Value of Magnetic Resonance Imaging for Diagnosis of Dentigerous Cyst

Odontogenic cysts have a high prevalence in the dental clinic population, with dentigerous cyst being one of the most frequent ones and whose aetiology involves accumulation of fluid between the reduced enamel epithelium and the crown of an unerupted tooth. In the diagnostic process of these lesions, one should consider complementary imaging exams such as conventional radiography and computed tomography, which are commonly used for providing anatomical information on the tissues compromised by the lesion, but not on the nature of it. Magnetic resonance imaging (MRI) scans are noninvasive modalities which, due to their unique acquisition characteristics, can provide distinct information on the nature of the lesion. This study reports on a case of dentigerous cyst in the mandible of a 9-year-old patient, documented by means of different imaging modalities. MRI played an important role in both diagnosis of the lesion and differential diagnosis between neoplastic lesions presenting similar imagenological behaviour under other techniques of radiography

Influence of voxel size on the accuracy of linear measurements of the condyle in images of cone beam computed tomography : a pilot study

To analyze the influence of voxel size and exposure time on the accuracy of linear measurements of the condyle. Four macerated hemi-mandibles of pigs were scanned in nine different voxel size protocols. Three-dimensional models of the condyle were generated in order to establish a comparison between linear measurements obtained with each voxel protocol and those obtained with a caliper (gold standard). The comparison between the protocols was performed considering the average of the two measurements of the condyle in the latero-medial (LM) and antero-posterior (AP) axes and also through repeated measurement ANOVA with rank transformation. The level of significance was 5%. A significant difference was found between the protocols regarding the LM and AP variables (p-values = 0.0027 and 0.0263, respectively). In the LM axis, the protocol P6 (voxel size of 0.3 mm with scan time of 4.8 seconds) did not show statistical difference compared to the gold standard. The protocols P4 and P5 (voxel size of 0.25 mm with scan times of 14.7 and 26.9 seconds, respectively) were both statistically similar compared to caliper, although they have presented a longer scan time. In the AP axis, the protocol P8 (voxel size of 0.4 mm with time scan of 4.8 seconds) was statistically similar to the gold standard. A smaller voxel size does not necessarily mean more accuracy regarding the linear measurements of the condyle. It is possible to obtain an acceptable level of accuracy with a larger voxel size and a shorter exposure time to radiation

Avaliação tridimensional de carcinoma mucoepidermoide em palato duro: relato de caso clínico

Mucoepidermoid carcinoma is of unknown aetiopathology, but it may be related to genetic factors, exposure to ionizing radiation and smoking habits as well. Mucoepidermoid carcinoma is considered the most common malignant neoplasm of salivary glands found in the oral cavity, with its clinical characteristics (e.g., size and shape) favoring the diagnosis and treatment planning. This report describes a case of mucoepidermoid carcinoma which infiltrates into the maxillary sinus and nasal fossa through the palate and highlights the importance of obtaining three-dimensional (3D) images of the tumor for volumetric analysis, thus improving the chances of a successful surgery. We have described the use of the segmentation technique in which the tumor’s volume was calculated to help in predicting surgical outcomes. A 50-year-old patient sought dental treatment because of a purplish swelling in the hard palate region on the left side. Computed tomography examination was performed for visualization of the lesion and incisional biopsy for obtaining a sample, which was sent to anatomopathological study. Histological characteristics of the lesion and presence of neoplastic cells showed positive immunohistochemical reactions for cytokeratin 7 antibody, leading to a diagnosis of mucoepidermoid carcinoma. In view of the malignant characteristics of the lesion, the patient was referred to a head and neck surgeon for treatment.O carcinoma mucoepidermoide possui etiopatogenia desconhecida, porém, pode ser relacionado a fatores genéticos, exposição à radiação ionizante e também ao hábito de fumar. Há a possibilidade de crescer de forma assintomática. É considerado a neoplasia maligna de glândulas salivares mais comum encontrada na cavidade oral e as suas características clínicas (por exemplo, sítio de predileção e forma como se apresenta) favorecem um melhor diagnóstico e planejamento de intervenção. Este relato apresenta um caso de carcinoma mucoepidermoide que se infiltra no seio maxilar e fossa nasal através do palato e destaca a importância da obtenção de imagens tridimensionais (3-D) do tumor para análise volumétrica e melhoria das chances de sucesso cirúrgico. Descrevemos o uso de uma técnica pictórica em que o volume do tumor foi calculado para ajudar a prever os resultados cirúrgicos. A paciente de 50 anos procurou atendimento odontológico devido ao aumento de volume com coloração arroxeada em região de palato duro do lado esquerdo, foi realizado o exame de Tomografia Computadorizada onde se verificou a lesão. A partir da biópsia incisional e o encaminhamento para avaliação anatomopatológica, suas características histológicas e as células neoplásicas mostraram-se positivas para as reações de imunohistoquímica contra anticorpo citoqueratina sete, o que concluiu o diagnóstico de carcinoma mucoepidermoide. Diante das características malignas da lesão, a paciente foi encaminhada para médico cirurgião de cabeça e pescoço para tratamento

