MSCT and MR on Chemical Shift Imaging Features of Minimal Fat Renal Angiomyolipoma Correlated with Pathology

Objective: To explore the Multi-slice CT(MSCT) and chemical shift imaging(CSI) manifestations of minimal fat renal angiomyolipoma(RAML) with pathology results and to improve its accuracy of diagnosis. Methods: The data of 16 cases of RAML patients were retrospectively analyzed in comparison with pathological results, including tumor size, shape, density, enhancement degree and patterns, CSI imaging features. Results: 16 lesions were all solid tumor masses. 10 lesions showed round, 6 lesions irregular in shape. moreover, split sign appearance was found in 9 lesions, cup sign in 6 lesions and cortical up sign in 5 lesions. On precontrast CT, 11 cases showed hyperattenuation, including 4 heterogeneous lesions with focal low density. Three pattern were demonstrated by enhanced scanning including wash-in and wash-out, continuous enhancement and delayed enhancement. but peak enhancement degree was lower than the renal cortex. Furthermore, 5 lesions showed hyperintensity on T2-weighted MRI. Hypointensity on out-phase CSI were seen in 3 lesions. Among them, one case showed high signal center surrounded by linear low signal ring. Conclusion: MSCT and MRI examination of minimal fat RAML demonstrates certain characteristic signs, thin layer out-phase CSI may be helpful for diagnosis of the disease.