What imaging studies are necessary for abdominal aortic endograft sizing? A prospective blinded study using conventional computed tomography, aortography, and three-dimensional computed tomography

Impact of intravascular ultrasound-guided endovascular therapy on periprocedural outcomes in patients with lower-extremity artery disease

BACKGROUND

Although technological improvements in intravascular ultrasound (IVUS) may reduce technical failures in endovascular therapy (EVT), perioperative complications (POCs) associated with IVUS use may increase.

AIMS

This study investigated the impact of IVUS on periprocedural outcomes in symptomatic lower-extremity artery disease (LEAD) patients undergoing EVT.

METHODS

This study evaluated 28,088 symptomatic LEAD patients who underwent EVT between January 2021 and December 2021 using a prospective nationwide registry in Japan. Outcome measures included periprocedural outcomes, including technical failure and POCs. To compare outcomes with and without IVUS use, propensity score matching analysis was performed for overall and for each arterial region (aortoiliac [AI], femoropopliteal [FP], and infrapopliteal [IP] arteries) using a binary logistic regression model.

RESULTS

IVUS was used in 75%, 72%, and 37% of AI, FP, and IP lesions, respectively. After propensity matching extraction, the IVUS group had a tendency of lower technical failure rate than the non-IVUS group, although not statistically different (3.9% vs. 5.4%, p = 0.054), without an increase in the POC rate (1.8% vs. 1.6%, p = 0.54). Regarding the per-regional analysis, the technical failure rate of FP-EVT was significantly lower in the IVUS group (3.1% vs. 4.2%, p = 0.006), whereas those of AI-EVT (2.2% vs. 3.1%, p = 0.12) and IP-EVT (6.8% vs. 6.1%, p = 0.37) were not significantly different between the two groups. Furthermore, IVUS did not increase the POC rate for any region (AI-EVT: 1.3% vs. 1.3%, p = 1.00; FP-EVT: 1.8% vs. 1.7%, p = 0.75; and IP-EVT: 2.0% vs. 1.7%, p = 0.56).

CONCLUSION

The current study revealed that IVUS did not increase the POCs and technical failure for overall lesions but reduced the incidence of FP-EVT technical failure.

Evaluation of Computerized Tomography Utilization in Comparison to Digital Subtraction Angiography in Patients with Peripheral Arterial Disease

BACKGROUND

Perform literature review to analyze current practices in imaging patient with peripheral arterial disease (PAD) and examine patterns in our practice in order to assess whether a lower extremity computed tomography angiography (CTA) in addition to digital subtraction angiography enhanced the assessment of vessel calcification, percentage of stenosis, and affected outcomes in patients with PAD.

METHODS

The study included patients who underwent lower extremity imaging and were followed up to 12 months. This population was divided into cases who had both an angiogram and CTA performed within 30 days (n = 20), and controls who underwent angiography only (n = 19). Baseline characteristics, imaging results, and clinical outcomes were analyzed.

RESULTS

Thirty-nine patients met study criteria (mean age was 58.4 years, 69.2% were males, and 33.3% had diabetes). Patients mostly presented with tissue loss/rest pain (10.3%), claudication (15.4%), acute limb (10.3%), and trauma (15.4%). We have not observed any statistically significant differences in various examined blood vessels when their features (e.g., vessel diameter, stenosis, calcifications) were assessed by CTA combined with angiography versus angiography alone. The exceptions were external iliac artery, superficial femoral artery and dorsalis pedis vessels. In external iliac artery percentage of stenosis was 1.11% as determined by computed tomography (CT) scan versus 30% by angiography (P = 0.009). For superficial femoral artery stenosis, the percentage determined by CT was 48.68% vs. 81.41% by angiography, and observed difference between 2 modalities was statistically significant (P = 0.025). For dorsalis pedis percentage of stenosis detected by CT scan was 60.63% vs. 22.73% by angiography, and the differences in findings by these modalities were statistically significant (P = 0.039). The most frequent perioperative complication was cardiac-related (35.5%). Nineteen patients were readmitted and 8 had reinterventions within 12 months.

CONCLUSIONS

Both imaging modalities yielded similar results for assessing vessel calcification and percentage of stenosis regardless of anatomic vessel location. Overall, utilization of CTA in addition to angiography for large vessels above the knee (e.g., iliac artery, superficial femoral artery) and below the knee for dorsalis pedis provided more detailed information on the properties of these vessels. Therefore, during preoperative assessments, CTA may be helpful in addition to angiography for planning surgical and endovascular interventions for symptomatic PAD treatment in larger vessels.

Editor's Choice -- European Society for Vascular Surgery (ESVS) 2024 Clinical Practice Guidelines on the Management of Abdominal Aorto-Iliac Artery Aneurysms

OBJECTIVE

The European Society for Vascular Surgery (ESVS) has developed clinical practice guidelines for the care of patients with aneurysms of the abdominal aorta and iliac arteries in succession to the 2011 and 2019 versions, with the aim of assisting physicians and patients in selecting the best management strategy.

