Multislice CT angiography in the assessment of peripheral aneurysms

Peripheral aneurysms are usually located in the femoro-popliteal district; these lesions may present some complications such as distal embolisation and thrombosis; rupture is quite rare, but may be life-threatening. The aim of this study is to test the accuracy of CT multislice angiography in the assessment of this pathology and to compare it with DSA, until now considered the gold standard in vascular imaging.

From January 2001 to May 2002 we studied 10 patients (8 males and 2 females) aged between 48 and 74 years with 14 lesions. All patients were affected by femoro-popliteal aneurysms. Eight patients underwent US as a first examination, 2 patients directly underwent DSA because of acute ischaemic symptoms; then, a CT angiography was performed. The first eight patients underwent CT and DSA after US. Hence, all patients underwent both DSA and CT. All CT examinations were performed with a multislice spiral CT scanner using the following parameters: 2 mm slice thickness, pitch 6, 2mm slice thickness, 1mm reconstruction interval, 120 mAs, 120 kVp. A nonionic contrast medium was infused intravenously at a biphasic rate. Angiography was performed by humeral artery catheterisation with a 4F device, the distal tip of the catheter was placed in the infra-renal abdominal aorta.

In 7/10 patients the diagnosis was correctly formulated after DSA; in two patients, only the obstruction of the popliteal artery was detected, but not the dilatation and the thrombus. In one patient the parietal annular thrombus simulated a normal artery. CT was diagnostic in all cases and all the complications were detected as well.

Multislice spiral CT angiography allows depiction of aneurysms, and of the precise site, dimensions, quantity and quality of parietal thrombus; multislice CT is to be considered, in our opinion, essential in the assessment of diagnosis and in the planning of therapy. Moreover, CT provides exact measurements of the vessels before and after the aneurysm, which is essential to plan stent-graft implantation. A very interesting feature comes from the execution of a complete 3D angiography of the entire lower extremity circulation with high spatial resolution. DSA cannot provide direct information about the wall of the vessel and about the thrombus; therefore, in some cases it is unable to provide the correct diagnosis. Today DSA remains the best examination to evaluate the quality of run-off in lower extremity, especially under the knee.