Preoperative assessment of extrathyroidal extension of papillary thyroid carcinoma: comparison of 2- and 3-dimensional sonography.
OBJECTIVE
The purpose of this study was to evaluate the diagnostic performance and interobserver agreement of 2-dimensional (2D) and 3-dimensional (3D) sonography for evaluating extrathyroidal extension of papillary thyroid carcinoma.


METHODS
A total of 79 papillary thyroid carcinomas in 79 patients who underwent both 2D and 3D sonography for preoperative staging of papillary thyroid carcinoma were included. When the lesion was abutting on the thyroid capsule on 2D sonography, 3D sonography was performed. Three radiologists reviewed 3 data sets: 2D sonography, 3D sonography, and a combined set of both for tumor staging. The diagnostic performance, including sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, for extrathyroidal extension was analyzed. Interobserver agreement of the 3 radiologists was assessed with κ values.


RESULTS
The overall accuracy rates for 2D sonography, 3D sonography, and the combined set in predicting extrathyroidal extension were 60.8%, 66.2%, and 67.9%, respectively. The accuracy of the combined set was significantly higher than that of 2D sonography (P = .016). The interobserver agreement of the 3 reviewers was fair (κ = 0.33) for 2D sonography and moderate for 3D sonography (κ = 0.46) and the combined set (κ = 0.49).


CONCLUSIONS
Adding 3D sonography to 2D sonography could improve the accuracy and interobserver agreement for predicting extrathyroidal extension of papillary thyroid carcinoma.
Department of Radiology, Gangnam Severance Hospital, 211 Eonjuro, Dogok-Dong, Gangnam-Gu, Seoul 135-720, Korea. chrismd@hanmail.net.
Hye Mi
HM
Gweon
Eun Ju
EJ
Son
Ji Hyun
JH
Youk
Jeong-Ah
JA
Kim
Cheong Soo
CS
Park
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D015588:Observer Variation; D011300:Preoperative Care / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D014463:Ultrasonography / Q000379:methods*
2-dimensional sonography; 3-dimensional sonography; extrathyroidal extension; papillary thyroid carcinoma; tumor staging; ultrasound