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Background: An odontogenic myxoma is an intraosseous tumor characterized by stellate and spindle-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. We herein describe an odontogenic myxoma that expanded not only to the bone marrow but also to the outside of the alveolar bone. Diagnosis of an odontogenic myxoma in a tooth-deficient region by imaging findings alone was difficult because the positional relationship between the tumor and the tooth is unknown. Furthermore, some of these odontogenic myxomas reportedly show rapid growth. Case Report: Here, we present the case of a patient, a 44-year-old man, who had a hard, bone-like swelling on his right mandible molar region and mild paresthesia on his right cheek. An odontogenic myxoma and ameloblastoma were suspected based on the imaging findings; however, pathological examination of the biopsy led to a diagnosis of odontogenic myxoma. Right segmental mandibulectomy was performed, and there was no recurrence observed after surgery. Conclusion: To improve the accuracy of imaging diagnosis, it is important to compare the imaging findings with the pathological findings of the surgical specimen. This comparison in the present case revealed differences in the magnetic resonance imaging signal intensity in regions with different types of cell components.

To examine the diagnostic usefulness and procedures of ultrasonography (US) for mass lesions in the soft tissue of the oral region.This study involved patients with mass lesions (tumorous lesions and cysts) who had undergone US and histopathological examinations from January 2017 to December 2019. The following points were evaluated by two observers using an evaluation scale: vascularity, echo intensity level, boundary, margin shape, distribution of internal echoes, and capsule. The usefulness of each point for differential diagnosis of tumorous lesions and cysts was statistically analyzed.Forty-five mass lesions in the soft tissue of the oral region (33 tumorous lesions and 12 cysts) were analyzed. There were significant differences in four evaluation points between the tumorous lesions and cysts: vascularity, echo intensity level, boundary, and margin shape. Cysts were almost completely excluded diagnostically, especially when vascularity was observed. There were also significant differences in two evaluation points between nonvascular tumorous lesions and cysts: echo intensity level and boundary.In US examination for mass lesions in the oral region, it was possible to diagnose tumorous lesions and exclude cysts when vascularity was observed. When vascularity was not observed, however, tumorous lesions and cysts could be identified using two evaluation points: echo intensity level and boundary.

Immune checkpoint inhibitors (ICIs) targeting programmed death ligand-1 (PD-L1) are highly promising therapies for oral squamous cell carcinoma (OSCC). The assessment of PD-L1 expression may help predicting the therapeutic effect of ICIs and, thus, benefit patient selection. Contrast index (CI) parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have been proven as efficient to assess microvessel density (MVD) in OSCC. The present study aimed to determine the correlation between DCE-MRI parameters and MVD and between DCE-MRI parameters and PD-L1 expression to determine whether DCE-MRI could be used non-invasively to evaluate PD-L1 expression in patients with OSCC. A total of 21 patients with primary OSCC who had undergone a 3T MRI scan, including DCE-MRI, were included in the present study, and CI curve-derived parameters were examined. The MVD and PD-L1 expression in the surgically resected specimens were analyzed using immunohistochemistry (IHC) staining for CD31 and IHC staining for PD-L1, respectively. The results demonstrated that the expression levels of these markers were correlated with DCE-MRI parameters. PD-L1 expression levels were found to be significantly correlated with the maximum CI (CI-max; P=0.007), peak CI (CI-peak; P=0.007), maximum CI gain (CI-gain; P=0.006) and MVD (P=0.001) values. The mean CI-max, CI-peak, CI-gain and MVD values were significantly higher in tumors with high PD-L1 expression (P

Objectives The aim of this systematic literature review was to focus on the use of diffusion-weighted magnetic resonance imaging (DWI) in the evaluation of salivary gland diseases. Study Design Databases were searched, and original research manuscripts up to 2018 were identified by using the keywords “diffusion” combined with “salivary gland,” “salivary gland neoplasm,” “sialadenitis,” “parotid gland,” “submandibular gland,” “sublingual gland,” “minor salivary gland,” “salivary gland fistula,” “salivary gland calculi,” “salivary ducts,” “xerostomia,” and “sialorrhea.” Only English language manuscripts and studies pertaining to DWI were selected. Results In all, 66 investigations regarding various salivary gland diseases, such as neoplasms, postirradiation changes, and inflammatory and autoimmune diseases, were included. Most study objectives involved the use of the apparent diffusion coefficient (ADC) in differentiating between benign lesions and malignant neoplasms. Histologic features of evaluated samples were heterogeneous. Conclusions DWI may improve the differential diagnosis of salivary gland diseases, particularly in distinguishing between benign and malignant neoplasms. A unique ADC cutoff value could not be established because of the heterogeneity of the methods applied for ADC assessment and the heterogeneity of the diseases. DWI and the ADC are valuable tools in the diagnosis of salivary gland disease.

Purpose The prevalence of supernumerary teeth has been reported to be between 0.1% and 3.8%. The aim of this study was to determine the prevalence, clinical significance, and associated pathologies of fourth molars based on a retrospective study and a literature review. Materials and Methods A 5-year retrospective prevalence study was conducted at the Department of Oral Diagnosis and Dentomaxillofacial Radiology of Okayama University Hospital, Okayama, Japan. The study involved extracting data from the digital records of patients from January 1, 2013 through December 31, 2017. The sampling frame included all patients who had panoramic radiographs, cone-beam computed tomography (CT), and multislice CT images during the period under review. Results A total of 26,721 cases were reviewed and 87 fourth molars were identified. The prevalence of fourth molars in the 5-year study at Okayama was calculated as 0.32%. The mean age of patients with a fourth molar was 30.43 years, and the male-to-female ratio was 1:0.98. The vast majority of cases were in the maxilla (92%) and had normal shapes (89.7%); furthermore, 82.8% of cases were unerupted. Conclusion The prevalence of fourth molars in the study population was found to be 0.32%, and fourth molars occurred with approximately equal frequency in males and females. Fourth molars were more common in the maxilla and were predominantly unerupted and small.

