Contrast-Enhanced Ultrasonography in Renal Angiomyolipoma with Minimal Fat: a Preliminary Study

Objective:To investigate the manifestation of contrast-enhanced ultrasonography(CEUS) in renal angiomyolipoma(AML) with minimal fat.Methods:The images of conventional Ultrasound(US) and CEUS were retrospectively analyzed in 11 renal AMLs with minimal fat which were confirmed by operation and pathology.The size,echo,boundary and color flow signals of renal lesions were observed by conventional US.Then the modality and phases of enhancement were observed,including the arrival time,the peak time,the washout time and the appearance of internal structures.Results: The maximum diameter range of the renal lesions was from 2.4 to 15.3cm.The conventional US detected almost hypoechoic lesions with partially hyperechoic heterogeneous in 9 cases and solid-cystic lesions in 2 cases.The rich color flow signals were observed in all lesions.The diagnostic accuracy was merely 36.4%(4/11) before operation.In cortical phase,11 lesions were showed delayed centripetal enhancement on CEUS.In peak time,hyperechogenicity and isoechogenicity compared to the normal renal cortex were detected in all cases,as well as homogeneous enhancement in 9 lesions.In parenchymal phase,CEUS detected isochronous washout in 4 cases,delayed washout in 5 cases and fast washout in 2 cases.Two AMLs displayed similar to renal cell carcinoma in round pseudocapsule.Conclusions: Delayed centripetal enhancement and homogeneous enhancement in peak time on CEUS might be main features of hypoechoic renal AML with minimal fat.