Coronary Computed Tomography Angiograms Research Articles

Reproducibility of a single-volume dynamic CT myocardial blood flow measurement technique: validation in a swine model

BackgroundWe prospectively assessed the reproducibility of a novel low-dose single-volume dynamic computed tomography (CT) myocardial blood flow measurement technique.MethodsThirty-four pairs of measurements were made under rest and stress conditions in 13 swine (54.3 ± 12.3 kg). One or two acquisition pairs were acquired in each animal with a 10-min delay between each pair. Contrast (370 mgI/mL; 0.5 mL/kg) and a diluted contrast/saline chaser (0.5 mL/kg; 30:70 contrast/saline) were injected peripherally at 5 mL/s, followed by bolus tracking and acquisition of a single volume scan (100 kVp; 200 mA) with a 320-slice CT scanner. Bolus tracking and single volume scan data were used to derive perfusion in mL/min/g using a first-pass analysis model; the coronary perfusion territories of the left anterior descending (LAD), left circumflex (LCx), and right coronary artery (RCA) were automatically assigned using a previously validated minimum-cost path technique. The reproducibility of CT myocardial perfusion measurement within the LAD, LCx, RCA, and the whole myocardium was assessed via regression analysis. The average CT dose index (CTDI) of perfusion measurement was recorded.ResultsThe repeated first (Pmyo1) and second (Pmyo2) single-volume CT perfusion measurements were related by Pmyo2 = 1.01Pmyo1 − 0.03(ρ = 0.96; RMSE = 0.08 mL/min/g; RMSE = 0.07 mL/min/g) for the whole myocardium, and by Preg2 = 0.86Preg1 + 0.13(ρ = 0.87; RMSE = 0.31 mL/min/g; RMSE = 0.29 mL/min/g) for the LAD, LCx, and RCA perfusion territories. The average CTDI of the single-volume CT perfusion measurement was 10.5 mGy.ConclusionThe single-volume CT blood flow measurement technique provides reproducible low-dose myocardial perfusion measurement using only bolus tracking data and a single whole-heart volume scan.Relevance statementThe single-volume CT blood flow measurement technique is a noninvasive tool that reproducibly measures myocardial perfusion and provides coronary CT angiograms, allowing for simultaneous anatomic-physiologic assessment of myocardial ischemia.Key PointsA low-dose single-volume dynamic CT myocardial blood flow measurement technique is reproducible.Motion misregistration artifacts are eliminated using a single-volume CT perfusion technique.This technique enables combined anatomic-physiologic assessment of coronary artery disease.Graphical

Abstract 18320: Vessel-Specific Coronary Inflammation Quantified Using Perivascular Fat Attenuation Index Score on CCTA Detects the Vulnerable Coronary Artery and Predicts Acute Plaque Events

Background: Coronary artery inflammation can be detected non-invasively on routinely performed coronary computed tomography angiograms (CCTA) by measuring the 3D changes of perivascular adipose tissue attenuation. Fat attenuation index (FAI) Score is the corrected metric of coronary inflammation measured in any of the 3 coronary arteries, and predicts acute myocardial infarction (AMI). Although FAI score is able to detect the vulnerable patient, it is unclear whether it can be used to detect the vulnerable artery in advance of an acute event. Aim: To evaluate the ability of FAI Score to detect the vulnerable coronary artery in patients undergoing CCTA for investigation of chest pain. Methods: Consecutive patients (n = 3,393, mean age 61±15, 57% male) from two UK hospitals in the Oxford Risk Factors and Non Invasive Imaging (ORFAN) study underwent CCTA between 2010-2018 for suspected coronary artery disease (CAD), and were followed up prospectively for a median of 7.7 years. AMI events were recorded via nationwide screening and the culprit vessel was identified based on the target lesion in percutaneous coronary intervention (PCI). FAI score was generated with CaRi-Heart® device. Results: A total of 296 AMI events occurred during the follow up period and 176 patients underwent PCI (59 attributed to the right coronary artery (RCA), and 93 to left anterior descending artery (LAD)). Patients with high FAI score in the LAD had 2 times higher risk for AMI in the LAD (Fig. A), but not in the RCA (HR 1.73 95% CI 0.96-3.08, p=0.07). Similarly, patients with high FAI score in the RCA had 1.9 times higher risk for AMI in the RCA (Fig. B), and modestly elevated risk for an AMI from the LAD. (HR 1.62, 95% CI 1.02-2.59, p=0.04) Conclusion: Vessel-specific FAI score predicts AMI caused by a culprit lesion in the corresponding coronary artery. The ability of FAI score to identify the vulnerable artery before it gives a plaque rupture event may be useful in planning targeted therapeutic interventions.