Objectives: The purpose of this study was to evaluate the usefulness of Hounsfield unit (HU) assessment with multislice-CT in the differentiation of radicular cysts (RCs), dentigerous cysts (DCs) and odontogenic keratocysts (OKCs). Methods: In total, 307 odontogenic cysts (RCs, DCs and OKCs) were included in this study. Cysts with lesion diameter Results: In total, 164 cysts were analysed in this study (64 RCs, 57 DCs and 43 OKCs). Regardless of the type of lesion, the Aquilion ONE scanner demonstrated a significant difference in HU value, compared with the Discovery CT750 HD scanner. Regardless of CT scanner model, HU values significantly differed between DCs and OKCs (p < 0.0001), as well as between OKCs and RCs (p < 0.0001). Conclusions: HU values were found to vary among CT scanners and should always be associated with other lesion imaging features while interpreting and elaboration diagnostic hypothesis. Notably, the results suggested that OKCs might be able to be differentiated from DCs and RCs by using HU values.

The numbers of abnormal findings incidentally detected in adjacent regions are increasing with advances in imaging modalities. The present study aimed to examine the prevalence and characteristics of incidental findings in the thyroid gland on computed tomography (CT) images of the oral and maxillofacial region. CT scans of the oral and maxillofacial region in patients obtained between January 2012 and December 2016 were retrospectively reviewed. Images that revealed incidental findings in the thyroid gland, including nodules, were recorded, together with the sizes and characteristics of the findings. The Japan Association of Breast and Thyroid Sonology (JABTS) guidelines were used for classification. The rate of descriptions of these findings in the radiographic interpretation reports were also examined. Of the 1,135 patients examined, 326 (28.7%) had several types of incidental findings. In particular, 169 (14.9%) of the 1,135 patients had nodules >5 mm in diameter, for which further careful examination is recommended in the JABTS guideline. The description rate for nodules >5 mm in diameter in the radiographic interpretation reports was 30.8% (52/169 patients), of whom 17.3% (9/52 patients) were referred to the endocrinology department for further careful examination. Incidental findings in the thyroid gland were relatively common on CT images of the oral and maxillofacial region. Oral radiologists tend to focus specifically on the oral and maxillofacial region during diagnosis on oral and maxillofacial CT images, but should pay the same careful attention to observe adjacent regions, such as the thyroid gland.

Background:We herein described a rare case of schwannoma of the hypoglossal nerve in the submandibular region with diagnostic imaging and histopathological findings.Case Report:A 31-years-old woman has had a palpable firm, rubbery, freely mobile mass in the submandibular region. Of imaging, MR images showed homogeneous isointensity on T1-weighted imaging (T1-WI), heterogeneous hypointensity on T2-WI, heterogeneous hyperintensity on short T1 inversion recovery (STIR), and heterogeneous enhancement on contrast-enhanced T1-WI. A clear capsule was observed on the margin and showed hypointense on T2-WI. Dynamic MRI showed heterogeneous gradual increased enhancement. The uptake of contrast medium was regionally slow. Diagnostic imaging using CT and MRI was suspected of salivary gland tumor or neurogenic tumor. In consideration of imaging diagnosis, a pleomorphic adenoma or a schwannoma was suspected. Final diagnosis was confirmed on the basis of histopathological finding and intraoperative findings.Conclusion:1. Histopathologic examination is inevitable, because MR findings are not specific.2. Schwannomas were said to have specific MRI properties, including specific signs (split-fat sign, fascicular sign, target sign). However, they are not always observed.3. This case confirmed the differential diagnosis on the basis of the intraoperative finding that the tumor was continuous with the hypoglossal nerve.

Adenoid cystic carcinoma (ACC) is a slowly growing malignant neoplasm with a propensity for perineural invasion. Microscopic invasion of ACC often prevents its detection on computed tomography (CT) or magnetic resonance imaging (MRI). We herein report a rare case of sublingual ACC presenting as a "skip lesion" that rapidly infiltrated the mandible after tumor resection. A 64-year-old man presented to Okayama University Hospital with an 18-month history of swelling in the right floor of the mouth. Clinical examination displayed an ulcerated swollen mass in that region. An enhanced mass was detected in the right sublingual space on CT and MRI. Bone surface erosion was observed at the inferior border of the mandible, but continuity with the sublingual mass or mass around that lesion was not detected by imaging. Sublingual tumor resection and selective neck dissection were performed by the pull-through method. Histopathologically, the surgical margins were free of cancer cells, and the tumor was diagnosed as ACC. Continuity with the sublingual mass and mandibular bone was not detected intraoperatively. However, marked bone resorption was detected in the anterior mandible 3 months after the operation. Biopsy was performed, and the findings indicated the same histological type of sublingual ACC. This case suggests that a malignant tumor close to the jaw bone requires the clinician to consider the possibility of bone invasion and to observe a wide region surrounding the tumor using imaging examination.

