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 contrast-enhanced 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 T₁-, slightly hyperintense (2) or slightly hypointense on T₂-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 T₂ signal intensity, intense and persistent delayed enhancement of the solid portion. (authors)