Contrast-enhanced ultrasound assessment of complex cystic lesions in renal transplant recipients with acquired cystic kidney disease: preliminary experience.

We prospectively studied the potential value of contrast-enhanced ultrasound (CEUS) to characterize complex acquired cystic kidney disease (ACKD) or suspected solid renal masses, avoiding the risk of inducing acute kidney injury in 138 renal transplant recipients by contrast-enhanced computed tomography (CT). Forty-three cases (31%) had ACKD; 15 ACKD patients (35%) showed suspicious or nondiagnostic ultrasound. The latter subgroup underwent CEUS and, if the suspicion was confirmed, a contrast-enhanced CT. Thirty five lesions were identified in the 15 patients studied by CEUS. According to the Bosniak classification, 27 cysts were type I (BI), four type II (BII), two type III (BIII) with enhancement at the level of thickened septa; we also identified two solid enhancing lesions (BIV). We followed the BI and BII lesions with serial CEUS, while the remaining four cases underwent contrast-enhanced CT showing two solid lesions and two complex cysts with contrast enhancement in the septea. The four patients underwent surgical resection yielding three renal cell carcinomas one papillary carcinoma as the pathological findings. This preliminary study characterized solid nodules and BIII lesions for further evaluation by CT. CEUS seems to correctly characterize BI and BII cysts that are not clearly defined by standard ultrasound.