Comparison of abdominal aortic aneurysm diameter measurements obtained with ultrasound and computed tomography: Is there a difference?

Temporal Pattern Analysis of Ultrasound Surveillance Data in Vascular Connective Tissue Disorders

BACKGROUND

Ehlers-Danlos syndrome (EDS), Marfan syndrome (MFS), and Loeys-Dietz syndrome (LDS) are connective tissue disorders frequently associated with vascular aneurysm formation, dissections, and subsequent major complications. Regular imaging surveillance is recommended for these conditions. However, no guidelines currently exist regarding imaging modality or surveillance intervals.

METHODS

This retrospective single-center observational study analyzed clinical and imaging data of patients attending an outpatient clinic for vascular connective tissue disorders between August 2008 and January 2024. Imaging (1424 data points in total) and clinical data were extracted from electronic health records. Analysis primarily included a comparison of vessel diameter progression across imaging modalities, with an additional review of the clinical history of vascular events.

RESULTS

In total, 19 patients with vascular connective tissue disorders (vCTDs) underwent consultations at our outpatient clinic. Nine (47.4%) patients experienced vascular events, while two (10.5%) passed away during the study period. Multimodal imaging surveillance revealed a tendency towards arterial diameter increase. Consistent ultrasound monitoring provided more reliable diameter progression data for the same arterial segment than a combination of imaging modalities. Temporal analysis indicated a tendency for the continuous growth of the abdominal aorta, the common and internal carotid artery, and the common femoral and popliteal artery.

CONCLUSION

The study highlights the importance of standardized, modality-specific imaging protocols in monitoring patients with vCTDs. The variability in disease progression among these patients further complicates surveillance strategies, contemplating the need for individualized approaches. Further research and prospective multicenter studies are required to refine and improve monitoring protocols.

Comparative Analysis of Micro-Computed Tomography and 3D Micro-Ultrasound for Measurement of the Mouse Aorta

Aortic aneurysms, life-threatening and often undetected until they cause sudden death, occur when the aorta dilates beyond 1.5 times its normal size. This study used ultrasound scans and micro-computed tomography to monitor and measure aortic volume in preclinical settings, comparing it to the well-established measurement using ultrasound scans. The reproducibility of measurements was also examined for intra- and inter-observer variability, with both modalities used on 8-week-old C57BL6 mice. For inter-observer variability, the μCT (micro-computed tomography) measurements for the thoracic, abdominal, and whole aorta between observers were highly consistent, showing a strong positive correlation (R2 = 0.80, 0.80, 0.95, respectively) and no significant variability (p-value: 0.03, 0.03, 0.004, respectively). The intra-observer variability for thoracic, abdominal, and whole aorta scans demonstrated a significant positive correlation (R2 = 0.99, 0.96, 0.87, respectively) and low variability (p-values = 0.0004, 0.002, 0.01, respectively). The comparison between μCT and USS (ultrasound) in the suprarenal and infrarenal aorta showed no significant difference (p-value = 0.20 and 0.21, respectively). μCT provided significantly higher aortic volume measurements compared to USS. The reproducibility of USS and μCT measurements was consistent, showing minimal variance among observers. These findings suggest that μCT is a reliable alternative for comprehensive aortic phenotyping, consistent with clinical findings in human data.

Current Imaging Strategies in Patients with Abdominal Aortic Aneurysms

BACKGROUND

 An abdominal aortic aneurysm (AAA) is defined as a localized dilatation of the abdominal aorta of ≥ 3 cm. With a prevalence of 4-8 %, AAA is one of the most common vascular diseases in Western society. Radiological imaging is an elementary component in the diagnosis, monitoring, and treatment planning of AAA patients.

METHOD

 This is a narrative review article on preoperative imaging strategies of AAA, incorporating expert opinions based on the current literature and standard-of-care practices from our own center. Examples are provided to illustrate clinical cases from our institution.

RESULTS AND CONCLUSION

 Radiological imaging plays a pivotal role in the initial diagnosis and monitoring of patients with AAA. Ultrasound is the mainstay imaging modality for AAA screening and surveillance. Contrast-enhanced CT angiography is currently considered the gold standard for preoperative imaging and image-based treatment planning in AAA repair. New non-contrast MR angiography techniques are robustly applicable and allow precise determination of aortic diameters, which is of critical importance, particularly with regard to current diameter-based surgical treatment guidelines. 3D imaging with multiplanar reformation and automatic centerline positioning enables more accurate assessment of the maximum aortic diameter. Modern imaging techniques such as 4D flow MRI have the potential to further improve individualized risk stratification in patients with AAA.

KEY POINTS

  · Ultrasound is the mainstay imaging modality for AAA screening and monitoring. · Contrast-enhanced CT angiography is the gold standard for preoperative imaging in AAA repair. · Non-contrast MR angiography allows for accurate monitoring of aortic diameters in AAA patients. · Measurement of aortic diameters is more accurate with 3D-CT/MRI compared to ultrasound. · Research seeks new quantitative imaging biomarkers for AAA risk stratification, e. g., using 4D flow MRI.

ACR Appropriateness Criteria® Pulsatile Abdominal Mass, Suspected Abdominal Aortic Aneurysm: 2023 Update

Abdominal aortic aneurysm (AAA) is defined as abnormal dilation of the infrarenal abdominal aortic diameter to 3.0 cm or greater. The natural history of AAA consists of progressive expansion and potential rupture. Although most AAAs are clinically silent, a pulsatile abdominal mass identified on physical examination may indicate the presence of an AAA. When an AAA is suspected, an imaging study is essential to confirm the diagnosis. This document reviews the relative appropriateness of various imaging procedures for the initial evaluation of suspected AAA. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Thoracic and abdominal aortic alterations in dogs affected with systemic hypertension

Aortic remodeling is the consequence of untreated systemic hypertension along with aortic dilatation as a marker for target organ damage in human literature. Therefore, the present study was planned to detect the changes in aorta at the level of aortic root via echocardiography, thoracic descending aorta via radiography and abdominal aorta via ultrasonography in healthy (n = 46), diseased normotensive (n = 20) and systemically hypertensive dogs (n = 60). The aortic root dimensions were measured at the level of aortic annulus, sinus of valsalva, sino-tubular junction and proximal ascending aorta via left ventricular outflow tract view of echocardiography. The thoracic descending aorta was subjectively assessed for any disparity in size and shape of aorta via lateral and dorso-ventral view of chest radiography. The abdominal aorta was assessed via left and right paralumbar window for calculating the aortic elasticity along with aortic and caudal venacaval dimensions to calculate the aortic-caval ratio. The aortic root measurements were dilated (p < 0.001) in systemically hypertensive dogs with a positive correlation (p < 0.001) with systolic blood pressure (BP). Thoracic descending aorta was also (p < 0.05) altered in the size and shape (undulation) of systemically hypertensive dogs. Abdominal aorta was markedly stiffened with reduced elasticity (p < 0.05) along with dilatation (p < 0.01) in hypertensive dogs. Also, there was a positive correlation (p < 0.001) of aortic diameters and aortic-caval ratio and negative correlation (p < 0.001) of aortic elasticity with systolic BP. Therefore, it was concluded that aorta could be considered as an important target organ damage of systemic hypertension in dogs.

