Magnetic resonance imaging of the inferior alveolar nerve with special regard to metal artifact reduction

Assessment of traumatic mandibular nerve using MR neurography sequence: a preliminary study

BACKGROUND

Iatrogenic mandibular nerve damage resulting from oral surgeries and dental procedures is painful and a formidable challenge for patients and oral surgeons alike, mainly because the absence of objective and quantitative methods for diagnosing nerve damage renders treatment and compensation ambiguous while often leading to medico-legal disputes. The aim of this study was to examine discriminating factors of traumatic mandibular nerve within a specific magnetic resonance imaging (MRI) protocol and to suggest tangible diagnostic criteria for peripheral trigeminal nerve injury.

METHODS

Twenty-six patients with ipsilateral mandibular nerve trauma underwent T2 Flex water, 3D short tau inversion recovery (STIR), and diffusion-weighted imaging (DWI) acquired by periodically rotating overlapping parallel lines with enhanced reconstruction (PROPELLER) pulse sequences; 26 injured nerves were thus compared with contra-lateral healthy nerves at anatomically corresponding sites. T2 Flex apparent signal to noise ratio (FSNR), T2 Flex apparent nerve-muscle contrast to noise ratio (FNMCNR) 3D STIR apparent signal to noise ratio (SSNR), 3D STIR apparent nerve-muscle contrast to noise ratio (SNMCNR), apparent diffusion coefficient (ADC) and area of cross-sectional nerve (Area) were evaluated.

RESULTS

Mixed model analysis revealed FSNR and FNMCNR to be the dual discriminators for traumatized mandibular nerve (p < 0.05). Diagnostic performance of both parameters was also determined with area under the receiver operating characteristic curve (AUC for FSNR = 0.712; 95% confidence interval [CI]: 0.5660, 0.8571 / AUC for FNMCNR = 0.7056; 95% confidence interval [CI]: 1.011, 1.112).

CONCLUSIONS

An increase in FSNR and FNMCNR within our MRI sequence seems to be accurate indicators of the presence of traumatic nerve. This prospective study may serve as a foundation for sophisticated model diagnosing trigeminal nerve trauma within large patient cohorts.

Magnetic resonance imaging in dental implant surgery: a systematic review

PURPOSE

To comprehensively assess the existing literature regarding the rapidly evolving in vivo application of magnetic resonance imaging (MRI) for potential applications, benefits, and challenges in dental implant surgery.

METHODS

Electronic and manual searches were conducted in PubMed MEDLINE, EMBASE, Biosis, and Cochrane databases by two reviewers following the PICOS search strategy. This involved using medical subject headings (MeSH) terms, keywords, and their combinations.

RESULTS

Sixteen studies were included in this systematic review. Of the 16, nine studies focused on preoperative planning and follow-up phases, four evaluated image-guided implant surgery, while three examined artifact reduction techniques. The current literature highlights several MRI protocols that have recently investigated and evaluated the in vivo feasibility and accuracy, focusing on its potential to provide surgically relevant quantitative and qualitative parameters in the assessment of osseointegration, peri-implant soft tissues, surrounding anatomical structures, reduction of artifacts caused by dental implants, and geometric accuracy relevant to implant placement. Black Bone and MSVAT-SPACE MRI, acquired within a short time, demonstrate improved hard and soft tissue resolution and offer high sensitivity in detecting pathological changes, making them a valuable alternative in targeted cases where CBCT is insufficient. Given the data heterogeneity, a meta-analysis was not possible.

CONCLUSIONS

The results of this systematic review highlight the potential of dental MRI, within its indications and limitations, to provide perioperative surgically relevant parameters for accurate placement of dental implants.

Morphological Studies to Identify the Nasopalatine and Inferior Alveolar Nerve Using a Special Head and Neck MRI Coil

OBJECTIVES

Procedures in oral and maxillofacial surgery bear a high risk of nerve damage. Three-dimensional imaging techniques can optimize surgical planning and help to spare nerves. The aim of this study was to investigate the diagnostic value of a 1.5 T magnetic resonance imaging (MRI) scanner with a dedicated dental signal amplification coil for the assessment of nerves in the oral cavity as compared with cone beam computed tomography (CBCT).

METHODS

Based on 6 predefined criteria, the assessability of the inferior alveolar and nasopalatine nerves in CBCT and MRI with a dedicated 4-channel dental coil were compared in 24 patients.

