuous visibility in 3D-DESS MRI in 19 patients with an indication for removal of mandibular impacted third molars, using a 5-point scale (4 = excellent to 0 = none). Six LN anatomical intermediate points (IP) were selected and checked for their detectability by a 4-point scale (4 = yes to1 = no). Inter- and intra-rater agreement was evaluated using intraclass correlation coefficient and percentage of agreement. Results The average nerve continuity score was 3.3 ± 0.46. In 35% of the cases, the entire course was continuously visible. In 10%, the proximal and 60%, the distal part of the nerve was not continuously visible. Inter- and intra-reader agreement was good (ICC = 0.76, ICC = 0.75). The average detectability score of all IP was 3.7 ± 0.41. From IP1 to IP5, the detectability was excellent; meanwhile, IP6 had lower visibility. The inter- and intra-reader percentage of agreement was 77% and 87%. Conclusions The 3D-DESS sequence allowed accurate and continuous visualization of the LN with high reproducibility in more than one-third of the patients. This could improve the preoperative clarification of the LN position and thereby reduce complications during dentoalveolar surgical interventions. Clinical relevance 3D-DESS MRI might be beneficial in clinical scenarios where the second molar is elongated or presents a difficult rotational position while simultaneously having a close positional relationship to the third molar. Thereby, osteotomy performed more lingually, indicating extended lingual flap detachment may increase the risk of LN damage.

Visualization of Inferior Alveolar and Lingual Nerve Pathology by 3D Double-Echo Steady-State MRI: Two Case Reports with Literature Review

“…In this context, new developments target novel MRI protocols modified for dental applications, such as 3D-DESS and 3D short-tau inversion recovery (STIR), which enable high-resolution and high-contrast reliable assessment of the MTM region [ 23 ]. In addition to simultaneous visualization of bone and soft tissues, it is possible to visualize the positional relationship between the IAN/LN and MTM [ 18 ], to precisely determine the localization of the IAN within the osseous boundaries of the mandibular canal [ 14 ], and to visualize the lingual nerve up to its insertion into the tongue both focally and continuously [ 12 ]. In these dedicated black bone MRI protocols, the free induction decay (FID) signals of fast imaging with steady-state precession (FISP) are combined with the echo signal of a time-reversed FISP (PSIF), reducing signal dropout due to dephasing while simultaneously increasing its T2* specificity.…”

“…However, conventional radiographic imaging techniques can only visualize the IAN indirectly via the osseous boundaries of the mandibular canal, whereas the nervous tissue of the IAN and LN per se cannot be depicted directly. For this purpose, magnetic resonance imaging (MRI), with the recently introduced black-bone MRI sequences, can simultaneously visualize osseous structures and neural tissue in the oral cavity with high spatial resolution and excellent soft-tissue contrast [ 11 , 12 , 13 , 14 ]. Although most LN and IAN injuries recover spontaneously, therapy should be initiated early in selected cases with evident nerve damage, although the literature is inconsistent regarding the therapeutic time window [ 15 ].…”

Dental MRI of Oral Soft-Tissue Tumors—Optimized Use of Black Bone MRI Sequences and a 15-Channel Mandibular Coil

“…A comparison of black bone MRI sequences in their application in the dental field confirmed that they are best suited to overcome the limitations of hard tissue imaging in oral and maxillofacial radiology [ 12 , 17 , 33 ]. The STIR sequence offered the best signal-to-noise ratio and contrast-to-noise ratio between nerves and muscles, while the DESS protocols were suitable for comparing quantitative parameters [ 17 , 33 ].…”

“…A comparison of black bone MRI sequences in their application in the dental field confirmed that they are best suited to overcome the limitations of hard tissue imaging in oral and maxillofacial radiology [ 12 , 17 , 33 ]. The STIR sequence offered the best signal-to-noise ratio and contrast-to-noise ratio between nerves and muscles, while the DESS protocols were suitable for comparing quantitative parameters [ 17 , 33 ]. For visualization of more complex medical diseases, especially space-occupying malignant lesions, the contrast-enhanced 3D SPACE STIR sequence could accurately detect the localization of the pathological process with higher spatial resolution and image quality [ 34 ].…”

“…MRI has evolved rapidly over the past decades with various technical novelties and advanced imaging protocols, providing a broad spectrum of new diagnostic capabilities for the dental field [ 13 ]. Dental MRI with the recently introduced black bone MRI sequences is another step towards simultaneous radiation-free imaging of soft and hard tissues in the oral and maxillofacial region [ 14 , 15 , 16 , 17 ]. It allows for better characterization and staging of benign and malignant oral changes, providing the clinician with surgically relevant information such as the exact depth extent of clinically suspicious lesions, or information on other, clinically unsuspected, changes [ 18 , 19 , 20 , 21 ].…”