Colour Doppler ultrasound in renal artery stenosis: intrarenal waveform analysis

Abstract

Renal artery stenosis (RAS) is the commonest secondary cause of hypertension and may result in renal ischaemia with resultant renal failure. Recent studies hve suggested that colour Doppler ultrasound, with spectral analysis of the intrarenal waveforms, can identify those patients with a significant RAS. A prospective study was performed in which colour Doppler ultrasound was compared with angiography in 73 patients (143 kidneys) presenting for renal angiography. Colour Doppler ultrasound was unsuccessful in 16% of kidneys due to a combination of technical failures and small kidney size. Accessory renal vessels were present in 14% of kidneys on angiography but none was detected by ultrasound. Of the 120 kidneys that had both examinations, no significant difference in intrarenal pulsatility or resistive index was noted between the angiographically stenosed and normal arteries. There were significant differences for intrarenal peak and end diastolic velocities, and acceleration time and index. Of these measurements, acceleration time was the best indicator of RAS. The probability of detecting a high grade RAS in an individual patient did not reach 90% until the acceleration time was prolonged to more than 0.12 s. Intrarenal colour Doppler ultrasound is not a general screening test for RAS and it should be reserved for selected patient groups where the incidence of disease is high. Patients with prolonged acceleration times of more than 0.12 s have a high likelihood of at least 70% RAS and should proceed directly to angiography.

Renovascular disease in patients with hypertension: detection with duplex ultrasound

“…9,[11][12][13][19][20][21][22][23] In order to overcome these limitations, others have suggested the technique of duplex ultrasound examination of the intrarenal vasculature. 8,10,[24][25][26][27][28][29][30] Analysis of the Doppler spectral waveform, with several criteria, ie mean resistive index, tardusparvus phenomena and acceleration time, has been proposed as an alternative to detect upstream stenosis. With the lateral approach to the kidney, duplex examination of the intrarenal arteries is easier to perform resulting in a higher number of complete examinations than with direct scanning of the renal arteries.…”

“…However, the results of studies concerning the validity of duplex ultrasound are sometimes conflicting and there is no general agreement about its value as a screening test for renovascular disease. 8,9 The aim of this study was to evaluate the accuracy of duplex ultrasound for the diagnosis of renal artery stenosis in a cohort of unselected hypertensive patients with clinical suspicion of renovascular disease using conventional renal angiography as the Journal of Human Hypertension standard of reference. In addition, we tried to determine the most useful combination of thresholds for the applied ultrasound parameters.…”

Ultrasonography in Vascular Diagnosis

“…An acceleration index of less than 300 cm/s and an acceleration time of more than 0.07 s are abnormal and indicate greater than 60% stenosis (Baxter et al 1996;Kliewer et al 1997;Stavros et al 1992;Nazzal et al 1997;Martin et al 1991) with sensitivities of 78-89% and specificities of 92-98%. Some investigators therefore propose an acceleration time cutoff of 0.1-0.12 s, which has been found to be more specific (Dawson 1996;Baxter et al 1996;. Some investigators therefore propose an acceleration time cutoff of 0.1-0.12 s, which has been found to be more specific (Dawson 1996;Baxter et al 1996;.…”

Is Nonalbuminuric Renal Insufficiency in Type 2 Diabetes Related to an Increase in Intrarenal Vascular Disease?

“…We did not specifically screen patients for the presence of undiagnosed renal artery stenosis by performing a Doppler evaluation of the main renal arteries but did assess renal size and blood flow at the renal hilum. None of the 325 patients that were included in this study had an hilar acceleration time Ͼ100 mm/s or had evidence of kidney atrophy (Ͻ9 cm in length), parameters that are suggestive of renal artery stenosis Ͻ60% (10,11). Furthermore, no patients with renal insufficiency were included in this study if they had a mean resistance index value Ͻ0.45, a value associated with bilateral renal artery stenosis, or a difference in resistance index values Ͼ8% between the two different kidneys, a value associated with the presence of unilateral renal artery stenosis (12).…”