The purpose of this study was to evaluate the use of three-dimensional rendering of Computed Tomography Angiography (CTA) data for the evaluation of the poplitea before and after the placement of an endoprosthesis using scans both with the knee in flexion and extension. In 12 patients, 17 poplitea aneurysms were found, of which 12 were selected for endovascular treatment. Before and after the treatment of the patient a CTA was performed both in extension and flexion and the acquired data were volume rendered using special purpose volume rendering software. The results were presented to the vascular surgeon as movies showing a full rotation of a three-dimensional image of the poplitea area. With the use of three-dimensional (3D) visualization, especially with the knee in flexion, locations of kinking and coiling of the popliteal artery were clearly observed. Based on these observations the endograft was exactly positioned during the endovascular procedure. The goal of the treatment was to bypass both the aneurysm and bending points in the artery. Correct placement of the endograft was evaluated by control CTA in flexion and extension, Although the endograft was positioned at the desired location residual kinking sites were observed. During follow-up in three cases the endograft failed. Urokinasis treatment was successful in all three cases. In two cases a severe stenosis had developed at the specific residual kinking sites at the end of Hunter's channel. In both cases PTA and additional stent placement was performed. A second control CTA showed no residual kinking or stenosis. In one case a stenosis developed in the popliteal artery just distal of the endograft, which was treated with a PTA. This study showed that high resolution CTA scanning in flexion and extension of the popliteal artery both before and after intervention is feasible. High quality three-dimensional visualization of the popliteal artery has a high predictive value in the determination of future kinking sites of the artery after endograft placement. Therefore it is helpful in the selection, work-up and evaluation of patients for endovascular treatment of popliteal aneurysms.
