Post-EVAR surveillance


The Eurostar contributors’ meeting held during this year’s European Society for Vascular Surgery meeting focused on post-operative surveillance after endovascular aneurysm repair. Among the issues tackled was whether it is still appropriate to rely on CT scans, which are expensive, time-consuming and subject patients to relatively high levels of radiation.

During the Eurostar meeting, Dr Rodney White, Chief of Vascular Surgery at Harbor-UCLA Medical Center, Torrance, California, gave a brief overview of the American Lifeline Registry of procedures for endovascular aneurysm repair. The failings of the current Eurostar protocol for follow up surveillance were then addressed by Jaap Buth. Jean-Pierre Becquemin asked how effective duplex ultrasound is and Richard McWilliams looked at the role of plain x-ray. St©phan Haulon of Lille University Hospital, France, then went on to look at the role of magnetic resonance imaging (MRI).

Dr Haulon explained that Helical CT is currently widely used for endoleak detection. However, it has its limitations, specifically false negative results in patients with angiographically documented type II endoleaks. MRI techniques have the potential to become an alternative to helical CT for the detection of endoleaks, he said.The early detection of such leaks is potentially of major clinical importance given the propensity to favor aneurysm rupture, and because effective treatment by selective embolization is now possible, continued Haulon.

In MRI, a body coil array is positioned on the abdomen. T1 and T2 weighted images in axial mode are performed to study the diameter of the aneurysm and the type of signal in thrombus. A three dimensional magnetic resonance angiogram with injection of gadolinium is then performed in coronal acquisition with axial reconstruction (MultiPlanar Reformation, MPR) and three dimensional Maximum Intensity Projection. Finally a second set of T1 weighted images are taken after gadolinium injection (3 to 5 min).

Haulon then presented a study of 31 patients treated by stent grafts. All patients had helical CT and MRI examinations at one and six months, and arteriography at 12 months (see tables below for results).

Haulon’s conclusions about MRI were:

  • It is most sensitive for Type 2 endoleak detection

  • It can provide early endoleak diagnosis

  • It limits exposure to contrast medium (nephrotoxicity and potential allergic reactions) and to ionizing radiation

  • Stainless steel stents are unsuitable for MRI evaluation