CT and MRI features of solitary fibrous tumors in abdomen and pelvis

Abstract

Objective To observe the CT and MRI results of solitary fibrous tumors(SFT) in the abdomen and pelvis, analyze their characteristic imaging, and improve the accuracy of diagnosis and understanding of the disease. Methods Retrospective analysis of 18 cases confirmed by pathology from January 2008 to June 2017[9 men, 9 women, age 41- 71(53.0±10.6) years old] through imaging findings and clinical and pathological data of patients with pelvic SFT. Among the 18 patients, 13 received dynamic CT and 5 received dynamic MRI. The tumor size(maximum diameter),morphology, density or signal, dynamic enhancement characteristics, arterial tumor vessels, and tumors were mainly analyzed. Fisher's exact test was conducted to examine the relationship between tumor size, boundary, and morphology of benign and malignant tumors. The differences among the three characteristics in malignant tumors were determined by Fisher' s test. Results ① Characteristics of CT imaging: The maximum diameter of tumor lesions in the 13 patients with CT was(2.7–23.4) cm, and the mean diameter was(10.53±6.21) cm. Among the 13 cases, 8 were lobulated and 7 exhibited cystic degeneration. One patient showed calcification. Furthermore, 11 cases of nonuniform enhancement by dynamic enhancement was observed. Delayed enhancement was observed in 8 cases. Mild to moderate enhancement was observed in 2 cases. In 10 cases, pointy and linear enhancement of vessels could be seen at the arterial stage, and in 8 cases, tortuous vessels were observed around the lesions. The maximum diameter of the lesions was (10.0–13.4) cm and the mean diameter was(11.93±3.21) cm. ② Characteristics of MRI: The lesion boundaries of 5 patients were clear, and the lesions were lobulated in 4 of 5 patients. In T2 weighted imaging, cystic changes were observed in 3 patients. In 4 cases, scarlike or flaky low-signal areas were found in the lesions, 1 case showed uniform isobaemic signals, and 5 cases presented empty vascular shadows. Moreover, 4 cases indicated an obvious uneven enhancement. Delayed enhancement was observed in 4 cases, and uniform enhancement was observed in 1 case. In 5 cases, vessels were strengthened in the lesion at the arterial stage. ③ Pathology results showed that among the 18 SFT cases, 7 were malignant and 11 were benign. For the malignant SFT, 5 of 7 cases exceeded the average diameter[(10.88±5.62) cm], whereas for the benign SFT, only 2 of 11 cases exceeded the mean. The maximum diameter was different between the benign and malignant lesions(χ2=5.103, P=0.039), showing statistical significance. Conclusions Although radiological findings on abdomino-pelvic SFT vary between dynamic contrast enhanced CT and MRI, a hypervascular mass with delayed enhancement is the imaging feature. Peripheral tortuous vessels and filiform vessels in the lesion may reinforce the diagnosis. The low signal of T2 weighted imaging in MRI also has a certain diagnostic value. Key words: Solitary fibrous tumor; Tomography, X-ray computed; Magnetic resonance imaging