The role of directional power Doppler in vascular characterization of renal masses.

Objectives: The purpose of our study was to characterize the vascularization of frequently detected renal masses with directional power Doppler (dpD).

Materials And Methods: We analyzed 38 renal masses with B-mode sonography (US), dpD, computer tomography (CT) and/or magnetic resonance (MR) and, in some cases, also with percutaneous renal biopsy (RB). The study population included 14 renal cell carcinomas (RCC), 10 angiomyolipomas (AML), 5 other types of lesions, as complex cysts, anatomical malformations and focal pyelonephritis (PLN), 9 mass lesions classified indeterminate by imaging studies and have defied characterization by RB. The dpD evaluated the peri or intra-lesional vessels distribution according to Jinzaki vascular patterns, the presence of artero-venous fistulas (AVF) and Doppler spectrum of these lesions, especially blood-flow systolic peak velocity (SPV).

Results: At US, there was no statistically significant difference in lesion size, but significant difference was found in echogenicity of AML resulted all hyperechoic in respect of other types of lesions. At dpD, the vascular distribution in most of CCRs (11/14) was classified as pattern 3 or 4 (peripheral and mixed penetrating/peripheral, respectively) and was significantly different in respect to AMLs, that showed patterns 1 and 2 (intratumoral focal and penetrating, respectively), in respect to other types of lesions, that were with prevalent pattern 2, and in respect of indeterminate lesions, that presented all patterns (from 1 to 4). The SPV was more elevated in CCRs than in all other types of lesions. Three CCRs presented AVF.

Conclusions: The dpD adds very important information to simple US in vascular pattern evaluation of small solid renal lesions and improve the diagnostic accuracy.