Parotid tumors: differentiation of benign and malignant tumors with quantitative sonographic analyses.

We asked in this study if the quantitative sonographic analysis could diagnose effectively the benign and malignant tumors of the parotid gland. Sonographic analyses using mean grey values and SDs of echo levels were performed on the 21 benign tumors and 22 malignant tumors of the parotid glands. Both the mean grey level and the SD of the echo levels were significantly and characteristically different among the different parotid tumor groups. Discrimination analysis showed that, compared with single uses, a combined use of these two criteria improved diagnostic accuracy to 81% (carcinoma vs. pleomorphic adenomas), 93% (malignant lymphomas vs. pleomorphic adenomas), 91% (carcinomas vs. malignant lymphomas), 100% (pleomorphic adenomas vs. Warthin's tumors), 100% (carcinomas vs. Warthin's tumors) and 100% (malignant lymphomas vs. Warthin's tumors). These findings suggest that quantitative sonographic analysis is effective in differentiating benign and malignant tumors of the parotid gland.

Combination of helical CT and Doppler sonography in the follow-up of patients with clinical N0 stage neck disease and oral cancer.

BACKGROUND AND PURPOSE: Correctly diagnosing metastatic nodes is important for the follow-up of patients with clinical N0 stage neck disease and oral cancer. A combination of helical CT and Doppler sonography may facilitate the accurate detection of lymph node metastasis in patients with clinical N0 stage neck disease. METHODS: A combination of contrast-enhanced helical CT and Doppler sonography was performed to monitor the necks of 58 patients with initial clinical N0 stage neck disease. Of these patients, 17 underwent surgery; nodal metastasis in the neck was histopathologically confirmed. A node was diagnosed as metastatic if it fulfilled the CT criteria for metastatic nodes (short-axis diameter equal to or greater than the cutoff points for each level of the neck or central nodal necrosis) and if, additionally, it did not exhibit sonographic features for nonmetastatic nodes (normal hilar echogenicity and hilar flows). The presence of metastasis was confirmed histopathologically. RESULTS: During the follow-up periods, metastatic nodes were histologically confirmed in 17 (29%) patients. Of 30 metastatic nodes from the 17 patients with metastatic nodes, 22 (73%) appeared within the first year and 28 (93%) within the first 2 years; 20 developed from nonmetastatic nodes, and 10 were newly detectable. The combined criteria were effective in revealing 26 (87%) nodes, yielding 87% sensitivity, 100% specificity, and 100% positive and 99% negative predictive values. The independent use of one of these techniques alone resulted in low (67%) or moderate (87%) positive predictive values for sonography and CT, respectively. Seven hundred forty-one (97%) of 761 nodes that were nonmetastatic at initial examination remained nonmetastatic (737 nodes) or had disappeared (four nodes). As a result, a combination of CT and sonography was effective in revealing all 17 cases of metastatic nodes. CONCLUSION: A combination of contrast-enhanced helical CT and Doppler sonography is useful for the follow-up study of clinical N0 stage neck disease.

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.