片桐 誠¹, 有田 清三郎², 福林 雅裕³, 山根 康彦¹, 原田 種一¹

Makoto KATAGIRI¹, Seizaburou ARITA², Masahiro FUKUBAYASHI³, Yasuhiko YAMANE¹, Tanekazu HARADA¹

¹川崎医科大学内分泌・甲状腺外科, ²川崎医科大学数学教室, ³川崎医科大学中央検査部

¹Division of Endocrine Surgery, Kawasaki Medical School, ²Department of Mathematics, Kawasaki Medical School, ³Department of Clinical Laboratories, Kawasaki Medical School

キーワード : 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.