Value of 18F-FDG-PET/CT and 131I-WBS in the detection of differentiated thyroid cancer progression

  • Purpose: to compare the diagnostic efficacy of 18F-FDG-PET/CT and 131I-whole body scintigraphy (WBS) in the detecting of differentiated thyroid cancer (DTC) progression.

    Material and Methods: the results of 120 18F-FDG-PET/CT and 120 131I-WBS studies in 82 DTC patients. 18F-FDG-PET/CT performed on a positron emission tomograph combined with a 16-slice computer tomograph. Post-therapeutic 131I-WBS (after 33-135 mCi) performed during each course of radioiodine therapy on the single-detector gamma camera.

    Results. 18F-FDG-PET/CT has a high sensitivity in detecting tumor progression(89%) and superior to 131I-WBS,p  The predictive value of the negative result of 18FDG-PET/CT in 62% significantly exceeds that of 131I-WBS in 34%. Therefore, in the negative 18F-FDG-PET/CT, progression can be more confidently rejected than in the negative 131I-WBS result. The predictive value of the positive result of 18F-FDG-PET/CT  and 131I-WBS was similar – 92% and 95%,respectively. Therefore, according to the positive results of 18F-FDG-PET/CT and 131I-WBS, it is possible to assert with the same certainty the presence of progression. The following types of tumor progression were identified: in 34%-isolated locoregional recurrence, in 36%-isolated distant metastasis, in 30,5% -a combination of locoregional recurrence with distant metastases. The sensitivity of 18F-FDG-PET/CT in detecting all types of progression was quite high without statistically significant difference,(p>0.05. For 131I-WBS isolated distant metastasis is best reveals then other types of recurrence(p <0.05). 18F-FDG-PET/CT superior to 131I-WBS in the diagnosis of all three types of progression,(p <0.05)

    Conclusion.The inclusion of 18F-FDG-PET/CT in the diagnostic algorithm of DTC patients during the monitoring of combined treatment allows to detect or exclude the presence of metastatic foci in 87% and to change the tactics of treatment and follow-up in 49% of cases. 


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