RESULTS

Compared with CBCT, MRI with the dental coil showed significantly better evaluability of the inferior alveolar nerve in the sagittal and axial plane and the nasopalatine nerve in the axial plane. In the sagittal plane; however, the assessability of the nasopalatine nerve was significantly better in CBCT as compared with MRI. Yet, pertaining to overall assessability, no significant differences between modalities were found.

CONCLUSIONS

In this pilot study, it can be reported that 1.5- T MRI with a dedicated dental coil is at least equivalent, if not superior, to CBCT in imaging nerve structures of the stomatognathic system.

CLINICAL RELEVANCE

Preoperative, 3-dimensional images are known to simplify and refine the planning and execution of operations in maxillofacial surgery. In contrast to computed tomography and CBCT, MRI does not cause radiation exposure while enabling visualization of all relevant hard and soft tissues and, therefore, holds an advantage over well-established techniques.

Magnetic resonance imaging artefacts caused by orthodontic appliances and/or implant-supported prosthesis: a systematic review

OBJECTIVES

Dental materials, including orthodontic appliances and implants, are commonly mentioned as a possible source of artefacts in magnetic resonance imaging (MRI). The aim of the present study was to undertake a systematic review of the relevant literature on MR image artefacts due to dental materials, limited to orthodontic appliances and implant-supported dental prosthesis, on both technical and diagnostic levels.

METHODS

The MEDLINE (PubMed) bibliographic database was searched up to September 2020. The search was limited to studies published in English, using the search string: (MRI or magnetic resonance) and (artefact or artifact) and (dental or ortho or implant or restoration or restorative). The studies were assessed independently by three reviewers, focusing on the following parameters: MRI sequences, tested materials, assessed parameters, efficacy level and outcome.

RESULTS

The search strategy yielded 31 studies, which were included in this systematic review. These studies showed that metallic dental materials, commonly present in orthodontic appliances and implant-supported dental prosthesis led to diverse types/severities of artefacts in MR images. Fifteen studies were in vivo, based on human subjects. The studies differed substantially in terms of tested materials, assessed parameters, and outcome measurements.

CONCLUSIONS

Metallic dental materials cause artefacts of diverse types and severities in MR images of the head and neck region. However, the diagnostic relevance of the investigated artefacts for the diverse MRI applications is yet to be studied.

Dental MRI-only a future vision or standard of care? A literature review on current indications and applications of MRI in dentistry

MRI is increasingly used as a diagnostic tool for visualising the dentoalveolar complex. A comprehensive review of the current indications and applications of MRI in the dental specialities of orthodontics (I), endodontics (II), prosthodontics (III), periodontics (IV), and oral surgery (V), pediatric dentistry (VI), operative dentistry is still missing and is therefore provided by the present work.The current literature on dental MRI shows that it is used for cephalometry in orthodontics and dentofacial orthopaedics, detection of dental pulp inflammation, characterisation of periapical and marginal periodontal pathologies of teeth, caries detection, and identification of the inferior alveolar nerve, impacted teeth and dentofacial anatomy for dental implant planning, respectively. Specific protocols regarding the miniature anatomy of the dentofacial complex, the presence of hard tissues, and foreign body restorations are used along with dedicated coils for the improved image quality of the facial skull.Dental MRI poses a clinically useful radiation-free imaging tool for visualising the dentoalveolar complex across dental specialities when respecting the indications and limitations.

SEMAC + VAT for Suppression of Artifacts Induced by Dental-Implant-Supported Restorations in Magnetic Resonance Imaging

The purpose of this study was to assess the feasibility of SEMAC + VAT to reduce artifacts induced by dental implant-supported restorations, such as its impact on the image quality. Dental-implant supported restorations were installed in a dry mandible. Magnetic resonance scans were acquired on a 3-Tesla MRI system. Artifact suppression (SEMAC + VAT) was applied with different intensity modes (weak, moderate, strong). Artifacts assessment was performed by measuring the mandible volume increase in MRI images prior (reference dataset) and after installation of dental implant-supported prosthesis. Image quality was assessed by two examiners using a five-point scale. Inter-examiner concordance and correlation analysis was performed with Cronbach's alpha and Spearman's test with a significance level at p = 0.05. Mandible volume increased by 60.23% when no artifact suppression method was used. By applying SEMAC + VAT, the volume increase ranged from 17.13% (strong mode) to 32.77% (weak mode). Visualization of mandibular bone was positively correlated with SEMAC intensity degree. SEMAC + VAT reduced MRI artifacts caused by dental-implant supported restorations. A stronger suppression mode improved visualization of mandibular bone in detriment of the scanning time.

