Editor's Choice - Infra-Renal Aortic Diameter and Cardiovascular Risk: Making Better Use of Abdominal Aortic Aneurysm Screening Outcomes.

OBJECTIVE: Aortic diameter (AD), used traditionally for abdominal aortic aneurysm (AAA) screening may have a role in assessing cardiovascular risk. Unfortunately, AD estimates for those without AAA are underutilised, whilst cardiovascular risk is sub-optimally managed in those with AAA. Our objective was to examine the association between AD measurements and future cardiovascular risk. METHODS: Retrospective analysis of three databases of male participants screened for aortic aneurysm disease. Imaging and clinical data were obtained from three independent sources: 1) the Multi-centre Aneurysm Screening Study (MASS) trial (n = 26 882 men); 2) the 2013/14 cohort of the English NHS AAA Screening Programme (NAAASP) (n = 237 441 men) linked with NHS hospital admission and death registry data; and 3) the Framingham Heart Study (FHS) offspring cohort (n = 649). Associations between maximal aortic diameter, as measured on ultrasound or computed tomography, and cardiovascular outcomes were examined. RESULTS: Cardiovascular mortality in the MASS trial, was higher in men with AAA at 13 years of follow up, compared to those without (Hazard Ratio [HR] 2.22, 95% CI 1.97-2.50, p < .001). Contemporary risk of major adverse cardiovascular events in the NAAASP was highest in those with an AAA (HR 2.91, 95% CI 2.00-4.25), whilst, extremes of aortic diameter were associated with increased risk for cardiovascular events. Aortic diameter was an independent risk factor for cardiovascular events in the FHS dataset. CONCLUSION: Irrespective of the diagnosis of AAA, men attending for AAA screening who are found to have an abnormal aortic diameter are at high risk of future cardiovascular events. This currently unutilised data from AAA screening programmes has the potential to improve preventative management of cardiovascular risk.

[Hybrid treatment of patients with aneurysms and dissections of the aortic arch and descending portion of the thoracic aorta]. / Gibridnoe lechenie bol'nykh s anevrizmami i rassloeniiami dugi i niskhodiashchego otdela grudnoi aorty.

The authors share herein their experience with hybrid surgical treatment of 21 patients presenting with lesions of the aortic arch and descending thoracic aorta. Aortic pathology included dissection of the thoracoabdominal aorta (n=15), a sacciform aneurysm of the aortic arch (n=5), and a spindle-shaped aneurysm of the distal portions of the aortic arch (n=1). The first stage consisted of the following operations: transposition of the left subclavian artery into the left common carotid artery (n=9; 42.8%), partial debranching (n=11; 52.5%), and total debranching (n=1; 4.7%). The second stage consisted in implantation of a stent graft: to the thoracic aorta in 18 (85.8%) cases, and to the thoracic and abdominal portions of the aorta in 3 (14.2%) cases. The most significant complications of the immediate postoperative period included acute cerebral circulation impairment (n=1) and local dissection of the ascending aorta (n=1). Type I endoleaks were observed in 4 (19%) patients, type II endoleaks in 1 (4.7%), and type III endoleaks in 1 (4.7%). The mean duration of the follow up after discharge from hospital amounted to 11.6±7.9 months. In 4 patients after 6 months the findings of the control MSCT angiography showed no significant changes of the endoleaks. 1-year patency of the shunted branches of the aortic arch amounted to 95.2%. The cumulative survival rate amounted to 95.2%.

Underutilization of Routine Ultrasound Surveillance after Endovascular Aortic Aneurysm Repair.

