Dynamic magnetic resonance angiography of the aneurysm neck: Conformational changes during the cardiac cycle with possible consequences for endograft sizing and future design

Abstract

In patients with (atherosclerotic) aneurysm disease, the aortic dimensions at the level of and proximal to the aneurysm neck change during the cardiac cycle. This phenomenon is preserved after EVAR. Therefore, maximum diameter using dynamic MRA may not be similar to the maximum diameter with static CTA in all patients, and a standard regimen of 10% to 15% oversizing of an endograft based on static CTA images may be inadequate for some patients. Further studies using dynamic MRA to evaluate effects of different endografts are anticipated, with possible consequences for endograft designs.

Update in the management of type B aortic dissection

“…74,77 Mis-sizing of the stent-graft can be avoided by keeping in mind the dynamic behavior of the aorta. [78][79][80] Adequate device size should be based on the diameter of the aorta proximal to the dissected segment. Furthermore, a proximal aortic neck length of at least 2 cm is needed to achieve adequate fixation of the stent-graft.…”

Motion Calculations on Stent Grafts in AAA

“…Most studies related to the motion of stent grafts focus on measuring the stent's diameter changes (van Herwaarden, Bartels, Muhs, Vincken, Lindeboom, Teutelink, Moll & Verhagen, 2006) or determining the motion at a sparse set of points on the stent (Langs et al, 2007). A model that enables capturing material properties and high level knowledge regarding the stent graft characteristics would be valuable to gain more insight in the stent's in vivo behavior (Langs et al, 2007).…”

“…This information will be beneficial for designing future devices and can be valuable in predicting stent graft failure in individual patients (Langs et al, 2007). Motions of (stent grafts in) AAA can be measured using fluoroscopic roentgenographic stereophotogrammetric analysis (FRSA) (Koning et al, 2007), dynamic magnetic resonance imaging (van Herwaarden, Muhs, Vincken, van Prehn, Teutelink, Bartels, Moll & Verhagen, 2006), and ECG-gated CT (Teutelink et al, 2007). Although ultrasound is also used (van der Laan et al, 2003), it does not produce the three dimensional images that are required for the quantitative analysis of the whole stent graft.…”

Dynamic characterization of aorta morphology and function in presence of an aneurysm

“…In addition, in case of stent-graft deployment, imaging techniques such as computed tomography (CT) have the fundamental role in the search for anatomic details necessary to evaluate the most suitable anatomy for stent-graft and in the postoperative follow-up after stent graft placement. It is well known that this knowledge is crucial to improve its durability and results [1,2].…”

“…In addition, in case of stent-graft deployment, imaging techniques such as computed tomography (CT) have the fundamental role in the search for anatomic details necessary to evaluate the most suitable anatomy for stent-graft and in the postoperative follow-up after stent graft placement. It is well known that this knowledge is crucial to improve its durability and results [1,2].Since no analysis software is available on the CT imaging system to extract quantitative parameters that could be very useful to evaluate aorta morphology and function, in clinical practice, medical doctors usually perform manual measurements of aorta diameters in specific anatomical sites. This procedure is subjective and time-consuming.…”