Yasutoshi Honda

Assessment of pleomorphic adenomas using MRI and dynamic contrast enhanced MRI

We evaluated magnetic resonance images (MRI) and the value of dynamic contrast enhanced MRI (DCE-MRI) of pleomorphic adenomas retrospectively. MRI was performed for 18 pleomorphic adenomas, including 11 cases with DCE-MRI. We obtained the following results on the MRI and DCE-MRI. (a). Pleomorphic adenomas showed a predilection for homogeneous intermediate signal intensity on T1-weighted images (T1WI), heterogeneous high signal intensity on T2-weighted images, and heterogeneous enhancement on Gd-T1WI. (b). Of 11 contrast index (CI) curves of pleomorphic adenomas, nine CI curves (81.8%) increased gradually to 600 s or increased gradually, reached a plateau, and sustained the plateau to 600 s. The remaining two (18.2%) increased gradually and decreased gradually thereafter. (c). CI curves reached the maximum CI index at 135-300 s.

MR imaging in the assessment of a solitary bone cyst

Abstract Introduction: It might be difficult to differentiate solitary bone cysts (SBCs) from other cysts and tumors when the lesion occurs at an unusual location and/or shows atypical radiographic features. Magnetic resonance imaging (MRI) is the most useful modality for evaluating the internal structure of lesions and may have the ability to distinguish SBCs from other lesions. However, few studies exist regarding MRI of SBCs in the oral region. The present study reports on the MR imaging of nine patients with SBCs and describes the diagnostic value of the MRI findings. Materials and methods: Nine patients with SBCs in the mandible were examined using MRI. In all patients, T1- and T2-weighted images (T1-WI, T2-WI) were obtained and contrast enhanced images and dynamic MRI were performed in four cases. Results: MR findings revealed homogeneous intermediate signal intensities (SI) on T1-WI and high SI on T2-WI in all cases. These SI indicated that the SBCs included homogeneous liquid. On the dynamic MRIs in all cases, the SBCs were enhanced from the margin to the inner part, indicating a gradual exudation of the contrast agent from the surrounding medullae to the inner part. These phenomena were not observed on the dynamic MRIs of the other true cysts with epithelial lining. Conclusion: MRI, especially dynamic MRI, can provide useful information for distinguishing SBCs from other cysts or tumors. Furthermore, dynamic MRI findings suggested that the liquid components of SBCs might have infiltrated from the surrounding medullae.

Radiographic and morphologic studies of multiple miliary osteomas of cadaver skin

OBJECTIVES The purpose of this study was to examine the frequency, chemical composition, and radiographic and morphologic features of multiple miliary osteomas of the facial skin. STUDY DESIGN Facial skin was obtained from 33 cadavers. After contact radiographs were taken, osteomas were examined by photo and scanning electron microscopy. Radiographic microanalysis of inorganic elements of the osteomas was also performed. In addition, clinical dental radiographic examinations were performed on 158 living subjects. RESULTS Radiographic examination revealed milia-like osteomas in the facial skin of all of the cadavers. Nodules of 0.5 to 2.0 mm in diameter were scattered symmetrically in the skin of the cheek, mandibular angle, and forehead. Each nodule consisted of a concentric, multilamellated, osteoid cortex and an adipose medulla. Microanalysis suggested the presence of hydroxyapatite similar in composition to that of normal cortical bone. The condition was detected in 28% (44/158) of the living subjects by clinical dental radiographic examination. CONCLUSION Multiple miliary osteoma is a very common condition and may not be related to specific diseases.

Application of dynamic CT for various diseases in the oral and maxillofacial region.

