AIM:To describe the imaging features of solitary fibrous tumors(SFTs)in the abdomen and pelvis,and the clinical and pathologic correlations.METHODS:Fifteen patients with pathologically confirmed SFTs in the abdomen and pelvis were retrospectively studied with imaging techniques by two radiologists in consensus.Patients underwent unenhanced and contrast-enhanced imaging,as follows:3 with computed tomography(CT)and magnetic resonance imaging(MRI)examination,8 with CT examination only,and 4 with MRI examination only.Image characteristics such as size,shape,margin,attenuation or intensity,and pattern of enhancement were analyzed and correlated with the microscopic findings identified from surgical specimens.In addition,patient demographics,presentation,and outcomes were recorded.RESULTS:Of the 15 patients evaluated,local symptoms related to the mass were found in 11 cases at admission.The size of the mass ranged from 3.4 to 25.1cm(mean,11.5 cm).Nine cases were round or oval,6were lobulated,and 10 displaced adjacent organs.Unenhanced CT revealed a heterogeneous isodense mass in 7 cases,homogeneous isodense mass in 3 cases,and punctuated calcification in one case.On MRI,most of the lesions(6/7)were heterogeneous isointense and heterogeneous hyperintense on T1-weighted images and T2-weighted images,respectively.All tumors showed moderate to marked enhancement.Heterogeneous enhancement was revealed in 11 lesions,and 7of these had cysts,necrosis,or hemorrhage.Early nonuniform enhancement with a radial area that proved to be a fibrous component was observed in 4 lesions,which showed progressive enhancement in the venous and delayed phase.No statistical difference in the imaging findings was observed between the histologically benign and malignant lesions.Three patients had local recurrence or metastasis at follow-up.CONCLUSION:Abdominal and pelvic SFTs commonly appeared as large,solid,well-defined,hypervascular masses with variable degrees of necrosis or cystic change that often displaced adjacent structures.