The aim of this study was to evaluate the tooth movement efficacy of retraction springs made of a new β-titanium alloy, “gum metal”, which has a low Young’s modulus and nonlinear super elasticity. Using double loop springs incorporated into an archwire made of gum metal (GUM) and titanium molybdenum alloy (TMA), the maxillary anterior teeth were moved distally to close an extraction space. The long-term movements were simulated by the finite element method. Its procedure was constructed of two steps, with the first step being the calculation of the initial tooth movement produced by elastic deformation of the periodontal ligament, and in the second step, the alveolar socket was moved by the initial tooth movement. By repeating these steps, the tooth moved by accumulating the initial tooth movement. The number of repeating calculations was equivalent to an elapsed time. In the GUM and TMA springs, the anterior teeth firstly tipped lingually, and then became upright. As a result of these movements, the canine could move bodily. The amount of space closure in GUM spring was 1.5 times that in TMA spring. The initial tipping angle of the canine in the GUM spring was larger than that in the TMA spring. The number of repeating calculations required for the bodily movement in the GUM spring was about two times that in the TMA spring. It was predicted that the speed of space closure in the GUM spring was smaller than that in the TMA spring.

Objectives This systematic literature review addresses the use of diffusion-weighted magnetic resonance imaging (DWI) and apparent diffusion coefficient (ADC) for the evaluation of benign maxillomandibular odontogenic lesions. Study Design Databases were searched and original research studies or case report manuscripts up to April 2019 were included using the keyword "diffusion" combined with the keywords “maxillofacial pathology”, “oral pathology”, “odontogenic tumors”, “dental tissue neoplasms”, “odontogenic cysts”, and the histological denomination of benign odontogenic lesions according to the World Health Organization classification. Only English language manuscripts and studies pertaining to DWI were selected. Results Fifteen investigations (11 original articles and 4 case reports) regarding distinct benign odontogenic lesions were included. Most studies did not include exclusively odontogenic lesions in their samples. Conclusions It is too early to reach a conclusion that DWI and ADC can provide useful information in the differentiation of the histological type of some benign odontogenic lesions based on the available data in the literature.

Adenoid cystic carcinoma (ACC) is a rare epithelial tumor of the head and neck region, and one of the most common malignant tumors of the salivary glands. ACC is a slow-growing tumor characterized by perineural invasion and often has a high-recurrence rate. We describe a case of oropharyngeal ACC invading the mandibular bone through the mandibular foramen that showed a rare pattern of origin and invasion. A 70-year-old woman complained of noise and pain around the right temporomandibular joint. Osteomyelitis was suspected on the initial imaging examinations, although the findings were slightly atypical. However, a mass was observed in the right oropharyngeal wall on subsequent imaging examinations, and mandibular bone invasion, rather than osteomyelitis, was additionally suspected. The mass in the right oropharyngeal wall and right mandible was surgically excised. On postoperative histopathological examination, the mass was finally diagnosed as ACC. As tumor cells were also observed around the inferior alveolar nerve, mandibular bone invasion through the mandibular foramen was suspected. An oropharyngeal ACC invading the mandibular bone through the mandibular foramen is extremely rare. The present case suggests that bone invasion should be considered carefully with several imaging examinations when a malignant tumor such as ACC is observed around the jaw bone.

The number of significant incidental findings identified on radiographic examinations has increased. In total, 169 patients, 87 males and 82 females, with a mean age of 67.3 years (range, 17-92 years), as well as 65 patients (38.5%), 43 (66.2%) female and 22 (33.8%) male had abnormal findings in the thyroid for one year in our institution. Thyroid nodules are the most common incidental findings on oral and maxillofacial evaluations. Computed tomography (CT) and magnetic resonance imaging (MRI) examination are frequently used to detect thyroid abnormality. The present study reported a case of papillary thyroid carcinoma (PTC) detected following CT and MRI examination of a mandibular lesion. The CT examination of the oral and maxillofacial region included the thyroid, which must be examined carefully to detect various diseases, including PTC. Collaboration between radiologists and clinicians is important to manage these incidental findings.

Objective The antilingular prominence (AP) is a well-known landmark used during planning of intraoral vertical ramus osteotomy (IVRO) in order to prevent inferior alveolar nerve (IAN) injury, but the location of this landmark is not always clear. In this study, we analyzed the anatomical relationship between the mandibular foramen (MF) and the lateral surface shape of the mandibular ramus for use during IVRO. Patients and methods We retrospectively analyzed 276 mandibular halves in 67 patients with mandibular deformity and 71 patients without deformity imaged at our department from April 2003 to March 2014. We defined 17 points on the mandibular ramus, and examined the anatomical relationships using multi-planar reconstruction (MPR) images and three-dimensional computed tomography (3DCT) created from preoperative CT data. Results The prevalence of the AP was 57.6% (159/276) of all cases. The MF was located inferior to the AP in all cases; it was posterior to the AP in 50.3% (80/159) of cases and the sigmoid notch (SN) in 24.6% (68/276) of cases. The minimum horizontal distance between the mandibular posterior ramus border and the MF was 9.28 mm in all cases. Conclusion The AP cannot always serve as a reference point to prevent IAN damage during IVRO. The osteotomy incision should be placed within 9 mm of the posterior mandibular ramus border in order to prevent intraoperative IAN damage. However, preoperative review of planned osteotomy incisions is necessary in every case.

