Imaging of renal artery stenosis.
Renal artery stenosis is the cause of progressive ischemic nephropathy and of renovascular hypertension. Due to the invasiveness of arteriography, which is claimed to be the gold standard at the present time, several noninvasive imaging techniques are available. Colour Doppler sonography is cost-effective, but magnetic resonance angiography and computer tomography are more expensive; however, both are potential candidates for the definition of a new gold standard. Evaluation of renal vasculature by means of Doppler sonography includes intra- and extrarenal scanning as well as power Doppler and the use of contrast agents for enhancement of the Doppler signals. Computed tomography angiography is a minimally invasive method for the diagnosis of renal artery stenosis. There is high diagnostic accuracy that is not significantly different from that of angiography with respect to main and accessory renal arteries and detection of clinically significant renal artery stenoses. The main advantages over angiography are the use of an intravenous approach, and direct information provided about the vessel wall and adjacent structures. However, the nephrotoxicity of contrast material remains a major concern. Magnetic resonance angiography of the abdominal aorta and renal arteries has advanced considerably over the past few years. Recently developed breath-hold three-dimensional magnetic resonance angiography provides a new promising, noninvasive technique to evaluate the abdominal aorta and its large branch vessels. Using this technique, high sensitivity and specificity is achieved. The improved image quality and the ability to detect vascular lesions is due to short acquisition time with elimination of respiratory artifacts over an entire imaged volume by single breath-hold acquisition. Computed tomography angiography with its fast acquisition time and high spatial resolution compares favorably with magnetic resonance angiography and colour Doppler sonography. However, as compared with Doppler sonography and magnetic resonance angiography, computed tomography angiography images display only anatomic information and lack of flow sensitivity.
Krumme
B
B
Departments of Internal Medicine and Diagnostic Radiology, University Hospital Freiburg, Freiburg, Germany. krumme@mm41.ukl.uni-freiburg.de
Blum
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U