Contrast-enhanced US Evaluation of Endoleaks after Endovascular Stent Repair of Abdominal Aortic Aneurysm

Ruptured abdominal aortic aneurysm (AAA) carries high morbidity and mortality. Elective repair of AAA with endovascular stent-grafts requires lifetime imaging surveillance for potential complications, most commonly endoleaks. Because endoleaks result in antegrade or retrograde systemic arterialized flow into the excluded aneurysm sac, patients are at risk for recurrent aneurysm sac growth with the potential to rupture. Multiphasic CT has been the main imaging modality for surveillance and symptom evaluation, but contrast-enhanced US (CEUS) offers a useful alternative that avoids radiation and iodinated contrast material. CEUS is at least equivalent to CT for detecting endoleak and may be more sensitive. The authors provide a general protocol and technical considerations needed to perform CEUS of the abdominal aorta after endovascular stent repair. When there are no complications, the stent-graft lumen has homogeneous enhancement, and no contrast material is present in the aneurysm sac outside the stented lumen. In patients with an antegrade endoleak, contrast material is seen simultaneously in the aneurysm sac and stent-graft lumen, while delayed enhancement in the sac is due to retrograde leak. Recognition of artifacts and other potential pitfalls for CEUS studies is important for examination performance and interpretation. Online supplemental material is available for this article. ^©RSNA, 2022.

Ultrasound Transducer Pressure: An Unexplored Source of Abdominal Aortic Aneurysm Measurement Error

This study was aimed at quantifying the abdominal aortic aneurysm (AAA) compression phenomenon and assessing the use of a new tool to estimate transducer pressure in vivo. In this cross-sectional study, 47 participants with AAA and a median anterior-to-posterior (AP) AAA diameter of 46 mm (range: 30-76 mm) were included. The majority of the patients were overweight with body mass indexes >25 (33/47, 70%). A standardized ultrasound (US)-compatible gel pad, with a pre-defined thickness (15 mm) and mass (150 g), was interposed between the US transducer and participant to estimate the applied transducer pressure. A firm transducer pressure significantly lowered the median AP diameter from 46.1 mm (range: 29.7-76.3) to 39.4 mm (range: 21.7-67.5) (p = 0.001). The mean diameter bias between light and firm transducer pressure was 6.1 mm (95% confidence interval: 4.9-7.3). The applied transducer pressure varied significantly and could be measured by translating the deformation of a low-tech gel pad interposed between the US transducer and the participant.

Automatic measurement of maximal diameter of abdominal aortic aneurysm on computed tomography angiography using artificial intelligence

INTRODUCTION

The treatment of abdominal aortic aneurysm (AAA) relies on surgical repair and the indication mainly depends on its size evaluated by the maximal diameter (Dmax). The aim of this study was to evaluate a new automatic method based on artificial intelligence (AI) to measure the Dmax on computed tomography angiography (CTA).

METHODS

A fully automatic segmentation of the vascular system was performed using a hybrid method combining expert system with supervised deep learning (DL). The aorta centreline was extracted from the segmented aorta and the aortic diameters were automatically calculated. Results were compared to manual segmentation performed by two human operators.

RESULTS

The median absolute error between the two human operators was 1.2 mm (IQR 0.5- 1.9). The automatic method using the DL algorithm demonstrated correlation with the human segmentation, with a median absolute error of 0.8 (0.5- 4.2) mm and a coefficient correlation of 0.91 (p<0.001).

CONCLUSION

Although validation in larger cohorts is required, this method brings perspectives to develop new tools to standardize and automate the measurement of AAA Dmax in order to help clinicians in the decision-making process.

Validation of an assessment tool for estimation of abdominal aortic aneurysm compression in diagnostic ultrasound

The study investigated ultrasound (US) transducer push, tantamount to applied transducer pressure, during abdominal aortic aneurysm (AAA) US scanning in a simulated non-clinical setup. During an assessment of maximal AAA diameter on a three-dimensional print-based AAA phantom, US transducer push varied as much as 2000% (range: 0.52-12.45 kPa) amongst 16 experienced sonographers. The mean transducer push was 5.54 ± 3.91 kPa (CV = 0.71). Deformation of a standardized gel-pad allowed for transducer push calculation based on US images; Young's modulus of the gel-pad was estimated to 44,26 N/m2. The method is theoretically validated in a safe and non-clinical environment. Future investigations with the aim of clinical validation of the gel-pad principle on AAA patients are suggested, including the objectification of the magnitude of an eventual transducer push-related error during US AAA diameter measurement.

Aortic enlargement and coronary artery calcification in a general population cohort

AIMS

The role of atherosclerosis in the pathogenesis of aortic enlargement is uncertain. We aimed to evaluate the relationship between the diameters of the ascending, descending and abdominal aorta, and coronary artery calcification.

METHODS AND RESULTS

Individuals in the Copenhagen General Population Study underwent thoracic and abdominal computed tomography. Maximal aortic diameters were measured in each aortic segment and coronary artery calcium scores (CACS) were calculated. Participants were stratified into five predefined groups according to CACSs and compared to aortic dimensions. The relation between aortic diameter and CACS was adjusted for risk factors for aortic dilatation in a multivariable model. A total of 2678 eligible individuals were included. In all segments of the aorta, aortic diameter was associated to CACSs, with mean increases in aortic diameters ranging from 0.7 to 3.5 mm in individuals with calcified coronary arteries compared to non-calcified subjects (P-value < 0.001). After correction for risk factors, individuals with CACS above 400 had larger ascending, descending and abdominal aortic diameter than the non-calcified reference group (P-value < 0.01).

CONCLUSION

Enlarged thoracic and abdominal aortic vascular segments are associated with co-existing coronary artery calcification in the general population.

