Role of I-131WBS versus FDG PET/CT in the Diagnosis and Assessment of Therapy Outcome in Recurrent Locoregional Thyroid Carcinoma
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- Category: Vol. 85, March 2017
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Role of I-131WBS versus FDG PET/CT in the Diagnosis and Assessment of Therapy Outcome in Recurrent Locoregional Thyroid Carcinoma, MANAR H. ABD EL-SATTAR, OMNIA M. TALAAT and SHERIF B. OMAR
Abstract
Background: Thyroid carcinoma is the most prevalent endocrine malignancy and accounts for 1% of all human cancers. Approximately 90% of thyroid malignancy is well Differentiated Thyroid Carcinoma (DTC). However, 30% of patients may develop loco-regional recurrence after total thyroidectomy [2]. These loco-regional DTC recurrences have a wide spectrum of behaviors, presentation and prognosis which are reflected on selection of diagnostic imaging and therapy.
Aim of Work: To assess the clinic-pathological, diagnostic and therapy outcome differences between I-131 avid and FDG avid loco-regional recurrence in Differentiated Thyroid Car-cinoma (DTC) patients.
Patients and Methods: 125 patients with pathologically proved loco-regional recurrent DTC after initial remission with complete radio-surgical thyroid ablation were included. Clinico-pathological data, serum thyroglobulin levels, diag-nostic radiology, I-131WBS and FDG PET/CT scanning, therapeutic approaches and follow up data were collected.
Results: 125 patients with loco-regional recurrence were divided into: (I) I-131 avid group: 60 patients with 112 confirmed recurrent malignant lesions (8 thyroid bed, 104 nodal). (II) FDG avid group: 65 patients with 206 confirmed recurrent malignant lesions (14 thyroid bed, 192 nodal). Out of clinic-pathological data, significantly higher pathological grading was demonstrated in FDG avid group (49 patients) compared to I-131 avid group (18 patients) p<0.05. In I-131 avid group the sensitivity, specificity and accuracy for I-131 WBS were 77%, 100% and 81% and for neck US were 87.5%, 30% and 77% respectively. In FDG avid group the sensitivity, specificity and accuracy for FDG PET/CT were 95.1%, 76.1% and 91.5%, for neck US were 78%, 37.5% and 72.2% and for CT were 83%, 47% and 79% respectively. The added value of post-operative RAI-131 therapy results in better outcome in I-131 avid group.
Conclusion: FDG avid loco-regional recurrence seemed to be linked to higher pathological grading with less favorable