片桐 誠, 吉川 啓一, 山根 康彦, 原田 種一

Makoto KATAGIRI, Keiichi YOSHIKAWA, Yasuhiko YAMANE, Tanekazu HARADA

川崎医科大学内分泌・甲状腺外科

Division of Endocrine Surgery, Kawasaki Medical School

キーワード : Ultrasonic cancer diagnosis, Subjective estimation, Fuzzy inference

Ultrasonic cancer diagnosis of the thyroid is usually based upon a subjective estimation of the findings by an examiner. Such subjective estimations, however, differ from person to person, and this difference may lead to differences in the diagnostic results, even if the same diagnostic criteria are used. In order to evaluate differences in subjectivity in ultrasonic diagnosis, ultrasonic images from 50 cases of histologically confirmed thyroid nodules, consisting of 22 cases of papillary carcinoma and 28 cases of benign nodules, were studied by nine examiners; five surgeons, one internist and three medical technicians, with varying degrees of experience. The degree of variation in the findings of each item was measured using a fuzzy scale and was evaluated by a newly devised diagnostic system using fuzzy inference. The distribution of the degree of variation in the findings differed among the examiners for the items of shape, margin, boundary and internal echoes, but was relatively similar for the items of hyperechoic spots, cysts and echo level. The sensitivity of cancer diagnosis made with our diagnostic system using the subjective estimations of the examiners was 84.9%, while that of the diagnoses without the system was 71.7% (p<0.05). There was no statistically significant difference in the mean diagnostic accuracy due to the results of the specificity. We believe that this diagnostic system will be useful for any physician, but especially for novice physicians.