Three-dimensional ultrasound improves identification of patients with abdominal aortic aneurysms reaching the threshold for repair

OBJECTIVE

Conventional two-dimensional ultrasound (2D-US) has been the recommended and preferred modality for the diagnosis and surveillance of abdominal aortic aneurysms (AAAs). Measurement of the aneurysm diameter using three-dimensional ultrasound (3D-US) has shown promising results in a research setting, improving agreement and reproducibility. However, studies evaluating 3D-US in a clinical context are lacking, which could hinder the optimal usage of this new modality. In the present study, we investigated the clinical value of 3D-US for AAA surveillance compared with the current standard 2D-US examination.

METHODS

Data from 126 patients with infrarenal AAAs <50 mm and 55 mm (female and male, respectively) were available for analysis. Eligibility was determined using the standard 2D-US anteroposterior (AP) diameter with a dual-plane technique. All the patients had subsequently undergone additional 3D-US and computed tomography angiography (CTA). Using CTA as the reference standard, the maximal standard 2D-US AP diameter was compared with that from 3D-US.

RESULTS

All 126 AAAs were, per the inclusion criteria, small, with no intervention indicated. With the addition of 3D-US imaging to the 2D-US-based surveillance program, the AAA diameter threshold (50 and 55 mm) was exceeded for 31 of the 126 patients (25%). These 31 patients were withdrawn from the present study and referred for treatment planning. Compared with the CTA AP diameter (mean, 49 ± 7.2 mm), the mean 3D-US AP diameter (mean, 49 ± 6.7 mm) was significantly more accurate than the standard mean 2D-US AP diameter (45 ± 6.2 mm; kappa value, 0.86 ± 0.05; 95% confidence interval, 0.76-0.96; kappa value, 0.01 ± 0.04; 95% confidence interval, -0.05 to 0.09, respectively).

CONCLUSIONS

For clinical use, the AAA diameter assessment using 3D-US was significantly more accurate than that with 2D-US and can substantially change the clinical management, from surveillance to operative treatment, for approximately one fourth of patients with an AAA. Further studies evaluating the clinical consequences of the 2D to 3D paradigm shift in AAA diagnostics are warranted, including sensitivity, specificity, agreement, and reproducibility estimation.

An association between rs7635818 polymorphism located on chromosome 3p12.3 and the presence of abdominal aortic aneurysm

The association between gene variant rs7635818 located on chromosome 3p12.3 and abdominal aortic aneurysm (AAA) was not unambiguously determined by the results of genome-wide association studies. The aim of our study was to examine this possible association in the Slovak population, with respect to the presence and severity of AAA.A cross-sectional study was conducted between August 2016 and March 2020. The study included 329 participans, 166 AAA patients and a control group of 163 subjects without confirmed AAA with comparable distribution of genders. The anteroposterior diameter of the abdominal aorta was determined by duplex ultrasonography. AAA was defined as subrenal aortic diameter ≥ 30 mm. DNA samples were genotyped using real-time polymerase chain reaction and subsequent high-resolution melting analysis in presence of unlabelled probe. Genetic models studying the possible association were adjusted to age, sex, smoking, arterial hypertension, diabetes mellitus, creatinine and body mass index (BMI) in multivariate analysis. In the additive model, presence of each C-allele of rs7635818 polymorphism was associated with an almost 50 % increase in probability of developing AAA (OR 1.49; 95 % CI 1.06-2.08; p=0.020). Compared to GG homozygotes, CC homozygotes had more than two times higher risk of developing AAA (OR 2.23; 95 % CI 1.14-4.39; p=0.020). The risk of AAA was also in the recessive model higher for CC homozygotes compared to G-allele carriers (GC/GG) (OR 1.79; 95 % CI 1.01-3.19; p=0.047).The abdominal aortic diameter in CC homozygotes of the rs7635818 polymorphism was 7.66 mm greater compared to GG homozygotes (42.5±22.0 mm vs 34.8±21.3 mm; p=0.022) and 5.88 mm greater compared to G-allele carriers (GC/GG) (42.5±22.0 mm vs 36.6±21.0 mm; p=0.04) in univariate analysis. C-allele variant in rs7635818 G>C polymorphism is associated with a higher probability of developing AAA in the Slovak population.

Aortic aneurysm screening using duplex ultrasound: Choosing wisely who to examine

The noninvasive vascular laboratory plays a critical role in screening patients at risk for development of abdominal aortic aneurysm (AAA). One-time duplex ultrasound screening reduces aneurysm-related mortality due to rupture and is cost-effective. Population screening based on AAA risk factors is recommended, as it allows for proactive, elective repair of aneurysms at risk for rupture, and surveillance of smaller aneurysms for enlargement. Utilization of societal screening guidelines, such as those published by the Society for Vascular Surgery, can be employed by vascular laboratories to justify individual patient screening, aid primary care physicians to refer patients for testing, and encourage integrated medical health care systems to build prompts in patient electronic health records to ensure compliance with a AAA screening program. Risk factors for developing AAA, that is, age older than 65 years, male sex, family history, and a smoking history of >100 cigarettes, should be used to recommend patient screening, including for women and other elderly (older than 75 years) patients who fall outside of professional societal guidelines.

Editor's Choice - Assessment of Correlation Between Mean Size of Infrarenal Abdominal Aortic Aneurysm at Time of Intact Repair Against Repair and Rupture Rate in Nine Countries

OBJECTIVE

This study aimed to analyse the mean abdominal aortic aneurysm (AAA) diameter for repair in nine countries, and to determine variation in mean AAA diameter for elective AAA repair and its relationship to rupture AAA repair rates and aneurysm related mortality in corresponding populations.

METHODS

Data on intact (iAAA) and ruptured infrarenal AAA (rAAA) repair for the years 2010-2012 were collected from Denmark, England, Finland, Germany, Hungary, New Zealand, Norway, Sweden, and the USA. The rate of iAAA repair and rAAA per 100 000 inhabitants above 59 years old, mean AAA diameter for iAAA repair and rAAA repair, and the national rates of rAAA were assessed. National cause of death statistics were used to estimate aneurysm related mortality. Direct standardisation methods were applied to the national mortality data. Logistic regression and analysis of variance model adjustments were made for age groups, sex, and year.

