Role of F-18- FDG PET/CT in detection of hematogenous metastases of advanced differentiated thyroid carcinoma: a systematic review and meta-analysis

The aim of this study was to collect the evidence on the performance of 2- deoxy-2-[18F] fluoro- D-glucose (F-18-FDG) Positron Emission Tomography/Computed Tomography (PET/CT) in terms of detection rate (DR) and diagnostic accuracy in identifying hematogenous metastases in patients with differentiated thyroid cancer and compare its performance with that of other imaging techniques. A comprehensive PubMed/MEDLINE database research was carried out to retrieve studies documenting the performance of F-18-FDG PET/CT in depicting hematogenous metastases in patients with differentiated thyroid cancer. Statistical analysis was performed on a per-patient and per-lesion basis. The literature search yielded 15 articles to be included in the systematic review. F-18-FDG PET/CT showed a pooled DR of 85.08% on a per-patient analysis and 89.70% on a per-lesion analysis. For bone lesions, a high DR (81.78%) was found for F-18-FDG PET/CT. For the sub-group analysis of lung lesions, pooled DR was 92.77% for F-18-FDG PET/CT, 95.02% for CT, and 64.93% for magnetic resonance imaging (MRI). On a per- patient analysis, F-18-FDG PET/CT demonstrated a pooled sensitivity (SS) of 87.3% [95% confidence interval (CI): 77.3%-94%] and a pooled specificity (SP) of 95.6% (95%CI: 87.6-99.1). On a per-lesion analysis (328 metastases), PET/CT showed a pooled SS and SP of 86.3% (95%CI: 73.5%-93.5%) and 93.4% (95%CI: 71.7%-98.8%) in the detection of hematogenous metastases. The presented systematic review and meta-analysis favor the use of F-18-FDG PET/CT in the detection of hematogenous metastases in patients with differentiated thyroid cancer. The limited literature warrants further studies to confirm our findings.