Magnetic resonance imaging for preoperative diagnosis in third molar surgery: a systematic review

In recent years, magnetic resonance imaging (MRI) has made great strides through various technical improvements and new sequences, which have made it one of the most promising and leading imaging techniques in the head and neck region. As modern imaging techniques in dentistry aim to reduce radiation exposure, this systematic review evaluated the possibilities, advantages, and disadvantages of advanced imaging diagnostics using dental MRI and its evidence for clinical indications and limitations relevant to mandibular third molar (MTM) surgery. Two reviewers performed multiple database searches (PubMed MEDLINE, EMBASE, Biosis, and Cochrane databases) following the PICOS search strategy using medical subject headings (MeSH) terms, keywords, and their combinations. Ten studies were included in this systematic review. By providing high spatial resolution and excellent soft tissue contrast, black bone MRI sequences such as 3D Double Echo Steady State (DESS) and 3D Short Tau Inversion Recovery (STIR) imaging protocols have the potential to become a valuable alternative to cone-beam computed tomography (CBCT) in future dental clinical routines. Overall, radiation-free MRI represents another step toward personalized dentistry and improved decision-making that avoids ineffectiveness and minimizes risks in oral surgery by taking into account additional patient-side factors such as comorbidity, anatomical norm variations, and imaging biomarkers.

Neuroimaging in Pediatric Stroke

Pediatric stroke is unfortunately not a rare condition. It is associated with severe disability and mortality because of the complexity of potential clinical manifestations, and the resulting delay in seeking care and in diagnosis. Neuroimaging plays an important role in the multidisciplinary response for pediatric stroke patients. The rapid development of adult endovascular thrombectomy has created a new momentum in health professionals caring for pediatric stroke patients. Neuroimaging is critical to make decisions of identifying appropriate candidates for thrombectomy. This review article will review current neuroimaging techniques, imaging work-up strategies and special considerations in pediatric stroke. For resources limited areas, recommendation of substitute imaging approaches will be provided. Finally, promising new techniques and hypothesis-driven research protocols will be discussed.

Artifacts in magnetic resonance imaging caused by dental materials: a systematic review

OBJECTIVES

The purpose of this systematic review was to search in literature in which severity unintended effects are caused by dental materials in magnetic resonance imaging (MRI), such as to evaluate whether these artifacts hamper the diagnosis in the head and neck region.

MATERIALS AND METHODS

Clinical studies showing the severity of artifacts which dental materials are capable of causing in MRI of head and neck, such as their influence on diagnostic accuracy, were included in this review. The searches were conducted in four electronic databases (PubMed/Medline, Embase, Scopus and Web of Science), and a manual search was made in the reference lists of papers screened for full-text reading. Risk of bias was assessed using "Quality Assessment Tool for Diagnostic Accuracy Studies-2" (QUADAS-2). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was used to assess the quality of evidence.

RESULTS

From 151 studies selected for full-reading, 19 were considered eligible for this review. Artifacts caused by orthodontic appliances were well-documented, and stainless steel brackets were the materials most likely to cause artifacts in MR imaging of head and neck. The literature was scarce for dental implants and restorations. Diagnoses within the oral cavity, but also those of the brain and craniofacial structures, were affected.

CONCLUSION

Artifacts caused by orthodontic appliances may affect the diagnosis in oral cavity and craniofacial structures. Data regarding dental implants and prosthodontics restorations were inconclusive. The severity of artifacts in MRI and their influence on diagnosis is dependent on dental material features, location in the oral cavity, and magnetic resonance parameters.