BACKGROUND: Since 2009, the Society for Vascular Surgery has advocated annual surveillance imaging with ultrasound (US) after the first postoperative year for uncomplicated endovascular aneurysm repairs (EVARs). We sought to describe diffusion of US into long-term routine surveillance and to estimate potential cost savings among Medicare beneficiaries after EVAR. METHODS: Using Medicare claims data, we identified patients receiving EVAR from 2002 to 2010 and included only those who did not subsequently have reinterventions, late aneurysm-related complications, or death. We collected all relevant postoperative imaging (computed tomography [CT] and US) through 2011. Patients with follow-up less than 1 year were excluded. We estimated cost savings with increased use of US after the first postoperative year. RESULTS: The cohort comprised 24,615 patients with a mean follow-up of 3.9 ± 2.3 years. Mean number of images decreased from 2.23 in the first postoperative year to 0.31 in the 10th year. Utilization of US at the first postoperative year remained low but increased from 15.2% in 2003 to 28.8% in 2011 (P < 0.001). By the 10th postoperative year, the proportion of patients receiving US increased from 8.2% to 37.8%, while use of CT only remained high but decreased from 60.8% to 42.1%. Mean cost of surveillance imaging was $2,132/CT and $234/US. Performing US in 50-75% of patients beginning 1 year after EVAR would decrease costs by 14-48%/year. This translates to a mean cost savings of $338-$1135 per imaged patient per year, with an estimated savings to Medicare of $155 million to $305 million over 10 years. CONCLUSIONS: CT remains the primary modality of surveillance for up to 10 years after EVAR for patients without reinterventions or aneurysm-related complications. Increasing the use of US and decreasing the use of CT would save cost without compromising outcomes.

The prevalence and significance of thoracic findings in patients undergoing extended coverage computed tomography for assessment of abdominal aortic aneurysms.

OBJECTIVE: Many major vascular centres, including ours, incorporate coverage of the thoracic aorta in CT scans evaluating abdominal aortic aneurysms (AAAs) (extended coverage contrast-enhanced CT (EC-CECT) scan]. We sought to determine the prevalence of thoracic pathology in a large consecutive series of patients with AAA undergoing EC-CECT. METHODS: All patients who underwent EC-CECT for AAA between April 2013 and 2014 were identified from our radiology information system. Reports were retrospectively reviewed and for each study, sex, age and reported thoracic aortic and other non-vascular findings were extracted. Findings were initially categorized into "major" or "minor" depending on if they were mentioned in the report impression/conclusion. Any major thoracic pathology was termed "significant" if there was a new diagnosis/patient intervention/investigation and a change in patient management. RESULTS: Of the 150 scans included in the study, 97 (65%) had at least one thoracic finding. These findings included 24 scans (16%) with major findings and 73 scans (48%) with minor findings. In 13 scans (9%), the findings were significant and resulted in a delay (n = 11) or cancellation (n = 2) of AAA repair. CONCLUSION: Pre-procedural EC-CECT helps to identify significant intrathoracic findings in patients with AAA, which can have a major impact on AAA repair. This study supports the routine use of pre-procedural EC-CECT in planning AAA repair. ADVANCES IN KNOWLEDGE: This study describes the prevalence of significant thoracic pathology, which can impact on AAA repair. This information could potentially change the pre-procedure imaging protocol for patients with AAA.

The association among peri-aortic root adipose tissue, metabolic derangements and burden of atherosclerosis in asymptomatic population.

AIM: To describe the relationship between a novel measurement of peri-arotic root fat and ultrasound measures of carotid artery remodeling. MATERIALS AND METHODS: We studied 1492 consecutive subjects (mean age: 51.04 ± 8.97 years, 27% females) who underwent an annual cardiovascular risk survey in Taiwan. Peri-aortic root fat (PARF) was assessed by cardiac CT using three-dimensional (3D) volume assessment. Carotid artery morphology and remodeling were assessed by ultrasound. We explored the relationships between PARF volumes, cardiometabolic risk profiles and carotid morphology and remodeling. RESULTS: Mean PARF volume in current study was 20.8 ± 10.6 ml. PARF was positively correlated with measures of general adiposity, systemic inflammation, and several traditional cardiometabolic risk profiles (all p < 0.001) and successfully predicted metabolic syndrome (MetS) (AUROC: 0.75, 95%, confidence interval: 0.72-0.77). Higher PARF was independently associated with increased carotid artery intima-media thickness (IMT) (ß-coef.: 0.08) and diameter (ß-coef.: 0.08, both p < 0.05) after accounting for age, sex, BMI and other cardiovascular risk factors. The addition of PARF beyond metabolic syndrome components significantly provided incremental prediction value for abnormal IMT (ΔAUROC: 0.053, p = 0.0021). CONCLUSION: Peri-aortic root fat is associated with carotid IMT, even after adjustment for cardiometabolic risks, age and coronary atherosclerosis. Further research studies are warranted to identify the mediators of downstream pathophysiologic effects on carotid arteries by PARF and understand the mechanisms related to this correlation.

