Shigenobu Kanda

Imaging findings of lipomas in the orofacial region with CT, US, and MRI

OBJECTIVE The aim of this study was to document retrospectively the imaging findings of lipomas with the use of computed tomography, ultrasonography, and magnetic resonance imaging. STUDY DESIGN Thirteen patients with 11 lipomas and 2 lipomatoses were evaluated. Eleven cases were examined by computed tomography, 9 by ultrasonography, and 3 by magnetic resonance imaging. RESULTS Lipomas had a density ranging from -134 to -83 Hounsfield units, (mean-108) on the computed tomography images. The margins were ill defined in 9 of 10 cases. The superficial muscles were displaced externally in 8 cases and internally in 2 cases. With ultrasonography, 8 lesions were hypoechoic, and one was hyperechoic. All three lesions had a high signal intensity on both T1- and T2-weighted images. CONCLUSIONS Lipomas had a specific range of computed tomography Hounsfield unit values and also displaced the surrounding soft tissue. Although some variation in the ultrasonographic appearance was observed, the lesions tended to be hypoechoic. These findings may be useful for diagnosing lipomas in the orofacial region.

Idiopathic osteosclerosis of the jaws : Panoramic radiographic and computed tomographic findings

OBJECTIVE The purpose of this study was to determine the frequency and anatomic location of idiopathic osteosclerosis in the jawbones and to present computed tomographic findings of this lesion in Japanese patients. STUDY DESIGN Panoramic radiographs of 1047 patients were examined for the presence of idiopathic osteosclerosis in the jawbones. Computed tomography was performed in 11 patients of this series. RESULTS A total of 64 patients (6.1%) showed this radiopacity. The highest occurrence was in the mandibular first molar region. There was no statistically significant difference in the prevalence of idiopathic osteosclerosis between males and females. On computed tomography images, these radiopaque areas were divisible into two types: enostosis (five cases) and central sclerosis (six cases). CONCLUSION This is the first report of computed tomographic findings on idiopathic osteosclerosis in the jawbones, although the results on panoramic radiographs are similar to other investigators.

Assessment of image quality in dental radiography, part 2 Optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems

OBJECTIVE The purpose of this study was to compare 2 film systems and several digital intraoral systems with regard to visual image quality through use of a test phantom developed for this purpose. STUDY DESIGN The detectors used for digital imaging were as follows: Computed Dental Radiography (CDR), Digora, Dixel, and Sens-A-Ray without scintillator layer. Two types of digital images were prepared for the observer performance test: one with original gray scales and another with contrast enhancement. Images with and without enhancement from the 4 systems were displayed to 7 observers. The change in the average number of perceptible holes was plotted against exposure, and modified perceptibility curves were created and compared with curves for the film systems. The exposure level at which the maximum number of holes was perceived was defined to be optimum. The optimum exposure levels were determined for each digital system and compared with that of the film systems. At the optimum exposure, the average maximum numbers of perceptible holes in each digital system with and without contrast enhancement were compared with the maximum numbers for the film systems. The minimum exposure levels were determined to be those at which the number of perceptible holes exceeded the number for film, and the possibility of exposure reduction was evaluated. RESULTS All digital systems except the Digora system showed lower optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With the CDR, Digora, and Dixel systems, exposures could be further reduced by a considerable amount, with greater retention of information than was associated with film. CONCLUSIONS Our results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of small mass changes.

Ultrasonographic evaluation of inflammatory changes in the masseter muscle.

The ultrasonographic images of 32 patients with inflammatory change in the masseteric region were investigated to clarify the characteristic findings and to evaluate the utility of ultrasonography. Inflamed masseter muscles frequently demonstrated reduction of echo intensity and complete or partial absence of hyperechoic bands. The mean thickness of the masseter muscle on the unaffected side was 8.6 mm, whereas that on the affected side was 12.9 mm. Nine of 10 patients with heterogeneous hypoechoic area, but only 1 of 10 patients with homogeneous hypoechoic area, had received surgical treatment before ultrasonographic examination.

Assessment of image quality in dental radiography, part 1 ☆ ☆☆ ★ ★★: Phantom validity

OBJECTIVE The purpose of this study was to describe and validate an image-quality phantom to be used in dental radiography for comparison of film and digitally acquired images. STUDY DESIGN An aluminum block of 12 steps, with 7 holes in each step, was covered by acrylic blocks. This phantom was radiographed with Kodak Ultra-speed and Ektaspeed Plus films at 70, 65, and 60 kVp with the whole exposure range available. All together, 50 dental films were randomly sequenced and presented to 7 observers. The average number of perceptible holes from all steps was plotted against exposure for each tube voltage and film type, generating a modified perceptibility curve. The tentative optimum exposure level was determined from perceptibility curves in each experimental condition and compared with that determined by means of the standard aluminum stepwedge and the preset time of the x-ray machine. The density range of this phantom at the optimum exposure was compared with that of clinical dental radiographs. Validity of the phantom was evaluated according to the optimum exposure level from the modified perceptibility curves and the overall density range. Finally, the average maximum numbers of perceptible holes at the tentative optimum exposure level were compared for each tube voltage and film type. The statistical test used was a 2-way factorial analysis of variance. RESULTS The exposure at the perceptibility curve peak approximated that obtained by means of the standard aluminum step-wedge and the time preset by the manufacturer. The overall density range at the perceptibility curve peak covered the clinical density range for each tube voltage and film type. There were no statistically significant differences between film types or among tube voltages. CONCLUSIONS The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be quantitatively evaluated by means of the number of the holes seen in the phantom.

Sonographic analysis of recurrent parotitis in children: a comparative study with sialographic findings.