Deep-Learning for Epicardial Adipose Tissue Assessment With Computed Tomography: Implications for Cardiovascular Risk Prediction

BackgroundEpicardial adipose tissue (EAT) volume is a marker of visceral obesity that can be measured in coronary computed tomography angiograms (CCTA). The clinical value of integrating this measurement in routine CCTA interpretation has not been documented. ObjectivesThis study sought to develop a deep-learning network for automated quantification of EAT volume from CCTA, test it in patients who are technically challenging, and validate its prognostic value in routine clinical care. MethodsThe deep-learning network was trained and validated to autosegment EAT volume in 3,720 CCTA scans from the ORFAN (Oxford Risk Factors and Noninvasive Imaging Study) cohort. The model was tested in patients with challenging anatomy and scan artifacts and applied to a longitudinal cohort of 253 patients post-cardiac surgery and 1,558 patients from the SCOT-HEART (Scottish Computed Tomography of the Heart) Trial, to investigate its prognostic value. ResultsExternal validation of the deep-learning network yielded a concordance correlation coefficient of 0.970 for machine vs human. EAT volume was associated with coronary artery disease (odds ratio [OR] per SD increase in EAT volume: 1.13 [95% CI: 1.04-1.30]; P = 0.01), and atrial fibrillation (OR: 1.25 [95% CI: 1.08-1.40]; P = 0.03), after correction for risk factors (including body mass index). EAT volume predicted all-cause mortality (HR per SD: 1.28 [95% CI: 1.10-1.37]; P = 0.02), myocardial infarction (HR: 1.26 [95% CI:1.09-1.38]; P = 0.001), and stroke (HR: 1.20 [95% CI: 1.09-1.38]; P = 0.02) independently of risk factors in SCOT-HEART (5-year follow-up). It also predicted in-hospital (HR: 2.67 [95% CI: 1.26-3.73]; P ≤ 0.01) and long-term post–cardiac surgery atrial fibrillation (7-year follow-up; HR: 2.14 [95% CI: 1.19-2.97]; P ≤ 0.01). ConclusionsAutomated assessment of EAT volume is possible in CCTA, including in patients who are technically challenging; it forms a powerful marker of metabolically unhealthy visceral obesity, which could be used for cardiovascular risk stratification.

Aortic valve leaflet and root dimensions in normal tricuspid aortic valves: A computed tomography study.

The aim of this study was to use coronary computed tomography in patients with normal tricuspid aortic valves to perform detailed aortic root and aortic valve geometric analysis with a focus on the asymmetry of the three leaflets. Retrospective analysis of anonymized coronary computed tomography angiograms was performed using dedicated software, where manual aortic root segmentation and marking of several points of interest were followed by automated measurements of aortic root and leaflets. Asymmetry of the three leaflets in individual patients was assessed by calculating absolute and relative differences between the largest and the smallest of the three leaflets. We analyzed 70 aortic valves, the mean patient age was 53 ± 11 years, and 50% (n = 35) of patients were female. All aortic valves were tricuspid, without calcifications and aortic roots were of normal dimensions. Some degree of asymmetry was present in all analyzed valves. Absolute and relative differences for free margin length were 3.2 ± 1.4 mm and 9.3 ± 3.8%, respectively. The largest relative difference was noted in the coaptation area (36.5 ± 16.5%) and the smallest in leaflet effective height (6.1 ± 4.8%). Using predefined cutoff criteria for absolute differences in leaflet dimensions, 86% of the valves were classified as asymmetric. Most normal tricuspid aortic valves show some degree of asymmetry. Equal free margin length of the three leaflets is not needed for normal tricuspid aortic valve function. Leaflet effective height showed the least amount of asymmetry confirming its importance in keeping the aortic valve competent.

