Predicting the extrathyroid extension of papillary thyroid Microcarcinoma by US

ZHOU JinJin; WANG Chunguang; SUN Wenkui; WANG Yuling; LI Xiaomi; ZHANG Yanyan; SONG Qun

Abstract：Objective To evaluate the diagnostic value of high-resolution ultrasound ( US) for predicting the extrathyroid ex-tension of papillary thyroid microcarcinoma (PTMC).Methods One hundred and eighty patients (216 nodules) of PTMC con-firmd by surgical operation and pathologic examination were studied .According to the ultrasound findings , the PTMC nodules con-tact with the adjacent thyroid capsule were divided into four-grade, grade A:the nodules contacting with the adjacent thyroid cap-sule, grade B:the contact area ≥20%, grade C:the contact area ≥40%, grade D:adjacent capsule was disrupted .The snsi-tivity, specificity, predictive value and the area under the ROC curve were calculated respectively .Results In all the 216 nod-ules, 87(40.3%) nodules were diagnosed with extrathyroid extension by surgical operation and pathogic examination .Of the 111 nodules that were in contact with the adjacent capsule on US , 70(63.1%) were extrathyroid extension after pathology .Of the 105 cancers that had no contact with the adjacent capsule on US , 88(83.8%) were without extrathyroid extension after pathology . The difference was statistically significant ( P <0.001).More than 20%contact with the adjacent capsule (Az=0.656) was the most accurate index for predicting extrathyroidal extension compared with Contacting with the adjacent capsule (Az=0.640), more than 40%contact with the adjacent capsule (Az=0.470) and disruption at the adjacent capsule (Az=0.479).Conclu-sion The presence and degree of contact between a PTMC nodule and the adjacent capsule as found by US examination can pro -vide an important information to predict the extrathyroid extension before surgical operation .The present of more than 20%contact can be a useful mark .