1Division of Endocrine Surgery, Kawasaki Medical School, 2Department of Mathematics, Kawasaki Medical School, 3Department of Clinical Laboratories, Kawasaki Medical School
Fuzzy inference, Ultrasonic diagnosis, Incorrect diagnosis, Thyroid cancer
Using a fuzzy inference with a newly developed ultrasonic diagnostic system for thyroid carcinoma, the following results were obtained for surgically treated cases of thyroid nodules: a sensitivity rate of 96.8%, a specificity rate of 72.9%, and an accuracy rate of 81.1%. Only one in 31 cases of papillary carcinoma, was not clearly diagnosed as carcinoma because there were not enough ultrasonic characteristics of malignant neoplasna. Among the cases of benign nodules, 6 were not clearly diagnosed as benign nodules and 10 were incorrectly diagnosed as carcinoma. These incorrect diagnoses seemed to be due to histological degenerative changes in the nodules, such as hyalinization, fibrosis or calcification, which occur frequently in colloid nodules. Nodules in chronic thyroiditis tended to be unclearly delineated, thus leading to an incorrect diagnosis.