RESULTS

There was a variation in the mean diameter of iAAA repair (n = 34 566; range Germany = 57 mm, Denmark = 68 mm). The standardised iAAA repair rate per 100000 inhabitants varied from 10.4 (Hungary) to 66.5 (Norway), p<.01, and the standardised rAAA repair rate per 100 000 from 5.8 (USA) to 16.9 (England), p<.01. Overall, there was no significant correlation between mean diameter of iAAA repair and standardised iAAA rate (r² = 0.04, p = .3). There was no significant correlation between rAAA repair rate (n = 12 628) with mean diameter of iAAA repair (r² = 0.2, p = .1).

CONCLUSION

Despite recommendations from learned society guidelines, data indicate variations in mean diameter for AAA repair. There was no significant correlation between mean diameter of AAA repair and rates of iAAA repair and rAAA repair. These analyses are subject to differences in disease prevalence, uncertainties in rupture rates, validations of vascular registries, causes of death and registrations.

Aortic to caudal vena cava ratio measurements using abdominal ultrasound are increased in dogs with confirmed systemic hypertension

Chronically sustained systemic hypertension in dogs can damage the kidneys, eye, brain, heart, and vessels. In human medicine, systemic hypertension has been implicated as the most common risk factor for aorta dilation, which can progress to an aneurysm. Abdominal ultrasound has been commonly used to monitor the size of the abdominal aorta in people with systemic hypertension. In this retrospective cross-sectional abdominal ultrasound study, evaluation of the size of the abdominal aorta relative to the caudal vena cava was performed in 18 control dogs and 128 dogs with confirmed systemic hypertension. Preexisting conditions contributing to systemic hypertension in these dogs were renal disease, hyperadrenocorticism, diabetes mellitus, adrenal tumors, and previous administration of phenylpropanolamine or palladia. The abdominal aorta and caudal vena cava were assessed from longitudinal images cranial to the trifurcation with measurements made from outer border to outer border of the walls, being careful not to compress the caudal vena cava that would alter its size. Our hypothesis was the ratio of the diameter of the abdominal aorta to caudal vena cava would be higher in dogs with systemic hypertension compared to dogs with normal blood pressure. The mean abdominal aorta-caudal vena cava ratio was 1.028 in control dogs with a normal blood pressure and 1.515 in dogs with systemic hypertension. In dogs with confirmed systemic hypertension, the abdominal aorta was dilated compared to the caudal vena cava in the caudal abdomen. An increase in the abdominal aorta-caudal vena cava ratio in a dog should raise suspicion for the presence of systemic hypertension and prompt evaluation of blood pressure.

Relationship between metformin and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a life-threatening disease and pharmacologic agents to treat the disease remain lacking for clinical practice. Epidemiologic studies have highlighted a negative association between the use of antidiabetic drugs, including metformin, and AAA. Metformin is well-known for its blood glucose-lowering effect, but its action on both metabolism and inflammatory response has led to propose it as a potential therapeutic target in several cardiovascular diseases. In this review, we summarize the current knowledge on the link between metformin and AAA. Based on the known effects of the drug on the aortic wall, translational applications and clinical trials investigating the interest of metformin in the management of patients with AAA are discussed.

Metformin prescription status and abdominal aortic aneurysm disease progression in the U.S. veteran population

BACKGROUND

Identification of a safe and effective medical therapy for abdominal aortic aneurysm (AAA) disease remains a significant unmet medical need. Recent small cohort studies indicate that metformin, the world's most commonly prescribed oral hypoglycemic agent, may limit AAA enlargement. We sought to validate these preliminary observations in a larger cohort.

METHODS

All patients with asymptomatic AAA disease managed in the Veterans Affairs Health Care System between 2003 and 2013 were identified by International Classification of Diseases, Ninth Revision codes. Those with a concomitant diagnosis of diabetes mellitus who also received two or more abdominal imaging studies (computed tomography, magnetic resonance imaging, or ultrasound) documenting the presence and size of an AAA, separated by at least 1 year, were included for review. Maximal AAA diameters were determined from radiologic reports. Further data acquisition was censored after surgical AAA repair, when performed. Comorbidities, active smoking status, and outpatient medication records (within 6 months of AAA diagnosis) were also queried. Yearly AAA enlargement rates, as a function of metformin treatment status, were compared using two statistical models expressed in millimeters per year: a multivariate linear regression (model 1) and a multivariate mixed-effects model with random intercept and random slope (model 2).

RESULTS

A total of 13,834 patients with 58,833 radiographic records were included in the analysis, with radiology imaging follow-up of 4.2 ± 2.6 years (mean ± standard deviation). The average age of the patients at AAA diagnosis was 69.8 ± 7.8 years, and 39.7% had a metformin prescription within ±6 months of AAA. The mean growth rate for AAAs in the entire cohort was 1.4 ± 2.0 mm/y by model 1 analysis and 1.3 ± 1.6 mm/y by model 2 analysis. The unadjusted mean rate of AAA growth was 1.2 ± 1.9 mm/y for patients prescribed metformin compared with 1.5 ± 2.2 mm/y for those without (P < .001), a 20% decrease. This effect remained significant when adjusted for variables relevant on AAA progression: metformin prescription was associated with a reduction in yearly AAA growth rate of -0.23 mm (95% confidence interval, -0.35 to -0.16; P < .001) by model 1 analysis and 0.20 mm/y (95% confidence interval, -0.26 to -0.14; P < .001) by model 2 analysis. A subset analysis of 7462 patients with baseline AAA size of 35 to 49 mm showed a similar inhibitory effect (1.4 ± 2.0 mm/y to 1.7 ± 2.2 mm/y; P < .001). Patients' factors associated with an increased yearly AAA growth rate were baseline AAA size, metastatic solid tumors, active smoking, chronic obstructive pulmonary disease, and chronic renal disease. Factors associated with decreased yearly AAA growth rates included prescriptions for angiotensin II type 1 receptor blockers or sulfonylureas and the presence of diabetes-related complications.

CONCLUSIONS

In a nationwide analysis of diabetic Veterans Affairs patients, prescription for metformin was associated with decreased AAA enlargement. These findings provide further support for the conduct of prospective clinical trials to test the ability of metformin to limit progression of early AAA disease.

Correlation between transversal and orthogonal maximal diameters of abdominal aortic aneurysms and alternative rupture risk predictors

PURPOSE

There is no standard for measuring maximal diameter (Dmax) of abdominal aortic aneurysm (AAA) from computer tomography (CT) images although differences between Dmax evaluated from transversal (axialDmax) or orthogonal (orthoDmax) planes can be large especially for angulated AAAs. Therefore we investigated their correlations with alternative rupture risk indicators as peak wall stress (PWS) and peak wall rupture risk (PWRR) to decide which Dmax is more relevant in AAA rupture risk assessment.