Image quality in partially erased DenOptix® storage phosphor plates

This study aimed at investigating the effect of the partial erasing of DenOptix® system storage phosphor plates on the image quality of digital radiographs. Standardized digital radiographs were acquired of a phantom mandible, using size 2 intraoral DenOptix® storage phosphor plates (n = 10). Subsequently, the active areas of the plates were placed in a viewing box with a constant light intensity of 1,700 lux for 130 seconds to achieve complete erasing (control plate), as well as for 0, 5, 10, 15, 20, 25, 34, 66, and 98 seconds, to compose the experimental group of partially erased plates. The same exposure settings were repeated using the control and experimental plates, which were scanned at a resolution of 300 dpi. Five radiologists independently examined the pairs of digital radiographs obtained with the control and partially erased plates, in random order, and indicated the best image for oral diagnosis. Cochran-Mantel-Haenszel’s chi-square test, at a significance level of 5%, was used to compare the percentages of superior quality images in each combination of control and partially erased plates, subjectively assessed. No significant differences were found between radiographic images acquired with control and partially erased plates, except for the combination of 0 second (30%) versus 130 seconds (70%), p = 0.0047. It can be concluded that, under adequate light intensity conditions, erasing intraoral DenOptix® storage phosphor plates may require time intervals of as little as 5 seconds

Squamous odontogenic tumor: literature review focusing on the radiographic features and differential diagnosis

Since its first publication in 1975, the squamous odontogenic tumor remains the rarest odontogenic lesion, with around 50 cases in the English-language literature in which the microscopic characteristics are frequently very well demonstrated. However, articles which discuss the radiographic aspects are scarce, especially with emphasis on the differential diagnosis. The present treatise proposes an assessment of jaw lesions with the same radiographic characteristics of the squamous odontogenic tumor to clarify the main findings for dental clinicians during routine diagnosis

Lateral pterygoid muscle volume and migraine in patients with temporomandibular disorders

Lateral pterygoid muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher's exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this muscle in such patients because the hypertrophic LPM is not always palpable

Valor diagnóstico da ressonância magnética na análise do ameloblastoma: relato de dois casos

