Before people are deemed to be a suitable candidate for this treatment, they have to go through a rigorous set of tests. These include a CT scan of the complete thorax/abdomen/pelvis, and blood tests. The CT scan gives precise measurements of the aneurysm and the surrounding anatomy. In particular the calibre/tortuosity of the iliac arteries and the relationship of the neck of the aneurysm to the renal arteries are important determinants of whether the aneurysm is amenable to endoluminal repair. In certain occasions where the renal arteries are too close to the aneurysm, the custom-made fenestrated graft stent is now an accepted alternative to doing open surgery.