title: 18F-FDG-PET SUV AS A PROGNOSTIC MARKER OF INCREASING SIZE IN THYROID CANCER TUMORS.
abstract: OBJECTIVE
  Positron emission tomography/computed tomography (PET/CT) scans with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (18F-FDG) are used in high-risk thyroid cancer patients to identify metastasis. The prognostic significance of increases in standardized uptake values (SUVs) has not been clearly defined. This pilot study investigated the correlation between SUV increases and subsequent changes in individual lesion size.
  
  
  METHODS
  A retrospective chart review of patients with histologically confirmed thyroid cancer who were monitored with serial18F-FDG-PET/CT scans from 2008 to 2013 was performed. Forty-seven patients were selected for analysis. A mixed-effects statistical model was used after data normalization.
  
  
  RESULTS
  For a 10% increase in SUV, a 6% increase in tumor area was observed (P<.0001). Analysis on cube root-transformed data from serial scans was significant in 4 of 5 groups: scans 1 to 2 (P = .0001), scans 2 to 3 (P = .0005), scans 3 to 4 (P = .008), scans 4 to 5 (P = .66), and overall (P<.0001). After exclusion of outliers, for a 10% increase in SUV, the expected percentage increases in area on subsequent scans were found to be 3.4% (P = .0006), 2.6% (P = .005), 4% (P = .074), and 4.1% (P = .27) for the second, third, fourth, and fifth scans, respectively. The association was similarly significant in cases with a ≥25% increase in SUV. Secondary analysis showed a significant association of SUV with thyroglobulin (Tg) level (P = .035) but not with thyroid-stimulating hormone (TSH) level (P = .85).
  
  
  CONCLUSIONS
  A significant positive correlation was noted between the increase in lesional SUV and subsequent increase in lesion area. An increase in lesional SUV in subsequent scans may portend tumor growth and could prompt consideration for earlier or more aggressive intervention.
  
  
  BACKGROUND
  DTC = differentiated thyroid cancer EORTC = European Organization for Research and Treatment of Cancer18F-FDG = 2-[fluorine-18] fluoro-2-deoxy-D-glucose FNA = fine-needle aspiration MTC = medullary thyroid cancer PET/CT = positron emission tomography/computed tomography PVE = partial volume effect RAI = radioactive iodine SUV = standardized uptake value Tg = thyroglobulin TSH = thyroid-stimulating hormone.
authors.forename: Ishita
authors.initials: I
authors.lastname: Singh
authors.forename: Athanasios
authors.initials: A
authors.lastname: Bikas
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Garcia
authors.forename: Sameer
authors.initials: S
authors.lastname: Desale
authors.forename: Leonard
authors.initials: L
authors.lastname: Wartofsky
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Burman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D010865:Pilot Projects; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D051598:Whole Body Imaging
chemical_list: D014408:Biomarkers, Tumor; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin