title: Examining the Role of Preoperative Positron Emission Tomography/Computerized Tomography in Combination with Ultrasonography in Discriminating Benign from Malignant Cytologically Indeterminate Thyroid Nodules.
abstract: Cytologically defined indeterminate thyroid nodules are a diagnostic challenge. Surgical lobectomy remains the gold standard for definitive diagnosis. However, 70-85% of nodules are ultimately benign. The primary objective of this study was to evaluate the negative predictive value (NPV) of F18-fluorodeoxyglucose (FDG) positron emission computed tomography (PET/CT) in excluding cancer among cytologically indeterminate thyroid nodules within the authors' institution using surgical pathology as the gold-standard reference. In addition, a systematic review was performed of published prospective studies on the NPV of PET/CT in evaluating indeterminate thyroid nodules.
  
  
  
  A retrospective review was performed of all patients aged ≥18 years seen at the Mayo Clinic between January 1, 2000, and December 31, 2014, with cytologically defined indeterminate thyroid nodules (suspicious for Hürthle cell neoplasm or follicular neoplasm; N = 858), who had a PET/CT within one year of fine-needle aspiration (n = 80) and underwent definitive diagnostic lobectomy (n = 51). Nodules were considered PET negative if they had a standardized uptake value (SUV) <5. Additionally, a systematic review was performed of published prospective studies on the NPV of PET/CT across multiple sites.
  
  
  
  Fifty-one patients met the eligibility criteria. The retrospective review combined with a systematic review of eight prospective studies suggests that indeterminate nodules with a negative PET (SUV <5) have a low risk of malignancy (NPV 94%). The cancer prevalence in the institution is 14% and 27% in the combined prospective studies.
  
  
  
  PET/CT represents a preoperative, non-invasive tool that when combined with sonographic features can identify indeterminate nodules at low risk for malignancy.
authors.affiliation: 1 Division of Endocrinology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Michele M
authors.initials: MM
authors.lastname: Merten
authors.affiliation: 1 Division of Endocrinology, Mayo Clinic , Rochester, Minnesota.
authors.forename: M Regina
authors.initials: MR
authors.lastname: Castro
authors.affiliation: 2 Division of Laboratory Medicine/Pathology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.affiliation: 3 Department of Radiology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Durski
authors.affiliation: 1 Division of Endocrinology, Mayo Clinic , Rochester, Minnesota.|4 Division of Medical Oncology, Mayo Clinic , Rochester, Minnesota.
authors.forename: Mabel
authors.initials: M
authors.lastname: Ryder
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D057234:Preoperative Period; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D016606:Thyroid Nodule / Q000000981:diagnostic imaging*; D014463:Ultrasonography
keywords: Hürthle cell neoplasm; PET/CT; follicular neoplasm; indeterminate; thyroid nodules