METHODS

The guideline is based on scientific evidence completed with expert opinion on the matter. By summarising and evaluating the best available evidence, recommendations for the evaluation and treatment of patients have been formulated. The recommendations are graded according to a modified European Society of Cardiology grading system, where the strength (class) of each recommendation is graded from I to III and the letters A to C mark the level of evidence.

RESULTS

A total of 160 recommendations have been issued on the following topics: Service standards, including surgical volume and training; Epidemiology, diagnosis, and screening; Management of patients with small abdominal aortic aneurysm (AAA), including surveillance, cardiovascular risk reduction, and indication for repair; Elective AAA repair, including operative risk assessment, open and endovascular repair, and early complications; Ruptured and symptomatic AAA, including peri-operative management, such as permissive hypotension and use of aortic occlusion balloon, open and endovascular repair, and early complications, such as abdominal compartment syndrome and colonic ischaemia; Long term outcome and follow up after AAA repair, including graft infection, endoleaks and follow up routines; Management of complex AAA, including open and endovascular repair; Management of iliac artery aneurysm, including indication for repair and open and endovascular repair; and Miscellaneous aortic problems, including mycotic, inflammatory, and saccular aortic aneurysm. In addition, Shared decision making is being addressed, with supporting information for patients, and Unresolved issues are discussed.

CONCLUSION

The ESVS Clinical Practice Guidelines provide the most comprehensive, up to date, and unbiased advice to clinicians and patients on the management of abdominal aorto-iliac artery aneurysms.

Pulsatile Changes of the Aortic Diameter May Be Irrelevant Regarding Endograft Sizing in Patients With Aortic Disease

PURPOSE

Endovascular aortic repair has become the preferred elective treatment of infrarenal aortic aneurysms. Aortic pulsatility may pose problems regarding endograft sizing. The aims of this study are to determine the aortic pulsatility in patients with aortic disease and to evaluate the effect of pulsatility on the growth of aneurysms.

MATERIALS AND METHODS

In this retrospective study, analyses of computed tomography angiography (CTA) images of 31 patients under conservative treatment for small abdominal aortic aneurysms were performed. Reconstructions of the raw electrocardiography (ECG) gated dataset at 30% and 90% of the R-R cycle were used. After lumen segmentation, total aortic cross-sectional area was measured in diastole and systole in the following zones: Z0, Z3, Z5, Z6, Z8, and Z9. Effective diameters (EDs) were calculated from the systolic (ED_sys) and diastolic (ED_dia) cross-sectional areas to determine absolute (ED_sys - ED_dia, mm) and relative pulsatility [(ED_sys - ED_dia) / ED_dia, %]. Diameter of the aneurysms was measured on baseline images and the last preoperative follow-up study of each patient.

RESULTS

A total of 806 measurements were completed, 24 pulsatility and 2 growth measurements per patient. The mean pulsatility values at each point were as follows: Z0: 0.7±0.8 mm, Z3: 1.0±0.6 mm, Z5: 1.0±0.6 mm, Z6: 0.8±0.7 mm, Z8: 0.7±1.0 mm, Z9: 0.9±0.9 mm. Follow-up time was 5.5±2.2 years during which a growth of 13.42±9.09 mm (2.54±1.55 mm yearly) was observed. No correlation was found between pulsatility values and growth rate of the aneurysms.

CONCLUSION

The pulsatility of the aorta is in a submillimetric range for the vast majority of patients with aortic disease, thus probably not relevant regarding endograft sizing. Pulsatility of the ascending aorta is smaller than that of the descending segment, making an additional oversize of a Z0 implantation questionable.

CLINICAL IMPACT

Endovascular aortic repair reqiures precise preoperative planning. Pulsatile changes of the aortic diameter may pose issues regarding endograft sizing. In our retrospective single-centre study, aortic pulsatility of patients with AAA was measured on ECG gated CTA images. Pulsatility values reached a maximum at the descending aorta, however absolute pulsatility values did not exceed 1 mm at any point along the aorta. Therefore, significance of aortic pulsatility regarding the sizing of EVAR prostheses is questionable. Correlation between pulsatility and AAA growth was not found.

Hybrid room: Does it offer better accuracy in the proximal deployment of infrarenal aortic endograft?

PURPOSE

This work aims to evaluate the impact of hybrid rooms and their advanced tools on the accuracy of proximal deployment of infrarenal bifurcated endograft (EVAR).

METHODS

A retrospective single centre analysis was conducted between January 2015 and March 2019 including consecutive patients that underwent EVAR. Groups were defined whether the procedure was performed in a hybrid operating room (HOR group) or using a mobile 2D fluoroscopic imaging system (non-HOR group). The accuracy of the proximal deployment was estimated by the distance (mm) between the bottom of the lowest renal artery (LwRA) origin and the endograft radiopaque markers parallax (LwRA/EDG distance) after curvilinear reconstruction. The impact of HOR on the LwRA/EDG distance was investigated using a multiple linear regression model. A composite "proximal neck"-related complications event was studied (Cox models).