MATERIAL AND METHODS

The Dmax values were measured by a trained radiologist from 70 collected CT scans, and the corresponding PWS and PWRR were evaluated using Finite Element Analysis (FEA). The cohort was ordered according to the difference between axialDmax and orthoDmax (D_a-o) quantifying the aneurysm angulation, and Spearman's correlation coefficients between PWS/PWRR - orthoDmax/axialDmax were calculated.

RESULTS

The calculated correlations PWS/PWRR vs. orthoDmax were substantially higher for angulated AAAs (with D_a-o≥3mm). Under this limit, the correlations were almost the same for both Dmax values. Analysis of AAAs divided into two groups of angulated (n=38) and straight (n=32) cases revealed that both groups are similar in all parameters (orthoDmax, PWS, PWRR) with the exception of axialDmax (p=0.024).

CONCLUSIONS

It was confirmed that orthoDmax is better correlated with the alternative rupture risk predictors PWS and PWRR for angulated AAAs (D_A-O≥3mm) while there is no difference between orthoDmax and axialDmax for straight AAAs (D_A-O<3mm). As angulated AAAs represent a significant portion of cases it can be recommended to use orthoDmax as the only Dmax parameter for AAA rupture risk assessment.

Abdominal ultrasound-scanning versus non-contrast computed tomography as screening method for abdominal aortic aneurysm - a validation study from the randomized DANCAVAS study

Background

Validating non-contrast-enhanced computed tomography (nCT) compared to ultrasound sonography (US) as screening method for abdominal aortic aneurysm (AAA) screening.

Methods

Consecutively attending men (n = 566) from the pilot study of the randomized Danish CardioVascular Screening trial (DANCAVAS trial), underwent nCT and US examination. Diameters were measured in outer-to-outer fashion. Sensitivity and specificity were done testing each modality against each other as reference standard. Measurements were tested for correlation, variance in diameters, and mean differences were tested using paired t-test.

Results

Due to logistics, 533 underwent both nCT and US. In four patients, aortae could not be visualized with US, and two of these had an AAA (>30 mm) as diagnosed by nCT. Using nCT 30 (5.7%, 95% CI: 4.2;7.5%) AAA were found. US failed to detect 9 of these, but diagnosed 3 other cases, resulting prevalence by US was 4.5% (95% CI: 3.0;6.6%). Additionally, 5 isolated iliac aneurysms (≥20 mm) (0.9%, 95% CI: 0.3;2.2%) were discovered by nCT.

US performed reasonably, with sensitivity ranging from 57.1–70.4%, specificity however, ranged higher 99.2–99.6%. Comparably nCT performed with sensitivity ranging from 82.6–88.9%, nCTs specificity however ranged from 97.7–98.4%. Analysis showed good correlations with no tendency to increasing variance with increasing diameter, and no significant differences between nCT and US with means varying slightly in both axis.

Conclusions

nCT seems superior to US concerning sensitivity, and is able to detect aneurysmal lesions not detectable with US. Finally, the prevalence of AAA in Denmark seems to remain relatively high, in this small pilot study group.

Standardized 2D ultrasound versus 3D/4D ultrasound and image fusion for measurement of aortic aneurysm diameter in follow-up after EVAR

PURPOSE

To compare standardised 2D ultrasound (US) to the novel ultrasonographic imaging techniques 3D/4D US and image fusion (combined real-time display of B mode and CT scan) for routine measurement of aortic diameter in follow-up after endovascular aortic aneurysm repair (EVAR).

METHOD AND MATERIALS

300 measurements were performed on 20 patients after EVAR by one experienced sonographer (3rd degree of the German society of ultrasound (DEGUM)) with a high-end ultrasound machine and a convex probe (1-5 MHz). An internally standardized scanning protocol of the aortic aneurysm diameter in B mode used a so called leading-edge method. In summary, five different US methods (2D, 3D free-hand, magnetic field tracked 3D - Curefab™, 4D volume sweep, image fusion), each including contrast-enhanced ultrasound (CEUS), were used for measurement of the maximum aortic aneurysm diameter. Standardized 2D sonography was the defined reference standard for statistical analysis. CEUS was used for endoleak detection.

RESULTS

Technical success was 100%. In augmented transverse imaging the mean aortic anteroposterior (AP) diameter was 4.0±1.3 cm for 2D US, 4.0±1.2 cm for 3D Curefab™, and 3.9±1.3 cm for 4D US and 4.0±1.2 for image fusion. The mean differences were below 1 mm (0.2-0.9 mm). Concerning estimation of aneurysm growth, agreement was found between 2D, 3D and 4D US in 19 of the 20 patients (95%). Definitive decision could always be made by image fusion. CEUS was combined with all methods and detected two out of the 20 patients (10%) with an endoleak type II. In one case, endoleak feeding arteries remained unclear with 2D CEUS but could be clearly localized by 3D CEUS and image fusion.

CONCLUSION

Standardized 2D US allows adequate routine follow-up of maximum aortic aneurysm diameter after EVAR. Image Fusion enables a definitive statement about aneurysm growth without the need for new CT imaging by combining the postoperative CT scan with real-time B mode in a dual image display. 3D/4D CEUS and image fusion can improve endoleak characterization in selected cases but are not mandatory for routine practice.

Contemporary Applications of Ultrasound in Abdominal Aortic Aneurysm Management

Ultrasound (US) is a well-established screening tool for detection of abdominal aortic aneurysms (AAAs) and is currently recommended not only for those with a relevant family history but also for all men and high-risk women older than 65 years of age. The advent of minimally invasive endovascular techniques in the treatment of AAAs [endovascular aneurysm repair (EVAR)] has increased the need for repeat imaging, especially in the postoperative period. Nevertheless, preoperative planning, intraoperative execution, and postoperative surveillance all mandate accurate imaging. While computed tomographic angiography and angiography have dominated the field, repeatedly exposing patients to the deleterious effects of cumulative radiation and intravenous nephrotoxic contrast, US technology has significantly evolved over the past decade. In addition to standard color duplex US, 2D, 3D, or 4D contrast-enhanced US modalities are revolutionizing AAA management and postoperative surveillance. This technology can accurately measure AAA diameter and volume, and most importantly, it can detect endoleaks post-EVAR with high sensitivity and specificity. 4D contrast-enhanced US can even provide hemodynamic information about the branch vessels following fenestrated EVARs. The need for experienced US operators and accredited vascular labs is mandatory to guarantee the reliability of the results. This review article presents a comprehensive overview of the literature on the state-of-art US imaging in AAA management, including post-EVAR follow-up, techniques, and diagnostic accuracy.

