Peripheral arterial disease: the evolving role of non-invasive imaging.
ABSTRACT Peripheral arterial disease is usually secondary to stenotic or occlusive atherosclerosis and is both common and increasing in western society. The majority of symptomatic patients have intermittent claudication and only a minority (<2% and typically those with diabetes mellitus or renal failure) progress to critical limb ischaemia, heralded by the onset of rest pain and/or tissue loss. Imaging is largely reserved for patients with disabling symptoms in whom revascularisation is planned. In these patients, accurate depiction of the vascular anatomy is critical for clinical decision making as the distribution and severity of disease are key factors determining whether revascularisation should be by endovascular techniques or open surgery. Driven by advances in technology, non-invasive vascular imaging has recently undergone significant refinement and has replaced conventional digital subtraction angiography for many clinical indications. In this review, the relative merits and limitations of duplex ultrasound, CT angiography, and magnetic resonance angiography are discussed, emerging imaging techniques are described, and complications relating to the use of intravascular contrast agents are highlighted.
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ABSTRACT: The purpose of this study was to compare CT angiography (CTA) and MR angiography (MRA) for the detectability of 75% and 95% stenoses in phantoms using six different stents. Six different stents (Expander, Hemobahn, SelfX, Smart, Symphony, and Wallstent) were inserted into tubes filled with contrast agent (ioversol or gadoteric acid). To mimic stenoses of 75% and 95% of the patent lumen, 8-mm-diameter nylon cylinders were bored in the central axis (2 mm and 4 mm, respectively) and placed into the stent lumen. Intensity profiles across stenoses on 2-mm coronal reformatted sections of CTA or MRA were compared, and the detectability of the residual lumen was assessed using a subjective score. CTA showed relative in-stent signal attenuation for the in-stent stenoses of the tested stents ranging from 75% to 100% of the signal intensity of the control. SelfX and Symphony showed further shading of the residual lumen due to beam-hardening artifacts. Overestimation of stenosis was associated with low-grade stenoses in which the border of the lumen was closer to the stent struts. MRA showed relative in-stent signal attenuation of the in-stent stenoses ranging from 30% to 100% of the signal intensity of the control. Strut thickness tended to correlate with higher attenuation at CT. CTA may be more suitable for differentiation between 95% stenosis and occlusion; MRA has higher sensitivity in detecting 75% stenoses. Strut thickness and mesh size did not prove to be significant predictors for signal attenuation or overall image quality.American Journal of Roentgenology 12/2007; 189(5):1238-42. · 2.90 Impact Factor
- Nephrology Dialysis Transplantation 11/2006; · 3.37 Impact Factor
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ABSTRACT: Nephrogenic systemic fibrosis (NSF) is a debilitating disorder seen in-patient with advanced chronic kidney disease (CKD). Recent evidence suggests a link between NSF and the administration of gadolinium-based contrast agents (Gd-CA). In addition, other risk factors have also been suggested to facilitate the development of NSF in this population after Gd-CA. These include metabolic acidosis, high-dose erythropoietin therapy, and the altered mineral metabolism of CKD. While it is possible that these factors may increase the risk of NSF after Gd-CA exposure, they may also simply reflect conditions that increase the risk of getting exposed to Gd-CA, particularly at high doses. Furthermore, given the risk of NSF in CKD, physicians must weigh the risks of NSF versus the risk of contrast-induced nephropathy (CIN) with iodinated agents in this population. In this review, we will provide a nephrologist's perspective on these issues and the nephrologist's role in the prevention of NSF.European Journal of Radiology 06/2008; 66(2):208-12. · 2.51 Impact Factor