Highlights • The patient was a 59-year-old man presenting with a swollen right submandibular gland. Laboratory tests revealed IgG4 levels of 176 mg/dl (reference range: 4.8–105). • Histological examination of the submandibular gland showed an adenoid cystic carcinoma with lymphocytic infiltration containing many IgG4-positive plasma cells in the tumor stroma., Introduction Immunoglobulin G4-related disease (IgG4-RD) is an inflammatory condition associated with elevated serum IgG4 levels and tissue infiltration by IgG4-expressing plasma cells. We present a case of adenoid cystic carcinoma (ACC) of the submandibular gland with possible involvement of IgG4-RD. Presentation of case The patient was a 59-year-old man presenting with a swollen right submandibular gland. Laboratory tests revealed IgG4 levels of 176 mg/dl (reference range: 4.8–105). An initial open biopsy for histological diagnosis showed chronic sialadenitis. The region was monitored on an outpatient basis, and finally the right submandibular was totally resected because malignant tumor could not be excluded. Histological examination of the submandibular gland showed an ACC with lymphocytic infiltration containing many IgG4-positive plasma cells in the tumor stroma. Discussion We have described a case that indicated a possible involvement of ACC with IgG4-RD. This allows us to speculate that longstanding IgG4-RD may progress to malignancy or infiltration of IgG4-positive plasma cells through the signals of tumor stimuli. Further investigations are required to determine the potential pathogenic mechanism underlying this unique tumor. Conclusion This case underscores that caution is needed in the diagnosis of masses with high serum IgG4 levels, as the differential diagnosis includes malignancy.

Background Recent improvements in image quality have contributed to an increasing number of incidental findings (IF). Also called as "incidentalomas", this generic term refers to an entity discovered unexpectedly on an imaging examination performed for other reason. Commonly, normal variants, minor developmental anomalies and imaging artifacts are described as potential pathology. Some IF were reported in magnetic resonance imaging (MRI) exam of temporomandibular joint (TMJ), including IF in the brain, maxillary sinus, ethmoidal cells, mastoid cells, salivary glands, muscles. The aim of this study is to evaluate the prevalence of IF on MRI of TMJ from Japanese patients. Methods An image archive from 872 patients referred to MRI evaluation due to TMJ symptomatology was assessed. Three experienced radiologists evaluated all images, and the final diagnosis was achieved by consensus. The data regarding IF was recorded, considering only tumor and tumor-like lesions. Results A total of 12 (1.38%) of tumor and tumor-like lesions were observed from all 872 MRI exams evaluated. The most frequent lesion was arachnoid cyst (0.45%), followed by neoplastic lesions (0.22%). Conclusions The question "should every IF be reported?" is still difficult to answer. Relevant IF are rare, and radiologists are expected to be reasonable: think about the adverse effects of reporting an IF, and, based on their own judgment, choose for a positive or a negative answer.

It is well known that many tumor tissues show lower apparent diffusion coefficient (ADC) values, and that several factors are involved in the reduction of ADC values. The aim of this study was to clarify how much each factor contributes to decreases in ADC values. We investigate the roles of cell density, extracellular space, intracellular factors, apoptosis and necrosis in ADC values using bio-phantoms. The ADC values of bio-phantoms, in which Jurkat cells were encapsulated by gellan gum, were measured by a 1.5-Tesla magnetic resonance imaging device with constant diffusion time of 30sec. Heating at 42℃ was used to induce apoptosis while heating at 48℃ was used to induce necrosis. Cell death after heating was evaluated by flow cytometric analysis and electron microscopy. The ADC values of bio-phantoms including non-heated cells decreased linearly with increases in cell density, and showed a steep decline when the distance between cells became less than 3μm. The analysis of ADC values of cells after destruction of cellular structures by sonication suggested that approximately two-thirds of the ADC values of cells originate from their cellular structures. The ADC values of bio-phantoms including necrotic cells increased while those including apoptotic cells decreased. This study quantitatively clarified the role of the cellular factors and the extracellular space in determining the ADC values produced by tumor cells. The intermediate diffusion time of 30msec might be optimal to distinguish between apoptosis and necrosis.

We previously reported that dynamic contrast-enhanced MRI parameters and time–signal intensity curves (TICs; also known as contrast index curves) are useful for the differential diagnosis of jawbone lesions. In particular, odontogenic fibroma and ossifying fibroma, which possess similar histopathological features (i.e., a mixture of hard and soft tissue components), display unique TIC patterns, and we consider that the TIC patterns of these lesions reflect their hard and soft tissue components. Therefore, fibrous dysplasia, which contains fibrous tissue and immature isolated trabeculae composed of woven bone, is expected to display an interesting TIC. The purpose of this study was to assess the utility of TICs for differentiating between the abovementioned lesions, which have similar histopathological components.

It is known that the magnetic resonance (MR) imaging features of dentigerous cysts (DCs) are the same as those of other cysts. The cavities of DCs generally show low signal intensity (SI) on T1-weighted imaging (T1WI). However, in our experience, DCs often show high SI on T1WI, rendering them difficult to distinguish from keratocystic odontogenic tumors (KCOTs). In this study, we evaluated seven cases of DC and 23 cases of KCOT to assess whether MR imaging can provide additional information for the differential diagnosis of DC and KCOT. Two trials were evaluated. The first trial was an analysis of the cystic cavity SI on T1WI. To compare the SI between patients, we performed T1WI with contrast (T1c). The second trial analyzed the SI uniformity (U Σ) on T1WI, T2-weighted imaging (T2WI), and short inversion time inversion recovery (STIR) images of the cystic cavity, because it has been reported that an MR imaging feature of KCOT is heterogeneous SI. Statistical analyses were performed using the Mann–Whitney U test and a receiver operating characteristic (ROC) curve. The T1c values of DCs were significantly higher than those for KCOTs. The U Σ values on T1WI and STIR images were significantly higher for DCs than for KCOTs. The T1c cutoff values (0.66 and 0.84) and U Σ cutoff values for T1WI (82.1 %) and STIR images (79.8 %) were determined from the ROC analyses. T1c and U Σ values provide useful additional information for the differential diagnosis of DC and KCOT.

Summary Ameloblastomas and keratocystic odontogenic tumors (KCOT) are typical jawbone tumors. In addition, dentigerous cysts (DC) and radicular cysts are the most common cystic jawbone lesions, and simple bone cysts (SBC) are the most common jawbone pseudocysts. When these lesions are unilocular, it can be difficult to diagnose them by radiography. In recent years, adding magnetic resonance (MR) imaging to obtain information about soft tissue has been shown to improve the accuracy of jawbone lesion diagnosis. We also have reported MR imaging features of jawbone lesions. However, no systematic method for MR imaging diagnosis of jawbone lesions has been reported. In this review, we examine unilocular lesions such as ameloblastoma, KCOT, adenomatoid odontogenic tumour (AOT), DC, and SBC. First, we describe the MR imaging features of each lesion. Then, we describe our novel MR imaging diagnostic protocol. Using our MR imaging diagnostic protocol to diagnose 31 cases, we obtained a positivity rate of 71.0%. The use of our MR imaging diagnostic protocol for unilocular lesions, which are especially difficult to differentiate by radiography, would improve the morphological and qualitative diagnosis of soft tissue lesions.

Lymphoepithelial cysts, which are also known as branchial cleft cysts, commonly occur in the lateral cervical region. Lymphoepithelial cysts arising in the parotid gland are rare and must be distinguished from parotid gland tumors. Magnetic resonance imaging (MRI) is useful for diagnosing parotid gland lesions, and MR images of lymphoepithelial cysts typically display a cystic mass that appears homogeneously hypointense on T1-weighted images and homogeneously hyperintense on T2-weighted images. However, some parotid gland tumors that retain fluid in their inner sections show similar MRI findings to lymphoepithelial cysts. Furthermore, lymphoepithelial cysts are sometimes modified by inflammation, and these cases are hard to diagnose. We report the case of a 59-year-old female with a lymphoepithelial cyst that arose in the parotid gland. The cyst had been affected by inflammation and displayed atypical imaging findings, i.e., heterogeneous signal intensity of the liquid component and the presence of a well-enhanced capsule-like structure surrounding the liquid component. In addition, we compare the MRI findings of this case with those of two other cervical lymphoepithelial cysts.

The activity of the lateral pterygoid muscle has been regarded to be related to the pathological condition of the temporomandibular joint (TMJ) in the craniomandibular disorders. Because the lateral pterygoid muscle is a deep muscle, a needle electrode is necessary for EMG recordings. The purpose of this study was to establish a non-invasive method for the evaluation of muscle activity of the lateral pterygoid muscle using mechanomyogram (MMG). In three male subjects, surface electromyogram (EMG) in the left masseter muscle, left anterior and posterior belly of the temporal muscle, left anterior belly of the digastric muscle and needle EMG of the inferior head of the lateral pterygoid were recorded during mandibular movement tasks simultaneously with the MMG derived from a condenser microphone in the external ear canal. There were significant positive correlations between the needle EMG signal of the lateral pterygoid muscle and the MMG signal for the tasks of static jaw opened position of 30 mm of interincisal distance (p = 0.000, R(2)=0.725), static jaw opened position of 40 mm of interincisal distance (p = 0.000, R(2) = 0.753), 5 mm protruded mandibular position (p = 0.000, R(2) = 0.653), the most protruded mandibular position (p = 0.000, R(2) = 0803). On the contrary, for the task of maximal clenching, there was no significant correlation between the EMG signal of the lateral pterygoid muscle and the MMG signal. These results suggest that the activity of the lateral pterygoid muscle could be evaluated by the MMG signals recorded in the external ear canal, unless jaw closing major muscles show active contraction.

The purpose of this study was to determine the accuracy of a new high resolution digital camera-based three-dimensional system called Di3D by comparing with traditional direct anthropometry using digital calipers. The study sample consisted of 20 young adults, 10 male and 10 female. Facial soft tissue landmarks were identified and five linear distances were measured between the landmarks for each subject using the two methods; Di3D camera system and a digital caliper. No statistically significant differences (P › 0.05) were found for all five facial soft tissue distances measured by the Di3D camera system and the digital caliper. The magnitude of differences was very small (mean = 0.73 mm). Good congruence was observed between the means derived from the Di3D system and the digital caliper.The overall mean differences of the five measurements with these two methods were small enough to be clinically insignificant. The results show that both methods are concordant and one method can replace the other in clinical use.

Ameloblastic carcinoma is a rare malignant odontogenic carcinoma that has metastatic potential, and because of its rare incidence, there are few reports focusing on its radiologic imaging. If it shows aggressive appearances, it can be diagnosed as malignant tumor. But in case of negative appearance, it is difficult to distinguish ameloblastic carcinoma from ameloblastoma. We report a case of ameloblastic carcinoma of the maxilla in a 76-year-old female patient with radiologic images and pathologic features.

