In vitro evaluation of the accuracy of open-configuration MRI in endovascular techniques

The purpose of this study was to determine the accuracy of an interventiona l magnetic resonance imaging (iMRI) system to position an endsvascular cath eter in an in vitro model that simulated an infrarenal aortic aneurysm. Ade quate visualization of abdominal aortic aneurysms (AAAs) was shown previous ly in humans, A dedicated near-real-time imaging protocol readily available on a Signa SP 0.5T open-configuration MRI unit (General Electric Medical S ystems, Milwaukee, WI, USA) was used to image the AAAs of ten human volunte ers. A pulsatile in vitro model that simulated an AAA was built, which incl uded the kidneys, the renal arteries, the aorta, and the iliac arteries. A catheter was advanced to a predetermined target through one of the iliac li mbs of the model. Using two different techniques, the accuracy with which a n interventionist could position the endovascular catheter under the near-r ealtime guidance of the iMRI system was evaluated. The AAAs of all ten pati ents were visualized, including the aneurysm wall, the thrombus within it, and the residual lumen, while maintaining adequate contrast, signal, and im aging speed. The position of the catheter was evaluated on target in 42 in vitro procedures. This series of tests showed an average accuracy of 1 mm f or catheter positioning. The near-real-time imaging mode of the iMRI system enabled satisfactory evaluation of human AAAs, and it showed great accurac y for catheter positioning in the in vitro model. These results provide opt imism regarding the potential of iMRI in endovascular surgery.