The value of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in the detection and characterization of soft tissue metastasis

Metastatic tumours presenting as soft tissue metastasis (STM) are relatively rare. STM represents metastasis to the muscle and subcutaneous tissues. The majority of the currently available clinical or radiological data on STM consist of isolated case reports or reviews. The aim of this study was to report the manifestations, origin and distribution of STM detected by F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) and to assess the value of F-18-FDG PET/CT in the characterisation of STM. We reviewed 17 cases of patients with STM who underwent F-18-FDG PET/CT scanning. The imaging and clinical data of these patients were retrospectively analysed. This method is very sensitive in the detection of STM and provides ample information for clinical tumour staging. PET is more sensitive compared to CT in detecting lesions in muscle, before the density and morphology of the soft tissues are altered, providing a clear view within the soft tissue. Due to the limitations in resolution, PET is less sensitive compared to CT in detecting lesions in the subcutaneous tissues. The aim of this study was to improve our knowledge of F-18-FDG PET/CT findings in the diagnosis of STM and determine its value in the staging of malignant tumours.