title: Ultrasound assessment of degrees of extrathyroidal extension in papillary thyroid microcarcinoma.
abstract: OBJECTIVE
  This study aimed to assess the diagnostic accuracy of ultrasound (US)-based T staging of papillary thyroid microcarcinoma (PTMC).
  
  
  METHODS
  From January to June 2013, a total of 185 patients underwent preoperative thyroid US for the treatment of thyroid malignancy. A single radiologist immediately determined sonographic T staging for PTMC during real-time US examination. Based on histopathologic results, the diagnostic accuracy of sonographic T staging for PTMC and the difference in the frequency of level VI node metastasis according to the T stage of PTMC were evaluated.
  
  
  RESULTS
  Of 105 PTMC cases, the preoperative sonographic diagnoses included intraglandular location (n = 35), subcapsular location (n = 30), mild capsule abutment (n = 7), moderate capsule abutment (n = 19), and perithyroidal invasion without adjacent strap muscle invasion (n = 14). When the sonographic T stages were compared with histopathologic results, all the sonographic categories showed high specificity and low sensitivity. The intraglandular and subcapsular location cases in preoperative US diagnosis showed a low rate of extrathyroidal tumor invasion (6.2%, 4/65). The extrathyroidal tumor invasion cases in preoperative US diagnosis only included 26 extrathyroidal fat invasion cases, and 12 (46.2%, 12/26) true positives. There was a significant correlation between multifocality and histopathologic T stage, but no significant relationship between level VI node metastasis and histopathologic T stage was found.
  
  
  CONCLUSIONS
  The sonographic T staging categorization described here may be helpful for the preoperative evaluation of PTMC patients.
authors.affiliation: Department of Radiology, Inje University College of Medicine, Busan, South Korea.
authors.forename: Sun Jeong
authors.initials: SJ
authors.lastname: Moon
authors.affiliation: Department of Radiology, Inje University College of Medicine, Busan, South Korea.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Radiology, Inje University College of Medicine, Busan, South Korea.
authors.forename: Seong Jin
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of General Surgery, Inje University College of Medicine, Busan, South Korea.
authors.forename: Tae Kwun
authors.initials: TK
authors.lastname: Ha
authors.affiliation: Department of General Surgery, Inje University College of Medicine, Busan, South Korea.
authors.forename: Ha Kyoung
authors.initials: HK
authors.lastname: Park
authors.affiliation: Department of Pathology, Busan Paik Hospital, Inje University College of Medicine, Busan, South Korea.
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Jung