title: Preoperative staging of papillary thyroid carcinoma: comparison of ultrasound imaging and CT.
abstract: OBJECTIVE
  The purpose of this study was to compare the diagnostic accuracy of ultrasound imaging with that of CT in the preoperative evaluation of primary tumors and cervical lymph nodes in patients with papillary thyroid carcinoma and to determine whether CT has greater diagnostic value than ultrasound alone in the care of these patients.
  
  
  METHODS
  The study population consisted of 299 consecutively registered patients with pathologically proven papillary thyroid carcinoma. The diagnostic accuracies of ultrasound, CT, and the combination of ultrasound and CT in the evaluation of primary tumors and lymph node metastasis were compared. We performed subgroup analysis to compare the findings on papillary thyroid microcarcinoma (10 mm in maximum diameter or smaller) with the findings on papillary thyroid carcinoma larger than 1 cm in maximum diameter.
  
  
  RESULTS
  Ultrasound was more accurate than CT in prediction of the presence of extrathyroidal tumor extension and of malignant disease in both thyroid lobes (p < 0.05) for overall lesions and for the two subgroups. In prediction of central node (neck level VI) metastasis, CT had greater sensitivity than ultrasound alone (p = 0.04) for overall lesions. Although the combination of ultrasound and CT had greater sensitivity than ultrasound alone in prediction of the presence of central node metastasis in the two subgroups, the sensitivity of the combination of ultrasound and CT did not reach statistical significance for papillary thyroid microcarcinoma. Ultrasound alone and ultrasound with CT had greater sensitivity than CT in prediction of lateral node (levels II-V) metastasis, but there was no significant difference in diagnostic value between ultrasound and the combination of ultrasound and CT for overall lesions or for the two subgroups (p > 0.05).
  
  
  CONCLUSIONS
  High-resolution ultrasound can be accurate in preoperative evaluation for extrathyroidal tumor extension and lateral lymph node metastasis. CT had greater sensitivity than ultrasound alone in the detection of central lymph node metastasis for all lesions. For papillary thyroid microcarcinoma, however, there was no significant difference in the diagnostic accuracy rates of ultrasound, CT, and the combination of ultrasound and CT.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 120-752, Korea.
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Choi
authors.forename: Jinna
authors.initials: J
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Hang Seok
authors.initials: HS
authors.lastname: Chang
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D002291:Carcinoma, Papillary / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007472:Iohexol / Q000031:analogs & derivatives; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide