Noninvasive Computed Tomography Angiography Research Articles

Imaging Early Life Cardiovascular Phenotype.

The growing epidemics of obesity, hypertension, and diabetes, in addition to worsening environmental factors such as air pollution, water scarcity, and climate change, have fueled the continuously increasing prevalence of cardiovascular diseases (CVDs). This has caused a markedly increasing burden of CVDs that includes mortality and morbidity worldwide. Identification of subclinical CVD before overt symptoms can lead to earlier deployment of preventative pharmacological and nonpharmacologic strategies. In this regard, noninvasive imaging techniques play a significant role in identifying early CVD phenotypes. An armamentarium of imaging techniques including vascular ultrasound, echocardiography, magnetic resonance imaging, computed tomography, noninvasive computed tomography angiography, positron emission tomography, and nuclear imaging, with intrinsic strengths and limitations can be utilized to delineate incipient CVD for both clinical and research purposes. In this article, we review the various imaging modalities used for the evaluation, characterization, and quantification of early subclinical cardiovascular diseases.

Virtual pathology: Reaching higher standards for noninvasive CTA tissue characterization capability by using histology as a truth standard

AimsDespite advances in therapy, reduction in myocardial infarction or death remains elusive. Whereas computed tomography angiography (CTA) is increasingly appreciated, the analyses are often subjective or qualitative. Methods for specific tissue characterization using histopathologic correlates have recently been reported. We extend this here to demonstrate accurate discrimination between, and quantitation of, lipid-rich necrotic core (LRNC), intraplaque hemorrhage (IPH), and fibrotic tissues. MethodsNCT02143102 collected 576 tissue samples with paired CTA. Cardiovascular pathologists annotated LRNC, IPH, and dense calcification (CALC) regions as a reference standard. Blinded to histology, CTA was analyzed using ElucidVivo (Elucid Bioimaging Inc., Boston, MA USA). Structure and tissue characteristics of atherosclerotic plaque from CTA, accounting for both the imaging acquisition process and the biology, accounting for differences in density distributions that result from the different cellular and molecular level milieu of the relevant tissue types. ResultsLRNC was tested across a true range of 0–10 mm2, with a difference of 0.15 mm2 and a slope of 0.92. IPH was tested across a true range of 0–18 mm2, with a difference from histology of 1.68 mm2 and a slope of 0.95. CALC was tested across a range of 0–14 mm2, with a difference of −0.06 mm2 and a slope of 0.99. Matrix tissue (MATX) was tested across a range of 4–52 mm2, with a difference of 0.02 mm2 and a slope of 0.91. ConclusionLRNC, IPH, CALC, and MATX may be objectively quantified using histopathologic correlates automatically from CTA for use singly or in combination to optimize patient care. The availability of objectively validated quantitative markers that may be followed longitudinally may extend the clinical utility of CTA. Additionally, these measures contribute efficacy variables for developing novel drugs and clinical decision support tools for tailored therapeutics.

Image quality and radiation doses of volumetric 320-row computed tomography angiography with prospective electrocardiogram-gating in the assessment of coronary arteries in neonates and infants.

Diagnostic imaging of coronary arteries is required in neonates and infants suspected of congenital or acquired coronary artery anomalies and in pre- and postoperative assessment of complex congenital heart diseases (CHD). Our study aimed to evaluate the image quality of volumetric 320-row computed tomography angiography (CTA) with prospective electrocardiogram (ECG)-gating for coronary arteries in neonates and infants with heart diseases, analyze factors influencing image quality and assess a radiation dose related to the procedure. The study included 110 CTA performed in neonates and infants with CHD. CTA was performed in 37 girls and 73 boys at a median (interquartile range [IQR]) age of 3.0 (0.5-5.0) months, median (IQR) body weight of 5 (3.66-6.5) kg, and median heart rate (HR) of 133 (92-150) beats per minute. The orifices of the left coronary artery were visible in 100% of CTA, the orifices of the right coronary arteries were visible in 96%, whereas all coronary segments were assessable in 45% of CTA. Patients with non-diagnostic segments were significantly younger, median (IQR) age of 2.0 (0.21-5.00) months, had lower body weight of 4.6 (3.45-6.07) kg and faster HR of 136.5 (120-150) beats per minute (P <0.05) than patients with diagnostic image quality in all segments (4.0, 2-6 months, 6.0, 4.2-7 kg, and 130; 110-150 beats per minute, respectively; P <0.05). CTA performed with volumetric 320-row prospective ECG-gating allows for good visibility of the coronary arteries with an acceptable radiation dose. Children aged >15 days, with body weight >4.85 kg and HR <130 beats per minute are good candidates for excellent quality non-invasive CTA of all segments of coronary arteries.

Abstract 15832: Endothelial Shear Stress Assessment in Coronary Arteries: Comparison Between 3d Reconstructions Based on Invasive and Noninvasive Imaging

Introduction: Endothelial shear stress (ESS) identifies coronary plaques at high risk for progression and rupture leading to a future acute coronary syndrome. We developed an optimized methodology to derive ESS using computational fluid dynamics (CFD) in 3D models of coronaries from noninvasive computed tomography angiography (CTA). We hypothesized that ESS based on CTA has a high correlation with ESS based on the gold standard fusion of intravascular ultrasound (IVUS)/optimical coherence tomography (OCT) and CTA. Methods: In 14 patients, paired patient-specific CFD models based on invasive and CTA imaging of the left anterior descending (LAD) coronaries were created. 10 were used to optimize, and 4 patients to test the methodology. Time averaged ESS (TAESS) was calculated for both coronary models applying physiological data at the time of imaging. Each 3D reconstructed coronary was divided into 2 mm segments and further subdivided into 8 arcs (45 o ). TAESS was averaged per segment and arc. The paired segment and arc averaged TAESS were categorized into patient-specific tertiles (low, medium and high). Results: In the 10 LADs, used for optimization of the methodology, we found high correlations between invasively- and noninvasively-derived TAESS averaged over segments (n=263, r=0.86) and arcs (n=2104,r= 0.85,p&lt;0.001). The correlation was also strong in the 4 test patients with r=0.95 (n=117 segments p=0.001) and r=0.93 (n=936 arcs p=0.001). There was a high concordance of 78% of the three TAESS categories comparing both imaging at the segments and 76% at the arcs in the first 10 patients. This concordance was lower in the 4 test patients (64% and 64% in segment and arc averaged TAESS). Conclusions: We showed that we can accurately assess the TAESS distribution noninvasively from CTA and demonstrated a high correlation with TAESS using IVUS/OCT 3D models. Future studies should prove the prognostic value of CTA-based TAESS for plaque progression and clinical events.

Detection and Evaluation of Intracranial Aneurysms in the Posterior Fossa by Multidetector Computed Tomography Angiography - Comparison with Digital Subtraction Angiography.

Introduction:Posterior fossa hemorrhages are not so frequent but as posterior cranial fossa space is narrow and has many vital structures, even a small amount of bleed can lead to compression of brain stem and serious consequences. Identification and planning management of cause of bleed requires angiogram. Digital subtraction angiography (DSA) being invasive modality but is gold standard, so noninvasive computed tomography angiography (CTA) is compared to detect cause of bleed in the posterior fossa in this study.Materials and Methods:From January 2017 to October 2018, all patients with posterior fossa bleed who underwent CTA and DSA for evaluation were compared regarding identification of aneurysm as cause of bleed.Results:A total of 49 patients were evaluated in this study during study duration, of which 26 (53%) were male and 23 (47%) were female. Out of 49 patients evaluated, 47 patients had aneurysms detected on DSA. Of 25 patients who underwent both procedures, 23 patients had aneurysms, and correct diagnosis was made with CTA in 24 out of 25 aneurysms. One aneurysm missed by CTA was close to bony structure.Discussion:With advancement of CTA technology, sensitivity of detecting intracranial aneurysms has increased to >96%. The overall sensitivity in detecting aneurysms is 96% with sensitivity in detecting aneurysms >4 mm being 100%. The sensitivity of CTA for smaller sized aneurysms is low which is attributed partially to lower spatial resolution of CT compared to DSA.Conclusion:CTA is a simple, fast, and noninvasive imaging modality that can be used to detect and characterize intracranial aneurysms in the posterior fossa.

Congestive heart failure caused by silent ischemia and silent myocardial infarction

In asymptomatic patients with type2 diabetes (T2D), the prevalence of silent myocardial infarction on routine electrocardiograms is about 4% while for silent myocardial ischemia it is 20-30%. Some studies showed that silent myocardial infarction is associated with an increased risk of incident heart failure (HF), whereas no prospective study has ever reported such arisk in patients with silent myocardial ischemia. In patients with HF, however, previously unrecognized coronary artery disease (CAD) often seems to be involved. Brain natriuretic peptide (BNP) and N‑terminal pro-BNP (NT-proBNP) levels represent first-line diagnostic tools for patients with suspected HF and might also serve as biomarkers for silent CAD. Echocardiography provides adetailed report of cardiac alterations that includes changes suggestive of ischemia, heart failure, and left ventricular dysfunction in addition to strong prognostic indices. Diabetic patients with silent myocardial infarction or silent myocardial ischemia should be screened for asymptomatic changes in left ventricular function or structure. In patients with silent CAD, all risk factors need to be better controlled and the choice of antihyperglycemic agents adjusted. In patients with congestive HF and no obvious cause of HF, invasive coronary angiography (or noninvasive computed tomography angiography) should be performed to detect CAD, since the finding of CAD may involve revascularization and requires additional treatments including antiplatelet agents and statins. Future research is needed to examine the cost effectiveness of screening for silent myocardial ischemia as part of HF risk assessment, and to identify preventive therapies to lower the risk of HF among patients with silent myocardial infarction.

Numerical analysis of the pressure drop across highly-eccentric coronary stenoses: application to the calculation of the fractional flow reserve

BackgroundFractional flow reverse (FFR) is the gold standard assessment of the hemodynamic significance of coronary stenoses. However, it requires the catheterization of the coronary artery to determine the pressure waveforms proximal and distal to the stenosis. On the contrary, computational fluid dynamics enables the calculation of the FFR value from relatively non-invasive computed tomography angiography (CTA).MethodsWe analyze the flow across idealized highly-eccentric coronary stenoses by solving the Navier–Stokes equations. We examine the influence of several aspects (approximations) of the simulation method on the calculation of the FFR value. We study the effects on the FFR value of errors made in the segmentation of clinical images. For this purpose, we compare the FFR value for the nominal geometry with that calculated for other shapes that slightly deviate from that geometry. This analysis is conducted for a range of stenosis severities and different inlet velocity and pressure waveforms.Results and conclusionsThe errors made in assuming a uniform velocity profile in front of the stenosis, as well as those due to the Newtonian and laminar approximations, are negligible for stenosis severities leading to FFR values around the threshold 0.8. The limited resolution of the stenosis geometry reconstruction is the major source of error when predicting the FFR value. Both systematic errors in the contour detection of just 1-pixel size in the CTA images and a low-quality representation of the stenosis surface (coarse faceted geometry) may yield wrong outcomes of the FFR assessment for an important set of eccentric stenoses. On the contrary, the spatial resolution of images acquired with optical coherence tomography may be sufficient to ensure accurate predictions for the FFR value.

Diagnostic Performance of a Novel Method for Fractional Flow Reserve Computed from Noninvasive Computed Tomography Angiography (NOVEL-FLOW Study)

Coronary computed tomography angiography (CCTA)-derived fractional flow reserve from computed tomography (CT-FFR) may provide better diagnostic performance over CCTA alone, but the complexity of its method limits the use in clinical environment. The aim of the present study is to validate a newly developed vessel-length based computational fluid dynamics scheme for the computation of FFR based on CCTA data, compare them with invasively measured FFR, and evaluate its diagnostic performance with that of CCTA. One hundred seventeen patients from 4 medical institutions who had clinically indicated invasive coronary angiography for suspected coronary artery disease (CAD) were enrolled. Invasive FFR measurement was performed in 218 vessels and these measurements were regarded as the reference standard. The accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of CT-FFR on a per-vessel basis were 85.8%, 86.2%, 85.5%, 79.8%, and 90.3%, respectively, for CT-FFR ≤0.80, and 66.1%, 75.9%, 59.5%, 55.5%, and 78.8%, respectively, for CCTA ≥50%. A higher area under the receiver operating characteristic curve for CT-FFR was observed compared with CCTA (0.93 vs 0.74, p<0.0001). The CT-FFR and FFR correlated well (r= 0.76, p <0.001) with slight underestimation by CT-FFR (0.014 ± 0.077, p= 0.007). With a novel method of vessel-length based computational fluid dynamics scheme, CT-FFR can be performed at a personal computer enhancing its applicability in clinical situation. The diagnostic accuracy of CT-FFR for the detection of functionally significant CAD was good and was superior to that of CCTA within a population of suspected CAD.

Distinctive patterns on CT angiography characterize acute internal carotid artery occlusion subtypes.

Noninvasive computed tomography angiography (CTA) is widely used in acute ischemic stroke, even for diagnosing various internal carotid artery (ICA) occlusion sites, which often need cerebral digital subtraction angiography (DSA) confirmation. We evaluated whether clinical outcomes vary depending on the DSA-based occlusion sites and explored correlating features on baseline CTA that predict DSA-based occlusion site.We analyzed consecutive patients with acute ICA occlusion who underwent DSA and CTA. Occlusion site was classified into cervical, cavernous, petrous, and carotid terminus segments by DSA confirmation. Clinical and radiological features associated with poor outcome at 3 months (3–6 of modified Rankin scale) were analyzed. Baseline CTA findings were categorized according to carotid occlusive shape (stump, spearhead, and streak), presence of cervical calcification, Willisian occlusive patterns (T-type, L-type, and I-type), and status of leptomeningeal collaterals (LMC).We identified 49 patients with occlusions in the cervical (n = 17), cavernous (n = 22), and carotid terminus (n = 10) portions: initial NIH Stroke Scale (11.4 ± 4.2 vs 16.1 ± 3.7 vs 18.2 ± 5.1; P < 0.001), stroke volume (27.9 ± 29.6 vs 127.4 ± 112.6 vs 260.3 ± 151.8 mL; P < 0.001), and poor outcome (23.5 vs 77.3 vs 90.0%; P < 0.001). Cervical portion occlusion was characterized as rounded stump (82.4%) with calcification (52.9%) and fair LMC (94.1%); cavernous as spearhead occlusion (68.2%) with fair LMC (86.3%) and no calcification (95.5%); and terminus as streak-like occlusive pattern (60.0%) with poor LMC (60.0%), and no calcification (100%) on CTA.Our study indicates that acute ICA occlusion can be subtyped into cervical, cavernous, and terminus. Distinctive findings on initial CTA can help differentiate ICA-occlusion subtypes with specific characteristics.

Computed tomography versus invasive coronary angiography: design and methods of the pragmatic randomised multicentre DISCHARGE trial.

More than 3.5 million invasive coronary angiographies (ICA) are performed in Europe annually. Approximately 2 million of these invasive procedures might be reduced by noninvasive tests because no coronary intervention is performed. Computed tomography (CT) is the most accurate noninvasive test for detection and exclusion of coronary artery disease (CAD). To investigate the comparative effectiveness of CT and ICA, we designed the European pragmatic multicentre DISCHARGE trial funded by the 7th Framework Programme of the European Union (EC-GA 603266). In this trial, patients with a low-to-intermediate pretest probability (10-60%) of suspected CAD and a clinical indication for ICA because of stable chest pain will be randomised in a 1-to-1 ratio to CT or ICA. CT and ICA findings guide subsequent management decisions by the local heart teams according to current evidence and European guidelines. Major adverse cardiovascular events (MACE) defined as cardiovascular death, myocardial infarction and stroke as a composite endpoint will be the primary outcome measure. Secondary and other outcomes include cost-effectiveness, radiation exposure, health-related quality of life (HRQoL), socioeconomic status, lifestyle, adverse events related to CT/ICA, and gender differences. The DISCHARGE trial will assess the comparative effectiveness of CT and ICA. • Coronary artery disease (CAD) is a major cause of morbidity and mortality. • Invasive coronary angiography (ICA) is the reference standard for detection of CAD. • Noninvasive computed tomography angiography excludes CAD with high sensitivity. • CT may effectively reduce the approximately 2 million negative ICAs in Europe. • DISCHARGE addresses this hypothesis in patients with low-to-intermediate pretest probability for CAD.

