Naoya Kakimoto

Histopathologic and radiographic findings of the simple bone cyst

OBJECTIVE The purpose of this study is to examine the correlation between histopathologic and radiographic findings and to discuss the cause of the simple bone cyst. STUDY DESIGN Histopathologically, we classified 53 simple bone cysts into two types. Type A has a connective tissue membrane and type B has a partially thickened wall with dysplastic bone formation. Radiographically, we evaluated the following: margin, radiolucency, or radiopacity, relationship with tooth apices, bucco-lingual bone expansion, and displacement of the mandibular canal. RESULTS Bone expansion and radiopacity were closely related to histopathologic findings although there was no correlation between the histopathologic findings and radiographic margin, relationship with tooth apices, and displacement of mandibular canal. Local recurrence was more likely to be observed in patients diagnosed as having type B than type A lesions. CONCLUSIONS Type A and type B bone cysts may have different causes. Cysts determined radiographically to be radiopaque, those diagnosed as type B histopathologically, and cysts that have been treated surgically should all be followed by radiographic examinations.

Spatial relationships between the mandibular central incisor and associated alveolar bone in adults with mandibular prognathism.

OBJECTIVE To examine if there was any correlation between the labio-lingual inclinations of the mandibular central incisor and the associated alveolar bone, and to investigate the labio-lingual position of the mandibular central incisor root apex in the associated cancellous bone in adults with untreated mandibular prognathism. MATERIALS AND METHODS High-resolution computed tomography images of the mandible were recorded in 20 adult patients with mandibular prognathism. The labio-lingual inclinations of a central incisor and its associated alveolar bone, the thickness of the associated cancellous bone, and the distance from the central incisor root apex to the inner contour of both the labial and lingual cortical plates were measured. Correlations and differences between the measured variables were tested for statistical significance. RESULTS The labio-lingual inclination of the central incisor significantly correlated with the labio-lingual inclination of the associated alveolar bone, the thickness of cancellous bone, and the distance from the central incisor root apex to the inner contour of the lingual cortical bone. The distance from the central incisor root apex to the inner contour of the labial cortical plate of bone was significantly smaller than that to the lingual cortical plate. CONCLUSIONS In adults with untreated mandibular prognathism, when the mandibular central incisor was more lingually inclined, the associated alveolar bone was also more lingually inclined and thinner. The mandibular central incisor root apex was closer to the inner contour of the labial cortical bone than to the lingual cortical bone.

Results of low- and high-dose-rate interstitial brachytherapy for T3 mobile tongue cancer

PURPOSE To evaluate the treatment results of low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy (ISBT) for T3 mobile tongue cancer. MATERIAL AND METHODS Between 1974 and 1992, 61 patients with T3 mobile tongue cancer were treated with LDR ISBT using (192)Ir hairpins with or without single pins. In addition, between 1991 and 1999, 14 patients were treated with HDR ISBT. For nine patients treated with ISBT alone, the total dose was 59-94 Gy (median 72 Gy) within one week in LDR ISBT and 60 Gy/10 fractions/5 days in HDR ISBT. For 66 patients treated with a combination therapy of external beam radiotherapy (EBRT) and ISBT, the total dose was 12.5-60 Gy (median 30 Gy) of EBRT and 50-112 Gy (median 68 Gy) within 1 week in LDR ISBT or 32-60 Gy (median 48 Gy)/8-10 fractions/5-7 days in HDR ISBT. RESULTS The 2- and 3-year local control rates of all patients were both 68%. The 2- and 3-year local control rates of patients treated with LDR ISBT were both 67%, and those with HDR ISBT were both 71%. The local control rate of patients treated with HDR ISBT was similar to those with LDR ISBT. CONCLUSIONS ISBT for T3 mobile tongue cancer is effective and acceptable. The treatment result of HDR ISBT is almost similar to that of LDR ISBT for T3 mobile tongue cancer.

