Purpose : To investigate the usefulness of a US contrast agent in differentiation of renal cystic lesions, benign or malignant, on power Doppler US(PDUS).
Materials and Methods : Five patients with suspected renal cystic lesion on US were prospctively evaluated with PDUS by one examiner. PDUS was performed with ATL HDI 3000 using a 2-4 MHz curved-array probe. To provide standardized adequate US images, all patients were scanned according to the following protocol; PRF 1000 Hz, color gain 75-85%, wall filter medium. Serial images were obtained before and after injection of 300mg% LevovistR with 0.2ml/sec injection rate. And then, all patients underwent contrast-enhanced CT OR dynamic MR imaging. Five renal lesions were confirmed by biopsy, operation, or cell cytology of intracystic fluid, within 1-2 weeks after PDUS; infected parapelvic cyst(1), TCC(1), cystic RCC(1), paraganglioma(1), benign cortical cyst(1). Obtained US images were analyzed by two radiologists in consensus with focusing on tumor vascularity along intracystic septae or solid component, including comparison with other contrast-enhanced imaging.
Results : In all cases, conventional PDUS showed a lack of intra-or peritumoral blood flow signals. In three cystic or cyst-mimicking renal tumors, contrast-enhanced PDUS provided enhanced vascular signals in the tumor, which was well correlated with radiologic finding of postcontrast MR imaging in cystic RCC and superior to other postcontrast imaging in another two cases. In two benign cystic lesions, intratumoral blood flow signal was not depicted on contrast-enhanced PDUS as well as other
dynamic imaging study.
Conclusion : Contrast-enhanced PDUS provides excellent visualization of tumor vascularity such as enhanced flow signal along septae or intracystic solid portion as well as dynamic change of enhanced flow signal, which might be useful in differential diagnosis of renal problematic cystic lesions, benign or malignant.
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