Post-EVAR aortic neck elongation: is a real phenomenon or a conformational change during the cardiac cycle?

BACKGROUND: Stent-graft migration is a late-term complication of endovascular abdominal aortic aneurysm repair (EVAR). A recent published study suggests that stent graft migration could be explained only by aortic neck elongation, mimicking the appearance of distal stent graft migration. Several studies about the use of dynamic CT Angiography (CTA) in the evaluation of aortic conformation changes during the cardiac cycle demonstrate that axial aortic pulsatility exists. No studies have been carried out to evaluate if a longitudinal aortic pulsatility also exists, that could justify the aortic neck elongation previously reported. AIM: To assess variations in length of proximal neck and infrarenal abdominal aorta in patients selected to undergo EVAR; to assess if longitudinal aortic pulsatility could modify EVAR planning. PATIENTS AND METHODS: 40 patients with Abdominal Aortic Aneurysm (AAA) underwent both static and dynamic ECG-gated 64-CTA (0.625 mm-slice-collimation; 1.25 mm-reconstruction increment). Manual measurements of aortic neck length and infrarenal abdominal aorta were performed on modified coronal images to determine dynamic conformational changes. RESULTS: Significant longitudinal pulsatility was demonstrated within aneurysm neck (19.1 ± 8.6%) and infrarenal abdominal aorta (6.6 ± 1.6%). When compared to dynamic measurements, the endograft previously selected according to static images in terms of fixation, would be potentially changed in 6/40 patients (15%) whereas 4/40 (10%) patients were not eligible for EVAR. CONCLUSIONS: Dynamic ECG-gated CTA may provide information regarding longitudinal pulsatile motion that could change the EVAR planning based on static imaging. Reported post-EVAR elongation of infrarenal aortic neck could be an unreal phenomenon only due to a conformational change during cardiac cycle.

Foot CT perfusion in patients with peripheral arterial occlusive disease (PAOD): a feasibility study.

PURPOSE: To prospectively assess the technical feasibility and reproducibility of quantitative foot perfusion multidetector-row computed tomography (MDCT) in patients with peripheral occlusive artery disease (PAOD) and to evaluate perfusion parameters changes after endovascular treatment. MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained. 10 patients older than 65 years (mean 74.1 years, range 66-95 years) with PAOD and who were referred to our department for single-limb endovascular treatment were enrolled prospectively. All patients underwent foot CT perfusion examinations before and within 72 h after endovascular treatment. A 64-row CT lightspeed VCT scanner (GE Medical Systems) was used with acquisition of eight contiguous 5-mm reconstructed sections (60-s acquisition time; 40 mL Iomeprol 400 mgI/mL, @4 mL/s). Data were analyzed by two blinded readers using commercially available software to calculate perfusion parameters. Inter-observer and intra-observer agreement of perfusion CT analysis was assessed using Bland-Altman analyses and intra-class correlation coefficient (ICC). Changes in perfusion parameters after endovascular treatment were assessed using Wilcoxon's test. RESULTS: Good inter-observer and intra-observer agreement was obtained in all patients. Good agreement was obtained for perfusion parameters for the untreated foot and in repeated studies. By comparing perfusion parameters in the treated foot, a significantly shorter mean transit time (MTT) was obtained. CONCLUSIONS: Foot CT perfusion is a feasible and reproducible technique. A significant decrease of MTT between pre- and post-revascularization suggests improved flow in the below-the-knee arteries.

Multi-detector CT angiographic imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR).

BACKGROUND: Multidetector computed tomography (MDCT) angiography represents the standard of reference in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR), being effective in the detection of the full spectrum of possible complications on both axial and 3D images. METHODS: The purpose of this article is to review the normal CT angiography findings of the different types of stent-grafts and to describe the radiological findings of early and late complications after EVAR on axial and reconstructed images. A selection of cases of post-EVAR MDCT angiography is presented to learn the techniques most commonly used for endovascular treatment, the correct CT scanning technique to acquire the data, the full gamut of possible procedure-related complications and how these complications usually appear on CT images. CONCLUSION: MDCT angiography is an effective and specific technique in both the pre- and postoperative settings of EVAR procedures. A better understanding of the procedure, the devices, the normal postoperative imaging features and the possible procedure-related complications ensures optimal planning and follow-up of patients undergoing an EVAR procedure.

Aortic-neck dilation after endovascular abdominal aortic aneurysm repair (EVAR): can it be predicted?

PURPOSE: This study was performed to evaluate whether dynamic computed tomography (CT) can provide functional vessel information predicting outcomes of aortic neck in patients undergoing endovascular aneurysm repair (EVAR) of an abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Twenty patients with and 20 without AAA were enrolled. Electrocardiographically (ECG)-gated data sets were acquired with a 64-slice CT scanner. Axial pulsatility measurements were taken at three levels: 2 cm above the highest renal artery; immediately below the lowest renal artery; 1 cm below the lowest renal artery. Three independent readers performed the measurements. Systolic and diastolic blood pressures were measured in the brachial artery to calculate arterial-wall distensibility expressed as pressure strain elastic modulus (Ep). Cross-sectional area change, wall distensibility and Ep value were statistically compared. RESULTS: No significant differences were found in terms of Ep values in the suprarenal and juxtarenal level. In the AAA group, a significantly higher value was obtained at the infrarenal level. A subgroup of patients with AAA (45%) had a significantly higher Ep value at the infrarenal level. CONCLUSIONS: Dynamic CT provided insight into the abdominal aorta pathophysiology. Identifying patients with higher infrarenal distensibility could change selection of graft size to improve proximal fixation.