11C-Methionine PET for Detecting Solitary Fibrous Tumor Metastases: 2 Cases With Negative FDG-PET

Solitary fibrous tumors (SFTs) are rare mesenchymal neoplasms with a known tendency to metastasize. Although fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is commonly used to detect recurrence after surgery and metastatic disease in SFTs, we observed 2 cases of SFT metastasis with minimal FDG uptake. However, 11 C-methionine PET revealed significant tracer accumulation in these cases. To our knowledge, this report is the first to document cases in which 11 C-methionine PET/CT contributed to the detection of SFT metastasis, highlighting the potential clinical value of this imaging modality in post-treatment surveillance.