HEART score improves efficiency of coronary computed tomography angiography in patients suspected of acute coronary syndrome in the emergency department.

Aims:Coronary computed tomography angiography is increasingly employed in the emergency department for suspected acute coronary syndrome patients. The HEART score has been proposed for initial risk stratification in these patients. The aim of this study was to investigate the diagnostic value and efficiency of the HEART score before coronary computed tomography angiography.Methods and results:We included patients suspected of acute coronary syndrome who underwent coronary computed tomography angiography in the emergency department. Based on the HEART score, patients were stratified as low-risk (HEART≤3), intermediate-risk (HEART4–6) and high-risk (HEART≥7). We assessed coronary computed tomography angiography for the presence of significant coronary artery disease (>50% stenosis). The primary outcome, the level of major adverse cardiac events, was a composite endpoint of all-cause mortality, acute coronary syndrome or coronary revascularisation within 30 days. The study population consisted of 340 patients (mean age: 55.6±10.1 years, 44.7% women), major adverse cardiac events occurred in 45 (13.2%) patients. The incidence of major adverse cardiac events in patients stratified as low-risk (35.0%), intermediate-risk (56.8%) and high-risk (8.2%) was 3.4%, 12.4% and 60.7%, respectively. All four low-risk patients with major adverse cardiac events had a HEART score of three. An algorithm where coronary computed tomography angiography is reserved for patients with HEART 3–6 resulted in a sensitivity of 97.8%, specificity of 84.1%, negative predictive value of 99.6% and positive predictive value of 48.4%, while reducing the need for coronary computed tomography angiography by 22% (n=75).Conclusion:The predictive value of coronary computed tomography angiography for 30-day major adverse cardiac events in suspected acute coronary syndrome patients is good, and reserving coronary computed tomography angiography for HEART score 3–6 patients reduces the number of needed coronary computed tomography angiograms without affecting diagnostic accuracy.

Incorporation of the HEART Score Into a Low-risk Chest Pain Pathway to Safely Decrease Admissions.

Chest pain can be a challenging complaint to manage in the emergency department. A missed diagnosis can result in significant morbidity or mortality, whereas avoidable testing and hospitalizations can lead to increased health care costs, contribute to hospital crowding, and increase risks to patients. The HEART score is a validated decision aid to identify patients at low risk for acute coronary syndrome who can be safely discharged without admission or objective cardiac testing. In the largest and one of the longest studies to date (N = 31,060; 30 months), we included the HEART score into a larger, newly developed low-risk chest pain decision pathway, using a retrospective observational pre/post study design with the objective of safely lowering admissions. The modified HEART score calculation tool was incorporated in our electronic medical record. A significant increase in discharges of low-risk chest pain patients (relative increase of 21%; p < 0.0001) in the postimplementation period was observed with no significant difference in the rates of major adverse cardiac events between the pre and post periods. There was a decrease in the amount of return admissions for 30 days (4.65% fewer; p = 0.009) and 60 days (3.78% fewer; p = 0.020). No significant difference in length of stay was observed for patients who were ultimately discharged. A 64% decrease in monthly coronary computed tomography angiograms was observed in the post period (p < 0.0001). These findings support the growing consensus in the literature that the adoption of the HEART pathway or similar protocols in emergency departments, including at large and high-volume medical institutions, can substantially benefit patient care and reduce associated health care costs.

