When utilizing consistent centering protocols, this allows for reliable detection of kinks and stent graft migration to within 2 mm [54]. CT and CTA Due to its superior spatial resolution and rapid image acquisition, CTA with 3-D volumetric reconstruction and vessel analysis has gained wide acceptance as the gold standard for pre-EVAR evaluation. The utilization of 3-D reconstruction software has become paramount in EVAR planning, as it diminishes the impact of vessel tortuosity on diameter and length measurements, in addition to reducing intraobserver variability [55]. One author found that routine 3-D analysis of pre-EVAR images led to a significant reduction in Type I endoleaks [56]. Reformatted CTA images in the coronal and sagittal planes should be utilized for increased diagnostic accuracy. In most cases, a CTA of the abdomen and pelvis is appropriate to ensure coverage of the entire aneurysm and vascular access. The CTA should include the chest in patients with thoracoabdominal aortic aneurysms (TAAA). Aortography As aortography and radiography are unable to accurately provide aneurysm sac diameter measurements and landing zone assessment, these modalities are inadequate for pre-EVAR or open repair evaluation. However, aortography may be of value in assessing branch vessel patency and is usually part of branch vessel occlusion procedures before aneurysm repair. MRA For the purpose of pre-EVAR planning, T1-weighted spin-echo images and flow-based methods such as time of flight or phase contrast provide adequate details regarding aneurysm morphology and relevant vascular anatomy. However, these techniques are limited by low spatial resolution and signal-to-noise ratio and are therefore suboptimal for evaluating small-vessel lesions or diminutive side branches [33]. Furthermore, flow-based sequences are susceptible to flow artifacts that may overestimate the degree of stenosis or falsely demonstrate an occlusion [57].
Abdominal Aortic Aneurysm or Dissection Interventional Planning and Follow up. When utilizing consistent centering protocols, this allows for reliable detection of kinks and stent graft migration to within 2 mm [54]. CT and CTA Due to its superior spatial resolution and rapid image acquisition, CTA with 3-D volumetric reconstruction and vessel analysis has gained wide acceptance as the gold standard for pre-EVAR evaluation. The utilization of 3-D reconstruction software has become paramount in EVAR planning, as it diminishes the impact of vessel tortuosity on diameter and length measurements, in addition to reducing intraobserver variability [55]. One author found that routine 3-D analysis of pre-EVAR images led to a significant reduction in Type I endoleaks [56]. Reformatted CTA images in the coronal and sagittal planes should be utilized for increased diagnostic accuracy. In most cases, a CTA of the abdomen and pelvis is appropriate to ensure coverage of the entire aneurysm and vascular access. The CTA should include the chest in patients with thoracoabdominal aortic aneurysms (TAAA). Aortography As aortography and radiography are unable to accurately provide aneurysm sac diameter measurements and landing zone assessment, these modalities are inadequate for pre-EVAR or open repair evaluation. However, aortography may be of value in assessing branch vessel patency and is usually part of branch vessel occlusion procedures before aneurysm repair. MRA For the purpose of pre-EVAR planning, T1-weighted spin-echo images and flow-based methods such as time of flight or phase contrast provide adequate details regarding aneurysm morphology and relevant vascular anatomy. However, these techniques are limited by low spatial resolution and signal-to-noise ratio and are therefore suboptimal for evaluating small-vessel lesions or diminutive side branches [33]. Furthermore, flow-based sequences are susceptible to flow artifacts that may overestimate the degree of stenosis or falsely demonstrate an occlusion [57].