Prevalence and significance of incidentally noted dilation of the ascending aorta on routine chest computed tomography in older patients.

OBJECTIVE: The aim of this study was to determine the prevalence of incidental ascending aortic dilation and its significance over time in 55- to 80-year-olds undergoing routine computed tomographic scans. METHODS: Chest computed tomography reports for 64,092 patients who met the inclusion criteria were used to determine the prevalence of incidental ascending aortic dilation (4-5 cm) and, when possible, aortic growth rates. A chart review was performed to identify any aortic complication or intervention. RESULTS: The prevalence of incidental aortic dilation was 2.7% (671/24,992 patients). Of the 327 patients with aortic dilation and follow-up studies (mean, 3.4 years), only 3.7% (n = 12) demonstrated interval growth (mean of 0.9 mm/y). No patient underwent prophylactic surgery or intervention on the basis of aortic size or growth rate. One patient developed a type A dissection. CONCLUSIONS: Current guidelines for yearly surveillance imaging of aortic dilation could be revised to increase the follow-up interval and/or improve risk stratification to better identify the small subset of patients most likely to have disease progression.

Prognostic factors associated with radiotherapy for cervical cancer with computed tomography-detected para-aortic lymph node metastasis.

Patients with cervical cancer diagnosed with a para-aortic lymph node (PALN) metastasis by computed tomography (CT) scan were analyzed to identify associated prognostic factors. A total of 55 patients were reviewed, and 27 of these patients underwent extended-field radiotherapy (EFRT). The median PALN dose in patients receiving EFRT was 45 Gy (range, 27-57.6 Gy). Of the 55 patients, 28 underwent pelvic radiotherapy (RT); concurrent chemoradiotherapy (CCRT) was administered to 41 patients. The Kaplan-Meier method was used to calculate the actuarial rate. Multivariate analysis was performed using the Cox proportional hazards model. Five-year overall survival (OS) rates were 41% and 17.9% in patients undergoing EFRT and pelvic RT (P = 0.030), respectively. Age < 53 years (P = 0.023), FIGO Stage I-II (P = 0.002), and treatment with EFRT (P = 0.003) were independent predictors of better OS. The use of CCRT (P = 0.014), Stage I-II (P = 0.002), and treatment using EFRT (P = 0.036) were independent predictors of distant metastasis. In patients undergoing EFRT plus CCRT, the 5-year OS was 50%. Three-year PALN disease-free rates were 8.8%, 57.9% and 100% (P < 0.001) in CCRT patients who received PALN doses of 0 Gy, ≤45 Gy and ≥50.4 Gy, respectively. Although PALN metastasis is thought to be distant metastasis in cervical cancer, EFRT plus CCRT shows a good outcome, particularly in younger patients in an early FIGO stage. Cervical cancer with a PALN metastasis should not be considered incurable. Doses ≥50.4 Gy for treating PALN may result in better disease control.

Automated detection of healthy and diseased aortae from images obtained by contrast-enhanced CT scan.

PURPOSE: We developed the next stage of our computer assisted diagnosis (CAD) system to aid radiologists in evaluating CT images for aortic disease by removing innocuous images and highlighting signs of aortic disease. MATERIALS AND METHODS: Segmented data of patient's contrast-enhanced CT scan was analyzed for aortic dissection and penetrating aortic ulcer (PAU). Aortic dissection was detected by checking for an abnormal shape of the aorta using edge oriented methods. PAU was recognized through abnormally high intensities with interest point operators. RESULTS: The aortic dissection detection process had a sensitivity of 0.8218 and a specificity of 0.9907. The PAU detection process scored a sensitivity of 0.7587 and a specificity of 0.9700. CONCLUSION: The aortic dissection detection process and the PAU detection process were successful in removing innocuous images, but additional methods are necessary for improving recognition of images with aortic disease.

