Localization and identification of parapharyngeal metastases from differentiated thyroid carcinoma by 131I-SPECT/CT

Head Neck. 2011 Feb;33(2):171-7. doi: 10.1002/hed.21416.


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.

Conclusion: 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.

MeSH terms

  • Adult
  • Aged, 80 and over
  • Cell Differentiation*
  • China / epidemiology
  • Early Detection of Cancer
  • Female
  • Humans
  • Incidence
  • Iodine Radioisotopes*
  • Lymphatic Metastasis
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Pharyngeal Neoplasms / diagnosis*
  • Pharyngeal Neoplasms / epidemiology
  • Pharyngeal Neoplasms / secondary
  • Predictive Value of Tests
  • Prospective Studies
  • Sensitivity and Specificity
  • Thyroid Neoplasms / epidemiology
  • Thyroid Neoplasms / pathology*
  • Thyroidectomy
  • Tomography, Emission-Computed, Single-Photon* / methods
  • Tomography, X-Ray Computed*


  • Iodine Radioisotopes