RESULTS

Overall, 93 patients (87 %male, median age 73 years) were included with 49 in the HOR group and 44 in the non-HOR group. Preoperative CTA analysis of the proximal neck exhibited similar median length, but different median aortic diameter (p=0.012) and median beta angulation (p=0.027) between groups. The median LwRA/EDG distance was shorter in the HOR group (multivariate model, p=0.022). No difference in "proximal neck"-related complications was evidenced between the HOR and non-HOR groups (univariate analysis, p=0.620). Median follow-up time was respectively 25 [14-28] and 36 months [23-44] in the HOR group and in the non-HOR group (p<0.001).

CONCLUSION

HOR offer more accurate proximal deployment of infrarenal endografts, with however no difference in "proximal neck"-related complications between groups.

Fully automatic volume segmentation of infrarenal abdominal aortic aneurysm computed tomography images with deep learning approaches versus physician controlled manual segmentation

OBJECTIVE

Imaging software has become critical tools in the diagnosis and decision making for the treatment of abdominal aortic aneurysms (AAA). However, the interobserver reproducibility of the maximum cross-section diameter is poor. This study aimed to present and assess the quality of a new fully automated software (PRAEVAorta) that enables fast and robust detection of the aortic lumen and the infrarenal AAA characteristics including the presence of thrombus.

METHODS

To evaluate the segmentation obtained with this new software, we performed a quantitative comparison with the results obtained from a semiautomatic segmentation manually corrected by a senior and a junior surgeon on a dataset of 100 preoperative computed tomography angiographies from patients with infrarenal AAAs (13,465 slices). The Dice similarity coefficient (DSC), Jaccard index, sensitivity, specificity, volumetric similarity (VS), Hausdorff distance, maximum aortic transverse diameter, and the duration of segmentation were calculated between the two methods and, for the semiautomatic software, also between the two observers.

RESULTS

The analyses demonstrated an excellent correlation of the volumes, surfaces, and diameters measured with the fully automatic and manually corrected segmentation methods, with a Pearson's coefficient correlation of greater than 0.90 (P < .0001). Overall, a comparison between the fully automatic and manually corrected segmentation method by the senior surgeon revealed a mean Dice similarity coefficient of 0.95 ± 0.01, a Jaccard index of 0.91 ± 0.02, sensitivity of 0.94 ± 0.02, specificity of 0.97 ± 0.01, VS of 0.98 ± 0.01, and mean Hausdorff distance per slice of 4.61 ± 7.26 mm. The mean VS reached 0.95 ± 0.04 for the lumen and 0.91 ± 0.07 for the thrombus. For the fully automatic method, the segmentation time varied from 27 seconds to 4 minutes per patient vs 5 minutes to 80 minutes for the manually corrected methods (P < .0001).

CONCLUSIONS

By enabling a fast and fully automated detailed analysis of the anatomic characteristics of infrarenal AAAs, this software could have strong applications in daily clinical practice and clinical research.

Important issues regarding planning and sizing for emergent TEVAR

In the past decades, treatment of acute thoracic aortic syndrome underwent drastic changes with a central role for thoracic endovascular aortic repair (TEVAR). One of the essential factors in the success of TEVAR is accurate sizing of the endograft, as both under- and oversizing can lead to suboptimal results and disastrous complications. The aim of this review was to give an overview of issues regarding endograft sizing in emergent TEVAR. Sizing of the endograft can be complicated by specific factors related to the underlying disease. For instance, different types of the acute thoracic aortic syndrome, i.e. blunt thoracic injury, thoracic aortic aneurysm or dissection with concomitant rupture are associated with hemorrhagic shock and the need for resuscitation, which leads to profound changes in diameter of the thoracic aorta. These diameter changes should be taken into account during endograft sizing. Measuring the thoracic aorta based on the admission CTA can lead to inaccurate sizing, even if proper centerline-based measurements are performed. The use of real-time imaging, in particular intravascular ultrasound (IVUS), has been shown to provide more accurate endograft sizing in acute thoracic aortic syndromes, especially if associated with hypovolemia. Future research should provide additional data on the exact role of different intra-operative imaging modalities (e.g. IVUS, transesophageal echocardiography [TEE], three dimensional CTA) on endograft sizing and long-term outcomes to ultimately improve patient outcome.

Advanced Techniques for Treating Juxtarenal and Pararenal Abdominal Aortic Aneurysms: Chimneys, Periscopes, Sandwiches and Other Methods

The complex aortic anatomy of patients who present with juxtarenal and pararenal abdominal aortic aneurysms requires advanced techniques to ensure adequate coverage and complete exclusion of the aneurysm. Parallel stent grafting is one option for endovascular repair of complex aneurysms. Using chimneys, periscopes, or snorkels, it is possible to extend the length of the proximal seal zone and maintain perfusion to branch vessels. Because readily available stent grafts and covered stents are used, this technique is highly adaptable to each patient's unique anatomical challenges. However, the complexity of these procedures requires careful preoperative planning, excellent intraoperative imaging capabilities, a thorough understanding of technique, and anticipation of potential procedural pitfalls and complications. We present our experience with chimney/snorkel and sandwich techniques as a reliable and effective treatment strategy for complex aortic aneurysm repair.