Development of delineation for the left anterior descending coronary artery region in left breast cancer radiotherapy: An optimized organ at risk

Background and purposeThe left anterior descending coronary artery (LAD) and diagonal branches (DBs) are blurred on computed tomography (CT). We aimed to define the LAD region (LADR) with adequate inclusion of the LAD and DBs and contouring consistency. Methods and materialsThe LADR was defined using coronary CT angiograms. The inclusion ratio was used to assess the LAD and DBs inclusion by the LADR. Four radiation oncologists delineated the LAD and LADR, using contrast-enhanced CT of 15 patients undergoing left breast radiotherapy. The Sørensen–Dice similarity index (DSI), Jaccard similarity index (JSI), and Hausdorff distance (HD) were calculated to assess similarity. The mean dose (Dmean) and maximum dose (Dmax) to the LAD and LADR were calculated to compare consistency. Correlations were evaluated using Pearson’s correlation coefficient. ResultsThe inclusion ratio of the LAD by the LADR was 96%. The mean DSI, JSI, and HD values were respectively 27.9%, 16.7%, and 0.42mm for the LAD, and 83.1%, 73.0%, and 0.18mm for the LADR. The Dmean between the LAD and LADR were strongly correlated (r=0.93). ConclusionDelineation of the LADR significantly improved contouring similarity and consistency for dose reporting. This could optimize dose estimation for breast radiotherapy.

Abstract 197: Coronary Aneurysm and Ectasia In Adults

Background: We investigate the status of coronary aneurysm or ectasia in adults. Methods: We retrospectively reviewed all coronary angiograms and coronary computed tomography angiograms (CT) performed at Hanyang University Hospital between January 2011 and August 2014. Results: Coronary angiography was performed in 4383 patients. Coronary CT was performed in 4099 patients. Coronary aneurysm or ectasia was detected in 28 patients (0.63%) on coronary angiography and in 21 patients (0.51%) on coronary CT angiography. Mean age of patient with coronary aneurysm or ectasia on angiography or coronary CT is 60.5(SD 14.7) or 58.0(SD 11.2). Mean age of patient without coronary aneurysm or ectasia on angiography or coronary CT is 63.2(SD 12.7) or 57.2(SD 12.0). For 28 patients with coronary aneurysm or ectasia on coronary angiography, male and female ratio was 16:12. Age was for 57.6(SD 11.9) for male and 64.5(SD 17.6) for female. For 21 patients with coronary aneurysm or ectasia on CT angiography, male and female ratio was 14:7. Age was for 53.9(SD 8.3) for male and 66.1(SD 13.4) for female. The age gap between male and female was increased for patients with coronary aneurysm or ectasia on both studies. These suggest adult with coronary aneurysm or ectasia might have Kawasaki disease in young age. Conclusions: The mean age of male patients with coronary aneurysm or ectasia was lower than that of female patients without coronary aneurysm or ectasia. This indicates adult with coronary aneurysm or ectasia might have Kawasaki disease in young age.

Evaluation of Discrete Upper Septal Thickening on 64-Slice Coronary Computed Tomographic Angiography

Discrete upper septal thickening (DUST) has been well described in the echocardiology literature. To our knowledge, the computed tomography findings of DUST, however, have not been previously described. Five hundred consecutive coronary computed tomography angiograms were evaluated by 2 cardiothoracic radiologists for the presence of DUST. Of the 500 studies reviewed, 23 cases had features consistent with DUST (23/500 = 5%). The average systolic blood pressure of patients with DUST (150/77 mm Hg) was higher than that of patients without DUST (133/75 mm Hg). Patients with DUST were older (mean 63 y) than patients without DUST (mean 50 y). None of these patients had evidence of abnormal systolic anterior motion of the mitral valve on cine imaging. DUST is seen on coronary computed tomography angiograms and has imaging characteristics distinct from significant pathology, such as hypertrophic cardiomyopathy. Recognizing DUST is important because, unlike hypertrophic cardiomyopathy, previous studies have not found an associated adverse prognosis with DUST.