Advances in determining abdominal aortic aneurysm size and growth

Abdominal aortic aneurysm is a common pathology in the aging population of the developed world which carries a significant mortality in excess of 80% in case of rupture. Aneurysmal disease probably represents the only surgical condition in which size is such a critical determinant of the need for intervention and therefore the ability to accurately and reproducibly record aneurysm size and growth over time is of outmost importance. In the same time that imaging techniques may be limited by intra- and inter-observer variability and there may be inconsistencies due to different modalities [ultrasound, computed tomography (CT)], rapid technologic advancement have taken aortic imaging to the next level. Digital imaging, multi-detector scanners, thin slice CT and most- importantly the ability to perform 3-dimensional reconstruction and image post-processing have currently become widely available rendering most of the imaging modalities used in the past out of date. The aim of the current article is to report on various imaging methods and current state of the art techniques used to record aneurysm size and growth. Moreover we aim to emphasize on the future research directions and report on techniques which probably will be widely used and incorporated in clinical practice in the near future.

Ultrasound diagnostics of the abdominal aorta: English version

BACKGROUND AND OBJECTIVES

The ideal method for screening investigations is one which is as free as possible from side effects, is easily learnt, and can therefore be broadly used to detect abdominal aortic aneurysms (AAA) with a high degree of certainty. Although ultrasonography fulfils these criteria, the measurement method is not standardized. Different measurement methods are used in ultrasonography as well as in computed tomography (CT) studies and the measurement method is actually described sufficiently in only 57 % of cases.

METHODS

This article provides a critical review of the current literature on measurement methods and the validity of ultrasonography for the determination of aortic diameter, particularly in AAA, and presents the measurement principles for making measurements as precisely as possible.

RESULTS AND CONCLUSION

The most precise determination of aortic diameter is carried out by electrocardiogram (ECG) gating according to the leading-edge method with orthogonal slicing. Within the framework of screening investigations, sufficient measurement precision can be achieved by adherence to orthogonal slicing. Using these standardized measurement methods, ultrasonography shows valid and reproducible results even compared with CT and is the method of choice in screening investigations for AAA.

The pathophysiologic basis of abdominal aortic aneurysm progression: a critical appraisal

An aneurysm of the abdominal aorta is a common pathology and a major cause of sudden death in the elderly. Currently, abdominal aortic aneurysms (AAAs) can only be treated by surgery and an effective medical therapy is urgently missing. The pathophysiology of AAAs is complex and is believed to be best described as a comprehensive inflammatory response with an accompanying proteolytic imbalance; the latter being held responsible for the progressive weakening of the aortic wall. Remarkably, while interference in inflammatory and/or proteolytic cascades proves highly effective in preclinical studies, emerging clinical studies consistently fail to show a benefit. In fact, some anti-inflammatory interventions appear to adversely influence the disease process. Altogether, recent clinical observations not only challenge the prevailing concepts of AAA progression, but also raise doubt on the translatability of findings from rodent models for growing AAA.

Three-dimensional ultrasound evaluation of small asymptomatic abdominal aortic aneurysms

OBJECTIVE

Non-invasive and reproducible size measurements that correlate well with computed tomography (CT) are desirable in the management of small abdominal aortic aneurysms (AAA). Three dimensional ultrasound (3D-US) technology may reduce inaccuracy because of variations in orientation of the image planes and axis. This study aimed to determine any differences in paired size estimation associated with three 3D-US derived methods using 3D-CT as the gold standard. When CTA was not available, the patients were enrolled anyway to assess 3D-US reproducibility in terms of agreement between two physicians.

METHODS

In the period from 1 March 2013 to 27 February 2014, consecutive patients with a small AAA, <5.5 cm for men and <5.2 cm for women, underwent 3D-US examination and three AAA size measures were obtained: dual plane diameter, diameter perpendicular to the residual sac's centreline and a partial volume.

RESULT

In all, 122 consecutive US examinations were performed. Patients were excluded because of inadequate AAA size (n = 11) and for technical reasons (n = 11). Thus, 100 patients (F/M; 20/80) with a median maximum AAA diameter of 46 (range 31-55) mm were analysed. The mean US dual plane diameter and the 3D-US centreline diameter were 2.6 mm and 1.8 mm smaller than the mean 3D-CT centreline diameter, respectively (p = .003). The inter-observer reproducibility coefficient was 3.7 mm for the US dual plane diameter and 3.2 mm for the 3D-US centreline diameter (p = 0.222). For the partial volume, the reproducibility was 8-12%, corresponding to a diameter variability of ±3 mm. The median time used for post-processing of the 3D-US acquisition was 72 (range 46-108) seconds per examination.

CONCLUSION

3D-US demonstrated an acceptable reproducibility and a good agreement with 3D-CT, and has the potential to improve future AAA management through more reliable ultrasound guided size estimates.

Comparison of colour duplex ultrasound with computed tomography to measure the maximum abdominal aortic aneurysmal diameter

Introduction. Maximum diameter of an abdominal aortic aneurysm (AAA) is the main indication for surgery. This study compared colour duplex ultrasound (CDU) and computed tomography (CT) in assessing AAA diameter. Patients and Methods. Patients were included if they had both scans performed within 90 days. Pearson's correlation coefficient, paired t-test, and limits of agreement (LOA) were calculated for the whole group. Subgroup analysis of small (<5.0 cm), medium (5.0-6.5 cm), and large (>6.5 cm) aneurysms was performed. A P value of <0.05 was considered statistically significant. Results. 389 patients were included, giving 130 pairs of tests for comparison. Excellent correlation was in the whole group (r = 0.95) and in the subgroups (r = 0.94; 0.69; 0.96, resp.). Small LOA between the two imaging modalities was found in all subgroups. Conclusion. Small aneurysms can be accurately measured using CDU. CDU is preferable for small AAAs, but cannot supplant CT for planning aortic intervention.

Diagnostic accuracy of non-radiologist performed ultrasound for abdominal aortic aneurysm: systematic review and meta-analysis

BACKGROUND

Ultrasonography is increasingly used by clinicians to identify abdominal aortic aneurysms (AAA). We performed a systematic review and meta-analysis comparing the accuracy of non-radiologist performed ultrasound (NRPUS) for AAA disease to the 'gold standard' of radiologist performed aortic imaging (RPI), intra-operative findings or postmortem findings.

