Hideyoshi Nishiyama

Diagnostic imaging for a case of maxillary myxoma with a review of the magnetic resonance images of myxoid lesions

The findings of conventional radiography, computed tomography, and magnetic resonance imaging are reported for an odontogenic myxoma arising in the left anterior maxilla of a 50-year-old man. The magnetic resonance imaging characteristics of an intraosseous myxoma are described for the first time. The initial conventional radiographic examination disclosed a unilocular radiolucency with poorly delineated margins as typically seen in malignant tumors. Subsequently, acquired computed tomography scans displayed bony expansion and thinning of cortices on the labial aspect of the lesion. Magnetic resonance imaging revealed a well-defined, well-enhanced mass lesion with homogeneous signal intensity on every pulse sequence. The lesion showed intermediate signal intensity on the T1- and T2-weighted images. Magnetic resonance imaging of the present maxillary myxoma revealed a higher signal intensity on T1-weighted and a lower signal intensity on T2-weighted images than for previously reported myxomas of the soft tissues. This discrepancy might be related to the viscosity of the mucoid substance or the protein density of the tumor.

The lingual lymph node identified as a sentinel node on CT lymphography in a patient with cN0 squamous cell carcinoma of the tongue

We performed CT lymphography on an 81-year-old female patient with a histologically confirmed squamous cell carcinoma of the tongue with no clinical or radiological evidence of cervical lymph node involvement. The lateral lingual lymph node was identified as a sentinel node, which is the first lymph node to receive drainage from a primary tumour. CT lymphography also showed draining lymphatics passing through the sublingual space, the medial side of the submandibular gland and near the hyoid bone and connected with the middle internal jugular node. Although metastasis to the lateral lingual lymph node is known as one of the crucial events in determining survival outcome in cancer of the tongue and floor of the mouth, very few reports are available on the imaging of the lateral lingual lymph node metastasis. This is the first report regarding the lateral lingual lymph node identified as a sentinel node demonstrated on CT lymphography.

Inflammatory histopathogenesis of nasopalatine duct cyst: a clinicopathological study of 41 cases

OBJECTIVE The aim of this study is to characterize immunohistochemical profiles of lining epithelia of nasopalatine duct cyst (NPC) as well as to correlate those findings with their clinicopathological features to understand the histopathogenesis of NPC. MATERIALS AND METHODS Forty-one surgical specimens from NPC were examined for clinical profiles and expression of keratin-7, 13, MUC-1, and P63 by immunohistochemistry, compared to radicular cyst (RC) and maxillary sinusitis. RESULTS Nasopalatine duct cyst was clinically characterized by male predominant occurrence: 44% of the cases involved tooth roots, and 70% with inflammatory backgrounds. Lining epithelia of NPCs without daughter cysts were immunohistochemically distinguished into three layers: a keratin 7-positive (+) ciliated cell layer in the surface, a keratin-13+ middle layer, and a MUC-1+/P63+ lower half, indicating that they were not respiratory epithelia, and the same layering pattern was observed in RC. However, those immunolocalization patterns of the main cyst lining with daughter cyst were exactly the same as those of daughter cyst linings as well as duct epithelia of mucous glands. CONCLUSIONS Two possible histopathogenesis of NPC were clarified: one was inflammatory cyst like RC and the other was salivary duct cyst-like mucocele.

Finite element analysis of implant-embedded maxilla model from CT data: Comparison with the conventional model

PURPOSE There are no entire maxillary finite element analysis models available, as a base of reference for the dimensions of conventional segment finite element analysis models. The objectives of this study were: (1) to construct a maxillary model derived from a human skull and to investigate the strain distribution around a posterior implant embedded in it; (2) to investigate the usability of conventional segment maxillary models. METHODS CT DICOM data of a human dried skull maxilla was imported into the Mesh Generation Tools (ANSYS AI environment) and a computer-generated implant-abutment unit was bicortically embedded into it. In this Large model, Von Mises strains under axial and buccolingual loads were then calculated by a finite element program. Moreover, two simplified maxillary segments (Simplified models) were computer-generated and their Von Mises strains were similarly calculated. RESULTS Although absolute values differed markedly, strain distribution patterns in the cortical bone were similar to those in the Simplified models: high Von Mises strains in the cortical bone concentrated in the sinus floor around the implant apex under axial load, and in the alveolar crest around the implant neck under buccolingual load. CONCLUSIONS The simplified and segmented three-dimensional finite element models of the human maxilla showed the same locations of the highest equivalent strains as the full maxilla model created from CT DICOM data. If absolute strain values are not of interest, the Simplified models could be used in strain analyses of simulated posterior maxilla for diagnostic suggestions in implant placement.

Magnetic resonance imaging of human mandibular elevator muscles after repetitive maximal clenching exercise

Exercise can enhance the signal intensity (SI) of skeletal limb muscles on T2-weighted magnetic resonance imaging (MRI). The purpose here was to evaluate the effects of repetitive maximal clenching exercises involving the mandibular elevator muscles with T2-weighted MRI. Seven normal volunteers were imaged before and immediately after performing repetitive maximal clenching and at 3, 6, 9, 12, 15, 20 min after the exercise in a 1.5 T GE magnet with spin-echo sequences. SI in the masseter, medial pterygoid and temporalis increased significantly (p < 0.001) and the cross-sectional area (CSA) of masseter increased 10.11% on T2-weighted MRI after exercise. The increased SI and CSA declined approximately to the pre-exercise level in about 20 min after exercise. No SI and CSA changes were found in the inactive neck muscle and no SI changes in the mandibular bone marrow (p > 0.05). The findings suggest that the use of exercise-enhanced MRI might be helpful in the study of the function and dysfunction of muscles in the orofacial region.