[Endovascular repair of the thoracic aorta]

Degenerative aneurysms of the thoracic aorta are increasing in prevalence. The recognition of the decreased morbidity of this approach compared with open repair was readily apparent, as it avoided left thoracotomy, aortic cross-clamping, and left heart bypass. Repair of isolated descending thoracic aortic aneurysms using stent grafts was introduced in 1995, and in an anatomically suitable subgroup of patients with thoracic aortic aneurysm, repair with endovascular stent graft provides favorable outcomes, with decreased perioperative morbidity and mortality relative to open repair. The cornerstones of successful thoracic endovascular aneurysm repair are appropriate patient selection, thorough preprocedural planning, and cautious procedural execution. Since then, TEVAR is increasingly being used for other aortic pathologies such as complicated type B dissection, traumatic aortic transection, and aneurysmal disease extending into the arch or visceral segment, requiring debranching procedures.

A phantom study for the comparison of different brands of computed tomography scanners and software packages for endovascular aneurysm repair sizing and planning

Objectives Correct sizing of endoprostheses used for the treatment of abdominal aortic aneurysms is important to prevent endoleaks and migration. Sizing requires several steps and each step introduces a possible sizing error. The goal of this study was to investigate the magnitude of these errors compared to the golden standard: a vessel phantom. This study focuses on the errors in sizing with three different brands of computed tomography angiography scanners in combination with three reconstruction software packages. Methods Three phantoms with a different diameter, altitude and azimuth were scanned with three computed tomography scanners: Toshiba Aquilion 64-slice, Philips Brilliance iCT 256-slice and Siemens Somatom Sensation 64-slice. The phantom diameters were determined in the stretched view after central lumen line reconstruction by three observers using Simbionix PROcedure Rehearsal Studio, 3mensio and TeraRecon planning software. The observers, all novices in sizing endoprostheses using planning software, measured 108 slices each. Two senior vascular surgeons set the tolerated error margin of sizing on ±1.0 mm. Results In total, 11.3% of the measurements (73/648) were outside the set margins of ±1.0 mm from the phantom diameter, with significant differences between the scanner types (14.8%, 12.1%, 6.9% for the Siemens scanner, Philips scanner and Toshiba scanner, respectively, p-value = 0.032), but not between the software packages (8.3%, 11.1%, 14.4%, p-value = 0.141) or the observers (10.6%, 9.7%, 13.4%, p-value = 0.448). Conclusions It can be concluded that the errors in sizing were independent of the used software packages, but the phantoms scanned with Siemens scanner were significantly more measured incorrectly than the phantoms scanned with the Toshiba scanner. Consequently, awareness on the type of computed tomography scanner and computed tomography scanner setting is necessary, especially in complex abdominal aortic aneurysms sizing for fenestrated or branched endovascular aneurysm repair if appropriate the sizing is of upmost importance.

How Precise Are Preinterventional Measurements Using Centerline Analysis Applications? Objective Ground Truth Evaluation Reveals Software-Specific Centerline Characteristics

PURPOSE

To evaluate different centerline analysis applications using objective ground truth from realistic aortic aneurysm phantoms with precisely defined geometry and centerlines to overcome the lack of unknown true dimensions in previously published in vivo validation studies.

METHODS

Three aortic phantoms were created using computer-aided design (CAD) software and a 3-dimensional (3D) printer. Computed tomography angiograms (CTAs) of phantoms and 3 patients were analyzed with 3 clinically approved and 1 research software application. The 3D centerline coordinates, intraluminal diameters, and lengths were validated against CAD ground truth using a dedicated evaluation software platform.

RESULTS

The 3D centerline position mean error ranged from 0.7±0.8 to 2.9±2.5 mm between tested applications. All applications calculated centerlines significantly different from ground truth. Diameter mean errors varied from 0.5±1.2 to 1.1±1.0 mm among 3 applications, but exceeded 8.0±11.0 mm with one application due to an unsteady distortion of luminal dimensions along the centerline. All tested commercially available software tools systematically underestimated centerline total lengths by -4.6±0.9 mm to -10.4±4.3 mm (maximum error -14.6 mm). Applications with the highest 3D centerline accuracy yielded the most precise diameter and length measurements.

CONCLUSION

One clinically approved application did not provide reproducible centerline-based analysis results, while another approved application showed length errors that might influence stent-graft choice and procedure success. The variety and specific characteristics of endovascular aneurysm repair planning software tools require scientific evaluation and user awareness.