A novel tool for segmenting 3D medical images based on generalized cylinders and active surfaces.

Three-dimensional (3D) medical imaging has been incorporated in routine clinical practice, since the required infrastructure has become increasingly affordable. New algorithms and applications are needed to serve the additional image processing and analysis functions in 3D space. In this work we propose a system for semi-automatic modeling and segmentation of elongated salient and anatomical objects in 3D medical images. The proposed methodology is based on a novel mathematical formalization of a well-known class of geometric primitives, namely generalized cylinders (GCs), which exhibits advantages over the existing parametric definition. Since the anatomical objects have to be modeled by their intersection with the transverse image planes, the proposed methodology includes also a new seeded region growing (SRG) segmentation algorithm for ellipse detection in 2D images, based on a priori shape knowledge. Finally, the resulting GC model is used to initialize an active surface (AS) segmentation method, in order to accurately delineate the required object. In this work we present the proposed algorithms in detail, along with the evaluation of the accuracy of the model-based segmentation by experts. Results show that elongated objects like the aorta and the trachea may be segmented with sensitivity between 90% and 95%. The proposed SRG-ellipse detector requires minimal user-initialization and its executions requires only few seconds for each image slice on an average laptop. The evolution of the AS requires less than one second per iteration for a typical CT image. Comparisons are provided with state of the art semi-automatic medical image processing software, which validate the merit of the proposed work.

Evaluation of aortic root for definition of prosthesis size by magnetic resonance imaging and cardiac computed tomography: implications for transcatheter aortic valve implantation.

BACKGROUND: This study sought to compare cardiac magnetic resonance imaging (CMR) with dual source computed tomography (DSCT) for analysis of aortic root dimensions prior to transcatheter aortic valve implantation (TAVI). In addition, the potential impact of CMR and DSCT measurements on TAVI strategy defined by 2D-transesophageal echocardiography (TEE) was evaluated. METHODS: Aortic root dimensions were measured using CMR and DSCT in 58 patients referred for evaluation of TAVI. The TAVI strategy (choice of prosthesis size and decision to implant) was based on 2D-TEE annulus measurements. RESULTS: CMR and DSCT aortic root measurements showed an overall good correlation (r=0.86, p<0.001 for coronal aortic annulus diameters). There was also a good correlation between TEE and CMR as well as between TEE and DSCT for measurement of sagittal aortic annulus diameters (r=0.69, p<0.001). However, annulus diameters assessed by TEE (22.1±2.3mm) were significantly smaller than coronal aortic annulus diameters assessed by CMR (23.4±1.8mm, p<0.001) or DSCT (23.6±1.8, p<0.001). Regarding TAVI strategy, the agreement between TEE and sagittal CMR (kappa=0.89) as well as sagittal DSCT measurements (kappa=0.87) was statistically perfect. However, decision based on coronal CMR- or MSCT measurements would have modified TAVI strategy as compared to a TEE based choice in a significant number of patients (22% to 24%). CONCLUSION: In patients referred for TAVI, CMR measurements of aortic root dimensions show a good correlation with DSCT measurements and thus CMR may be an alternative 3D-imaging modality. Aortic annulus measurements using TEE, CMR and DSCT were close but not identical and the method used has important potential implications on TAVI strategy.

Anatomic differences of the distal aorta with dilatation or aneurysm between patients from Asia and Europe as seen on CT imaging.

