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R. Hojs, Kidney biopsy and power Doppler imaging, Nephrology Dialysis Transplantation, Volume 14, Issue 9, September 1999, Pages 2259–2260, https://doi.org/10.1093/ndt/14.9.2259
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Sir,
Percutaneous kidney biopsy is an important technique in clinical nephrology and involves certain complications. These can be classified as minor (gross haematuria; silent haematoma) and major (gross haematuria and haematoma requiring intervention; development of arteriovenous fistula (AVF); development of renal abscess; septicaemia; perforation of hollow viscous; death) [1,2]. Practically all complications are connected with haemorrhage. Microscopic haematuria is very common and not accepted as a complication by most authors [1,2]. The performance of biopsies with an automatic, spring-loaded Tru-cut biopsy device and under ultrasound (US) control has increased the safety of the method itself and decreased the number of serious complications [1]. In the last years the use of colour Doppler sonography in monitoring kidney biopsies was described [3]. We present the use of US technique named `power imaging' or `power Doppler' or `angio' (depending on the manufacturer) in performing kidney biopsies.
Colour Doppler sonography (CD), which is generally based on the mean Doppler frequency shift, has proved to be a useful adjunct in the sonographic diagnostic armamentarium and also in nephrology [4,5]. This method has shortcomings including a tendency for noise to overwhelm the flow signal if the gain is too high or the threshold too low, angle dependence and aliasing [4,5]. In an attempt to overcome these shortcomings a new US technique `power imaging'/`power Doppler' (PD) has been developed [4,5]. PD is based on the integrated Doppler power spectrum [5]. It is a type of sonography in which the colour scale is calculated from the number of red blood cells in blood volume insonated by the US beam [5]. PD has several advantages over CD: (i) PD can be performed with higher colour gains than CD before noise begins to obscure the image; (ii) it is nearly independent of the insonation angle and essentially angle-independent, and (iii) not subject to aliasing [4,5]. PD demonstrates the intrarenal vasculature better than CD and it is also possible to see smaller tortuous renal vessels with low flow [4]. It is possible to see segmental, interlobular and arcuate arteries and their accompanying veins with CD routinely, but with PD more of these vessels can be seen [4]. Diffuse blush of the renal cortex (visualization of interlobular vessels distal to the level of the arcuate vessels) was first seen with PD [4]. PD is much more susceptible to flash artifact from patient motion than CD [4]. However, this is not a true problem in our patients because they must hold their breath when biopsy is performed.
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