Catheter angiography

Catheter angiography provides exquisite image detail and can visualize vessels as small as 0.1 mm in diameter, considerably smaller than those seen by CT- and MR-based vascular imaging techniques. Catheter angiography also provides high temporal resolution, which can help to distinguish arteries from veins and to detect prolonged intravascular stasis of blood. 

At the other extreme are those acute stroke patients who have no visible arterial occlusion whatsoever, presumably because their infarcts were due to lesions in small arteries that cannot be imaged, or because an embolus in a large proximal artery has broken up spontaneously. Several smdies (again using catheter angiography rather than CTA) have shown that such patients generally enjoy relatively favorable outcomes. 

Catheter angiography Jugular vein cannulation Missile wounds Neck/oral Injury or surgery Blow to the neck... 

Diffusion-weighted MRI showing two areas of acute infarction in the left parietal and occipital regions, (b) Magnetic resonance angiography shows aberrant arterial anatomy with the posterior cerebral artery arising directly from the internal carotid artery (arrow) (c) This was confirmed on catheter angiography. 

Compared with cut-film selective intra-arterial catheter angiography recorded directly on to X-ray film, intra-arterial digital subtraction angiography (DSA) (Fig. 12.1) is quicker the images are easier to manipulate and store and contrast resolution is better although spatial resolution is less. However, there is no evidence that less contrast is used or that it is much safer (Warnock et al. 1993). Even for imaging only as far as the carotid bifurcation. 

Even with selective catheter angiography, there can be difficulty in distinguishing occlusion from extreme internal carotid artery stenosis, and then late views are needed to see contrast eventually passing up into the head. Moreover, because of the localized and non-concentric nature of atherosclerotic plaques, biplanar, and preferably triplanar (Jeans et al. 1986 Cuffe and Rothwell 2006), views of the carotid bifurcation are required to measure the degree of carotid stenosis accurately that is, to visualize the residual lumen without overlap of other vessels, to measure at the narrowest point and to compare with a suitable denominator to derive the percentage diameter stenosis. 

Until recently, catheter angiography was the standard imaging modality to confirm or exclude carotid or vertebral artery dissection (Fig. 12.2) because ultrasound was neither specific nor sensitive enough. However, there is now a widespread consensus that cross-sectional MRI, to show thrombus within the widened arterial wall, combined with MR angiography is the safest and best option. 

A similar trade-off between diagnostic accuracy and risk is necessary when imaging the carotid bifurcation in patients with TIA or ischemic stroke. Performing intra-arterial catheter angiography in everyone is clearly unacceptable because of the risks and cost. Fewer than 20% of patients will have an operable carotid stenosis even if only those with cortical rather than lacunar events are selected (Hankey and Warlow 1991 Hankey et al. 1991 Mead et oL 1999). Coirfining angiography to patients with a carotid bifurcation bruit will miss some patients with severe stenosis and still subject too many with mild or moderate stenosis to the risks. Nor will a combination of a cervical bruit with various clinical features do much better (Mead et al. 1999). 

If CT and CSF examination are normal within two weeks of headache onset, then SAH has been excluded. However, since xanthochromia is only detected in 70% of patients after three weeks and only 40% after four weeks, patients presenting beyond two weeks require investigation with CT or MR angiography or by catheter angiography. 

Low Risk. CTA has a lower rate of patient discomfort, is less expensive, and has considerably lower risk of stroke and other vascular complications compared to conventional catheter angiography. It is also advantageous in situations when MR is contraindicated or cannot be performed. CTA is typically more readily available than MR, especially in emergency settings. CTA, unlike MRA, lends itself to the imaging of acutely ill patients, as there are no restrictions on the type and quantity of associated support equipment, such as intravenous pumps, ventilators, or monitoring hardware. Because CT scan acquisition is more rapid than that of MRA, CTA is less prone to motion artifact. When CTA is combined with CT perfusion (CTP) for the evaluation of acute stroke, quantitative perfusion data can also be obtained, which is not typically possible with MR perfusion imaging. 

CTA has also been used to perform serial monitoring of patients with proven ICA occlusions. Surprisingly, spontaneous recanalization of an occluded ICA has been demonstrated [97]. In such cases, serial catheter angiography would have been prohibitive in terms of time, cost, and risk of complications. 

Chen CJ, Lee TH, Hsu HL et al (2004) Multi-Slice CT angiography in diagnosing total versus near occlusions of the internal carotid artery comparison with catheter angiography. Stroke 35 83-85. 

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