Takashi Kamio

Comparison of accuracy of intravoxel incoherent motion and apparent diffusion coefficient techniques for predicting malignancy of head and neck tumors using half-Fourier single-shot turbo spin-echo diffusion-weighted imaging.

PURPOSE To evaluate the use of the intravoxel incoherent motion (IVIM) technique in half-Fourier single-shot turbo spin-echo (HASTE) diffusion-weighted imaging (DWI), and to compare its accuracy to that of apparent diffusion coefficient (ADC) to predict malignancy in head and neck tumors. PATIENTS AND METHODS HASTE DW images of 33 patients with head and neck tumors (10 benign and 23 malignant) were evaluated. Using the IVIM technique, parameters (D, true diffusion coefficient; f, perfusion fraction; D*, pseudodiffusion coefficient) were calculated for each tumor. ADC values were measured over a range of b values from 0 to 1000s/mm(2). IVIM parameters and ADC values in benign and malignant tumors were compared using Students t test, receiver operating characteristics (ROC) analysis, and multivariate logistic regression modeling. RESULTS Mean ADC and D values of malignant tumors were significantly lower than those of benign tumors (P<0.05). Mean D* values of malignant tumors were significantly higher than those of benign tumors (P<0.05). There was no significant difference in mean f values between malignant and benign tumors (P>0.05). The technique of combining D and D* was the best for predicting malignancy; accuracy for this model was higher than that for ADC. CONCLUSIONS The IVIM technique may be applied in HASTE DWI as a diagnostic tool to predict malignancy in head and neck masses. The use of D and D* in combination increases the diagnostic accuracy in comparison with ADC.

Diagnosis and Endodontic Management of Fused Mandibular Second Molar and Paramolar with Concrescent Supernumerary Tooth Using Cone-beam CT and 3-D Printing Technology: A Case Report.

Supernumerary teeth in the molar area are classified as paramolars or distomolars based on location. They occur frequently in the maxilla, but only rarely in the mandible. These teeth are frequently fused with adjacent teeth. When this occurs, the pulp cavities may also be connected. This makes diagnosis and planning of endodontic treatment extremely difficult. Here we report a case of a mandibular second molar fused with a paramolar, necessitating dental pulp treatment. Intraoral and panoramic radiographs were obtained for an evaluation and diagnosis. Although the images revealed a supernumerary tooth-like structure between the posterior area of the mandibular second molar and mandibular third molar, it was difficult to confirm the morphology of the tooth root apical area. Subsequent cone-beam computed tomography (CBCT) revealed that the supernumerary tooth-like structure was concrescent with the root apical area of the mandibular second molar. Based on these findings, the diagnosis was a fused mandibular second molar and paramolar with a concrescent supernumerary tooth. A 3-dimensional (3-D) printer was used to produce models based on the CBCT data to aid in treatment planning and explanation of the proposed procedures to the patient. These models allowed the complicated morphology involved to be clearly viewed, which facilitated a more precise diagnosis and better treatment planning than would otherwise have been possible. These technologies were useful in obtaining informed consent from the patient, promoting 3-D morphological understanding, and facilitating simulation of endodontic treatment.

Analysis of elements in a minimal amount of temporomandibular joint fluid on fluid-attenuated inversion recovery magnetic resonance images

OBJECTIVE The aim of this study was to elucidate possible elements in minimal amounts of fluid (MF) in the temporomandibular joint by analyzing signal intensities in T2-weighted and fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) images. STUDY DESIGN Fifteen joints (15 patients) with MF were subjected to MR imaging to obtain T2-weighted and FLAIR images. Regions of interest were placed on MF, cerebrospinal fluid (CSF), and gray matter (GM), and their signal intensities were measured on both images. The signal intensity ratio (SIR) obtained by the signal intensity of GM between MF and CSF was compared in T2-weighted and FLAIR images. RESULTS The average SIR of MF was lower than that of CSF on T2-weighted images, whereas it was higher on FLAIR images. The average suppression ratio of the signal intensity was lower for MF (24.1%) than for CSF (71.4%). CONCLUSIONS MF may contain elements such as protein that are capable of inducing a shortened T1 relaxation time on MR images.

