title: The influence of body mass index on the diagnostic performance of pre-operative staging ultrasound in papillary thyroid carcinoma.
abstract: OBJECTIVE
  The aim of this study was to investigate the diagnostic performance of pre-operative staging ultrasound (US) according to body mass index (BMI) in patients with papillary thyroid carcinoma (PTC) PATIENTS AND METHODS: This retrospective study included 625 patients with PTC who underwent pre-operative staging US and surgical excision at a referral centre between December 2012 and April 2013. Four experienced radiologists prospectively evaluated the extent of primary tumours, multifocality and the presence of lymph node metastasis. Patients were grouped according to BMI (normal <25; overweight 25 ≤ and <30; obese ≥30, or nonobese <30; obese ≥30 kg/m(2) ). Diagnostic performances of pre-operative staging US (sensitivity, specificity, positive predictive value, negative predictive value and accuracy) were compared according to BMI based on pathologic findings of surgical specimens.
  
  
  RESULTS
  Pre-operative staging US in the obese group (BMI ≥30 kg/m(2) ) showed a significantly lower negative predictive value and accuracy in the detection of central lymph node metastasis (P = 0·010 and P = 0·025, respectively) than in the nonobese (BMI <30 kg/m(2) ) group. However, there were no significant differences in the diagnostic performance of pre-operative staging US for extrathyroidal extension, bilateral multifocality and lateral lymph node metastasis in analyses using the two (nonobese vs obese) and three BMI (normal vs overweight vs obese) groups, respectively.
  
  
  CONCLUSIONS
  Obesity (BMI ≥30 kg/m(2) ) may affect the pre-operative US staging of central lymph node metastasis in patients with PTC.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.|Department of Radiology, Samsung Medical Center, Seoul, Korea.
authors.forename: Ji Soo
authors.initials: JS
authors.lastname: Choi
authors.affiliation: Biostastistics Collaboration Unit, Medical Research Center, Severance Hospital, College of Medicine, Yonsei University, Seoul, Korea.
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Moon
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
mesh_terms: D000328:Adult; D015992:Body Mass Index; D002277:Carcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000601:surgery; D002291:Carcinoma, Papillary; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000601:surgery; D014463:Ultrasonography