AIM: The hypothesis of this research is that there are differences in morphology of dilated and aneurysm changed infrarenal aorta between the patients from Europe and Asia that are important for endovascular treatment. Authors analyzed the morphologic differences of the infra-renal segment of abdominal aorta (a.a.) and the iliac arteries, common iliac artery (c.i.a.) between the Asians and Europeans examined by computed tomography (64 MD CT) from the point of the clinical use of the endovascular stent-graft. MATERIALS AND METHODS: The research was conducted simultaneously in Europe and in Asia and 60 patients with distal aorta aneurysm were included (30 of each ethnic origin). The examinations were conducted at the identical types of 64 MD CT equipment, and under same conditions of examination technique and post-processing. RESULTS: There were statistically significant differences in regard to important morphology criteria for a.a. and c.i.a. between patients with the aneurysm from Asia and the Europe. Analysis was preformed referring to the gender, age, body weight (BW), height, body mass index (BMI), body surface (SA index), and various diameters of a.a. and c.i.a. at several linear and transversal levels, angle and volume of the aneurysm. The biggest differences relate to the width of the central part of aneurysm of a.a. and the length and volume of c.i.a. CONCLUSION: There were statistically significant differences in regard to important morphology criteria for a.a. and c.i.a. between patients with the aneurysm from Asia and the Europe.

Anatomic severity grading score predicts technical difficulty, early outcomes, and hospital resource utilization of endovascular aortic aneurysm repair.

BACKGROUND: In 2002, a system for the grading of abdominal aortic aneurysms (AAAs) was developed by the Society for Vascular Surgery (SVS). Because the correlation of the anatomic severity grading (ASG) score to patient outcomes has yet to be validated, we provide our experience with calculating the ASG score using three-dimensional (3-D) image-rendering software and provide the practical translation of this score into early outcomes and hospital charges. METHODS: All patients who underwent an endovascular aneurysm repair (EVAR) for infrarenal AAAs between 2009 and 2010 were retrospectively reviewed for demographics, intraoperative data, and 30-day outcomes. ASG scores were calculated from morphologic measurements, and two independent patient groups were created: those with a low ASG score (score <14) and a high ASG score (score ≥14). RESULTS: We identified 108 patients (mean age, 75 years), of whom 56 were in the low-score ASG group and 52 were in the high-score ASG group. Operative outcomes significantly different in the low-score group vs high-score group were number of endograft implants (three vs four, P = .001), operative time (113 vs 210 minutes, P < .0001), blood loss (227 vs 866 mL, P = .0002), and contrast volume (100 vs 131 mL, P = .032). In the low-score group compared with the high-score group, access site adjuncts were 14% vs 50% (P < .0001), and intraoperative adjuncts were 54% vs 80% (P = .004). Most adjuncts (75%) were endovascular. No EVARs were converted to open. Mean hospital stay was 2 days for the low-score group and 5 days for the high-score group (P = .012). The 30-day operative mortality was zero. No aneurysm-related deaths occurred during follow-up. In the low-score vs high-score groups, mean operating room supply charge was $16,646 vs $25,765 (P = .006), and the mean total hospital charge was $70,956 vs $105,153 (P = .016). CONCLUSION: The anatomic severity grading score can be easily and rapidly calculated from computed tomography images with the aid of 3-D image-rendering software. The anatomic severity grading score correlates with the technical difficulty of EVAR and the extent of hospital resource utilization.

[The importance of CT angiography for screening supra-aortic vascular damage in severely injured patients]. / Bedeutung der CT-Angiographie zum Screening supraaortaler Gefässverletzungen beim Schwerverletzten.

PURPOSE: Traumatic injury of supra-aortic vessels remains a challenge in the initial diagnostics of severely injured patients. The presented prospective study analyzed the impact of multislice computed tomography angiography (CTA) as the primary diagnostic method. METHODS: Patients with the following criteria were included and screened for a dissection of the supra-aortic vessels: a) admission directly from the scene, b) resuscitation room treatment indicated by the official criteria of the DGU (German Society for the Surgery of Trauma), c) suspected blunt trauma to head or trunk as well as d) age over 16 years. RESULTS: During a period of 18 months 374 patients were treated for blunt trauma in the resuscitation room. In 176 cases CTA of the supra-aortic vessels was performed and pathological findings were observed in 16 patients. In 4 cases (2%) a traumatic dissection of supra-aortal vessels was diagnosed and confirmed by magnetic resonance imaging (MRI). All patients received heparin in a PTT effective dosage for 2 weeks and after rehabilitation there were no neurologic deficits. CONCLUSION: Traumatic supra-aortic dissection was found in 2% of cases in the presented study group. The mechanisms of injury were not distinct in this group. Essentially MSCT angiography screening was demonstrated to be a safe diagnostic tool.