Computed Tomography and Magnetic Resonance Imaging in Neonates With Congenital Cardiovascular Disease

Most cardiac diseases in the newborn are caused by structural abnormalities developed in utero. With few exceptions, palliative and definitive treatments require cardiac surgery. The diagnosis and management decisions regarding uncomplicated lesions, such as atrial septal defect, ventricular septal defect, patent ductus arteriosus, and tetralogy of Fallot, can be accomplished by echocardiography alone. Abnormalities beyond the sonographic window, complex 3-dimensional lesions, and detailed functional information require additional imaging. In the past, this was fulfilled by catheter angiography, but today much of the information can be obtained from noninvasive computed tomography angiography and magnetic resonance imaging. This article discusses the design and application of these imaging techniques to the newborn, with emphasis on safety, efficacy, and image quality. Understanding the capabilities and limitations of these techniques is crucial for making rational choices among imaging options based on sound risk and benefit considerations. Important examples of congenital heart lesions have been illustrated with 3-dimensional reconstruction from computed tomography and magnetic resonance images.

Evaluating the use and utility of noninvasive angiography in diagnosing traumatic blunt cerebrovascular injury

Digital subtraction angiography (DSA) is the gold standard for radiographic diagnosis of blunt cerebrovascular injury (BCVI), but use of computed tomography angiography (CTA) and magnetic resonance angiography (MRA) has increased dramatically in BCVI screening. This study explores the utility, effectiveness, and cost of noninvasive CTA and MRA screening for BCVI. Medical records of 2,025 consecutive adults evaluated for acute blunt neck trauma and BCVI were reviewed retrospectively. The incidence of BCVI, level(s) of cervical injury, involvement of foramina transversaria and internal carotid canals, presence of bony dislocation or subluxation, and subsequent treatment received were assessed. Asymptomatic patients were analyzed based on fracture and injury patterns. The cost effectiveness of CTA compared with DSA and the effects of CTA sensitivity and screening yield were determined. Of reviewed patients, 196 received CTA or MRA. Thirty-eight patients (19.4%) were diagnosed with BCVI. Screening yield in patients symptomatic at presentation was 48.8%. Large-vessel internal carotid, vertebral, anterior spinal, and basilar artery occlusion were associated with a positive screen, as were concurrent stroke and spinal cord injury (p < 0.01). Of patients with injuries found with noninvasive imaging, 50.0% of BCVI involved C1-3 fracture, 34.2% involved subluxation, and 65.8% involved foramina transversaria. In both symptomatic and asymptomatic patients, CTA screening was more cost effective than DSA. Noninvasive imaging is a safe, accurate, and cost-effective tool for BCVI screening. Symptomatic presentation was the best predictor of BCVI. Significant cost savings were realized using CTA rather than DSA, with similar effectiveness and patient outcomes. Diagnostic study, level III; economic analysis, level IV.

Computed Tomography to Predict Surgical Revascularization of a Left Anterior Descending Artery Occlusion Incompletely Visualized by Conventional Angiography

Previous studies demonstrated that failure to visualize distal chronic total occlusion in conventional coronary angiography (CCA) does not preclude procedural success of coronary artery bypass grafting (CABG). We assessed the utility of computed tomography angiography (CTA) in guiding CABG to the occluded left anterior descending artery (LAD) incompletely visualized by CCA. Twenty-four symptomatic patients rejected for revascularization of an occluded LAD on the basis of CCA underwent a preoperative CTA before intended transmyocardial laser revascularization. Off-pump CABG to the LAD was attempted in all patients depending on the intraoperative findings. The primary outcome was defined as procedural success of CABG to the LAD. The success rate for CABG was 79.2%. By CCA, Rentrop 0/1 was present in 6 patients (25%), whereas Rentrop 2 was present in 18 patients (75%). By CTA, Rentrop 3 was seen in all patients. Compared with the CABG-failure group, the CABG-success group showed a larger mean distal LAD diameter (1.7 ± 0.2 mm vs. 1.3 ± 0.1 mm; P=0.001). By receiver-operating curve analysis, a cutoff value of 1.5 mm for the mean distal LAD diameter predicted CABG availability with 100% specificity and 95% sensitivity. The distal LAD short length and intramyocardial course were other significant correlates of CABG failure compared with CABG success (60% vs. 5.3%, P=0.018; 80% vs. 0%, P<0.001). Noninvasive CTA is not only superior to CCA in delineating distal coronary occlusion but also very precisely predicts the procedural success of CABG. CTA represents a robust evaluation tool for coronary mapping of chronic total occlusion with doubtful distal anatomy in CCA.