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

Injury to the peripheral branches of the trigeminal nerve, particularly the lingual nerve (LN) and the inferior alveolar nerve (IAN), is a rare but serious complication that can occur during oral and maxillofacial surgery. Mandibular third molar surgery, one of the most common surgical procedures in dentistry, is most often associated with such a nerve injury. Proper preoperative radiologic assessment is hence key to avoiding neurosensory dysfunction. In addition to the well-established conventional X-ray-based imaging modalities, such as panoramic radiography and cone-beam computed tomography, radiation-free magnetic resonance imaging (MRI) with the recently introduced black-bone MRI sequences offers the possibility to simultaneously visualize osseous structures and neural tissue in the oral cavity with high spatial resolution and excellent soft-tissue contrast. Fortunately, most LN and IAN injuries recover spontaneously within six months. However, permanent damage may cause significant loss of quality of life for affected patients. Therefore, therapy should be initiated early in indicated cases, despite the inconsistency in the literature regarding the therapeutic time window. In this report, we present the visualization of two cases of nerve pathology using 3D double-echo steady-state MRI and evaluate evidence-based decision-making for iatrogenic nerve injury regarding a wait-and-see strategy, conservative drug treatment, or surgical re-intervention.

Comparison of Preoperative Cone-Beam Computed Tomography and 3D-Double Echo Steady-State MRI in Third Molar Surgery

We investigated the reliability of assessing a positional relationship between the inferior alveolar nerve (IAN) and mandibular third molar (MTM) based on CBCT, 3D-DESS MRI, and CBCT/MRI image fusion. Furthermore, we evaluated qualitative parameters such as inflammatory processes and imaging fusion patterns. Therefore, two raters prospectively assessed in 19 patients with high-risk MTM surgery cases several parameters for technical image quality and diagnostic ability using modified Likert rating scales. Inter- and intra-reader agreement was evaluated by performing weighted kappa analysis. The inter- and intra-reader agreement for the positional relationship was moderate (κ = 0.566, κ = 0.577). Regarding the detectability of inflammatory processes, the agreement was substantial (κ = 0.66, κ = 0.668), with MRI providing a superior diagnostic benefit regarding early inflammation detection. Independent of the readers’ experience, the agreement of judgment in 3D-DESS MRI was adequate. Black bone MRI sequences such as 3D-DESS MRI providing highly confidential preoperative assessment in MTM surgery have no significant limitations in diagnostic information. With improved cost and time efficiency, dental MRI has the potential to establish itself as a valid alternative in high-risk cases compared to CBCT in future clinical routine.

Geometric accuracy of magnetic resonance imaging-derived virtual 3-dimensional bone surface models of the mandible in comparison to computed tomography and cone beam computed tomography: A porcine cadaver study

BACKGROUND

Providing accurate 3-dimensional virtual bone surface models is a prerequisite for virtual surgical planning and additive manufacturing in craniomaxillofacial surgery. For this purpose, magnetic resonance imaging (MRI) may be a radiation-free alternative to computed tomography (CT) and cone beam computed tomography (CBCT).

PURPOSE

The aim of this study was to assess the geometric accuracy of 3-dimensional T1-weighted MRI-derived virtual bone surface models of the mandible in comparison to CT and CBCT.

MATERIALS AND METHODS

Specimens of the mandible from porcine cadavers were scanned with (1) a 3-dimensional T1-weighted MRI sequence (0.6 mm isotropic voxel) optimized for bone imaging, (2) CT, and (3) CBCT. Cortical mandibular structures (n = 10) were segmented using semiautomated and manual techniques. Imaging-based virtual 3-dimensional models were aligned with a high-resolution optical 3-dimensional surface scan of the dissected bone (=ground truth) and global geometric deviations were calculated (mean surface distance [MSD]/root-mean-square distance [RMSD]). Agreement between the imaging modalities was assessed by equivalence testing and Bland-Altman analysis.

RESULTS

Intra- and inter-rater agreement was on a high level for all modalities. Global geometric deviations (MSD/RMSD) between optical scans and imaging modalities were 0.225 ± 0.020 mm/0.345 ± 0.074 mm for CT, 0.280 ± 0.067 mm/0.371 ± 0.074 mm for MRI, and 0.352 ± 0.076 mm/0.454 ± 0.071 mm for CBCT. All imaging modalities were statistically equivalent within an equivalence margin of ±0.3 mm, and Bland-Altman analysis indicated high agreement as well.

CONCLUSIONS

The results of this study indicate that the accuracy and reliability of MRI-derived virtual 3-dimensional bone surface models is equal to CT and CBCT. MRI may be considered as a reliable alternative to CT and CBCT in computer-assisted craniomaxillofacial surgery.

