title: Single photon emission computed tomography (SPECT)/computed tomography using Iodine-123 in patients with differentiated thyroid cancer: additional value over whole body planar imaging and SPECT.
abstract: OBJECTIVE
  The aim of the study was to assess the diagnostic performance of co-registered single photon emission computed tomography (SPECT)/computed tomography (CT) compared to Iodine-123 whole body gamma camera (WBGC) imaging and to SPECT alone in patients with differentiated thyroid cancer.
  
  
  METHODS
  WBGC and SPECT/CT (n=85) imaging of the neck and thorax was performed in 79 consecutive patients. Three experienced observers reviewed: i) WBGC images followed by ii) SPECT alone, and iii) co-registered SPECT/CT. Foci of increased radioiodine uptake were classified on a five-point scale. Biopsy, other imaging modalities, and clinical follow-up served as the reference standard.
  
  
  RESULTS
  Twenty-two patients had local recurrence or metastatic thyroid cancer (11 were radioiodine negative), 9 had remnant thyroid tissue, and 54 had no evidence of disease. When classifying equivocal, probably, and definitely malignant findings as positive for malignancy, the sensitivity, specificity, positive predictive value, and negative predictive value were as follows: 41, 68, 31, and 77% for WBGC imaging; 45, 89, 59, and 82% for WBGC plus SPECT imaging; and 50, 100, 100, and 85% for WBGC plus SPECT/CT imaging respectively. The specificity was improved by the addition of SPECT (P=0.0002) and SPECT/CT (P<0.0001) than to WBGC imaging. SPECT/CT was also more specific than WBGC plus SPECT imaging (P=0.016). In a study-based analysis, SPECT/CT provided additional diagnostic information in 42% (36/85) of cases. SPECT/CT provided further characterization in 70% (63/90) of foci and improved the diagnostic confidence of all three observers.
  
  
  CONCLUSIONS
  The addition of SPECT/CT significantly improved the diagnostic information over Iodine-123 WBGC imaging and WBGC plus SPECT imaging alone.
authors.affiliation: Department of Nuclear Medicine, Barts and The London School of Medicine and NHS Trust, Queen Mary, University of London, West Smithfield (QE II), London, UK.
authors.forename: Tara
authors.initials: T
authors.lastname: Barwick
authors.forename: Iain
authors.initials: I
authors.lastname: Murray
authors.forename: Hakim
authors.initials: H
authors.lastname: Megadmi
authors.forename: William M
authors.initials: WM
authors.lastname: Drake
authors.forename: P Nick
authors.initials: PN
authors.lastname: Plowman
authors.forename: Scott A
authors.initials: SA
authors.lastname: Akker
authors.forename: Shern L
authors.initials: SL
authors.lastname: Chew
authors.forename: Ashley B
authors.initials: AB
authors.lastname: Grossman
authors.forename: Norbert
authors.initials: N
authors.lastname: Avril
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging*; D000231:Adenocarcinoma, Papillary / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D015899:Tomography, Emission-Computed, Single-Photon; D051598:Whole Body Imaging
chemical_list: D007457:Iodine Radioisotopes