Corticomotor pathways may undergo neuroplastic changes in response to acquisition of new motor skills. Little is known about the motor control strategies for learning new tongue tasks. The aim of this study was to investigate the longitudinal effect of novel tongue-task training on corticomotor neuroplasticity. Thirteen healthy, right-handed men, aged 24-35 years (mean age ± SD: 27.3 ± 0.3 years), performed a training task consisting of standardized tongue protrusion onto a force transducer. The tongue task consisted of a relax-protrude-hold-relax cycle with 1.0 N as the target at the hold phase lasting for 1.5 s. Subjects repeated this task for 1 h. Functional magnetic resonance imaging was carried out before the tongue-task training (baseline), 1-h after the training, and one-day and one-week follow-up. During scanning, the subjects performed tongue protrusion in blocks interspersed with rest. A region-of-interest (ROI) approach and an explorative search were implemented for the analysis of corticomotor activity across conditions. All subjects completed the tongue-task training (mean success rate 43.0 ± 13.2%). In the baseline condition, tongue protrusion resulted in bilateral activity in regions most typically associated with a motor task including medial frontal gyrus (supplementary motor area [SMA]), precentral gyrus (tongue motor cortex), putamen, thalamus, and cerebellum. The ROI analysis revealed increased activity in the precentral gyrus already 1 h post-training. One day after the training, increased activity was observed in the precentral gyrus, SMA, putamen, and cerebellum. No increase was found 1 week after training. Correlation analyses between changes in success rates and changes in the numbers of voxels showed robust associations for left Area 4a in primary motor cortex 1 h, 1 day, and 1 week after the tongue-task training and for the left Area 4p in primary motor cortex and the left lateral premotor cortex 1 day after the training. In the unrestricted analysis, increased activity was found in the parahippocampal gyrus 1 h after the tongue-task training and remained for a week. Decreased activity was found in right post-central and middle frontal gyri 1 h and 1 week post-training. The results verified the involvement of specific corticomotor areas in response to tongue protrusion. Short-term tongue-task training was associated with longer-lasting (up to 1 week) changes in motor-related brain activity. The results suggested that primary motor areas are involved in the early and late stages, while other motor areas mainly are engaged in the later stage of corticomotor neuroplasticity of the tongue.

Typical MR images of ameloblastomas on T2-weighted image (WI) or short inversion time inversion-recovery (STIR) show multiple bright high-signal-intensity loci on a high-signal-intensity background. Unilocular cystic-type ameloblastomas show homogeneously bright high signal intensity on T2WI or STIR as a water-like signal intensity. Therefore, it is difficult to distinguish unilocular cystic-type ameloblastoma from other cystic lesions such as keratocystic odontogenic tumors, radicular cysts (residual cysts) and dentigerous cysts only on the basis of MRI signal intensity. In the present study, we evaluated whether contrast-enhanced (CE)-T1WI and dynamic CE-MRI (DCE-MRI) could provide additional information for differential diagnosis in unilocular cystic-type ameloblastoma. Images from 12 cases of suspected unilocular cystic-type ameloblastoma were evaluated in the present study. Of them, 5 had areas suspected of indicating a solid component on T1WI and T2WI (or STIR). Ten had undergone additional CE-T1WI and DCE-MRI. On 5 of 10 cases of CE-T1WI, a tiny enhancement area was detected. On 6 of 10 DCE-images, a time-course enhanced area which was suspected to be a solid component was detected. CE-T1WI was helpful in the diagnosis of ameloblastoma because the tiny enhanced areas were taken to indicate possible solid components. Moreover, the rim-enhancement area on CE-T1WI could be divided into small regions of interest, and some of these showed slightly increased enhancement on DCE-MRI, which was taken to indicate a solid component and/or intramural nodule with focal invasion of ameloblastoma tissue. DCE-MRIs of the four remaining cases, which provided no clues to the diagnosis of ameloblastoma in the manner of the above descriptions, showed thicker rim enhancement than odontogenic cysts. Thus, CE-T1WI and DCE-MRI were helpful in the differential diagnosis of unilocular cystic-type ameloblastomas with homogeneously bright high signal intensity on T2WI or STIR.

The purpose of this study was to reveal the relationship between chewing-side preference and anterior disc displacement (ADD) of the TMJ. Thirty-two healthy subjects with ages ranging from 26 to 34 years were selected from volunteer students at the Okayama University Dental School. Subjects were asked to chew freely with two kinds of test foods, beef jerky (hard food) and chiffon cake (soft food), thus expecting different amounts of mechanical loading on the TMJ. One, 4, and 7 s after starting the mastication, subjects were asked to open their mouth momentarily to have a digital image of their mouth taken. The bolus placement area was measured by processing the digital images, calculated as the number of pixel of bolus area. Area asymmetry index was used for the determination of preferred chewing side (PCS). Oblique sagittal MRI scanning in the closed mouth position was taken to evaluate the articular disc position. In asymptomatic subjects with ADD, a significant predominance of the PCS on the ipsilateral side of ADD was observed during the mastication of hard food. On the contrary, no correlation was found between unilateral ADD and PCS for the soft food. From the results of this study, it is suggested that ADD is the associating factor of PCS for hard food. Therefore, it would be necessary to break down the concept of PCS into at least two categories, one for hard food and one for soft food, considering the mechanical loading on the TMJ.

Aneurysmal bone cysts (ABCs) are classified as bone-related lesions based on the 2005 World Health Organization histological classification of odontogenic tumors. Most ABCs are diagnosed using a combination of conventional radiography, computed tomography, magnetic resonance imaging (MRI), and digital subtraction angiography. ABCs should be differentiated from true cysts or other pseudocysts because their treatment is different. Additionally, unlike other cysts, ABCs pose a hemorrhagic risk in surgery; thus, preoperative evaluation of intralesional blood flow is required. Here we report a case of a mandibular ABC in a 39-year-old woman and focus on its dynamic contrast-enhanced MRI (DCE-MRI) features. On DCE-MRI, the lesion was divided into two areas according to the enhancement pattern: the blood-pooling and blood-flow areas. The series of DCE-MR images of the blood-pooling area showed marked enhancement of the margin, but no enhancement in the inner part of the cavity. Additionally, the time-signal intensity curve (TIC) demonstrated no change in the signal intensity (SI) until approximately 15 min after gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA) administration. In contrast, the series of DCE-MR images of the blood-flow area exhibited marked enhancement in the cyst cavity in the early phase. The TIC showed a rapid increase in SI in the early phase, followed by a rapid decrease until 150 s, and finally a gradual decrease until approximately 15 min after Gd-DTPA administration. Thus, in the current patient, preoperative DCE-MRI clearly delineated the vessel-rich area within the lesion.

