Prospective evaluation of 68Ga-DOTANOC PET-CT in differentiated thyroid cancer patients with raised thyroglobulin and negative 131I-whole body scan: comparison with 18F-FDG PET-CT
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The purpose of the study was to evaluate the role of 68Ga-DOTANOC PET-CT in differentiated thyroid cancer (DTC) patients with negative 131I-whole body scan (WBS) along with serially increasing serum thyroglobulin (Tg), and compare the same with 18F-FDG PET-CT.
Sixty two DTC patients with serially rising Tg levels and negative 131I-WBS were prospectively enrolled. All patients underwent 68Ga-DOTANOC PET-CT and 18F-FDG PET-CT within an interval of two weeks. PET-CT analysis was done on a per-patient basis, location wise and lesion wise. All PET-CT lesions were divided into four categories-local, nodal, pulmonary and skeletal. Histopathology and/or serial serum Tg level, clinical and imaging follow up (minimum-1 year) were used as a reference standard.
Ga-DOTANOC PET-CT demonstrated disease in 40/62 (65 %) patients and 18F-FDG PET-CT in 45/62 (72 %) patients, with no significant difference on McNemar analysis (p = 0.226). Per-patient sensitivity and specificity of 68Ga-DOTANOC PET-CT was 78.4 %, 100 %, and for 18F-FDG PET-CT was 86.3 %, 90.9 %, respectively. Out of 186 lesions detected by both PET-CTs, 121/186 (65 %) lesions were seen on 68Ga-DOTANOC PET-CT and 168/186 (90.3 %) lesions on 18F-FDG PET-CT (p < 0.0001). There were 103/186 (55 %) lesions concordant on both. Excellent agreement was noted between 68Ga-DOTANOC PET-CT and 18F-FDG PET-CT for detection of local disease (ĸ = 0.92), while moderate agreement was noted for nodal and pulmonary disease (ĸ = 0.67). 68Ga-DOTANOC PET-CT changed management in 21/62 (34 %) patients and 18F-FDG PET-CT in 17/62 (27 %) patients.
Ga-DOTANOC PET-CT is inferior to 18F-FDG PET-CT on lesion based but not on patient based analysis for detection of recurrent/residual disease in DTC patients with negative WBS scan and elevated serum Tg levels. It can also help in selection of potential candidates for peptide receptor radionuclide therapy.
KeywordsDedifferentiated thyroid cancer PET-CT 68Ga-DOTANOC 18F-FDG
Conflict of interest
The authors declare that there is no conflict of interest.
No funding was received from any organization for this study.
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