Evaluation of kidney circulation using duplex Doppler ultrasonography

: Chronic kidney disease (CKD) is increasingly being recognized as a leading public health issue. CKD is associated with an increased risk of cardiovascular disease (CVD), and the convalescence of patients with CVD is greatly influenced by the renal function. CVD and CKD are closely related, and diagnosis/treatment of CVD while considering renal function are recommended. Renal duplex Doppler ultrasonography is a tool which can evaluate the renal hemodynamics and renal function noninvasively and is an important screening examination for renal disease. Renal artery stenosis is important as one of the renal diseases clinically related to arteriosclerosis. Using an increase in the renal artery peak systolic velocity (PSV) and the ratio of the PSV in the renal artery to the abdominal aorta, duplex scanning is able to predict significant renal arterial stenosis. On the other hand, the intrarenal resistive index (RI), which is a function of the blood velocity waveform of the artery in the kidney, is an index of the kidney's peripheral arterial resistance. It has been reported that the RI value is related to the aggravation of renal function disorder, and a renal insufficiency above 0.8 is related to an increase in peripheral arterial resistance.