Differences in coronary plaque composition by noninvasive computed tomography angiography in individuals with and without obstructive coronary artery disease

BackgroundCoronary CT angiography (CCTA) has emerged as a promising non-invasive tool to detect coronary artery disease (CAD) which provides additional information about atherosclerotic plaque composition. We aimed to assess whether differences in plaque composition and plaque burden exist across patients with more and <50% coronary stenosis. Methods1060 patients (58±11 years, 43% females) with an intermediate risk of CAD referred for 64-slice CCTA were studied. Plaque characteristics and burden was analyzed on CCTA images on a per-segment basis (modified 16-segment AHA classification). Plaques types were classified as: calcified (type 1), mixed (predominantly calcified) (type 2), mixed (predominantly non-calcified) (type 3), and non-calcified (type 4). Plaque types in patients with more and <50% stenosis were compared. ResultsOverall 373 (35.2%) patients had normal coronaries without evidence of plaque. In the remaining 687 patients, 353 (33%) and 334 (31%) were found to have luminal narrowing of <50% and ≥50% in at-least one coronary artery segment, respectively. Those with ≥50% stenotic CAD demonstrated were more likely to have segments with mixed plaque subtype and less likely to be exclusively non-calcified (relative distribution of 58%, 22%, 10%, 11% for type 1–4 respectively) compared to those with <50% stenosis with (59%, 11%, 6% and 24%, respectively (p=0.006). In multivariable adjustment models, individuals with significant CAD were 5-fold more likely to have increased burden type 1 plaque (≥3 coronary segments) as compared to those with non-obstructive CAD (OR: 5.00, 95% CI: 1.05–23.78). The respective odds ratio (95% CI) for ≥3 coronary segments of type 2, 3 and 4 were 8.73 (3.01–25.23), 4.62 (2.99–0.22–1.55), respectively. ConclusionsPlaque composition is different according to severity of CAD with a higher mixed plaque and lesser non-calcified plaque burden among those patients with ≥50% stenotic CAD. These findings should stimulate further investigations to assess the prognostic value of coronary plaque subtypes according to their underlying composition.

Computed tomographic coronary angiography in patients with surgically treated type A aortic dissection: preliminary results

Acute type A aortic dissection is a serious emergency with a mortality rate of up to 40% within the first 24 h when left untreated. Surgical therapy needs to be initiated promptly. Due to this urgent situation, preoperative evaluation of the coronary arteries is not routinely performed in these patients. The aim of this study was to evaluate the accuracy of 64-slice computed tomography angiography (CTA) for postoperative coronary artery assessment in these patients. Ten consecutive patients with two or more cardiovascular risk factors were prospectively enrolled. Patients had type A aortic dissection treated surgically with a supracoronary graft of the ascending aorta. Performance of CTA to exclude significant stenosis (>50% lumen narrowing) and/or coronary artery dissection was compared with quantitative coronary angiography. A total of 147 segments were evaluated. Three segments (2%) were excluded from analysis. CTA correctly assessed one of three significant stenoses in three patients and correctly excluded coronary artery disease (CAD) in six of ten patients. One patient was rated false positive. Overall accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT for identifying coronary artery disease by segment was 98%, 33%, 99%, 50%, and 99%, respectively (P<0.05). By patient, it was 70%, 33%, 86%, 50%, and 75%, respectively. No coronary artery dissection was found. Noninvasive CTA may be a viable alternative to conventional angiography for postoperative coronary artery evaluation in patients with surgically treated type A aortic dissection and cardiovascular risk factors. An NPV of 99% should allow for reliable exclusion of CAD. Further studies with higher patient numbers are warranted.

