Renal artery stenosis: value of contrast-enhanced ultrasonography

Abstract

Renal artery stenosis is the most common cause of potentially curable secondary hypertension. For a long time, angiography has been considered the "gold standard" in screening for renal arterial occlusive disease, but it is expensive and invasive. Magnetic resonance angiography and spiral computed tomography are safer alternatives to angiography but are expensive and not widely available. Due to the fact that duplex scanning is noninvasive, it has been advocated since the early 1980s as a screening test for renal vascular disorders. Factors that make duplex ultrasound an attractive screening measure for renovascular disease are its safety, suitability for outpatient use, and low cost. However, the frequency of artery variants, lengthy examination time, and technically inadequate test conditions limit the use of the direct duplex ultrasound detection of renal artery stenosis. Advances in Doppler technology may alleviate some of the current problems related to examination of renal arteries. One such technique is the use of echo-enhancing agents, which increase Doppler signal strength and can improve the sensitivity and specificity in Doppler ultrasound detection of renal artery stenosis.

The Value of Contrast-Enhanced Ultrasound versus Doppler Ultrasound in Grading Renal Artery Stenosis

“…The diameter of the main renal artery decreased significantly at the stenosed segment in patients with renal artery stenosis on DSA. The criteria of suspected renal artery stenosis can be determined by finding a parvus-tardus waveform, systolic acceleration time prolonged (>80 ms), peak velocity of blood flow increased (>80 m/s), ratio of renal artery flow velocity to aortic flow velocity increased (>3), and resistive index difference (≥5%) at the stenosed region of the renal artery by DUS examinations [ 24 , 26 , 27 ]. The results of DUS and CEUS with different grades of renal artery stenosis were compared with the gold standard DSA.…”

“…Although DUS has been widely used as an initial imaging modality for the diagnosis of renal artery stenosis [ 21 , 22 ], factors such as depth, obesity, complex anatomy, bowl gas, and operator dependent may limit the use of the Doppler ultrasound [ 23 ]. More recently, the use of CEUS in the detection of renal artery stenosis has raised the attention of many researchers [ 24 , 25 ]. CEUS has the advantages of noninvasion, nonradiation, cost effective, and easy operation.…”

Integrated evaluation of hypertensive patients with cardiovascular magnetic resonance

“…Duplex ultrasonography can provide images of the renal arteries and assess blood-flow velocity and pressure waveforms, but even with injection of contrast agent there is a high incidence of suboptimal tests. [22,23] Spiral computed tomographic angiography is useful for evaluating renal circulation and to identify associated diseases of the aorta, [24] but involves radiation and the use of nephrotoxic contrast agents. [25] As for CE-MRA, there is discussion on its accuracy to detect significant renal artery stenosis.…”

Ultrasound contrast agents in the study of kidney function in health and disease

“…MR scanning using gadolinium in patients with kidney disease has been shown to be associated with the devastating condition, nephrogenic systemic fibrosis. [43;44] Although Duplex ultrasonography has been shown to have sensitivity and specificity as high as 98% in detection of ARAS in some series [45][46][47][48][49], being operator dependent, time consuming and associated with a higher than desired technical failure rates limits its use as well. Factors such as obesity, bowel gas, depth, tortuosity and number of renal arteries, and the presence of nephropathy limit the utility of this technique.…”