LYMPH NODE METASTASIS OF EARLY ORAL TONGUE CANCER AFTER INTERSTITIAL RADIOTHERAPY

PURPOSE To examine the prognostic factors for lymph node metastasis after brachytherapy for early (T1-T2N0M0) oral tongue cancer. METHODS AND MATERIALS We reviewed the records of 571 patients (500 low dose rate and 71 high dose rate) treated at Osaka University Hospital between 1967 and 1999. RESULTS Patients with lymph node metastasis had tumor with an average diameter of 26 +/- 8 mm and a thickness of 9 +/- 5 mm; for patients without lymph node metastasis, the corresponding dimensions were 23 +/- 8 mm and 7.5 +/- 4 mm (p = 0.0004 and 0.001, respectively). After 5 years, the ulcerative (48%) and indurative/infiltrative (39%) types showed a higher ratio of nodal involvement than the exophytic (31%) and superficial (19%) types (p <0.0001). Multivariate analysis showed ulceration (p = 0.006) and a thickness of <or =6 mm (p = 0.04) to be statistically significant predisposing factors for lymph node metastasis. The lymph node control rate was 68% in 1967-1979, 71% in 1980-1990, and 66% in 1990-1999; the corresponding successful salvage rates for lymph node metastasis were 43%, 33%, and 58% (p = 0.04). CONCLUSION The appearance of the tumor, especially the presence or absence of ulceration and the diameter and thickness, are useful prognostic indicators for lymph node metastasis. Although the rates of lymph node metastasis did not change, the salvage outcome for recurrence after interstitial radiotherapy has recently improved.

Correlation between pixel values in a cone-beam computed tomographic scanner and the computed tomographic values in a multidetector row computed tomographic scanner.

Objectives: The studys objectives were to investigate the correlation between pixel values obtained from a cone-beam computed tomographic (CBCT) scanner and the computed tomographic (CT) values from a multidetector row CT scanner and to determine whether they have a linear relationship at various tube voltages and tube currents. Methods: A phantom with different concentrations of contrast medium at the center of a multidetector row CT and a CBCT scanner was scanned at various imaging parameters. Computed tomographic values and pixel values were measured using ImageJ. Regression analysis was performed, as well as correlation tests with a Pearson correlation coefficient. Results: A significant correlation between pixel values and the CT values of the same specimen was observed (P < 0.0001), and a linear relationship was found between the values from the 2 scanners at each parameter. Conclusions: A high correlation and linear relationship between the CT values and pixel values were found at each parameter. Therefore, linear functions can be used to convert a pixel value from the CBCT machine used in this study to the CT values.

Postoperative maxillary cysts: Magnetic resonance imaging compared with computerized tomography

OBJECTIVES The aim was to investigate magnetic resonance (MR) and computerized tomography (CT) images and compare MR and CT image features of postoperative maxillary cysts (POMC). STUDY DESIGN We retrospectively evaluated MR and CT images of 7 POMC patients. Number of the cysts, border, bone expansion, CT value, signal intensity, and contrast enhancement were observed. RESULTS On CT images, 15 cysts were detected. Fourteen cysts showed smooth border. Bone expansion was found in 10 cysts. Mean CT value of each cyst ranged from 23 to 50 Hounsfield units. On MR images, 18 cysts were detected. Twelve cysts showed smooth border. Bone expansion was not observed. Most cysts showed intermediate signal intensity on T1-weighted images, and high or nonhomogeneous intermediate/high signal intensity on T2-weighted images with the fat suppression technique. No cyst showed contrast enhancement in both examinations. CONCLUSION The CT images revealed bony information, and the MR images clearly demonstrated border of POMC. POMC should be evaluated with both CT and MR imaging.

Metallic artifacts caused by dental metal prostheses on PET images : a PET/CT phantom study using different PET/CT scanners

ObjectiveThe objective of this study was to investigate the effects of computed tomography (CT) artifacts caused by dental metal prostheses on positron emission tomography (PET) images.MethodsA dental arch cast was fixed in a cylindrical water-bath phantom. A spherical phantom positioned in the vicinity of the dental arch cast was used to simulate a tumor. To simulate the tumor imaging, the ratio of the 18F-fluoro-deoxy-glucose radioactivity concentration of the spherical phantom to that of the water-bath phantom was set at 2.5. A dental bridge composed of a gold–silver–palladium alloy on the right mandibular side was prepared. A spherical phantom was set in the white artifact area on the CT images (site A), in a slightly remote area from the white artifact (site B), and in a black artifact area (site C). A PET/CT scan was performed with and without the metal bridge at each simulated tumor site, and the artifactual influence was evaluated on the axial attenuation-corrected (AC) PET images, in which the simulated tumor produced the strongest accumulation. Measurements were performed using three types of PET/CT scanners (scanners 1 and 2 with CT-based attenuation correction, and 3 with Cesium-137 (137Cs)-based attenuation correction). The influence of the metal bridge was evaluated using the change rate of the SUVmean with and without the metal bridge.ResultsAt site A, an overestimation was shown (scanner 1: +5.0% and scanner 2: +2.5%), while scanner 3 showed an underestimation of −31.8%. At site B, an overestimation was shown (scanner 1: +2.1% and scanner 2: +2.0%), while scanner 3 showed an underestimation of −2.6%. However, at site C, an underestimation was shown (scanner 1: −25.0%, scanner 2: −32.4%, and scanner 3: −8.4%).ConclusionsWhen CT is used for attenuation correction in patients with dental metal prostheses, an underestimation of radioactivity of accumulated tracer is anticipated in the dark streak artifact area on the CT images. In this study, the dark streak artifacts of the CT caused by metallic dental prostheses may cause false negative finding of PET/CT in detecting small and/or low uptake tumor in the oral cavity.