Measuring of Abdominal Aortic Aneurysm with Three-Dimensional Computed Tomography Reconstruction before Endovascular Aortic Aneurysm Repair

PURPOSE

Conventional computed tomography (CT) is the gold standard method for case planning for endovascular aortic aneurysm repair (EVAR). However, aortography with a marking catheter is needed for measuring the actual length of an aneurysm. With advances in imaging technology, a 3-dimensional (3D) workstation can obviate the need for the aortography. The objective of this study was to determine whether a 3D workstation could obviate the need for aortography for EVAR.

MATERIALS AND METHODS

One vascular surgeon and 1 interventional radiologist retrospectively assessed axial CT scans and reformatted the 3D CT scans by using the iNtuition workstation (TeraRecon Inc., San Mateo, CA, USA) for 25 patients who underwent EVAR. Four measurements of diameter and length were obtained from each modality. The actual length of an aneurysm for the proper graft was decided by 2 observers by reviewing the aortography with a marking catheter.

RESULTS

The measurements from the 2 modalities were reproducible with intraobserver correlation coefficients of 0.89 to 1.0 for conventional CT and 0.98 to 1.0 for 3D workstation. Interobserver correlation coefficients were 0.29 to 0.95 for conventional CT and 0.85 to 0.99 for the 3D workstation. The length of the aneurysm for proper main graft coincided in 18 and 14 patients according to the conventional CT scan and in 21 and 18 patients according to the 3D workstation, respectively.

CONCLUSION

The interobserver agreement in planning EVAR was significantly better with the iNtuition 3D workstation. But aortography with a marking catheter may still be needed for selecting the proper graft.

Measurements After Image Post-processing Are More Precise in the Morphometric Assessment of Thoracic Aortic Aneurysms: An Intermodal and Intra-observer Evaluation

OBJECTIVES

Precise pre-procedural anatomical analysis of aneurysmal anatomy is essential for successful thoracic endovascular aortic repair (TEVAR). Since surgeons and radiologists have to perform multiple measurements in the same patient, high intra-observer reliability of any imaging method is mandatory. Commercially available three dimensional (3D) post-processing techniques are expected to be superior to conventional two dimensional multiplanar reconstructions (MPRs) derived from computed tomography angiograms (CTAs). However, few data exist to support this view. This study aims to evaluate the intermodal and intra-observer differences using 3D software (3surgery) in descending thoracic aortic aneurysms (dTAAs).

METHODS

Pre-operative CTAs (performed between 2004 and 2010) of 30 dTAAs (mean maximum diameter 61.4 ± 13 mm) were assessed by three independent investigators with different experience in the measurement of aortic pathologies. Intra-observer reliability and intermodal differences (3D vs. 2D) were investigated using pre-specified measurement points (distances of total length, maximum diameter, proximal and distal landing zones). Statistical analyses were performed using the Bland-Altman method and a mixed regression model.

RESULTS

Intermodal comparison showed that 2D measurements significantly underestimate the measured distances (maximum diameter 3.7 mm [95% CI -5.3 to -2.1] and landing zone maximum 1.4 mm [95% CI -2.0 to -0.2] shorter with 2D, p < .05). In almost all 3D measurements, all investigators showed lower variability comparing the intra-observer differences, most notably in the measuring point total length (reduction of the SD up to 7.9 mm).

CONCLUSIONS

These data show that both techniques led to significant measurement disparity. This occurs especially at the point of indication (maximum diameter) and the total length of the aneurysm (important for correct stent graft selection). But overall the variability is reduced with the 3D technique, which also tends to measure greater distances. The use of post-processing software therefore leads to more precise device selection for TEVAR in TAA.

Validation of the Simbionix PROcedure Rehearsal Studio sizing module: A comparison of software for endovascular aneurysm repair sizing and planning

An important determinant of successful endovascular aortic aneurysm repair is proper sizing of the dimensions of the aortic-iliac vessels. The goal of the present study was to determine the concurrent validity, a method for comparison of test scores, for EVAR sizing and planning of the recently introduced Simbionix PROcedure Rehearsal Studio (PRORS). Seven vascular specialists analyzed anonymized computed tomography angiography scans of 70 patients with an infrarenal aneurysm of the abdominal aorta, using three different sizing software packages Simbionix PRORS (Simbionix USA Corp., Cleveland, OH, USA), 3mensio (Pie Medical Imaging BV, Maastricht, The Netherlands), and TeraRecon (Aquarius, Foster City, CA, USA). The following measurements were included in the protocol: diameter 1 mm below the most distal main renal artery, diameter 15 mm below the lowest renal artery, maximum aneurysm diameter, and length from the most distal renal artery to the left iliac artery bifurcation. Averaged over the locations, the intraclass correlation coefficient is 0.83 for Simbionix versus 3mensio, 0.81 for Simbionix versus TeraRecon, and 0.86 for 3mensio versus TeraRecon. It can be concluded that the Simbionix sizing software is as precise as two other validated and commercially available software packages.

