FAP and metastatic malignant neoplasm in the lymph nodes: Conversely from what was observed for primary tumor assessment, FAP-guided PET showed discordant diagnostic performances compared to [18F]FDG PET imaging in detecting lymph node metastases and, despite our meta-analysis, reported a pooled sensitivity and specificity of 90% and 84% on a per patient-based analysis, in four studies FAP-targeted PET could detect fewer pathologic lymph nodes than a [18F]FDG scan [14,16,18,21].