METHODS

Cochrane Library, MEDLINE, EMBASE, SCOPUS-V.4, trial registries, conference proceedings, and article reference lists were searched to identify studies comparing NRPUS with RPI as the reference standard. Data abstracted from eligible studies was used to generate 2 × 2 contingency tables allowing calculation of pooled sensitivity and specificity values.

RESULTS

11 studies (944 patients) evaluated NRPUS for AAA detection. NRPUS had a pooled sensitivity of 0.975 [95% confidence interval (CI), 0.942-0.992] for AAA detection and a pooled specificity of 0.989 (95% CI, 0.979-0.995).

CONCLUSIONS

Non-radiologist performed ultrasound achieves acceptable sensitivity and specificity for both detection and measurement of AAA. There was no evidence of significant heterogeneity with respect to pooled sensitivity or specificity.

Ultrasound measurement for abdominal aortic aneurysm screening: a direct comparison of the three leading methods

OBJECTIVES

Ultrasound (US) is non-invasive and cost-effective for screening abdominal aortic aneurysms (AAAs) but there is no universally accepted method to measure the aortic diameter. This study evaluates the accuracy, reproducibility, and repeatability of three methods: inner-to-inner (ITI), leading-to-leading edge (LTL), and outer-to-outer (OTO). The secondary objective of this study was to determine whether aneurysm size or grade of operator had any effect on either intra- or inter-observer variability.

METHODS

Fifty static US images were measured by six assessors (2 vascular radiologists, 2 interventional radiology trainees, and 2 sonographers) on two separate occasions 6 weeks apart. Repeatability and reproducibility were calculated and compared with computed tomography (CT) as the gold standard.

RESULTS

All three methods have high repeatability and reproducibility when static images are used. The inter-observer reproducibility coefficients between assessors were 0.48 cm, 0.35 cm, and 0.34 cm for ITI, LTL and OTO, respectively. The intra-observer repeatability coefficients between assessors were 0.30 cm, 0.20 cm, and 0.19 cm for ITI, LTL and OTO, respectively. The mean difference between CT and OTO, LTL, and ITI was 1 mm, 3 mm, and 5 mm, respectively (all underestimations) (p < .0001).

CONCLUSIONS

US consistently underestimates aortic size when compared with CT, with ITI demonstrating the greatest underestimation (on average 5 mm). In the UK, this underestimation by the NHS Abdominal Aortic Aneurysm screening programme reduces the sensitivity of the screening test and may impact on the way in which vascular specialists interpret the findings of the screening programme.

Discrepancies in determination of abdominal aortic aneurysms maximum diameter and growth rate, using axial and orhtogonal computed tomography measurements

PURPOSE

Maximum diameter and growth rate of abdominal aortic aneurysms (AAAs) which are currently used as the only variables to set the indication for elective repair are recorded through computed tomography (CT) measurements on an axial plane or on an orthogonal plane that is perpendicular to vessel centerline, interchangeably. We will attempt to record possible discrepancies between the two methods, identify whether such differences could influence therapeutic decisions and determine in which cases this should be expected.

MATERIALS AND METHODS

We retrospectively reviewed sixty CT-scans performed in thirty-nine patients. Three-dimensional reconstruction of AAAs has been performed and differences in maximum diameter measured on axial and orthogonal planes were recorded. A measure for asymmetry was introduced termed ShapeIndex defined as the value of section minor over major axis and was related with differences in maximum diameter recordings. Growth rates were also determined using both axial and orthogonal measurements.

RESULTS

Axial measurements overestimate maximum diameter by 2 ± 2.7 mm (P<0.001) with a range of 0-12.3mm. Overall, 20% of the CTs had an axial maximum diameter >5.5 cm indicating the need for intervention whereas, orthogonal diameter was below that threshold. Asymmetry of the axial sections with ShapeIndex≤0.8 was found to be related to an overestimation of maximum diameter by >5mm. There were no significant differences in growth rates when determined using orthogonal or axial measurements in both examinations (median growth rate: 2.3mm and 3.3mm respectively P=0.2). However there were significant differences when orthogonal measurements were used at initial and axial measurements used at follow-up examination or vice versa (median growth rate: 4.9 mm and 0.9 mm respectively P<0.001).

CONCLUSIONS

Although the mean difference between measurements is low there is a wide range among cases, mainly observed in asymmetrical AAAs. ShapeIndex may identify those which are more likely to be misestimated. CT measurements performed to establish AAA growth rates should consistently use either the axial or orthogonal technique to avoid inaccuracies from occurring.

Management of small asymptomatic abdominal aortic aneurysms - a review

The approach for abdominal aortic aneurysms (AAAs) larger than 55 mm is well defined due to the risk of rupture being higher than 10% per year, and a 30-day perioperative mortality rate between 2.5% and 5%. However, the approach for small asymptomatic AAAs is less well defined.There are different definitions given to describe a small AAA. The one the authors accepted and applied is "a localized, permanent and irreversible dilation of the aorta of at least 50% in relation to the normal adjacent infrarenal or suprarenal aorta, with a maximum diameter between 30-55 mm".The investigators of the largest study on small AAAs (United Kingdom Small Aneurysm Trial [UK-SAT]) concluded, in brief, that ultrasound monitoring is the most appropriate solution because the results do not support a policy of surgical restoration for AAAs with a diameter of between 40 mm and 55 mm.The aim of the present review article is to highlight several challenges that could change the limits or create a more flexible deciding factor in the management of AAAs. There are multiple factors that influence surgical decision-making, and the limit on aneurysm diameter that indicates surgery should depend on the patient's age, life expectancy, general status, associated diseases, diameter in relation to body mass, risk factors, sex, anxiety and compliance during the follow-up period. Monitoring is an acceptable alternative for AAAs between 40 mm and 55 mm, and is probably the best solution for high-risk patients. Surgery is the most reasonable solution for patients who are at moderate risk, have a significant life expectancy, are less than 70 to 75 years of age, and/or have aortic aneurysms larger than 50 mm.