Reconstructions with identical filling (RIF) of the heart: a physiological approach to image reconstruction in coronary CT angiography

To compare image quality in coronary artery computed tomography angiography (cCTA) using reconstructions with automated phase detection and Reconstructions computed with Identical Filling of the heart (RIF). Seventy-four patients underwent ECG-gated dual source CT (DSCT) between November 2009 and July 2010 for suspected coronary heart disease (n = 35), planning of transcatheter aortic valve replacement (n = 34) or evaluation of ventricular function (n = 5). Image data sets by the RIF formula and automated phase detection were computed and evaluated with the AHA 15-segment model and a 5-grade Likert scale (1: poor, 5: excellent quality). Subgroups regarding rhythm (sinus rhythm = SR; arrhythmia = ARR) and potential premedication were evaluated by a per-segment, per-vessel and per-patient analysis. RIF significantly improved image quality in 10 of 15 coronary segments (P < 0.05). More diagnostic segments were provided by RIF regarding the entire cohort (n = 693 vs. 590, P < 0.001) and all of the subgroups (e.g. ARR: n = 143 vs. 72, P < 0.001). In arrhythmic patients (n = 19), more diagnostic vessels (e.g. LAD: n = 10 vs. 3; P < 0.014) and complete data sets (n = 7 vs. 1; P < 0.001) were produced. RIF reconstruction is superior to automatic diastolic non-edited reconstructions, especially in arrhythmic patients. RIF theory provides a physiological approach for determining the optimal image reconstruction point in ECG-gated CT angiography. Conventional CT coronary angiography suffers from numerous artefacts in patients with irregular rhythms. Coronary computed tomography angiograms (cCTA) were reconstructed with identical cardiac filling (RIF). RIF reconstructions provide improved image quality compared to non-edited standard reconstructions. RIF theory links physiology with cardiac CT.

Computational high-resolution heart phantoms for medical imaging and dosimetry simulations

Cardiovascular disease in general and coronary artery disease (CAD) in particular, are the leading cause of death worldwide. They are principally diagnosed using either invasive percutaneous transluminal coronary angiograms or non-invasive computed tomography angiograms (CTA). Minimally invasive therapies for CAD such as angioplasty and stenting are rendered under fluoroscopic guidance. Both invasive and non-invasive imaging modalities employ ionizing radiation and there is concern for deterministic and stochastic effects of radiation. Accurate simulation to optimize image quality with minimal radiation dose requires detailed, gender-specific anthropomorphic phantoms with anatomically correct heart and associated vasculature. Such phantoms are currently unavailable. This paper describes an open source heart phantom development platform based on a graphical user interface. Using this platform, we have developed seven high-resolution cardiac/coronary artery phantoms for imaging and dosimetry from seven high-quality CTA datasets. To extract a phantom from a coronary CTA, the relationship between the intensity distribution of the myocardium, the ventricles and the coronary arteries is identified via histogram analysis of the CTA images. By further refining the segmentation using anatomy-specific criteria such as vesselness, connectivity criteria required by the coronary tree and image operations such as active contours, we are able to capture excellent detail within our phantoms. For example, in one of the female heart phantoms, as many as 100 coronary artery branches could be identified. Triangular meshes are fitted to segmented high-resolution CTA data. We have also developed a visualization tool for adding stenotic lesions to the coronaries. The male and female heart phantoms generated so far have been cross-registered and entered in the mesh-based Virtual Family of phantoms with matched age/gender information. Any phantom in this family, along with user-defined stenoses, can be used to obtain clinically realistic projection images with the Monte Carlo code penMesh for optimizing imaging and dosimetry.

Posterior Interatrial Muscular Connection between the Coronary Sinus and Left Atrium: Anatomic and Functional Study of the Coronary Sinus with Multidetector CT