Radiologic evaluation of blunt thoracic aortic injury in pediatric patients.

OBJECTIVE: The objective of our study was to assess the mechanism of injury, associated injuries, and radiographic findings of pediatric patients presenting with blunt thoracic aortic injury. MATERIALS AND METHODS: The medical records and imaging studies of all pediatric patients presenting with blunt thoracic aortic injury from January 1986 through December 2007 (n = 17) were reviewed. The mechanism of injury, associated injuries, imaging findings, and surgical findings were recorded. The Fisher's exact test was used to assess changes in utilization of chest CT and thoracic aortography. RESULTS: The most frequent mechanism of injury was motor vehicle crash in which the patient was an unrestrained driver or unrestrained passenger (9/17 = 53%). The most common concurrent injury was solid abdominal organ injury (9/17 = 53%). The most frequent finding was a prominent or indistinct aortic knob (16/17 = 94%) on chest radiography, a periaortic hematoma and aortic contour abnormality on chest CT (9/10 = 90%), and aortic contour abnormality on thoracic aortography (11/11 = 100%). There was a statistically significant increase (p = 0.03) in chest CT examinations performed between January 1986 and December 1997 (4/9 = 44%) compared with between January 1986 and December 2007 (8/8 = 100%). There was a statistically significant decrease (p = 0.05) in thoracic aortography examinations performed between January 1986 and December 1997 (8/9 = 89%) compared with between January 1986 and December 2007 (3/8 = 38%). CONCLUSION: Blunt thoracic aortic injury is a rare injury in the pediatric population. Radiologic evaluation of pediatric patients presenting with this injury has changed. More chest CT examinations and fewer thoracic aortography examinations are being performed. Furthermore, surgeons are choosing to perform surgery on the basis of chest CT findings consistent with aortic injury.

Long-term outcomes and resource utilization of endovascular versus open repair of abdominal aortic aneurysms in Ontario.

OBJECTIVE: Two large randomized trials showed that elective endovascular aneurysm repair (EVAR) had similar all-cause long-term mortality rates but increased costs compared with open repair for nonruptured abdominal aortic aneurysms (AAAs). Despite these data, the use of EVAR continues to increase in North America. Currently, there are very limited adjusted population-based data examining long-term outcomes and resource utilization. METHODS: All patients who underwent elective AAA repair between April 2002 and March 2007 in Ontario were identified using data from hospital discharge abstracts. Patients were identified with a validated algorithm. A propensity score analysis was used to adjust for treatment allocation. Clinical outcomes included time to all-cause death and discharge to a nursing home or long-term care facility. Resource utilization outcomes included imaging utilization, hospital utilization, and reintervention rates. RESULTS: Overall, 6461 patients underwent treatment of nonruptured AAAs, comprising 888 EVARs and 5573 open repairs. EVAR patients were older and had more comorbidities. The adjusted mortality was significantly lower in the EVAR group at 30 days (adjusted odds ratio [adj-OR], 0.34; 95% confidence interval [95% CI], 0.20-0.59), but long-term mortality was similar (adj-OR, 0.95; 95% CI, 0.81-1.05). EVAR patients were significantly less likely to be discharged to a nursing home or other chronic care facility (adj-OR, 0.55; 95% CI, 0.41-0.74). Imaging utilization as well as urgent and vascular readmissions were significantly higher in the EVAR group. However, the EVAR group had a significantly shorter length of stay and less intensive care unit use for the index hospitalization and decreased hospital length of stay during follow-up. There was a trend toward a slightly increased risk of reintervention with EVAR (adj-OR, 1.3; 95% CI, 0.98-1.75). CONCLUSION: Compared with open repair, EVAR significantly reduced short-term but not long-term mortality. The EVAR patients spent less time in health institutions, including long-term care facilities, but underwent more imaging studies. Future improvements in EVAR could result in further decreases in reinterventions and subsequent radiologic monitoring.

