河合 岳郎, 小林 薫, 廣川 満良, 福島 光浩, 藪田 智範, 太田 寿, 森田 新二, 西原 永潤, 網野 信行, 宮内 昭

Takeo KAWAI, Kaoru KOBAYASHI, Mitsuyoshi HIROKAWA, Mitsuhiro FUKUSHIMA, Tomonori YABUTA, Hisashi OTA, Shinji MORITA, Eijyun NISHIHARA, Nobuyuki AMINO, Akira MIYAUCHI

隈病院外科

Department of surgery, Kuma Hospital

キーワード : thyroid, ultrasound, diagnosis, classification, criteria

目的：甲状腺結節（腫瘤）の診療において超音波検査は最初に行う重要な検査である．結節の診断において良性・悪性の2段階評価の診断基準とそれ以上の多段階評価の診断基準がある．今回，我々は甲状腺結節に対する超音波検査による5段階評価による診断基準を細胞診，病理学的診断と対比して，その妥当性と有用性を検討した．対象と方法：5段階評価の超音波クラスは結節の形状，内部充実性か否か，内部エコーの性状，微細多発高エコーの有無，甲状腺外への浸潤の有無などを観察して5段階に評価した．2008年1年間の初診患者の甲状腺結節に対してこの診断基準を用いて診断し，それぞれの結節の超音波クラスを評価した．結節の超音波クラスの分布，超音波クラスと細胞診の相関，超音波クラスと病理学的診断との相関，超音波クラスごとの悪性の頻度，診断法の精度を検討した．結果と考察：分布では超音波クラス2の結節が最多を示した．超音波クラスと細胞診と病理学的診断の相関においては，超音波クラスが上がるにしたがって悪性の比率が増加した．病理学的診断を標準にして，超音波クラス4，5を悪性と規定すると，感度77.1％，特異度94.7％を示した．甲状腺結節に対する5段階評価による超音波診断法は細胞診，病理学的診断における良性・悪性の診断と相関した．結論：この超音波診断法は甲状腺結節の診療において充分に妥当性が存在し，臨床診断に有用である．

Purpose: Ultrasonic diagnosis is the first important step in the practical management of thyroid nodules. We have our own ultrasound classification system for the diagnosis of thyroid nodules, which consists of five ultrasound classes (USC) based on characteristics of thyroid nodules such as regular or irregular shape, solid or cystic content, presence or absence of microcalcifications, extraglandal invasion, and so on. USC-1 and 2 is defined as benign, USC-3 as border, and USC-4 and 5 as malignant. The purpose of the present study is to verify the accuracy of the ultrasound classification system. Subjects and Methods: Ultrasonographic examination was performed for all primary patients with thyroid nodules during the course of one year (2008) at Kuma Hospital. A total of 13,293 thyroid nodules in 8,469 consecutive patients were included in this study. All the thyroid nodules were divided into five classes according to the ultrasound classification criteria. The cytological and pathological diagnoses of nodules were made by a pathologist independently of ultrasonic diagnosis. The relationship between the ultrasonic diagnosis and the cytological and pathological diagnoses was statistically investigated. Results and Discussion: Ultrasonic diagnosis of thyroid nodules based on our own ultrasound classification system was significantly correlated with the cytological and pathological diagnoses. The sensitivity and specificity of the ultrasound system were 77.1% and 94.7%, respectively, when USC 4 and 5 were regarded as malignant and USC 1, 2, and 3 as benign. The ultrasonic diagnosis based on the system correctly reflects the cytological and pathological diagnoses of thyroid nodules. Conclusion: This ultrasound classification system was considered to be useful for the practical management of thyroid nodules as part of an objective assessment.