Incidental findings during head and neck MRI screening in 1717 patients with temporomandibular disorders

ObjectiveMagnetic resonance imaging (MRI) plays an important role in the evaluation of temporomandibular disorders (TMDs). At our institution, we perform additional head and neck screening using head coils when performing MRI screening of the temporomandibular joint (TMJ) to detect lesions in areas other than the TMJ (lesions discovered by chance, or incidental findings; IFs) and to conduct a diagnosis of exclusion. The objective of this study was to determine the number and frequency of IFs detected during head and neck screening, according to sites and diseases.Materials and methodsThe study evaluated 1717 patients with clinically suspected TMDs who underwent MRI of the TMJ. IFs were assessed on horizontal sections of images of the craniofacial region obtained by the short tau inversion recovery imaging technique.ResultsThe patients undergoing MRI of the TMJ comprised 433 males and 1284 females. Among the patients, at least one IF was detected on images in 461 patients. The most common IF site was the maxillary sinus. Based on diagnostic imaging, there were 21 IFs (1.2%) associated with TMD symptoms, or for which an association with TMD symptoms could not be ruled out.ConclusionsCombination of conventional MRI imaging of the TMJ with craniofacial MRI screening may allow detection of lesions other than TMDs, thereby confirming the usefulness of MRI. Detection of IFs may require development of different therapeutic strategies than those for TMDs.

Postoperative Conversion Disorder in Elderly Oral Cancer Patient

Conversion disorder is a condition in which psychological stress in response to difficult situations manifests as physical symptoms. Here, we report a case of postoperative coma due to conversion disorder in an elderly oral cancer patient. An 82-year-old woman was referred to Tokyo Dental College Chiba Hospital with a mass lesion on the tongue. A biopsy revealed a well-differentiated squamous cell carcinoma. Surgical treatment was performed for the tongue carcinoma and tracheotomy for management of the airway. On postoperative day 5, the patient exhibited loss of consciousness (Glasgow Coma Scale: E1, VT, M1; Japan Coma Scale: III-300). The patients vital signs were all normal, as were the results of a full blood count, brain-CT, MRI, and MRA. Only the arm dropping test was positive. Therefore, the cause of the coma was diagnosed as conversion disorder. Seven hours later, the patient showed a complete recovery.

Utility of preoperative imaging diagnosis for a malignant tumor of the mandible: a malignant tumor of the mandible is difficult to discriminate from bisphosphonate-related osteonecrosis of the jaw

We report our experience of a case with a malignant tumor of the mandible in which diagnostic imaging played an important role in the differential diagnosis and therapeutic strategy decisions. The patient was a 78-year-old woman who visited our hospital because of poor healing after tooth extraction. Multiple cytological diagnoses provided class II results, and a histopathological diagnosis of a biopsy also failed to show malignant findings. Therefore, a definitive diagnosis could not be made. Although the patient had a history of osteoporosis treatment, details of her medications were unclear. Therefore, bisphosphonate-related osteonecrosis of the jaw (BRONJ) could not be excluded, causing difficulty in management of the patient’s condition. Eventually, we mainly focused on the diagnostic imaging and planned the therapeutic strategy in accordance with treatment for a malignant tumor. A postoperative histopathological examination of the surgical specimen revealed squamous cell carcinoma. It is sometimes difficult to differentiate among atypical diseases such as malignant tumors of the mandible and BRONJ, based solely on clinical or diagnostic imaging results. However, in the present patient, diagnostic imaging suggested a malignant tumor, and the appropriate treatment could be selected.

A case of myoepithelioma emerging in the buccal region: verification of the primary site based on magnetic resonance imaging, computed tomography, histopathological, and anatomical findings

A case of myoepithelioma presumed to have arisen from an accessory parotid gland is reported. Preoperative fine-needle aspiration cytological findings suggested a malignant tumor, possibly an adenoid cystic carcinoma, while histopathological findings acquired during surgical resection revealed a myoepithelioma. The tumor was located adjacent to the Stensen duct, suggesting an accessory parotid gland origin. The diagnostic potential of magnetic resonance imaging and contrast-enhanced computed tomography in diagnosing this disease is discussed.

Changes in EMG frequency and oxygen dynamics in anterior belly of digastric muscles by anterior traction of mandible

Abstract Oral appliances (OAs) are widely used for anterior positioning of the mandible, and many studies have investigated change in activity in the jaw-closing muscles, including the masseter muscle, caused by such appliances. Few studies, however, have investigated their effect on the jaw-opening muscles. In the present study, we chose the masseter and jaw-opening muscles because they allow non-invasive measurement by means of surface electromyography. We investigated physiological changes in the digastric and masticatory muscles brought about by OAs using electromyography and an oximeter. Subjects comprised 7 healthy males. Fabricated OAs were placed in the mouth to obtain either 70% maximal protrusion (advanced mandibular position: AMP) or a centric relation (CR). Subjects were then instructed to open their mouth 2 mm vertically for 180 s, during which time electromyograms were obtained and blood flow volume determined. No significant difference was observed between AMP and CR in the frequency analysis of the anterior belly of the digastric muscle (Dig). No significant difference was noted in muscle activity between CR and AMP. No stable tendency was observed in the masseter or temporal muscles. Oxygen content recovery time in Dig was significantly longer at 1, 5 and 7 h in AMP than in CR. Seven-hour retention in AMP caused physiological change in Dig and a delay in recovery time from muscle fatigue. However, recovery from muscle fatigue occurred shortly after OA removal.