Adenoid cystic carcinoma of sublingual gland involving the submandibular duct

We report an unusual case of adenoid cystic carcinoma (ACC) arising in the sublingual gland and extending into the submandibular duct. Our article mainly describes the MR findings. The margin of the mass was well-defined and the mass was divided into two parts - anterior and posterior. The anterior part of the mass showed isointense to surrounding muscle on T(1) weighted images and hyperintense on fat-saturated T(2) weighted images. The posterior part of the mass showed hyperintense both on T(1) weighted and fat-saturated T(2) weighted images. The findings indicated that the cystic space of the posterior part was filled with tumour mass which extended from the anterior part. ACC of the sublingual gland extending into the submandibular duct is rare and the MR findings have not been previously described in the literature.

The clinicoradiologic predictability of perforations of the soft tissue of the temporomandibular joint

One hundred thirty-one arthrographic examinations of temporomandibular joints were performed on 119 patients. The relationships between clinical symptoms, tomographic findings, and soft-tissue perforation were examined. Perforations of the articular disk or posterior attachment were revealed in 58 joints. Joints with crepitation showed a high frequency of perforation (20 of 22). Pain in the joint area and limitation of opening correlated to disk reduction. Perforations were observed in 12 of 21 joints with continuous pain. Osseous changes were detected in 89 joints. Joints with abnormal radiodensity (erosion, sclerosis) combined with abnormal shape (pocket erosion, osteophyte formation, deformity) showed a high frequency of perforation (41 of 45), which corresponded to 84% in this study. In those cases with osseous change or crepitation, positive predictive values of perforation were both 91%. These types of osseous change and their clinical significance might predict soft-tissue perforation with high accuracy before an arthrogram is performed.

Relationships among maxillofacial morphologies, bone properties, and bone metabolic markers in patients with jaw deformities

The aim of this study was to determine the relationships among bone properties, bone metabolic markers, and types of jaw deformity. The subjects were 55 female patients with jaw deformities. Skeletal morphology was examined using lateral cephalograms, and the patients were divided into three groups according to the type of anteroposterior skeletal pattern. Serum osteocalcin, bone alkaline phosphatase, and tartrate-resistant acid phosphatase isoform 5b, as well as deoxypyridinoline in urine, were measured as bone metabolic markers. Quantitative ultrasound (QUS) measurements were used to assess bone properties at the calcaneal bone. The bone volume and bone density of the condylar process were measured in 43 patients by computed tomography. There were no significant differences in bone metabolic markers and QUS parameters between the groups, although bone formation and resorption markers tended to be higher in patients with a protrusive mandible. On the other hand, patients with mandibular retrusion had a higher tendency to have small and dense condylar processes. In conclusion, the results suggest that growth depression or a degenerative change in the mandibular condyle is involved in the pathogenesis of mandibular retrusion, although risk factors for progressive condylar resorption were not determined.

Longitudinal study of patients with TMJ dysfunction by tomographic examination: Condylar position and clinical sign

For patients with TMJ dysfunction, operators often change the condylar position by various methods. The aim of this study is to investigate how much the changes with time of condylar positions are related to the changes of clinical signs.The subjects were 584 joints of 127 patients with TMJ dysfunction to whom the serial lateral TMJ tomography was performed more than twice.In the most of cases where the condylar position had moved downward, inter-incisal distance had increased and TMJ noise had ameliorated. Furthermore, in many cases where the condylar position had moved forward, the amelioration of the TMJ pain was observed.It was considered that those ameliorations occurred because the positional relationship between the condylar head and the articular disk or posterior attachment had been improved.

The relationship between masseter muscle pain and T2 values in temporomandibular joint disorders

OBJECTIVE Myofascial pain in temporomandibular joint disorders (TMDs) is evoked by various factors, including edematous change. We investigated whether the pain pattern is related to edematous change by using T2 mapping generated by magnetic resonance imaging to detect water content in the tissue. STUDY DESIGN One hundred and five patients diagnosed with TMDs, with or without unilateral masseter muscle pain, were divided into 6 groups according to their pain experience: pain on compression (23 cases), pain on movement (13 cases), spontaneous pain (4 cases), pain on compression and movement (14 cases), pain on compression and spontaneous pain (2 cases), and no pain (49 cases). Differences in the mean T2 values of the masseter muscle between the group with pain on only one side (5 unilateral pain groups) or pain-free on both the right and left sides (pain-free group) were compared with paired t tests. Significant differences were assumed at P < .05. RESULTS Significant differences in mean T2 values were found between the painful and pain-free sides in the group with pain on compression. CONCLUSIONS The findings of edematous change in the masseter muscle of patients with pain on compression may affect treatment planning and lead to investigation of treatment options for myofascial pain in TMDs.