Post-Tx Renal Monitoring with B-Flow Ultrasonography

The examination of blood vessels and the study of arterial districts have been already revolutionized by the introduction of B-mode ultrasonography, widely used to evaluate the blood flow. The lumen and vessel wall together with microscopic characteristics, can be clearly evidenced with this method thanks to the use of Color Doppler Flow Ultrasounds (CDFU) (Wescott 2000). This methodic is able to show the flow direction and the velocity of red blood cells as well as vascular structures. The color signals and generated angiographylike visualization of the vascular lumen surface can be shown by the integration with the Power Doppler Ultrasounds (PDU). Consequently, CDFU and PDU give not an approximate estimation but a precise measure of the residual lumen of the vessels more reliable than with conventional B-mode imaging in case of stenosis (Wescott 2000). Recently a new technology for the detection of blood circulation has been developed by using digitally encoded sonography to boost blood echoes and to preferentially suppress non-moving tissue signals. This method is known as the B-Flow Ultrasonography (BFU) and it has higher spatial and temporal resolution than Doppler imaging because of the clearer definition of the vessel lumen (Henry 2000). BFU allows the direct visualization of blood reflectors without the limitations of Doppler technology such as aliasing, signal dropout at orthogonal detection angles and wall filter limitations. B-flow visualizes real-time hemodynamic flow in relation to stationary tissue (Jung 2007, Wachsberg 2007). We evaluated the efficacy of BFU in examining the arterial and venous anastomoses, the cortical flow and other parameters of the graft in patients who underwent kidney transplantation for chronic renal disease.