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

The aim of this study was to evaluate the inferior alveolar nerve's (IAN) intraosseous position within the inferior alveolar canal (IAC) using a 3D double-echo steady-state MRI sequence (3D-DESS). The IAN position was prospectively evaluated in 19 patients undergoing mandibular third molar (MTM) surgery. In the coronal reference layer, the IAC was divided into six segments. These segments were checked for the presence of hyperintense tubular MRI signals representing the IAN's nervous tissue and assessed as visible/non-visible. Furthermore, the IAN in MRI and the IAC in MRI and CBCT were segmented at the third and second molar, determining the maximum diameter in all planes and a conversion factor between the imaging modalities. Regardless of the positional relationship at the third and second molar, the IAN showed the highest localization probability in the central segments (segment 2: 97.4% vs. 94.4%, segment 5: 100% vs. 91.6%). The conversion factors from IAC in CBCT and MRI to IAN in MRI, respectively, were the following: axial (2.04 ± 1.95, 2.37 ± 2.41), sagittal (1.86 ± 0.96, 1.76 ± 0.74), and coronal (1.26 ± 0.39, 1.37 ± 0.25). This radiation-free imaging modality, demonstrating good feasibility of accurate visualization of nervous tissue within the nerve canal's osseous boundaries, may benefit preoperative assessment before complex surgical procedures are performed near the IAC.

Is MRI a viable alternative to CT/CBCT to identify the course of the inferior alveolar nerve in relation to the roots of the third molars?

Objectives

To assess the reliability of judging the spatial relation between the inferior alveolar nerve (IAN) and mandibular third molar (MTM) based on MRI or CT/CBCT images.

Methods

Altogether, CT/CBCT and MRI images of 87 MTMs were examined twice by 3 examiners with different degrees of experience. The course of the IAN in relation to the MTM, the presence/absence of a direct contact between IAN and MTM, and the presence of accessory IAN were determined.

Results

The IAN was in > 40% of the cases judged as inferior, while an interradicular position was diagnosed in < 5% of the cases. The overall agreement was good (κ = 0.72) and any disagreement between the imaging modalities was primarily among the adjacent regions, i.e., buccal/lingual/interradicular vs. inferior. CT/CBCT judgements presented a very good agreement for the inter- and intrarater comparison (κ > 0.80), while MRI judgements showed a slightly lower, but good agreement (κ = 0.74). A direct contact between IAN and MTM was diagnosed in about 65%, but in almost 20% a disagreement between the judgements based on MRI and CT/CBCT was present resulting in a moderate overall agreement (κ = 0.60). The agreement between the judgements based on MRI and CT/CBCT appeared independent of the examiner’s experience and accessory IAN were described in 10 cases in MRI compared to 3 cases in CT/CBCT images.

Conclusions

A good inter- and intrarater agreement has been observed for the assessment of the spatial relation between the IAN and MTM based on MRI images. Further, MRI images might provide advantages in the detection of accessory IAN compared to CT/CBCT.

Clinical relevance

MRI appears as viable alternative to CT/CBCT for preoperative assessment of the IAN in relation to the MTM.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-020-03716-4.

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

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.

MRI of the inferior alveolar nerve and lingual nerve-anatomical variation and morphometric benchmark values of nerve diameters in healthy subjects

OBJECTIVE

Since MRI using dedicated imaging sequences has recently shown promising results in direct visualization of the inferior alveolar nerve (IAN) and the lingual nerve (LN) with high spatial resolution, the aim of this study was to generate suitable standard specifications to reliably depict the IAN and LN in MRI and to delineate the anatomy and its variants of these nerves in healthy subjects.

METHODS

Thirty healthy volunteers were examined on a 3-T scanner (Elition, Philips Healthcare, Best, the Netherlands). The sequence protocol consisted of 3D STIR, 3D DESS, and 3D T1 FFE "black bone" sequences.

RESULTS

The study reconfirmed a good feasibility of direct visualization of proximal and peripheral portions of the IAN and of the proximal course of the LN. The STIR sequence showed the highest apparent signal to noise ratio (aSNR) and best apparent nerve-muscle contrast to noise ratio (aNMCNR) for IAN and for the LN. The applied MRI sequences allowed to differentiate the tissue composition of the neurovascular bundle inside the mandibular canal.

CONCLUSION

Dedicated MRI sequence protocols proved effectively to detect the IAN and LN and their course in healthy volunteers. The tissue composition of the mandibular neurovascular bundle was conclusively distinguishable as was the varying topography inside multiple bony channels.