Diagnostic Accuracy of Computed Tomography Angiography in Patients After Bypass Grafting: Comparison With Invasive Coronary Angiography

We sought to evaluate the contribution of noninvasive dual-source computed tomography angiography (CTA) in the comprehensive assessment of symptomatic patients after coronary artery bypass grafting (CABG). Assessment of bypass grafts and distal runoffs by invasive coronary angiography is cumbersome and often requires extra procedure time, contrast load, and radiation exposure. Dual-source CTA was performed in 52 (41 men, mean age 66.6 +/- 13.2 years) symptomatic post-CABG patients scheduled for invasive coronary angiography. No oral or intravenous beta blockers or sedation were administered before the scan. Mean interval between CABG surgery and CTA was 9.6 +/- 7.2 (range 0 to 20) years. Mean heart rate during scanning was 64.5 +/- 13.2 (range 48 to 92) beats/min. Seventy-five percent of patients had both arterial and venous grafts. A total of 152 graft segments and 142 distal runoffs vessels were analyzed. Native coronary segments were divided into nongrafted (n = 118) and grafted segments (n = 289). A significant stenosis was defined as >or=50% lumen diameter reduction, and quantitative coronary angiography served as reference standard. The diagnostic accuracy of CTA for the detection or exclusion of significant stenosis in arterial and venous grafts on a segment-by-segment analysis was 100%. Sensitivity, specificity, positive predictive value, and negative predictive value to detect significant stenosis were 95% (95% confidence interval [CI]: 73% to 100%), 100% (95% CI: 96% to 100%), 100% (95% CI: 79% to 100%), 99% (95% CI: 95% to 100%) in distal runoffs respectively; 100% (95% CI: 97% to 100%), 96% (95% CI: 90% to 98%), 97% (95% CI: 93% to 99%), 100% (95% CI: 95% to 100%) in grafted native coronary arteries respectively; and 97% (95% CI: 83% to 100%), 92% (95% CI: 83% to 96%), 83% (95% CI: 67% to 92%), 99% (95% CI: 92% to 100%) in nongrafted native coronary arteries, respectively. Noninvasive CTA is successful for evaluating bypass grafts in symptomatic post-CABG patients, whereas invasive coronary angiography is still required for the assessment of significant stenosis in distal runoffs and native coronary arteries.

Non-invasive Computed Tomography Angiography of the Coronaries – Is There Enough Evidence?

Over the past decade, great strides have been made in the field of cardiac imaging, particularly in cardiac computed tomography (CT) to view the coronary artery lumen and plaque.1 Performance of cardiac CT angiography (CTA) has been challenging, given rapid cardiac motion, small vessel diameters, tortuous anatomical patterns and overlapping cardiac structures.

Computed tomography angiography in detection and characterization of ruptured anterior cerebral artery aneurysms at uncommon location for emergent surgical clipping

Introduction Cerebral subarachnoid hemorrhage may result from rupture of saccular aneurysms at uncommon location [excluding the anterior communicating artery (ACOM)] of the anterior cerebral artery (ACA). The purpose of this study was to evaluate the usefulness of helical computed tomography angiography (CTA) in detection and characterization of intracranial aneurysms at such uncommon locations before emergent surgical clipping. Materials and methods Between 1998 and 2003, records for 50 consecutive patients who underwent emergent surgical clipping for intracranial aneurysms were reviewed. Eighteen of these patients had aneurysms in the ACA. After those patients with unequivocal ACOM aneurysms were excluded, eight patients with eight aneurysms in an uncommon location of the ACA were recruited to this study. Plain computed tomography (CT) and CTA were performed in eight patients, and digital subtraction angiographies were done in three patients. Each aneurysm was evaluated for the detection, quantification, and characterization of the aneurysms with 2D multiplanar reformatted and 3D volume-rendering techniques. Results There were two small aneurysms arising from the A1 segment, one from the A2 segment, two at the junction of triplicated ACAs, two at the junction of A2 and A3 segments, and one at the junction of A2 and A3 segments of the azygos ACA. The average diameter of the aneurysmal sac was 4.44 mm (range, 2.7–7.0 mm), and the aneurysmal neck averaged 2.59 mm (range, 1.2–3.5 mm) in size. The smallest aneurysm measured 2.2×1.8×2.7 mm (neck, 1.2 mm) in the A1 segment of the left ACA. Three patients had intracerebral hematoma, seven had intraventricular hemorrhage, and three had acute hydrocephalus. Conclusion Aneurysms in uncommon locations of ACAs exhibited characteristic features. Rupture of these aneurysms can cause intracerebral hematoma, intraventricular hemorrhage, and/or acute hydrocephalus. Noninvasive CTA can reliably detect and characterize intracranial aneurysms at such uncommon location for planning of emergent surgical intervention.