CT and MRI of solitary fibrous tumor in the abdomen and pelvis with pathologic correlation

Objective To analyze the CT and MRI features of solitary fibrous tumor(SFT) of the abdomen and pelvis.Methods Unenhanced and contrast-enhanced CT and MRI of 14 patients with histologically confirmed SFT of the abdomen and pelvis were retrospectively analyzed and correlated with pathologic features.Results The 14 tumors were located in the liver(2),pancreas(1),abdominal wall(2),abdomen(4) and pelvis(5) with ill-defined(10) or well-defined(4) tumor margins.Of 11 patients,the CT densities of the tumors were heterogeneous in 9 and homogeneous in 2.In all 8 patients who underwent multiple-phase contrastenhanced CT,tumor enhancement was maximal in the portal phase with persistent enhancement or slow washout on delayed imaging.Of 3 patients with MRI examinations,the tumors were isointense(1) or slightly hypointense(2) on T_1-,slightly hyperintense(2)or slightly hypointense on T_2-weighted images with persistent enhancement pattern.Conclusion SFT of the abdomen and pelvis has CT and MRI characteristics of well-defined solitary mass with necrosis,low T_2 signal intensity,intense and persistent delayed enhancement of the solid portion.