CLINICAL RELEVANCE

The presented data on the precise and valid visualization of the IAN and LN have clinical implications in respect to local anesthesia prior to dental treatments in the mandible but also regarding surgical procedures and implant insertion in the molar region.

Quantitative evaluation of artefact reduction from metallic dental materials in short tau inversion recovery imaging: efficacy of syngo WARP at 3.0 tesla

OBJECTIVES

To evaluate the effects of syngo WARP on reducing metal artefacts from dental materials.

METHODS

Short tau inversion recovery (STIR) with syngo WARP [a dedicated metal artefact reduction sequence in combination with view-angle-tilting (VAT)] was performed using phantoms of three dental alloys: cobalt-chromium (Co-Cr), nickel-chromium (Ni-Cr), and titanium (Ti). Artefact volumes and reduction ratios of black, white and overall artefacts in the standard STIR and syngo WARP images with several different parameter settings were quantified according to standards of the American Society for Testing and Materials F2119-07. In all sequences, the artefact volumes and reduction ratios were compared. The modulation transfer function (MTF) and contrast-to-noise ratio (CNR) were also measured for evaluation of image quality.

RESULTS

In standard STIR, the overall artefact volume of Co-Cr was markedly larger than those of Ni-Cr and Ti. All types of artefacts tended to be reduced with increasing receiver bandwidth (rBW) and VAT. The effect of artefact reduction tended to be more obvious in the axial plane than in the sagittal plane. Compared with standard STIR, syngo WARP with a matrix of 384 × 384, receiver bandwidth of 620 Hz/pixel, and VAT of 100 % in the axial plane obtained reduction effects of 30 % (white artefacts), 45 % (black artefacts), and 38 % (overall artefacts) although MTF and CNR decreased by 30 and 22 % compared with those of standard STIR, respectively.

CONCLUSIONS

syngo WARP for STIR can effectively reduce metal artefacts from dental materials.

Magnetic resonance imaging-a diagnostic tool for postoperative evaluation of dental implants: a case report

OBJECTIVE

Compared with cone beam computed tomography (CBCT), magnetic resonance imaging (MRI) might be superior for the diagnosis of nerve lesions associated with implant placement.

STUDY DESIGN

A patient presented with unilateral pain associated with dysesthesia in the region of the right lower lip and chin after implant placement. Conventional orthopantomography could not identify an association between the position of the inferior alveolar nerve and the implant. For 3-dimensional display of the implant in relation to the surrounding anatomy, CBCT was compared with MRI.

RESULTS

MRI enabled the precise depiction of the implant position and its spatial relation to the inferior alveolar nerve, whereas the nerve position and its exact course within the mandible could not be directly displayed in CBCT.

CONCLUSION

MRI may be a valuable, radiation-free diagnostic tool for the visualization of intraoral hard and soft tissues, offering an objective assessment of nerve injuries by a direct visualization of the inferior alveolar neurovascular bundle.

Fluorescence based characterization of early oral squamous cell carcinoma using the Visually Enhanced Light Scope technique

OBJECTIVES

Several diagnostic tools have been developed to assess benign and potentially malignant disorders of soft tissues. In this study, we aimed to assess the value of the VELscope^® (Visually Enhanced Light Scope) imaging device as a technical tool to investigate malignant lesions of the oral cavity.

MATERIAL AND METHODS

In this retrospective study we analyzed the photographs of 90 patients who suffered from malignant oral soft tissue lesions or carcinoma in situ (CIS) from 2008 to 2014 in the Clinic of Oral and Maxillofacial Surgery of LMU in Munich.

RESULTS

In 85.6% of the cases fluorescence quenching/loss could be detected. The average value for the colour red shows a significant difference in pathologic and physiologic tissues (p = 0.007) with a higher median for pathologic tissues. For the colours green and blue our measurements show significantly higher values in the healthy tissue (p < 0.001.). The shade of red showed significantly higher values for pathologic tissues when compared to all three colours (p < 0.001). Furthermore, the shades of green and blue showed significantly lower values in the pathologic tissue (p < 0.001).

CONCLUSION

In the near future, VELscope^® could help to a greater extent than visual observation alone in identifying the margins of tumor resections. VELscope^® still lacks the ability to identify the overall risk level of oral lesions.