Detection Rate and Variability in Measurement of Mandibular Incisive Canal on Cone-Beam Computed Tomography: A Study of 220 Dentate Hemi-Mandibles from Italy.

The mandibular incisive canal (MIC) is a small bony channel located in the interforaminal region; it represents the anterior continuation of the mandibular canal. Cone-beam computed tomography (CBCT) is the most commonly utilized radiological technique for assessing the MIC. The main purpose of this study was to evaluate the detectability and variability in measurements of the MIC on CBCT. A total of 220 dentate hemi-mandibles were retrospectively selected for this study. For each hemi-mandible, the detectability, diameter, and distance of the MIC from anatomical landmarks (cortical plates and tooth apices) were evaluated in consensus by two observers. The analysis was performed at four different levels (first premolar, canine, lateral incisor, and central incisor) and was repeated after one month. The variability of MIC measurements was expressed as the coefficient of repeatability (CR), obtained from the Bland-Altman analysis. The MIC detection rate reduced from the first premolar to the central incisor (from 82.3% to 0.5%). The CR of MIC measurements (diameter and distances from anatomical landmarks) was ≤0.74 mm. Although the MIC is difficult to detect in a non-negligible percentage of cases, the limited variability in measurements confirms that CBCT is an effective technique for the assessment of the MIC.

Endoscopic surgery for fibrous dysplasia of the sinonasal tract in pediatric patients.

Fibrous dysplasia (FD) is a non-neoplastic, expansile lesion of unknown origin. In about one-fourth of cases this disorder affects the head and neck area, where the mandible and maxilla are the most frequently involved sites. Its localization to the ethmoid is a rare event. Since the disease slowly progresses, its management is delayed until significant clinical symptoms or non-well-tolerated aesthetic deformities are present. When required, surgery is the treatment of choice. Several external procedures have been used to manage the lesion, but recently, more conservative transnasal approaches have been proposed. We report the history of a 6-year-old boy with fibrous dysplasia of the ethmoid labyrinth that underwent successful transnasal endoscopic removal. Furthermore, an analysis of the literature is presented with particular emphasis on clinical picture, diagnosis, and treatment of this rare illness.

Diagnostic accuracy of magnetic resonance imaging in the assessment of mandibular involvement in oral-oropharyngeal squamous cell carcinoma: a prospective study.

OBJECTIVE: To evaluate the sensitivity, specificity, accuracy, and predictive values of magnetic resonance imaging (MRI) in the assessment of mandibular involvement in oral-oropharyngeal squamous cell carcinoma. DESIGN: Prospective study. SETTING: University hospital. PATIENTS: Forty-three patients with oral or oropharyngeal squamous cell carcinoma undergoing marginal or segmental mandibulectomy between January 1, 1994, and January 31, 2003. INTERVENTIONS: Indications for mandibulectomy were MRIs suggestive of bony invasion, tumor involving the retromolar trigone or the alveolar ridge, recurrent or persistent lesion, or intraoperative suspicion of periosteal invasion. Detection of tumor signal replacing the hypointense cortical rim was considered the main radiologic finding for mandibular invasion. MAIN OUTCOME MEASURES: The MRI findings were subsequently compared with histopathologic data of surgical specimens with reference to the presence of cortical and/or medullary mandibular involvement. RESULTS: Sixteen patients had MRI findings suggestive of mandibular involvement. Segmental mandibulectomy was performed in 15 cases and marginal resection in the remaining case. In 14 patients, bony invasion was confirmed. All of the other 27 patients who underwent marginal or segmental mandibulectomy with negative MRI findings had no histopathologic evidence of mandibular involvement, except in 1 patient: on histopathologic examination, despite cortical integrity, neoplastic vascular embolization into the bony lacunae was detected. Sensitivity of MRI in detecting mandibular involvement was 93%; specificity, 93%; accuracy, 93%; and negative and positive predictive values, 96% and 87.5%, respectively. CONCLUSIONS: Magnetic resonance imaging is commonly considered the technique of choice for treatment planning in advanced oral and oropharyngeal squamous cell carcinoma because of its accuracy in depicting soft-tissue involvement. This study demonstrates the additional diagnostic value of MRI in detecting bone invasion.

TMJ disorders and pain: assessment by contrast-enhanced MRI.

Though magnetic resonance (MRI) is a widely accepted standard for the assessment of patients with temporomandibular joint (TMJ) disorders, efforts to correlate symptoms to MRI findings have often given controversial results. Aim of this study was to investigate the correlation between TMJ pain and findings of contrast-enhanced MRI. Thirty-eight consecutive patients with TMJ dysfunction syndrome (study group) were examined with MRI. Protocol included T2 turbo spin-echo sequence, T1 spin-echo sequence, and T2 gradient-echo (acquired with closed jaw, at intermediate and maximal opening). Post-contrast phase was obtained through a fat sat 3D T1 gradient-echo sequence (VIBE). Post-contrast findings in the study group were matched with those obtained in a control group of 33 patients submitted to MRI of the paranasal sinuses. Statistically significant difference was found between condylar medullary bone enhancement in painful TMJ, in painless TMJ and control group. In addition the average thickness of joint soft tissue enhancement in painful TMJ was superior to painless TMJ (p<0.0001) and to control group. On multivariate logistic regression analysis, the odds ratio that a painful TMJ showed disk displacement, osteoarthrosis, effusion and JST enhancement were 3.05, 3.18, 1.2 and 11.36, respectively. Though not histologically proven, TMJ enhancement could reflect the presence of inflammation in painful joints. Furthermore, the administration of contrast could be of help for the assessment of patients with orofacial pain, particularly when clinical exploration is insufficient to ascribe the pain to TMJ.