Accuracy of Centerline of Flow Measurement for Sizing of the Zenith AAA Endovascular Graft and Predictive Factor for Risk of Inadequate Sizing

Comprehensive comparison of three different workstations for accurate planning of endovascular stent implantation in patients with thoracic aortic aneurysms

Purpose

To assess the diagnostic precision of three different workstations for measuring thoracic aortic aneurysms (TAAs) in vivo and ex vivo using either pre-interventional computed tomography angiography scans (CTA) or a specifically designed phantom model.

Methods

This retrospective study included 23 patients with confirmed TAA on routinely performed CTAs. In addition to phantom tube diameters, one experienced blinded radiologist evaluated the dimensions of TAAs on three different workstations in two separate rounds. Precision was assessed by calculating measurement errors. In addition, correlation analysis was performed using Pearson correlation.

Results

Measurements acquired at the Siemens workstation deviated by 3.54% (range, 2.78–4.03%; p = 0.14) from the true size, those at General Electric by 4.05% (range, 1.46–7.09%; p < 0.0001), and at TeraRecon by 4.86% (range, 3.22–6.45%; p < 0.0001). Accordingly, Siemens provided the most precise workstation at simultaneously most fluctuating values (scattering of 4.46%). TeraRecon had the smallest fluctuation (scattering of 2.83%), but the largest deviation from the true size of the phantom. The workstation from General Electric showed a scattering of 2.94%. The highest overall correlation between the 1st and 2nd rounds was observed with measurements from Siemens (r = 0.898), followed by TeraRecon (r = 0.799), and General Electric (r = 0.703). Repetition of measurements reduced processing times by 40% when using General Electric, by 20% with Siemens, and by 18% with TeraRecon.

Conclusions

In conclusion, all three workstations facilitated precise assessment of dimensions in the majority of cases at simultaneously high reproducibility, ensuring accurate pre-interventional planning of thoracic endovascular aortic repair.

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Pre-interventional planning of TEVAR in patients with TAAs using CTA is feasible.

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All three workstations facilitated accurate measurements in vivo and ex vivo.

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Repetition of measurements resulted in faster processing due to learning effects.

Current status of endovascular treatment for thoracoabdominal aortic aneurysms

Open surgical repair (OSR) for thoracoabdominal aortic aneurysms (TAAAs) is maximally invasive and associated with high rates of operative mortality and perioperative complications including spinal cord ischemia (SCI), despite improvements in surgical techniques and perioperative care. Elderly patients, patients with a history of aortic surgery, and patients with severe comorbidities are often considered ineligible for this surgery and endovascular treatment may be their only treatment option. Total endovascular aneurysm repair (t-EVAR) without debranching surgery does not require thoracotomy and laparotomy and could improve the outcomes of these patients. t-EVAR includes fenestrated EVAR (f-EVAR), multi-branched EVAR (b-EVAR), and physician-modified fenestration endograft (PMFG). Although these techniques have achieved lower mortality rates than OSR, there are concerns about perioperative complications including limb ischemia, SCI, and long-term outcomes such as endograft migration and endoleaks (ELs). This article provides an overview of available endovascular devices for TAAAs and reviews the short and mid-term results of t-EVAR, as well as alternative options.

Measuring the greater curvature length of virtual stent graft can provide accurate prediction of stent graft position for thoracic endovascular aortic repair

OBJECTIVE

The objective of this study was to assess the accuracy of predicting stent graft position for thoracic endovascular aortic repair by measuring three lengths of the virtual stent graft: smaller curvature (SC), center lumen line (CL), and greater curvature (GC).

