- To present the technique of examination (with main technical limitations) and appropriate indications for renal Doppler ultrasonography (RDU) with typical diagnostic imaging findings - Review the main diagnostic criteria proposed for RDU (with special emphasis on renal artery stenosis - RAS as the most common cause of renovascular hypertension - RVHT)

RDU is usually the first-line modality for evaluating flow in native renal vessels and parenchyma. Waveforms, which represent flow in each of the major and segmental vessels, have been well described, hence their appearance should be recognized, and the mechanisms behind their generation should be understood by radiologists, mainly because renovascular disease is an important and potentially correctable cause of secondary hypertension.

Sonography (a combination of gray-scale B-mode, color Doppler/CDUS and power spectral Doppler/PW) represents a totally non-invasive, easily available, low-cost and well tolerated technique that is able to detect RAS and renovascular diseases. The resistive index (RI), pulsatility index, systolic/diastolic ratio, peak systolic velocity (PSV), acceleration time, acceleration index, and other parameters are used to quantitatively analyze the characteristics of Doppler waveforms of renal blood flow. Of these parameters, the RI and PSV are most commonly used clinically. Since consistent RI values are obtained regardless of...

RDU represents technically very demand examination (30-45 min total duration; renal arteries depth; obesity and intraabdominal gas may hinder renal arteries visualisation; respiratory motions; more than 25% of people have more than one renal artery on one or both sides). Considering that the prevalence of RVHT in the general population of hypertensive patients is very low (only 2–6%), it is very hard to develop effective screening program for early RAS and RVHT detection. RDU is the best initial diagnostic test for showing if there is...

D. J. Petrovic MD; - nothing to disclose Center of Radiology and MRI, Clinical Center of Serbia, Pasterova 2, Belgrade 11000, Serbia. email: [email protected]

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