Introduction It can be difficult to differentiate simple bone cysts (SBCs) from true cysts in the jaw when these lesions appear unilocular. The present study reports the MR imaging of subjects with SBCs and describes the diagnostic value of the MRI findings. Materials and methods Ten subjects with SBCs in the jaw were examined using MRI. T1- and T2-weighted images (T1WI, T2WI) were obtained, and contrast-enhanced images and dynamic contrast-enhanced MRI (DCE-MRI) were acquired. Results In all cases, the contrast-enhanced T1WI acquired approximately 6 minutes after the administration of Gd-DTPA showed marked enhancement of the margin and slight enhancement of the inner part of the cyst cavity. In all cases, the time–signal intensity (SI) curves show a gradual increase in the SI until approximately 15 minutes after the administration of Gd-DTPA. These findings might not be observed on the DCE-MRIs of the other true cysts with epithelial lining that show no enhancement in a cavity. Conclusion MRI, especially DCE-MRI, can provide useful information for distinguishing SBCs from other cysts.

OBJECTIVES: To investigate the correlations among various temporomandibular joint (TMJ) findings on MRI and the relationships between MRI findings and symptoms. METHODS: 425 patients (850 TMJs) with temporomandibular joint disorders (TMDs) who underwent MRI were enrolled. Oblique sagittal proton density-weighted and T (2) weighted images in open- and closed-mouth positions were evaluated. MRI findings included disc configuration, disc position, condylar morphology, bone marrow pattern, and joint effusion. Symptoms included TMJ pain, TMJ noise, and limitation of mouth opening. For statistical analyses, Spearman's rank correlation coefficient and logistic regression analysis were applied. RESULTS: Folded disc, disc displacement without reduction (DDWOR), and osteophytes had significant negative correlations with other normal MRI findings (p < 0.01). DDWOR and marrow edema were associated with TMJ pain. Conversely, osteophytes [odds ratio (OR): 0.52; 95% CI (0.30–0.90)] and combination-type condylar degeneration [OR: 0.45; 95% CI (0.24–0.83)] were associated with decreased risk of TMJ pain. Condylar flattening was positively associated with TMJ noise [OR: 5.25; 95% CI (1.44–19.07)] and negatively associated with limitation of mouth opening [OR: 0.34; 95% CI (0.11–0.99)]. High-grade joint effusion was significantly associated with TMJ pain and noise. CONCLUSIONS: DDWOR and high-grade joint effusion (an indicator of inflammation in the articular cavity) were associated with TMD symptoms. This finding suggests that treatment strategy for DDWOR and decreasing inflammation might lessen clinical TMD symptoms. Condylar degeneration was not associated with indicators of inflammation or TMJ symptoms. These results suggest that patients with TMD symptoms should undergo initial MRI to allow rapid selection of appropriate therapies.

Odontoma is the most common type of benign odontogenic tumor, and often causes disturbances in the eruption of its associated tooth. Odontomas usually occur in the permanent dentition, and rarely occur solely in the primary dentition. This case report documents a six-year-old-child with a compound odontoma located in the mandible, which caused the impaction of the primary second molar.

Summary We evaluated the relationship between histopathological prognostic factors, tumor proliferation microvessel density (MVD), and enhancement parameters in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in oral squamous cell carcinoma (SCC). Twenty-eight T2 and T3 patients with primary oral SCC underwent DCE-MRI using three-dimensional fast imaging with a steady-state precession sequence. Tumor cell proliferation and MVD of all surgical specimens were evaluated using immunohistochemical staining with CD34 and the antibody for proliferating cell nuclear antigen (PCNA). Regression analysis was used to statistically analyze the relationship between the PCNA labeling index or MVD and each of three DCE-MRI parameters: maximum CI (CI-max), maximum CI gain (CI-gain) and the CI-gain / CI-max ratio). The PCNA labeling index and MVD showed significant correlations with the CI-gain/CI-max ratio ( P = 0.0012, r = 0.581 and P = 0.00141, r = 0.574, respectively). The assessment of DCE-MRI parameters may prove to be a valuable non-invasive method for assessing tumor cell proliferation and MVD of patients with oral cancer.

Objectives To compare MRI manifestations according to gender and age and to identify correlations between clinical manifestations and MRI findings in patients with temporomandibular disorder (TMD) as based on a large series. Materials and Methods Fat suppressed oblique sagittal images of the open and closed mouth were acquired, and MRI scanning parameters were applied. Results The patients consisted of 946 females (average, 36.6 years old), and 319 males (average, 34.3 years old). In all TMD patients, 945 had symptoms in the unilateral temporomandibular joint (TMJ) and 320 in the bilateral TMJ. There were significant differences in the distribution of disk positions based on age, regardless of gender, in the unilaterally and bilaterally symptomatic groups; however, the results were not significant in the asymptomatic group. There were significant differences with respect to the distribution of disk positions between males and females in asymptomatic group and in the unilaterally symptomatic group, although the bilaterally symptomatic group did not show significant differences in this regard. As regards the disk positions in the joints of the three groups (asymptomatic group, unilaterally and bilaterally symptomatic groups), there were significant interactive effects of disk positions, regardless of gender. There were statistically significant age-related differences in disk deformities in all symptom groups, regardless of gender, except for in the group of males lacking symptoms in either joint. As regards disk deformities among the three groups studies here, there were significant interactive effects for disk positions, regardless of gender.