Fate of Aneurysmal Common Iliac Artery Landing Zones Used for Endovascular Aneurysm Repair

PURPOSE

To determine outcomes of aneurysmal common iliac arteries (aCIA) used for landing zones (LZs) during endovascular aneurysm repair (EVAR).

METHODS

This single-center study retrospectively compared 57 EVAR patients (mean age 72±8 years; 56 men) with 70 aCIAs (diameter ≥20 mm) to 25 control EVAR subjects (mean age 73±7 years; 20 men) with 50 normal (≤15-mm) CIA LZs treated consecutively during the same time interval. The CIA LZ measurements were analyzed using random effects linear mixed models to determine diameter change over time. Life tables were used to estimate freedom from endoleak, reintervention, and all-cause mortality.

RESULTS

The mean maximum preoperative CIA diameter in the aCIA LZ group was 24.8±4.5 mm (range 20.0-47.3, median 23.9) vs 13.6±1.5 mm (range 9.2-15.0, median 13.9; p<0.001) in the controls. Nineteen aCIA LZs were treated outside the instructions for use of the device. Median follow-up in the aCIAs LZ cohort was 39.2 months [interquartile range (IQR) 15, 61] vs 49.3 months (IQR 36, 61) in the controls (p=0.06). The rate of aCIA LZ change (0.09 mm/mo, 95% CI 0.07 to 0.1) was significantly greater than controls (0.03 mm/mo, 95% CI -0.009 to 0.07; p<0.0001). No type Ib endoleaks developed in either group; however, aCIA LZ patients had 6 (11%) iliac limb-related reinterventions. There were significantly more endograft-related reinterventions in the aCIA LZ patients (n=10, 14%) compared with controls (n=2, 4%; p=0.06). There was no difference in mortality or freedom from any post-hospital discharge endoleak.

CONCLUSION

Aneurysmal CIA LZs used during EVAR experience greater dilatation compared with normal LZs, but no significant difference in outcome was noted in midterm follow-up. However, an increased incidence of graft limb complications or endograft-related reintervention may be encountered. Use of aCIA LZs appears to be safe; however, greater patient numbers and longer follow-up are needed to understand the clinical implications of morphologic changes in these vessels when used during EVAR.

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.

Three-dimensional aortic aneurysm model and endovascular repair: an educational tool for surgical trainees

OBJECTIVES

Endovascular aortic aneurysm repair (EVAR) is a current valid treatment option for patients with abdominal aortic aneurysms (AAAs). The success of EVAR depends on the selection of appropriate patients, which requires detailed knowledge of the patient's vascular anatomy and preoperative planning. Three-dimensional (3D) models of AAA using a rapid prototyping technique were developed to help surgical trainees learn how to plan for EVAR more effectively.

METHOD

Four cases of AAA were used as prototypes for the models. Nine questions associated with preoperative planning for EVAR were developed by a group of experts in the field of endovascular surgery. Forty-three postgraduate trainees in general surgery participated in the present study. The participants were randomly assigned into two groups. The 'intervention' group was provided with the rapid prototyping AAA models along with 3D computed tomography (CT) corresponding to the cases of the test, while the control group was provided with 3D CTs only.

RESULTS

Differences in the scores between the groups were tested using the unpaired t test. The mean test scores were consistently and significantly higher in the 3D CT group with models compared with the 3D CT group without models for all four cases. Age, year of training, sex and previous EVAR experience had no effect on the scores.

CONCLUSION

The 3D aortic aneurysm model constructed using the rapid prototype technique may significantly improve the ability of trainees to properly plan for EVAR.

Preprocedural planning for endovascular stent-graft placement

Endovascular stent grafts have become a viable treatment for aortic thoracic and abdominal aneurysms in both elective and emergent situations. Computed tomographic (CT) angiography is the primary tool for determining eligibility for this procedure. This article discuses the preprocedural evaluation of an endovascular stent candidate. Evaluation begins with identification of the aneurysm pathology and its relationship to treatment efficacy. The radiologist must evaluate the aneurysm geometry for compatibility with stent hardware. Aneurysm features that suggest a contraindication must be recognized. Procedures that involve a combination of endovascular stenting and surgical revascularization are discussed so that the reader understands the limits of stent eligibility. Vascular access for stent placement must also be evaluated for the ability to accommodate stent delivery. The radiologist also must be familiar with CT imaging protocols and alternative methods of imaging that can evaluate stent feasibility. The utility of three-dimensional processing is discussed.

Two-dimensional versus three-dimensional CT angiography in analysis of anatomical suitability for stentgraft repair of abdominal aortic aneurysms

BACKGROUND

The morphological analysis prior to endovascular abdominal aneurysm repair (EVAR) plays an important role in long-term outcomes. Post-imaging analysis of computed tomographic angiography (CTA) by three-dimensional reconstruction with central lumen line detection (CLL 3D-CTA) enables measurements to be made in orthogonal slices. This might be more precise than equal post-imaging analysis in axial slices by two-dimensional computed tomographic angiography (2D-CTA).

