CTA aids accurate limb ischemia management

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Peripheral arterial occlusive disease (PAOD) is becoming an increasingly more common presentation, particularly as the population ages in the industrial world. The utilization of CT angiography (CTA) to visualize and evaluate the extent of the disease can be a more attractive option compared with the current diagnostic standard of digital subtraction angiography, which is an invasive and expensive examination.

A team of clinicians from the department of radiology, division of cardiovascular and interventional radiology at the Medical University of Vienna in Austria recently a conducted retrospective analysis of clinical outcome among patients referred for CTA during a 13-month period because of peripheral occlusive disease in Fontaine stage IV (tissue loss). Their results, published in this month’s edition of the American Journal of Roentgenology, found that CTA lead to accurate recommendations for the management of critical limb ischemia

“To our knowledge, no studies have been focused on stage IV PAOD, the end stage of the disease, which is accompanied by several co-morbid conditions, such as hypertension and diabetes mellitus, the latter leading to microangiopathy,” the authors wrote.

CT angiogram (16-MDCT scanner, 16 × 0.75 mm slice collimation, 100 mL of iomeprol) shows femoropopliteal bypass grafts in both legs. In left leg, inflow and outflow of patent bypass are occluded. All three vessels of left lower leg are patent to ankle. Bypass graft on right side exhibits minimal aneurysmatic extension of proximal and distal anastomoses but is patent in all segments. Proximal part of right posterior tibial artery is occluded. Other segments and anterior tibial artery and peroneal artery are patent without substantial stenosis. Image and caption courtesy of the American Roentgen Ray Society.

The researcher’s cohort for their study was 28 patients with stage IV PAOD from a group of 150 consecutive patients referred to the department for CTA of the peripheral arteries. All patients underwent CTA with a 16-slice CT scanner (Somatom Sensation 16, Siemens Healthcare) from the level of the renal arteries through the forefoot.

Image reconstruction was performed on a dedicated workstation, and semiautomatic bone editing was performed for construction of maximum intensity projections (MIPs). In addition, the vessels were tracked semiautomatically for computation of a 3D branching tree of arterial centerlines. The images were then reviewed on a PACS viewing station as part of the department’s normal clinical routine.

“Multiple-path curved planar reformations were primarily used for vessel evaluation, whereas MIP images were checked for identification of collateral vessels,” the authors noted.

The treatment reports, discharge summaries and follow-up examinations were reviewed to ascertain the number of patients correctly treated on the basis of the CTA findings.

After CTA, endovascular treatment was indicated for eight patients, surgical revascularization for four patients, and a combined endovascular and surgical approach for two patients, the team reported. That the correct treatment decision had been made in all 14 cases was confirmed on the basis of successful endovascular or surgical revascularization. In eight patients, medical treatment was indicated, and one patient underwent amputation at the thigh.

In addition, toe amputation was indicated in six patients. Three of these patients underwent bypass surgery before toe amputation, and one patient underwent percutaneous transluminal angioplasty before toe amputation.

“That all endovascular and surgical treatments were performed as indicated by the CT angiographic findings emphasizes the value of CTA in the management of PAOD,” the authors wrote.

The team noted that other research has found that the advantages of CTA over MR angiography is higher image resolution for better evaluation of the small vessels in the calves and higher patient acceptance owing to a shorter examination time.

“Thus CTA seems to be an important technique in the management of stage IV PAOD in patients without an absolute contraindication to CTA,” the researchers concluded.