Use of colour duplex ultrasound as a first line surveillance tool following EVAR is associated with a reduction in cost without compromising accuracy

INTRODUCTION

CT scanning remains the postoperative surveillance imaging modality of choice following EVAR. Concerns regarding cost, exposure to ionising radiation and intravenous contrast have led to a search for a less expensive, equally efficacious and safer method of monitoring EVAR patients after endograft deployment. This study evaluated the cost saving obtained if CDUS was employed as a first line surveillance tool following EVAR, as well as comparing the two entities in terms of efficacy.

PATIENTS & METHODS

Postoperative surveillance CTs and CDUS scans in the 145 patients who have undergone EVAR from 1st June 2003 to 1st July 2010 were compared for the detection of endoleak and determination of residual sac size.

RESULTS

Adopting a protocol where CDUS was employed as the first line surveillance tool following EVAR would result in a reduction in the number of postoperative CTs required in 2010 from 235 to 36. Based on 2010 costings, this would equate to an estimated reduction in expenditure from €117,500 to €34,915 a saving of €82,585. CDUS had a sensitivity of 100% and a specificity of 85% in the detection of endoleaks compared to CT. The positive predictive value was 28% and negative predictive value 100%. The Pearson Coefficient correlation of 0.96 indicates a large degree of correlation between CDUS and CT when measuring residual aneurysm size following EVAR.

CONCLUSION

CDUS can replace CT as the first line surveillance tool following EVAR. This is associated with a significant reduction in the cost of surveillance without any loss of imaging accuracy.

Agreement between computed tomography and ultrasound on abdominal aortic aneurysms and implications on clinical decisions

OBJECTIVES

The United Kingdom abdominal aortic aneurysm (AAA) screening programme refers aneurysms with ultrasound (US) diameters of ≥5.5 cm to vascular services for consideration of computed tomography (CT) and intervention. We investigated the discrepancy between US and CT, implications on clinical decisions and question at which stage CT be used.

DESIGN/METHODS

AAA USs over 5 years were retrospectively analysed. Patients included had aneurysms measuring ≥5 cm on US with subsequent CT within 2 months (n = 123). Based on maximum US diameters, 44 patients had aneurysms between 5 and 5.4 cm (group I) and 79 patients ≥5.5 cm (group II). Results were cross-referenced. Correlation and limits of agreement were calculated. Two radiologists re-measured 44 pairs of CT/US scans and the inter-observer bias in determining discrepancies between imaging modalities calculated.

RESULTS

Mean difference between imaging modalities was 0.21 cm (±0.39 cm, p < 0.001). Limits of agreement were -0.55 to 0.96 cm, exceeding clinical acceptability. Mean difference was higher and significant in group I (0.39 cm, p < 0.001) compared to group II (0.10 cm, p > 0.05). Seventy-percent of group I patients had CT scans revealing diameters of ≥5.5 cm. Inter-observer bias was not significant.

CONCLUSION

Significant differences between imaging modalities, more in US diameters of below 5.5 cm, exist. We recommend AAAs measuring ≥5 cm on US should undergo earlier referral to a vascular service and CT.

Increased metabolic activity in abdominal aortic aneurysm detected by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT)

OBJECTIVES

Abdominal aortic aneurysms (AAAs) are associated with an inflammatory cell infiltrate and enzymatic degradation of the vessel wall. The aim of this study was to detect increased metabolic activity in the wall of the AAA with 18F-fluorodeoxyglucose ((18)F-FDG), mediated by glucose transporter protein (GLUTs), using a dedicated hybrid PET/64-detector CT. DESIGN, METHOD AND MATERIALS: 14 patients (All male, mean age 73.6 years, range 61-82) with AAA under surveillance underwent PET/CT scanning with 175 MBq of intravenous (18)F-FDG. The maximum aneurysm diameter and calcification score were determined on the attenuation correction CT. A volume of interest was placed on the aneurysm sac and the maximum Standardised Uptake Value (SUV(max)) measured.

RESULTS

The mean aneurysm diameter was 5.4 cm (SD+/-0.8). Two aneurysms had the CT characteristics of inflammatory aneurysms. Twelve aneurysms showed increased FDG uptake (SUV(max)>2.5). There was no significant difference in FDG uptake between heavily calcified aneurysms and non-heavily calcified aneurysms (t-test). There was a significant increase in the FDG uptake in the two inflammatory aneurysms compared to the other twelve aneurysms (t-test; P=0.04).

CONCLUSION

The findings in this study offer in vivo evidence that the AAA wall shows increased glucose metabolism, mediated by the GLUTs: this increased metabolic activity as detected by PET/CT may be present in most AAAs.

Comparison with computed tomography of two ultrasound devices for diagnosis of abdominal aortic aneurysm

Screening for abdominal aortic aneurysms (AAAs) in patients at risk will become more cost effective if a simple, inexpensive, and reliable ultrasound device is available. The aim of this study was to compare a 2-dimensional, handheld ultrasound device and a newly developed ultrasound volume scanner (based on bladder scan technology) with computed tomography (CT) for diagnosing AAA. A total of 146 patients (mean age 69 +/- 10 years; 127 men) were screened for the presence of AAAs (diameter >3 cm) using CT. All patients were examined with the handheld ultrasound device and the volume scanner. Maximal diameters and volumes were used for the analyses. AAAs were diagnosed by CT in 116 patients (80%). The absolute difference of aortic diameter between ultrasound and CT was <5 mm in 88% of patients. Limits of agreement between ultrasound and CT (-6.6 to 9.4 mm) exceeded the limits of clinical acceptability (+/-5 mm). An excellent correlation between ultrasound and CT was observed (r = 0.98). The correlation coefficient between the volume scanner and CT was 0.86, with agreement of 90% and kappa value of 0.73. Using an optimal cut-off value of >56 ml, defined by receiver-operating characteristic curve analysis, sensitivity, specificity, and the positive and negative predictive values of the volume scanner for detecting AAA were 90%, 90%, 97%, and 71%, respectively. In conclusion, this study shows that a 2-dimensional, handheld ultrasound device and a newly developed ultrasound volume scanner can effectively identify patients with AAAs confirmed by CT.

Ultraschalldiagnostik des rupturierten Bauchaortenaneurysmas bei Nierenkolik

The ruptured abdominal aortic aneurysm is a rare, but life-threatening disease that demands fast diagnosis. We report in the following about a patient who was admitted with symptoms of urinary obstruction and an acute abdomen. Ultrasound investigation at admission confirmed urinary obstruction of the right kidney. Causative for that however was a right pararenal ruptured abdominal aortic aneurysm, which led secondarily to ureter compression. Thus, in our opinion, primary ultrasound examination represents an important instrument in differential diagnosis.