A comparative study of geometry-based methods and intra-arterial pressure measurements to assess the hemodynamic significance of equivocal iliac artery stenoses.

OBJECTIVES: To date, the ultimate decision to treat iliac artery stenoses in patients suffering from symptomatic peripheral arterial disease is based on the patient's symptoms and on visual inspection of angiographical images. The primary aim of this study was to investigate the accuracy of geometry-based methods (i.e. visual inspection and quantitative vascular analysis (Viewforum version R7.2v1 Advanced vessel analysis, Philips Healthcare, Best, The Netherlands) of 3D rotational angiography) to identify the severity of equivocal iliac artery stenosis in peripheral arterial disease patients with intra-arterial hyperemic pressure measurements (gold standard) as a reference. METHODS: Twenty patients with symptomatic iliac artery stenoses were subjected to 3D rotational angiography. Intra-arterial pressure measurements under hyperemic conditions were performed across 24 visually identified iliac artery stenoses. Three experienced interventional-radiologists retrospectively estimated the lumen diameter reduction by visual inspection. Furthermore, quantitative vascular analysis was performed on the 3D rotational angiography data. Geometry-based estimates were classified into two groups: lumen diameter reduction of <50% (non-significant) and diameter reduction ≥ 50% (significant), and compared to the intra-arterial hyperemic pressure gradients. A stenosis causing a pressure gradient (Δp) ≥10 mmHg was considered hemodynamically significant. RESULTS: Visual inspection and quantitative vascular analysis correctly identified hemodynamically significant stenoses in, respectively, 83% and 67% of the 24 iliac artery stenoses. Quantitative vascular analysis-based identification of hemodynamic significant stenoses (Δp ≥ 10 mmHg) could be optimized by lowering the threshold to a 42% lumen diameter reduction which improved the accuracy from 67% to 83%. CONCLUSIONS: Visual inspection of 3D rotational angiography by experienced interventional-radiologists has an 83% accuracy to identify hemodynamic significant iliac artery stenoses (Δ p ≥10 mmHg). The use of quantitative vascular analysis software did not improve accuracy.

Subtraction computed tomography imaging to detect endoleaks after endovascular aneurysm sealing with sac anchoring.

Background Early detection of small type I endoleaks after endovascular aneurysm sealing is mandatory because they can rapidly progress and lead to severe complications. Recognition of endoleaks can be challenging due to the appearances on computed tomography unique to endovascular aneurysm sealing. We aimed to validate the accuracy and added value of subtraction computed tomography imaging using a post-processing software algorithm to improve detection of endovascular aneurysm sealing-associated endoleaks on postoperative surveillance imaging. Methods The computed tomography scans of 17 patients (16 males; median age: 78, range: 72-84) who underwent a post-endovascular aneurysm sealing computed tomography including both non-contrast and arterial phase series were used to validate the post processing software algorithm. Subtraction images are produced after segmentation and alignment. Initial alignment of the stent segmentations is automatically performed by registering the geometric centers of the 3D coordinates of both computed tomography series. Accurate alignment is then performed by translation with an iterative closest point algorithm. Accuracy of alignment was determined by calculating the root mean square error between matched 3D coordinates of stent segmentations. Results The median root mean square error after initial center of gravity alignment was 0.62 mm (IQR: 0.55-0.80 mm), which improved to 0.53 mm (IQR: 0.47-0.69 mm) after the ICP alignment. Visual inspection showed good alignment and no manual adjustment was necessary. Conclusions The possible merit of subtraction computed tomography imaging for the detection of small endoleaks during surveillance after endovascular aneurysm sealing was illustrated. Alignment of different computed tomography phases using a software algorithm was very accurate. Further studies are needed to establish the exact role of this technique during surveillance after endovascular aneurysm sealing compared to less invasive techniques like contrast-enhanced ultrasound.

Endovascular treatment of complex abdominal aortic aneurysms by combining different types of endoprostheses.

PURPOSE: To describe an off-the-shelf method for the treatment of abdominal aortic aneurysms with hostile (large, >30 mm) neck and/or small (<20 mm) aortic bifurcation. CASE REPORT: We describe five patients with large aortic necks and/or small aortic bifurcations, which were treated by combining an AFX endoprosthesis with a Valiant Captiva endograft, and additional proximal endoanchors when deemed necessary. Initial technical success was 100%. Follow-up ranged from 228 to 875 days. One patient suffered a type 1A and 1B endoleak at 446 days follow-up, which were successfully treated by endovascular means. CONCLUSION: Combining the AFX and Valiant Captiva endografts is an off-the-shelf solution for treatment of large diameter aortic necks and small aortic bifurcations in patients deemed unfit for open repair or declined for fenestrated endografts. Longer follow-up is required to assess the long-term safety with special focus on aortic neck dilation.