OBJECTIVE To investigate whether dynamic CT enables quantitative differentiation between inflammation, benign tumors, and malignant tumors in oral and maxillofacial regions. METHODS Sixteen malignant tumors (14 squamous cell Ca, one adenoid cystic Ca, one mucoepidermoid Ca), six benign tumors (one Warthin tumor, two pleomorphic adenomas, one lipoma, one Schwanoma, one hemangioma), and seven inflammation cases (three submandibular adenitis, two osteomyelitis, two perimandibular inflammations) were examined. Contrast agent (0.8 ml/kg) was injected intravenously at 5 ml/s. CT (Toshiba TCT 900S) scanning was performed at the time of the beginning of contrast medium injection. Parameters from the time-density curve were investigated: peak height (PH), relative CT value from the base CT value when the curve reached peak point; peak time (PT), the time when the curve reaches the peak point from contrast medium infusion; transit time (TT), time between two transit points on the time-density curve; and peak time ratio (PR), the ratio of peak time from the lesion to the artery and peak time from the vein to the artery. RESULTS PH was highest in inflammation, followed by malignant tumors and benign tumors. TT was significantly longer in benign tumor cases compared with malignant tumor and inflammation cases. PR for malignant tumor and inflammation were between the artery and vein phase, and that for benign tumor was beyond the vein phase. CONCLUSION Parametrical analysis of a contrast enhanced dynamic CT study may serve to differentiate the lesions in the oral and maxillofacial region.

Kinetic MRI Using High-Speed Sequence to Evaluate Swallowing -Comparison with Videofluorography-

ObjectiveThe aim of the present study was to evaluate the ability of high-speed magnetic resonance imaging (MRI) to dynamically capture images during the swallowing process and compare the results with videofluorography.MethodsTen subjects underwent both videofluorography and kinetic MRI, which was used in a high-speed sequence mode known as “turbo-fast low-angle shot (turbo-FLASH)” using prune extract (Miki prune®: Miki Corporation) as the contrast medium. Three radiologists assessed 18 agreed-upon items in the kinetic MR images with respect to the oral and pharyngeal phases.ResultsKinetic MRI provided high-quality images of the direct visualization of the soft tissue during swallowing. In the oral phase, the motion of the lip, tongue, and soft palate and keeping of the contrast medium were scored higher than the equivalent videofluorographic images. The motion of the mandible and the transport to the dorsum of the tongue were evaluated as approximately the same between the two methods, and the import of the contrast medium to the oral cavity, the transport to the pharynx, and the keeping of the contrast medium were inferior to the equivalent videofluorographic images. In the pharyngeal phase, the motion of the soft palate and the tongue base were depicted approximately the same as in the videofluorographic images. The hyoid bone, the elevating and closing of the larynx, the wave of the pharynx, the opening of the pharyngo-esophageal segment, and the passage and keeping of the contrast medium were depicted less clearly than in videofluorography.ConclusionsDespite some limitations, high-speed kinetic MRI is a promising tool for evaluating swallowing features, as it directly provides anatomical and functional information during the entire course of swallowing using prune extract as the contrast medium.

Diagnosis of multiple synchronously occurring cystic jaw lesions in 23 patients: prognostic implications related to basal cell nevus syndrome

ObjectivesWe rarely find multiple cystic lesions in the jaw in panoramic radiographs. Most reports of multiple cystic lesions have described keratocystic odontogenic tumors (KOTs) in patients with basal cell nevus syndrome. In this study, we performed radiographic and clinical examinations of patients with multiple cystic jaw lesions found during their first visit to our department to determine the proportion of basal cell nevus syndrome among multiple cystic lesions.MethodsPatients who had a panoramic radiograph taken at Okayama University Hospital between 1993 and 2000 were examined. Twenty-three patients with multiple cystic jaw lesions on a first panoramic radiography examination were entered into this study.ResultsOf the 23 patients, 12 (52.2%) were diagnosed with basal cell nevus syndrome and 11 (47.8%) were not. Of the 14 patients with multiple KOTs, 12 (85.7%) were diagnosed as having basal cell nevus syndrome. Of the nine remaining patients with multiple cystic jaw lesions, only seven had multiple dentigerous cysts and two had multiple simple bone cysts. Cleft palate was observed in four of the 12 patients (33.3%) with basal cell nevus syndrome.ConclusionDiagnosing basal cell nevus syndrome based on multiple cystic jaw lesions carries a high risk of misdiagnosis. A strong possibility exists that patients with multiple jaw KOTs have basal cell nevus syndrome. Furthermore, cleft palate should be considered an important oral finding in basal cell nevus syndrome because its occurrence was relatively frequent in our study.