Complementary value of Contrast-enhanced ultrasound (CEUS) after contrast-enhanced computed tomography (CECT) in evaluation of indeterminate small hypovascular renal masses

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Purpose: To assess the value of contrast-enhanced ultrasonography (CEUS) in the characterization of indeterminate small renal masses (SRM) seen on contrast-enhanced CT (CECT) and its promising role in diagnostic algorithm.

Materials and Methods: From January 2011 to September 2014, 66 consecutive patients (age range, 45-86 years; 38 men, 28 women) with SRM (< 4 cm) underwent renal surgery, after preoperative CECT for lesion characterization and treatment planning. Thirtyfive patients with hypervascular lesions at CECT were submitted to surgery with no additional imaging examination. CECT findings demonstrated indeterminate characteristics of SRM in 31 patients, with pseudo-enhancement or unclear endolesional vascularization. These patients underwent CEUS to evaluate real-time lesional wash-in in order to better define their further management (surgery or follow-up). Results: Twentythree out of 31 patients showed contrast enhancement wash-in into the lesion and therefore underwent surgery. Pathologic findings confirmed malignancy in 19 patients (3 clear cell carcinoma, 14 papillary renal cell carcinoma, 2 cromophobe) and benign lesions in 4 patients (2 oncocytoma, 2 angiomyolipoma, 1 emorrhagic cysts). Nine lesions with no clear enhancement at CEUS are currently under follow-up (CEUS and MRI) with no evidence of modified pattern (median follow-up 15 months) representing complicated cysts Bosniak II. Conclusions: CEUS can be an useful tool to determinate real-time enhancement in SRM, especially for tumors with indeterminate pattern at CECT. Contrast-enhanced ultrasonography is very sensitive in detecting slight tumor blood flow, facilitating the evaluation of tumor perfusion by analyzing tumor vascular enhancement patterns. The promising role of CEUS should be considerated in newer diagnostic algorithms of SRM management, also as problem solving in undeterminate findings at CECT or MRI. ==fine abstract==