[Prevalence of renal artery stenosis in patients undergoing cardiac catheterization: when should abdominal aortography be performed? Results in 467 patients]. / Prévalence des sténoses des artères rénales dépistées au cours de coronarographies diagnostiques: dans quels cas doit-on réaliser une aortographie abdominale? A propos de 467 patients.

PURPOSE: To define a subgroup of patients at increased risk of renal artery stenosis (RAS) in a population of patients undergoing cardiac catheterization. MATERIALS AND METHODS: A total of 467 patients (mean age of 64 Years +/-11) underwent cardiac catheterization and aortography Results were evaluated to detect correlations between the presence or absence of RAS and clinical and biological parameters. RESULTS: A total of 42 (9%) patients had a renal artery stenosis. Univariate analysis defined parameters correlated with the presence of RAS: systolic blood pressure (p=0.03), pulse pressure (p=0.005), age (p<0.0001), creatinine clearance (p<0.0001), 2-vessel (p=0.028) and 3-vessel (p=0.037) coronary artery diseases. Multivariate analysis showed that the presence of RAS correlated to creatinine clearance (p=0.02) and 2-vessel coronary artery disease. A creatinine clearance between 30 and 60 ml/min and multi-vessel coronary artery disease defined a subgroup at increased risk of RAS with sensitivity, specificity, positive and negative predictive values of: 47.6, 90.1, 32.3 and 94.6%. The prevalence of renal artery stenosis was 5.2% when both parameters were absent. CONCLUSION: Patients with mild renal insufficiency and multi-vessel coronary artery disease defined a subgroup of patients at increased risk of RAS (32.5%) that may benefit from abdominal aortography performed at the time of cardiac catheterization.

Interactive segmentation of abdominal aortic aneurysms in CTA images.

A model-based approach to interactive segmentation of abdominal aortic aneurysms from CTA data is presented. After manual delineation of the aneurysm sac in the first slice, the method automatically detects the contour in subsequent slices, using the result from the previous slice as a reference. If an obtained contour is not sufficiently accurate, the user can intervene and provide an additional manual reference contour. The method is inspired by the active shape model (ASM) segmentation scheme (), in which a statistical shape model, derived from corresponding landmark points in manually labeled training images, is fitted to the image in an iterative manner. In our method, a shape model of the contours in two adjacent image slices is progressively fitted to the entire volume. The contour obtained in one slice thus constrains the possible shapes in the next slice. The optimal fit is determined on the basis of multi-resolution gray level models constructed from gray value patches sampled around each landmark. We propose to use the similarity of adjacent image slices for this gray level model, and compare these to single-slice features that are more generally used with ASM. The performance of various image features is evaluated in leave-one-out experiments on 23 data sets. Features that use the similarity of adjacent image slices outperform measures based on single-slice features in all cases. The average number of slices in our datasets is 51, while on average eight manual initializations are required, which decreases operator segmentation time by a factor of 6.

Effect of contrast material injection duration and rate on aortic peak time and peak enhancement at dynamic CT involving injection protocol with dose tailored to patient weight.