OBJECTIVE The sonographic features of recurrent parotitis in children were studied to clarify a relationship between sonographic and sialographic findings in this disease. STUDY DESIGN Twenty-one glands (7 on follow-up) were examined by 7.5 MHz ultrasonography and sialography. Echo intensity level, distribution of the internal echoes, and size of hypoechoic areas were compared with the size of punctate shadows on the sialograms. Twenty other histopathologic specimens were analyzed to investigate the entity of hypoechoic areas. RESULTS Sonography showed hypoechoic, heterogeneous internal echoes, the level of which increased as the punctate shadows enlarged. Hypoechoic areas, all of which were larger than the sialographic punctate shadows, were observed in 62% of the glands. Histopathologic analysis suggests that these hypoechoic areas represent dilated peripheral ducts with lymphocytic infiltration. Sonography was likely to detect changes over time more sensitively than sialography. CONCLUSIONS Sonography should be performed as the test of first choice, both in the primary and follow-up stages, in cases of recurrent parotitis in children.

Morphologic analysis of odontogenic cysts with computed tomography

PURPOSE The purpose of this study was to analyze the effects of lesion site and epithelial keratinization on the morphologic characteristics of odontogenic cysts and clarify determinate factors for cyst morphology. MATERIAL AND METHODS Computed tomographic images of 92 odontogenic cysts were analyzed: 31 primordial, 31 dentigerous and 30 radicular. Thirty-four cysts were located in the maxilla (6 primordial, 10 dentigerous, and 18 radicular) and 58 in the mandible (25 primordial, 21 dentigerous, and 12 radicular). Histologically, 31 cysts showed epithelial keratinization (18 primordial and 13 dentigerous). No keratinization was seen in radicular cysts. The morphologic features of cysts were assessed by measuring long length parallel to dental arch and short length vertical to it and calculating the long/short ratio. In addition, the computed tomography pattern of the cyst was classified into unilocular, lobulated, and multilocular patterns. Appearance of the sclerotic rim and surrounding cortex were classified into three and four patterns respectively to evaluate the developmental features of the cyst. RESULTS As a whole, the long length of the primordial cysts was statistically larger than the other two cyst groups and resulted in a larger long/short ratio. Statistical differences of CT pattern were also seen among cyst groups. There was no preference in any cyst group for the appearance of the sclerotic rim and cortex. There were statistical differences between maxilla and mandible in short axis and long/short ratio. The maxillary cysts generally showed round shapes irrespective of their histologic characteristics. A multilocular pattern was more frequent in the keratinized group of mandibular primordial cysts. In dentigerous cysts, a multilocular pattern was seen only in the keratinized group and the long/short ratio was statistically larger; cyst shape was elliptical along the long axis. CONCLUSION Our results demonstrated morphologic differences of odontogenic cysts caused by lesion site and keratinization. The dentigerous cyst with predominant keratinization should be included in the primordial cyst (odontogenic keratocyst) group.

Multimodality imaging of cervicofacial actinomycosis

Actinomycosis is an uncommon chronic disease usually caused by Actinomyces israelii. It affects the soft tissue mainly but sometimes spreads to involve salivary glands, bone, or even the skin of the face and neck. Five cases have been seen in our department. Several imaging modalities were used to assist in making the diagnosis. The cases are presented and the literature reviewed. Ultrasonography was found to be a useful diagnostic tool especially in developing the differential diagnosis.

Radiographic patterns of osteomyelitis in the mandible Plain film/CT correlation

Mandibular osteomyelitis often is associated with involvement of the masticator space. Assessment of mandibular osteomyelitis should therefore involve assessment of soft tissue involvement of the lesion. The purpose of this study was to clarify the relationship between computed tomography patterns and the presence of inflammation in soft tissues. Thirty-three cases diagnosed with osteomyelitis of the mandible were analyzed radiologically with conventional radiographs and with computed tomography scans. Computed tomography patterns of osteomyelitis were classified into four types, lytic, mixed, sclerotic, and sequestrum patterns. Location, extent of the lesion, and change of the cortical plate were evaluated and compared with conventional radiographic findings. Mixed pattern cases displayed diffuse bone abnormalities, which sometimes were accompanied by cortical plate disruption and periosteal reaction. In addition, most mixed pattern cases showed soft tissue involvement, especially of the masseter muscle. Inflammation of the masseter muscle was found to be related to periosteal reaction and disruption of the buccal cortical plate. The data demonstrate a close interaction between cortical plate disruption and muscle inflammation. The extent of inflammation including soft tissue involvement was better appreciated with computed tomography in osteomyelitis, especially in mixed pattern cases.

Value of contrast-enhanced magnetic resonance imaging in differentiation of hemangiomas from lymphangiomas in the oral and maxillofacial region

OBJECTIVE The purpose of this study was to investigate the ability of contrast-enhanced magnetic resonance imaging to differentiate hemangioma from lymphangioma in the oral and maxillofacial region. STUDY DESIGN Contrast-enhanced magnetic resonance imaging was performed in 20 patients (21 masses: 17 hemangiomas and 4 lymphangiomas) through use of either a 0.2-T permanent system or a 0. 5-T superconductive system and spin-echo pulse sequences. RESULTS After intravenous administration of contrast medium, enhancement was observed in all hemangiomas in areas corresponding to those with high signal on T(2)-weighted images. Unequivocally increased signal was observed in 10 masses, and slightly increased signal was observed in 7 masses. On the other hand, none of the lymphangiomas showed an enhancing mass on contrast-enhanced T(1)-weighted images. CONCLUSIONS Although contrast-enhanced T(1)-weighted imaging may not improve delineation of masses in all cases, it can be used to differentiate between deep hemangiomas and lymphangiomas.