Ameloblastoma is an odontogenic tumor that shares clinical and imaging characteristics with other lesions of the jaws, such as odontogenic keratocyst, which makes the diagnosis difficult.However, in addition to radiographic and tomographic examinations, Magnetic Resonance Imaging (MRI) has been increasingly used, contributing with relevant additional information about thedifferentiation between solid and liquid components of the lesion. This case report was conducted to present two variations of ameloblastoma and discuss the radiographic, tomographic and MRI contribution in the differential diagnosis between ameloblastoma and odontogenic keratocyst. The signal intensity in T1-weighted MRI revealed internal fluid content in both cases, which was important in the differential diagnosis with other intraosseous lesions such as odontogenic keratocysts. This is probably due to the presence of keratin that increases the viscosity of the content and also for an intermediate signal intensity signal in T2-weighted MRI. Therefore, MRI revealed important internal characteristics of the reported lesions, which was very useful in the establishment of the differential diagnosis with other lesions223425431O ameloblastoma é um tumor odontogênico que compartilha características clínicas e de imagem com outras lesões da mandíbula, como o ceratocisto odontogênico, o que dificulta o seu diagnóstico. Entretanto, além dos exames radiográficos e tomográficos, a ressonância magnética (RM) tem sido cada vez mais utilizada, contribuindo com informações adicionais relevantes sobre a diferenciação entre componentes sólidos e líquidos da lesão. Este relato de caso apresenta duas variações de ameloblastoma e discuti a contribuição radiográfica, tomográfica e da RM no diagnóstico diferencial entre o ameloblastoma e o ceratocisto odontogênico. A RM ponderada em T1 revelou conteúdo líquido interno em ambos os casos relatados, o que foi importante no diagnóstico diferencial com outras lesões intraósseas, como os ceratocistos odontogênicos. Isto ocorre devido à presença de queratina aumentar a viscosidade do conteúdo e também gerar um sinal de intensidade intermediária na RM ponderada em T2. Portanto, a RM revelou importantes características internas das lesões relatadas, o que foi muito útil no estabelecimento do diagnóstico diferencial com outras lesõe

Evaluation measure of 3d volumetry of masseter hypertrophy: association with modalities of imaging

Masseteric hypertrophy is a benign condition, asymptomatic and rare, characterized by the excessive development of the masseter muscle, which usually results in aesthetic complaints. The imaging exams for differential diagnosis of pathologies in the parotid-masseteric region is always recommended. This work aims the imaging characterization of masseteric hypertrophy through the report of two clinical cases combining different imaging modalities: panoramic radiography, magnetic resonance imaging, computed tomography, ultrasonography and 3D volumetry. Two male subjects with no family history of masseteric hypertrophy were referred to a diagnostic center in dentomaxillofacial radiology due to an increase in bilateral facial volume in the masseteric region. Images of the panoramic radiography showed an increase of the bilateral mandibular angle in both cases. Using computerized tomography, bilateral masseter muscle hypertrophy was demonstrated in the patients, and magnetic resonance scan and ultrasound examination were performed for better visualization and muscle measurement. 3D volumetry assessment of musculature showed as additional tool to evaluate the status of the masseter muscles in patients with Masseteric hypertrophy. Therefore, the association of imaging examinations allowed to perform the imaging characterization of masseteric hypertrophy with presence of bone exostosis

3D Morphology Analysis of TMJ Articular Eminence in Magnetic Resonance Imaging

Purpose. The objective of this study was to evaluate the computational reconstruction of the articular eminence of the temporomandibular joint (TMJ) based on magnetic resonance imaging (MRI) and semiautomatic volumetric segmentation techniques for morphological classification of the TMJ structure. Materials and Methods. A total of 36 MRI scans of TMJ individuals were selected and formatted by using the ITK-SNAP software, consisting of MRI segmentation and generation of 3D models. The TMJ articular eminences were also classified according to the morphology analysis of the articular eminence in 3D reconstructions. Two independent trained and calibrated investigators performed the image analysis, which was repeated after thirty days. Results. There was no association between sex and eminence shape (p=0.456). Fisher’s test revealed no statistically significant association between disc classification and eminence shape on both sides (p=0.629). Chi-square test showed a significant statistically association between disc classification and disc displacement (p=0.000). Intra- and interrater correlation coefficients showed excellent reproducibility values. Conclusions. Anatomical variability of the sample investigated was found, with predominantly round shape and presence of correlation between this shape and normal disc position. The correlation of flattened and convex shapes with disc position reduction indicated that type of disc derangement is more prevalent