title: Double-phase (131)I whole body scan and (131)I SPECT-CT images in patients with differentiated thyroid cancer: their effectiveness for accurate identification.
abstract: OBJECTIVE
  This study aims to determine whether a (131)I double-phase whole body scan (WBS) and SPECT-CT images have added value over a single-phase WBS image in identifying benign and malignant lesions in patients with well-differentiated thyroid cancer (DTC) at their first radioactive iodine (RAI) treatment.
  
  
  METHODS
  This study included 42 DTC patients who underwent their first radioablation. Post-therapeutic WBS images were acquired after 3 days (early phase) and 7 days (delayed phase). Following early-phase WBS, SPECT-CT images were obtained. The images were reviewed independently of the clinical data by 2 board-certified observers with a 6-point scoring system (benign to malignant -3 to +3).
  
  
  RESULTS
  The double-phase WBS and SPECT-CT images showed 115 radioiodine-avid localizations (81 benign and 34 malignant accumulations). Confidence levels of benign accumulations were significantly higher with SPECT-CT (average score -2.40 ± 1.06) compared to those of the early-phase WBS (average score -1.39 ± 1.88) (p < 0.0001) and delayed-phase WBS images (average score -1.49 ± 1.19) (p < 0.0001). When the analysis was restricted to accumulations with a low confidence score in the early-phase WBS image, the confidence level of the delayed-phase WBS was higher compared to that of the early-phase WBS images (p = 0.0012). The confidence levels of malignant accumulations were significantly higher with SPECT-CT images (average score 2.37 ± 0.96) compared to the early-phase WBS (average score 1.44 ± 1.21) (p < 0.0001) and the delayed-phase WBS images (average score 1.50 ± 1.13) (p < 0.0001).
  
  
  CONCLUSIONS
  Post-therapeutic SPECT-CT image was superior to the early-phase WBS image in enhancing the confidence level and accurately localizing the lesions. The delayed-phase WBS image contributed to the accurate diagnosis of benign lesions with a low confidence level in the early-phase WBS image.
authors: Department of Nuclear Medicine, Kanazawa University Hospital, 13-1 Takara-machi, Kanazawa, Ishikawa 920-8641, Japan. wakabayashi@nmd.m.kanazawa-u.ac.jp
authors: Hiroshi
authors: H
authors: Wakabayashi
authors: Kenichi
authors: K
authors: Nakajima
authors: Makoto
authors: M
authors: Fukuoka
authors: Anri
authors: A
authors: Inaki
authors: Ayane
authors: A
authors: Nakamura
authors: Daiki
authors: D
authors: Kayano
authors: Seigo
authors: S
authors: Kinuya
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D015588:Observer Variation; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging / Q000379:methods*
chemical_list: D007457:Iodine Radioisotopes