To examine oral and maxillofacial lesions other than those related to the chief complaint in panoramic radiographs taken at the department of paediatric dentistry at our hospital.We retrospectively reviewed all 1092 patients who had visited the department of paediatric dentistry at our hospital and had a panoramic radiograph taken between August 1999 and October 2004. The following information was obtained from the patients' files and panoramic radiographs: gender, age, chief complaints and the presence or absence of lesions.Lesions were observed in 140 of the 1092 panoramic radiographs (12.8%). Among the 140 patients discovered to have lesions in the panoramic radiographs, 66 (47.1%, or 6.05% of the entire group of 1092 patients) had different lesions from those underlying the chief complaint. These 66 patients ages ranged from 3 years to 14 years and the lesions involved 39 (59.1%) missing teeth, 20 (30.3%) mesiodentes, 4 supernumerary teeth, 1 odontoma, 1 radicular cyst and 1 impacted tooth. The missing teeth were observed in the central and lateral incisor, canine, and first and second premolar positions of both jaws, especially in the lower lateral incisor and upper central incisor positions.We were able to detect incidental lesions at a rate of 6.05% (66 of 1092 patients) and at a relatively early age (mean 6.8 years) in the present study. Early treatment of these lesions could avoid maxillofacial deformity and other complications.

We have designed a three-dimensional magnetic circuit consisting of various pieces of magnetic blocks for a unilateral MRI device, which generates a homogeneous magnetic flux density at a remote region. The direction of the remanent flux density of the main outer magnetic blocks is parallel to the surface of the device; hence the direction of the magnetic flux density in the remote region is also parallel to the surface of the device. The magnitudes of the remanent flux density of the magnetic blocks are adjusted so as to minimize the variation of the magnetic flux density in the remote region. This magnetic circuit, with an outer dimension of 400 mm × 400 mm × 200 mm, produces a magnetic flux density in a 20 mm × 20 mm × 5 mm region of interest at a distance of 55 mm from the surface of the device with a magnitude of 64.5 mT (2.75 MHz in resonant frequency) and a uniformity of 275 ppm (755 Hz in band width). © 2008 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 33B: 201–208, 2008

Various types of lesion have been reported in the submental region, but submental masses can be difficult to diagnose. Our objective was to attempt to diagnose submental masses by using magnetic resonance imaging (MRI) along with clinical data. We attempted to diagnose seven cases in which the chief complaint was submental swelling; diagnosis was carried out on the basis of features visualized by MRI. Seven types of lesions were observed: phlegmone and abscess caused by osteomyelitis; epidermoid cyst; thyroglossal duct cyst; abscess-forming granulomatous lymphadenitis; T-cell lymphoma (suspected Hodgkin’s disease); non-Hodgkin’s B-cell lymphoma; and lymph node metastasis from squamous cell carcinoma in the tongue. The magnetic resonance images of each lesion revealed characteristic features. Thus, MRI may be useful for the differential diagnosis of submental swelling before the initiation of treatment.

The radiographical differentiation of adenomatoid odontogenic tumor (AOT) from dentigerous cysts, calcifying odontogenic cysts, calcifying epithelial odontogenic tumors, odontogenic keratocysts and amelobastomas is sometimes difficult. We attempted to differentiate AOT from other lesions similar to AOT in radiographic findings using MRI. The MRI features of AOT in our three cases included homogeneous low SI in the cystic portion and homogeneous intermediate SI in the solid portion on T1WI, homogeneous high SI in the cystic portion and intermediate to slightly high SI in the solid portion on T2WI and enhancement of only the solid portion on CE-T1WI although none of the sequences included SI of calcifications. The contrast index curves in the three cases of AOT showed a gradual increase to 300 s, which signified a benign tumor. These MRI features were characteristic features of AOT and might be a basis for differentiating AOT from the above possible lesions in radiographic examinations.

In this study, we attempted to diagnose malignant lymphoma on the basis of magnetic resonance imagings (MRIs) and dynamic contrast-enhanced MRI (DCE-MRI). Eighteen lesions (in eight patients), all of which had been proven histopathologically, were detected on MRI. The eight patients included five patients with diffuse large B-cell lymphoma, one with B-cell low-grade MALT lymphoma, one with follicular lymphoma, and one with Hodgkin's lymphoma. Nine lesions were located in the submandibular region, three in the buccal region, two in the orbit region, two in the submental region, and one each in the palatal and tonsil regions. The diameter of the lesions ranged between 9 and 42.2 mm (average: 22.4 mm). The signal intensities (SIs) of the 18 lesions were examined on T1-weighted (T1WI), T2WI, and gadopentetate (Gd)-T1WI. One lesion in case 8 was excluded from DCE-MRI findings, i.e., the regions of interest could not be adequately set on DCE-MRIs. The contrast index (CI) curves of the remaining 17 lesions were prepared. All 18 lesions showed almost the same images on T1WI, T2WI, and Gd-T1WI, although they represented four types of lymphoma. The images showed homogeneous SI that was intermediate to slightly high SI on T1WI, slightly high SI on T2WI, and moderately enhanced on Gd-T1WI. Thus, the cases of malignant lymphoma in this study showed relatively characteristic features based on MRI; however, these features might be non-specific. The CI curves in this study showed a relatively rapid increase, reaching a maximum CI at 45–120 s, and a relatively rapid decrease in most lesions (14/17; 82.4%); on the other hand, the curves of 3 of the 15 lesions (17.6%) showed relatively rapid increase, sustenance of a plateau, and a gradual decrease thereafter. These patterns of CI curves may indicate characteristic features useful for distinguishing malignant lymphomas from other lesions.