PURPOSE

To evaluate the intra- and interobserver variability of CLL 3D-CTA and 2D-CTA post-imaging analysis methods and the agreement between them in pre-EVAR suitability analysis of patients with abdominal aortic aneurysm (AAA).

MATERIAL AND METHODS

Anonymized CTA data-sets from 70 patients with AAA were analyzed retrospectively. Length measurements included proximal and distal aortic neck lengths and total distance from the lower renal artery to the higher iliac bifurcation. Width measurements included proximal and distal neck diameters, maximum AAA diameter and common iliac diameters just above the iliac bifurcations. The measurements were performed in random order by two vascular surgeons, twice per method with 1-month interval between readings. In the CLL 3D-CTA method we used semi-automated CLL detection by software and manual measurements on CTA slices perpendicular to CLL. The equal measurements in 2D-CTA were performed manually on axial CTA slices using a DICOM viewer workstation. The intra- and interobserver variability, as well as the agreement between the two methods were assessed by Bland-Altman test and bivariate correlation analysis.

RESULTS

The intraobserver variability was significantly higher in 2D-CTA measurements for both readers. The interobserver variability was significant in 2D-CTA measurements of proximal neck dimensions while the agreement in CLL 3D-CTA analysis between the two readers was excellent in all studied parameters. The agreement between the two suitability analysis techniques was poor for both readers, especially in measurements of proximal neck's dimensions and in total aortoiliac length (p = 0.001).

CONCLUSION

In pre-EVAR morphological evaluation of AAAs the CLL-3D CTA post-imaging analysis has better intra- and interobserver correlation than 2D-CTA and might represent a useful tool for the proper selection of endograft's type and size.

Sizing for endovascular aneurysm repair: clinical evaluation of a new automated three-dimensional software

BACKGROUND

To assess the reproducibility and accuracy of the sizing procedure before aortic endograft implantation using new sizing automated software as compared with standard radiological procedures.

METHODS

On the basis of original spiral-computed tomography images, the sizing of 32 patients with abdominal aortic aneurysm treated by endovascular aneurysm repair (EVAR) was retrospectively compared. The first sizing was performed by a radiologist using a standard workstation (General electrics) and software (Advanced vessel analysis). The second was performed twice by two surgeons using a personal computer with automatic three-dimensional sizing software (Endosize; Therenva, Rennes, France). All diameters and lengths required before EVAR were measured (17 items). Moreover, 13 qualitative criteria regarding EVAR feasibility, including neck length, were compared. Intra- and interobserver variability with Endosize, as well as the variability between the two measurement methods were analyzed using the intraclass correlation coefficient (ICC) and Bland and Altman's method. Qualitative variables were analyzed using Fischer's exact test and kappa coefficient.

RESULTS

Intraobserver variability with Endosize proved to be efficient. None of the ICCs were lower than 0.9, and more than 90% of the absolute differences between two measurements were less than 2 mm. Interobserver variability with Endosize was assessed in a similar manner. Measurement variability of vessel diameters was less marked than that of vessel lengths. This trend was observed for all datasets. Comparison of the two measurement methods demonstrated a good correlation (minimum ICC = 0.697; maximum ICC = 0.974), although less so than that observed using Endosize. Mean time consumption using Endosize was 13.1 ± 4.53 minutes (range: 7.2-32.7). Analysis of the alarm sets demonstrated a high agreement between observers (kappa coefficient = 0.81).

CONCLUSIONS

Sizing using the Endosize software is as reliable as conventional radiological procedures. Sizing by surgeons using an automated, user-friendly, and mobile tool appears to be reproducible.

Current state of dynamic imaging in endovascular aortic aneurysm repair

Dynamic imaging, in which the time dimension has a specific function in data (image) interpretation, is becoming increasingly important when contemplating endovascular aneurysm repair. Clinical parameters and complications, including proper sizing, successful aneurysm sac exclusion, optimal stent-graft design, endoleaks, graft migration, and stent fracture are beginning to be better understood through dynamic magnetic resonance, ultrasound, and dynamic computed tomography. The current practice using static 3-dimensional reconstructions for the planning and follow-up of aortic aneurysm endograft treatment will most likely evolve, and the use of dynamic aortic imaging will continue to increase. Validation of these imaging modalities in larger scale trials is needed.

Advances in vascular imaging

Advances in vascular surgery have mirrored advances in diagnostic imaging. Indeed, the endovascular revolution has been made possible largely by advances in computed tomography, magnetic resonance imaging, and vascular ultrasound. As technology allows better noninvasive vascular diagnosis, conventional angiography, once the gold standard for the diagnosis of vascular disease, is now reserved largely for intervention. This article discusses the current state of vascular imaging. Specific emphasis is placed on the comparative clinical utility of different imaging modalities in the detection and management of vascular disease.

