In order to establish simple and reliable diagnostic criteria for differential diagnosis of thyroid tumors, real-time data of 107 nodules, which consisted of 40 malignant nodules and 67 benign nodules, were analyzed by multivariant analysis. The following scoring system was established. 1 point for a regular shape, and 0 for an irregular shape;2 points when a cyst is present, and 0 for no cyst; -4 points for calcification, and 0 for no calcification, when the total score is 1 point or more, the lesion is judged as being benign and when 0 or less, it is judged as being malignant. The criteria were tested with 33 malignant nodules and 48 benign nodules. Good results(sensitivity of 81.8%, specificity of 77.1 %)were obtained with these external amples and the criteria were considered to be highly reliable.