Perineural spread of adenoid cystic carcinoma in the oral and maxillofacial regions: evaluation with contrast-enhanced CT and MRI.

OBJECTIVES The objective of this study was to compare the accuracy of contrast-enhanced CT (CECT) and contrast-enhanced MRI (CEMRI) in the detection of perineural spread (PNS) of adenoid cystic carcinoma (ACC) in the oral and maxillofacial regions. METHODS This study consisted of 13 ACCs from 13 patients, all of which were histopathologically diagnosed. Both CECT and CEMRI were performed in all patients before the treatment. The images of each patient were retrospectively evaluated for the detection of PNS. The definitions of PNS included abnormal density/signal intensity, contrast enhancement or widening of the pterygopalatine fossa, palatine foramen, incisive canal, mandibular foramen and mandibular canal, and enlargement or excessive contrast enhancement of a nerve. RESULTS 11 out of 13 cases were proven to exhibit PNS histopathologically. 8 of the 11 cases for which PNS was histopathologically proven exhibited PNS on MR images. Six of the eight cases for which PNS was exhibited on MR images also exhibited PNS on CT images. The sensitivity, specificity and accuracy for the detection of PNS were 55%, 100% and 62% on CT images and 73%, 100% and 77% on MR images, respectively. Although the accuracy of PNS on MR images was slightly superior to that on CT images, there were no statistically significant differences between the detection of PNS on CT images and on MR images. CONCLUSIONS CT and MR images are equally useful for the detection of PNS of ACC in the oral and maxillofacial regions.

(18)F-FDG accumulation in the oral cavity is associated with periodontal disease and apical periodontitis: an initial demonstration on PET/CT.

ObjectiveThe objective of this study was to prospectively investigate the relationship between high accumulation of 2-deoxy-2-[18F] fluoro-d-glucose (FDG) in the oral cavity and dental infections on positron emission tomography/computed tomography (PET/CT).MethodsFDG-PET/CT scans of 103 patients who underwent a health screening were evaluated. The dental examination was performed prior to each PET/CT scan, and dental infections were assessed. Dental infections were classified into six blocks. The severity of dental caries was classified into five grades, and periodontal disease and apical periodontitis were classified into three grades. Two radiologists classified the PET images in the same manner as the dental examination. They evaluated the intensity of FDG uptake by a four-point visual PET image score for each block. The comparison of the dental examination, as a gold standard, and the visual PET image score was performed on a patient or block basis.ResultsOn a patient-based analysis, 21 of 103 patients (20.4%) showed PET positive findings in the oral cavity; 18 of the 21 patients (85.7%) had dental infections. On a block-based analysis, 25 of 605 blocks (4.1%) showed PET positive findings in the oral cavity; 22 of the 25 blocks (88.0%) had dental infections. On a detailed block-based analysis, a significant difference was observed between the presence of periodontal disease, or apical periodontitis and the positivity of the visual PET image findings (P < 0.01). Their severity correlated with the visual PET image score (P < 0.05).ConclusionsPeriodontal disease or apical periodontitis, but not dental caries, caused FDG accumulation in the oral cavity. This finding should be taken into account when a head and neck FDG-PET study is interpreted.

Calcifying cystic odontogenic tumor and adenomatoid odontogenic tumor: radiographic evaluation

OBJECTIVES The aim of this study was to describe the radiographic features of calcifying cystic odontogenic tumors (CCOTs) and adenomatoid odontogenic tumors (AOTs) and to compare the radiographic findings for these 2 lesions. STUDY DESIGN We retrospectively reviewed radiographs of CCOTs and AOTs. Location, border, relationship of the lesion with the impacted tooth, calcification patterns, tooth displacement, and root resorption were evaluated. RESULTS Nine CCOTs and 8 AOTs were reviewed. Most CCOTs and AOTs had smooth borders. Three CCOTs and 7 AOTs enclosed impacted teeth. Of these cases, the radiolucencies of 3 CCOTs and 1 AOT were attached to the impacted teeth at the cementoenamel junctions. Three AOTs enclosed more portions of the roots, and the other 3 AOTs enclosed the entire teeth. Calcification in CCOTs appeared as a thin radiopaque line (2 cases) and discrete radiopaque foci (1 case), whereas AOTs had numerous dispersed or clustered radiopaque foci (4 cases). CONCLUSIONS Radiolucency with numerous radiopaque foci (particularly when the radiolucency surrounds a portion of the root or entire tooth) is suggestive of an AOT rather than a CCOT.