PURPOSE: To investigate the effect of duration and rate of contrast material injection on aortic peak time and peak enhancement in an injection protocol in which the contrast material dose is adjusted according to patient weight. MATERIALS AND METHODS: One hundred ninety-nine patients were randomly divided into three groups in which the fixed duration of contrast material injection was 25 seconds (group A) or 35 seconds (group B) or the fixed injection rate was 4.0 mL/sec (group C). Computed tomography (CT) at the L3 vertebral level was performed before and after contrast material injection. Aortic peak time, aortic peak enhancement, and period when aortic enhancement is 200 HU or greater (T200) were calculated. The Pearson product-moment correlation coefficient (r) was used to investigate relationships between patient weight and aortic peak time, aortic peak enhancement, and T200 in each group. RESULTS: A significant correlation between aortic peak time and patient weight (r = 0.91, P <.001) was observed in group C. No significant correlations between patient weight and aortic peak time were observed in group A (r = 0.16, P =.21) or B (r = -0.05, P =.69). A significant inverse correlation between aortic peak enhancement and patient weight (r = -0.70, P <.001) was observed in group C. No significant correlations between patient weight and aortic peak enhancement were observed in group A (r = 0.09, P =.48) or B (r = 0.10, P =.41). A significant correlation between T200 and patient weight (r = 0.72, P <.001) was observed in group C. No significant correlations between patient weight and T200 were observed in group A (r = 0.12, P =.34) or B (r = 0.001, P =.99). CONCLUSION: Aortic peak time, aortic peak enhancement, and T200 were closely related to injection duration in the protocol with contrast material dose determined according to patient weight.

New post-imaging software provides fast and accurate volume data from CTA surveillance after endovascular aneurysm repair.

PURPOSE: To quantify intra- and interobserver variabilities when measuring total aneurysm volume after endovascular aneurysm repair using the Vitrea 2 System and to compare it in terms of accuracy and processing time with the gold standard methods using the Easy Vision workstation. METHODS: Total aneurysm volumes from 30 postendograft CTA datasets were randomly selected from a database consisting of approximately 400 CTA datasets recorded in 89 patients. The intra- and interobserver variabilities were measured on the Vitrea workstation by 2 investigators. The intermodality variability was calculated for the same measurements using the Easy Vision workstation. The differences of each pair of measurements were plotted against their mean, and the repeatability coefficient (RC) was calculated. The mean differences were also expressed as a percentage of the first measurements. RESULTS: The intraobserver mean difference was 1.6 mL (1.4%) with an RC of 10.8 mL (10.1%) and the interobserver mean difference was -1.4 mL (-1.4%) with an RC of 11.7 mL (10.2%). The intermodality mean difference was 1.8 mL (2.0%) with an RC of 15.8 mL (11.1%). The Vitrea workstation required a median of 8 minutes (interquartile range 7-10) for 1 observer and 6 minutes (interquartile range 5-8) for the other to perform a complete volume segmentation of each patient dataset compared to an estimated average of 30 minutes using the Easy Vision workstation. CONCLUSIONS: The Vitrea workstation provides fast and accurate volume data from spiral CTA follow-up of endovascular aneurysm repair. This software may enhance the acceptability of volume surveillance in daily practice.

Aorta and iliac arteries: single versus multiple detector-row helical CT angiography.

PURPOSE: To compare single- versus four-channel helical computed tomographic (CT) aortography. MATERIALS AND METHODS: Forty-eight patients with aortic aneurysm or dissection underwent four- and one-channel CT angiography. Scan pairs covered the thoracic inlet to the diaphragm (n = 10) and supraceliac abdominal aorta (n = 19) or thoracic inlet (n = 19) to the femoral arterial bifurcations. For four-channel CT, nominal section thickness and pitch were 2.5 mm and 6.0, respectively, and for one-channel CT, 3.0 mm and 2.0 to the infrarenal aorta and 5.0 mm and 2.0 to the femoral arteries. Effective section thickness, scanning duration, scanning coverage, dose of iodinated contrast material, and mean aortoiliac attenuation were compared. Data were summarized as speed (coverage/duration), scanning efficiency (speed/section thickness), and contrast efficiency (mean aortic attenuation/dose of contrast material). RESULTS: At four- versus one-channel CT, CT angiography was 2.6 times faster, scanning efficiency was 4.1 times greater, contrast efficiency was 2.5 times greater, dose of contrast material was reduced (mean, 57%; 97 vs 232 mL) without a significant change in aortic enhancement, and sections were thinner (mean, 40%; 3.2 vs 5.3 mm) despite a 59% shorter scanning duration (22 vs 56 seconds). CONCLUSION: Substantially reduced doses of contrast medium, shorter scanning durations, and narrower effective sections result with four- versus one-channel CT aortography. No advantages of one-channel CT aortography were demonstrated.