Feasibility of renal artery stenting before, during, and after endovascular aneurysm repair with suprarenal fixation endograft

Suprarenal fixation by means of proximal bare stent may help prevent endograft migration and proximal endoleak. It seems not to compromise renal perfusion and function; however, it is still unclear whether its presence is in conflict with stenting of the renal arteries to treat associated renal stenosis. We report five cases of renal artery stenting performed before, at the same time, or after endovascular treatment of abdominal aortic aneurysm with a suprarenal fixation endograft (Zenith; Cook, Biaverskov, Denmark). Suprarenal fixation endograft seems not to affect renal artery stenting regardless the timing of the procedure.

Long-term outcomes after endovascular abdominal aortic aneurysm repair: the first decade

OBJECTIVE

The proper role of endovascular abdominal aortic aneurysm repair (EVAR) remains controversial, largely due to uncertain late results. We reviewed a 12-year experience with EVAR to document late outcomes.

METHODS

During the interval January 7, 1994 through December 31, 2005, 873 patients underwent EVAR utilizing 10 different stent graft devices. Primary outcomes examined included operative mortality, aneurysm rupture, aneurysm-related mortality, open surgical conversion, and late survival rates. The incidence of endoleak, migration, aneurysm enlargement, and graft patency was also determined. Finally, the need for reintervention and success of such secondary procedures were evaluated. Kaplan-Meier and multivariate methodology were used for analysis.

RESULTS

Mean patient age was 75.7 years (range, 49-99 years); 81.4% were male. Mean follow-up was 27 months; 39.3% of patients had 2 or more major comorbidities, and 19.5% would be categorized as unfit for open repair. On an intent-to-treat basis, device deployment was successful in 99.3%. Thirty-day mortality was 1.8%. By Kaplan-Meier analysis, freedom from AAA rupture was 97.6% at 5 years and 94% at 9 years. Significant risk factors for late AAA rupture included female gender (odds ratio OR, 6.9; P = 0.004) and device-related endoleak (OR, 16.06; P = 0.009). Aneurysm-related death was avoided in 96.1% of patients, with the need for any reintervention (OR, 5.7 P = 0.006), family history of aneurysmal disease (OR, 9.5; P = 0.075), and renal insufficiency (OR, 7.1; P = 0.003) among its most important predictors. 87 (10%) patients required reintervention, with 92% of such procedures being catheter-based and a success rate of 84%. Significant predictors of reintervention included use of first-generation devices (OR, 1.2; P < 0.01) and late onset endoleak (OR, 64; P < 0.001). Current generation stent grafts correlated with significantly improved outcomes. Cumulative freedom from conversion to open repair was 93.3% at 5 through 9 years, with the need for prior reintervention (OR, 16.7; P = 0.001) its most important predictor. Cumulative survival was 52% at 5 years.

CONCLUSIONS

EVAR using contemporary devices is a safe, effective, and durable method to prevent AAA rupture and aneurysm-related death. Assuming suitable AAA anatomy, these data justify a broad application of EVAR across a wide spectrum of patients.

Continuity of care experience of residents in an academic vascular department: Are trainees learning complete surgical care?

BACKGROUND

It is widely accepted that exemplary surgical care involves a surgeon's involvement in the preoperative, perioperative, and postoperative periods. In an era of ever-expanding therapeutic modalities available to the vascular surgeon, it is important that trainees gain experience in preoperative decision-making and how this affects a patient's operative and postoperative course. The purpose of this study was to define the current experience of residents on a vascular surgery service regarding the continuity of care they are able to provide for patients and the factors affecting this experience.

METHODS

This prospective cohort study was approved by the Institutional Review Board and conducted at the University of British Columbia during January 2005. All patients who underwent a vascular procedure at either of the two teaching hospitals were included. In addition to type of case (emergent, outpatient, inpatient), resident demographic data and involvement in each patient's care (preoperative assessment, postoperative daily assessment, and follow-up clinic assessment) were recorded. Categoric data were analyzed with the chi2 test.

RESULTS

The study included 159 cases, of which 65% were elective same-day admission patients, 20% were elective previously admitted patients; and 15% were emergent. The overall rate of preoperative assessment was 67%, involvement in the decision to operate, 17%; postoperative assessment on the ward, 79%; and patient follow-up in clinic, 3%. The rate of complete in-hospital continuity of care (assessing patient pre-op and post-op) was 57%. Emergent cases were associated with a significantly higher rate of preoperative assessment (92% vs 63%, P < .05). For elective cases admitted before the day of surgery compared with same-day admission patients, the rates of preoperative assessment (78% vs 58%, P < .05) and involvement in the decision to operate (16% vs 4%, P < .05) were significantly higher.

CONCLUSIONS

The continuity-of-care experiences of vascular trainees are suboptimal. This is especially true for postoperative clinic assessment. Same-day admission surgery accounted for most of the cases and was associated with the poorest continuity of care. To provide complete surgical training in an era of changing therapeutic modalities and same-day admission surgery, vascular programs must be creative in structuring training to include adequate ambulatory experience.