Koichi Yonetsu

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.

Sonography as a replacement for sialography for the diagnosis of salivary glands affected by Sjögren's syndrome

Recently, it has been suggested that sonographic evaluation of the salivary glands is useful in the diagnosis of Sjogrens syndrome. Kawamura et al and, more recently, Ariji et al , showed that descriptive and quantitative assessment of the salivary glands by sonography efficiently differentiated between diseased and normal glands in patients with Sjogrens syndrome.1,2 They showed that the proposed sonographic gradings correlated well with the sialographic gradings. These findings suggest that sonography might be an alternative diagnostic tool for Sjogrens syndrome. Here, we attempted to determine whether sonography can take the place of sialography as an alternative technique for the assessment of salivary gland involvement in Sjogrens syndrome. Sialography and sonography were performed on 294 patients who presented with sicca syndrome (171 positive and 123 negative for Sjogrens syndrome). We diagnosed patients with Sjogrens …

Three-Dimensional Cephalometry Using Helical Computer Tomography: Measurement Error Caused by Head Inclination

We performed a study of three-dimensional (3-D) linear measurements in the maxillofacial region using helical computer tomography (CT). The high accuracy of the linear measurements showed errors of less than 5% from the actual measures. But, it is possible that the accuracy was influenced by inaccurate head positions. In this study, we evaluated the errors when the head positions were tilted using the 3-D measurement system. Helical CT was used to scan a dry skull, and the data were reconstructed into a 3-D image. A total of 18 points were plotted on the 3-D images, and the distance between two points was calculated when the points were expressed as coordinates. A dry skull was tilted by 10 degrees from the reference position in the horizontal, sagittal, and frontal planes and was then tilted in a combination of directions. Scanning was performed with slice thicknesses of 1 mm, 3 mm, 5 mm, and 7 mm. The length between two points measured by 3-D cephalometry was compared with the actual length determined using an antenna meter and a caliper and expressed as percentage errors of the actual length. In all head positions, errors in all linear measurements on the images and the actual length measured on the skull were less than 5% when a slice thickness of 1 mm or 3 mm was used. But, on using a slice thickness of 5 mm or 7 mm, some linear measurements showed larger measurement errors. Therefore, a thickness of less than 3 mm was thought to be clinically appropriate because the accuracy of the measurements was not influenced by head rotation.

Salivary Spect and Factor Analysis in Sjögren's Syndrome

Salivary SPECT and factor analysis in Sjögrens syndrome were performed in 17 patients and 6 volunteers as controls. The ability of SPECT to detect small differences in the level of uptake can be used to separate glands from background even when uptake is reduced as in the patients with Sjögrens syndrome. In control and probable Sjögrens syndrome groups the uptake ratio of the submandibular gland to parotid gland on salivary SPECT (S/P ratio) was less than 1.0. However, in the definite Sjögrens syndrome group, the ratio was more than 1.0. Moreover, the ratio in all patients with sialectasia, which is characteristic of Sjögrens syndrome, was more than 1.0. Salivary factor analysis of normal parotid glands showed slowly increasing patterns of uptake and normal submandibular glands had rapidly increasing patterns of uptake. However, in the definite Sjögrens syndrome group, the factor analysis patterns were altered, with slowly increasing patterns dominating both in the parotid and submandibular glands. These results suggest that the S/P ratio in salivary SPECT and salivary factor analysis provide additional radiologic criteria in diagnosing Sjögrens syndrome.