METHODS

From January 2012 to December 2016, patients treated at our institution were analyzed retrospectively. Patients who were treated with more than two devices, patients treated for aortic dissection, and cases without complete preoperative or postoperative computed tomography (CT) data were excluded. From the preoperative CT data, the virtual stent graft image based on the SC (SCVS) was created so that its SC length matched that of the stent graft actually used. In the same manner, virtual stent graft images based on the CL (CLVS) and GC (GCVS) were created. These virtual stent graft images were created using SYNAPSE VINCENT software (Fujifilm Co, Tokyo, Japan) and superimposed on the postoperative CT image to measure the misalignment between these virtual stent graft images and the actual stent graft. These misalignments were compared using Wilcoxon signed rank sum test. In addition, the actual length (AL) of the stent graft was measured on the basis of the CL from postoperative CT data and compared with its original length (OL).

RESULTS

A total of 35 cases were analyzed. Twenty-six patients were men. The average age of the patients was 72.4 ± 13.0 years. The proximal landing zone were located at the descending aorta (n = 11) and the aortic arch (n = 24). The misalignment between SCVS, CLVS, and GCVS and actual stent graft position was -47.8 ± 18.1 mm, -21.5 ± 9.4 mm, and 5.3 ± 7.4 mm, respectively. The difference in means between the three groups was significant (P < .001). The relationship between the AL based on CL and OL was represented by the formula AL = OL * 0.92 - 0.05 (in the descending aorta) and AL = OL * 0.77 + 9.85 (in the aortic arch).

CONCLUSIONS

Compared with CLVS and SCVS, GCVS was the most accurate predictor of stent graft position for thoracic endovascular aortic repair.

Repair of abdominal aortic aneurysms: preoperative imaging and evaluation

Imaging is a critical component of the pre-procedure evaluation and planning of endovascular aneurysm repair (EVAR). Imaging is the mainstay for proper assessment of procedural candidacy, relevant vascular anatomy, device selection, and surgical approach. Computed tomography angiography (CTA) has long been considered the preferred modality for pre-operative imaging and evaluation prior to EVAR. Recently, advances in image quality and software technology have further enhanced the proceduralist's ability to plan and perform EVAR. In this review, we highlight the current state of the art to provide interventionalists a contemporary assessment of the available tools for pre-operative imaging and evaluation prior to EVAR.

Morphological analysis using geometric parameters for splenic aneurysms

Background Considering the unique characteristics of splenic artery aneurysms, we hypothesized that hemodynamic forces could play an important role in splenic artery aneurysm formation and that splenic artery geometry should be correlated with aneurysm development. Methods Tortuosity of the splenic artery was evaluated three-dimensionally by calculating the curvature using software and the original modeling system. We selected 54 splenic artery aneurysm patients who had undergone thin-slice computed tomography imaging with contrast. We compared the splenic artery aneurysm group to non-vascular patients via propensity-score matching (35 patients in each group). The splenic artery length index, average curvature, and maximum curvature were analyzed. Results Splenic artery aneurysm patients tended to have a longer splenic artery and the curvature was more severe compared to the non-vascular control patients. The average curvature of splenic artery aneurysm patients was associated with the dilatation rate in female patients. Conclusion Females with a tortuous splenic artery may have an increased risk of aneurysm formation.

A systematic review of protocols for the three-dimensional morphologic assessment of abdominal aortic aneurysms using computed tomographic angiography

The morphology of infrarenal abdominal aortic aneurysms (AAAs) directly influences the perioperative outcome and long-term durability of endovascular aneurysm repair. A variety of methods have been proposed for the characterization of AAA morphology using reconstructed three-dimensional (3D) computed tomography (CT) images. At present, there is lack of consensus as to which of these methods is most applicable to clinical practice or research. The purpose of this review was to evaluate existing protocols that used 3D CT images in the assessment of various aspects of AAA morphology. An electronic search was performed, from January 1996 to the end of October 2010, using the Embase and Medline databases. The literature review conformed to PRISMA statement standards. The literature search identified 604 articles, of which 31 studies met inclusion criteria. Only 15 of 31 studies objectively assessed reproducibility. Existing published protocols were insufficient to define a single evidence-based methodology for preoperative assessment of AAA morphology. Further development and expert consensus are required to establish a standardized and validated protocol to determine precisely how morphology relates to outcomes after endovascular aneurysm repair.