title: Localization and identification of parapharyngeal metastases from differentiated thyroid carcinoma by 131I-SPECT/CT.
abstract: BACKGROUND
  Parapharyngeal metastasis is a rare event in differentiated thyroid carcinoma (DTC). The (131) I-single photon emission CT (SPECT)/CT allows better localization and definition for metastases in DTC. The aim of this study was to assess the value of (131) I-SPECT/CT for the diagnosis of parapharyngeal metastasis in patients with DTC.
  
  
  METHODS
  Consecutive patients with DTC (n = 561) treated with (131) I for the ablation of remnant or treatment of metastases were enrolled. A (131) I-SPECT/CT was performed when there were abnormal findings indicative of parapharyngeal metastasis on (131) I-whole-body scan (WBS).
  
  
  RESULTS
  A total of 15 lesions were found to be parapharyngeal metastasis in 14 of 561 patients with DTC after the use of (131) I-SPECT/CT. The incidence rate of parapharyngeal metastasis was about 2.5% in DTC. Of the 15 lesions, only 5 lesions were CT-positive. The remaining 10 lesions were either ignored or indeterminate by the CT alone.
  
  
  CONCLUSIONS
  The (131) I-SPECT/CT can identify parapharyngeal metastasis at an early stage. Parapharyngeal metastasis in DTC is relatively frequent after the use of (131) I-SPECT/CT.
authors.affiliation: Department of Nuclear Medicine, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, 600 Yishan Road, Shanghai 200233, China.
authors.forename: Zhong-Ling
authors.initials: ZL
authors.lastname: Qiu
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Xu
authors.forename: Hong-Jun
authors.initials: HJ
authors.lastname: Song
authors.forename: Quan-Yong
authors.initials: QY
authors.lastname: Luo
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D002454:Cell Differentiation; D002681:China / Q000453:epidemiology; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010610:Pharyngeal Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000556:secondary; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000453:epidemiology / Q000473:pathology*; D013965:Thyroidectomy; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014057:Tomography, X-Ray Computed
chemical_list: D007457:Iodine Radioisotopes