Minimally Invasive Investigation

Most patients are still managed in a district general hospital (DGH) setting by clinical and radiology department staff who have other responsibilities than "vascular" patients. It is intended that care will evolve towards fewer number of larger specialist units, comparable to those in place in the larger centres. The transition may take many years. The diagnostic and treatment pathway for a patient depends on local practices and resources.

Although ultrasound (US) is less labour intensive than angiography it should not be employed indiscriminately, but it is harmless, and in combination with history and examination will usually demonstrate presence and absence of significant disease separately in the aortoiliac, femoropopliteal and distal segments. Angiography is rarely required for further diagnosis. US is usually carried out by radiographers from the X-ray department, but may be under the auspices of a vascular laboratory.

Computed tomography (CT) angiography is frequently requested for preoperative assessment of aortic aneurysm, and follow-up of radiological endovas-cular aneurysm repair. When proximal major vessels are occluded and conventional angiography is not feasible, CT can demonstrate the distal vessels beyond the blockage to aid surgical planning for bypass (Figure 3.2.1). It requires

Fig. 3.2.1: CT angiogram of the carotid artery demonstrating a tight stenosis at the origin of the internal carotid artery with a calcified plaque.

intravenous contrast pumped through a cannula in a peripheral vein and the usual caution is necessary regarding interaction with metformin in renal failure, and the exceedingly rare and unpredictable severe contrast reaction. Rarely, contrast is extravasated into the soft tissues but this is unlikely to lead to problems.

Magnetic resonance imaging (MRI) angiography can provide similar information to CT, but there are essentially no contrast risks. Some patients are unable to tolerate the feeling of confinement inside the magnet bore. Time on the machine is in great demand because of the numerous applications in many aspects of medical care, providing information which often cannot be obtained by other investigations.

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