To demonstrate coronary sinus-left atrium connections and evaluate coronary sinus function and anatomy in detail by using multidetector computed tomography (CT). In this institutional review board-approved retrospective study, the authors evaluated coronary CT angiograms obtained in 65 patients with normal sinus rhythm (normal group) and seven with atrial fibrillation at CT (atrial fibrillation group). Coronary sinus-right atrium muscle continuity was indirectly evaluated by measuring the length of the coronary sinus contraction during atrial systole. The length, number, and extent of coronary sinus-left atrium connections were recorded. The accuracy of CT was validated by comparing microscopic images of autopsied hearts with corresponding CT images. Comparisons were performed by using Student t tests for continuous variables. P ≤ .05 was considered indicative of a statistically significant difference. In the normal group, coronary sinus contraction was seen in 60 of the 65 patients (92%, mean length ± standard deviation, 25.7 mm ± 8.0). The coronary sinus narrowed 26% from middiastole to atrial systole (P < .0001). Coronary sinus-left atrium muscle connections were seen in 58 of the 65 patients (89%). A single connection was seen in 43 of the 65 patients (66%), with a mean length of 21.0 mm ± 14.0 within 12.0 mm ± 11.0 of the coronary sinus ostium. In 10 of the 43 patients (26%) with single connections, the connection extended to the coronary sinus ostium. In 10 of the 65 patients (15%), the entire coronary sinus was attached to the left atrial wall. Fifteen patients (23%) had two connections; distal connections measured 9 mm ± 2.4 in length within 2.2 mm ± 3.8 of the coronary sinus ostium, and proximal connections measured 15.4 mm ± 10.0 in length within 24.0 mm ± 8.0 of the coronary sinus ostium. In seven patients (11%), no coronary sinus-left atrium connection was seen; however, all showed a coronary sinus constriction during atrial systole, indicating that coronary sinus-right atrium muscle continuity is likely the primary cause for coronary sinus contractions. In the atrial fibrillation group, no coronary sinus contraction was seen. All images in the atrial fibrillation group showed a coronary sinus-left atrium connection, which was single in five patients and double in two. The area of the coronary sinus during diastole was larger in the atrial fibrillation group than in the normal group (114 mm(2) ± 37 vs 77 mm(2) ± 40, respectively; P = .02). CT can provide excellent information about coronary sinus function and coronary sinus-left atrium muscle connections.

Coronary Venous Aneurysm in Patients Without Cardiac Arrhythmia as Detected by MDCT: An Anatomic Variant or a Pathologic Entity

The aim of this study was to determine the prevalence of coronary venous aneurysm in patients with no history of cardiac arrhythmia using 64-slice multidetector computed tomography. Coronary vein aneurysm frequently has been reported in association with cardiac arrhythmias such as ventricular pre-excitation. Coronary computed tomography angiograms of 187 patients (108 men, 79 women; mean age +/- SD, 60 +/- 12 years) were analyzed retrospectively for the presence of a focal coronary venous aneurysm. Fusiform aneurysm was defined as a focal dilatation of twice the normal vein. However, any size of diverticular aneurysms was included. Cross-sectional diameters of normal and aneurysmal segments of the posterior interventricular vein, great cardiac vein, and coronary sinus (CS) were measured at mid-diastole, late systole, and atrial systole. The Student t test was used for continuous variables and contingency tables were used for categorical variables. A single aneurysm was found in 19 (10%) patients (fusiform, n =16; diverticular, n = 3). The most common anatomic location was the posterior interventricular vein near the confluence with the CS (n = 14), followed by the great cardiac vein near the junction with the CS (n = 3), and the CS (n = 2). The mean diameter of the aneurysms was 9.3 +/- 1.2 mm (range, 8.1 to 11.4 mm) at mid-diastole and 10.4 +/- 1.4 mm (range, 8.5 to 12.7 mm) at late systole. However, the difference was not statistically significant. All normal CSs and 1 aneurysm arising from the CS showed contraction during atrial systole, which may suggest atrial myocardial coverage of these structures. Patients with a venous aneurysm were significantly older than patients without an aneurysm (67.6 +/- 11 vs. 59 +/- 12 years, respectively; p = 0.006). Coronary vein aneurysms (especially the fusiform type) were seen in up to 10% of patients with no history of cardiac arrhythmia and can be well visualized on computed tomography angiograms.

Coronary Artery Stenosis in High-risk Patients: 64–Section CT and Coronary Angiography—Prospective Study and Analysis of Discordance

To assess the diagnostic accuracy of multisection (64-section) computed tomography (CT) versus coronary angiography in detection of and assignment of grades for coronary artery stenoses in a high-risk population and to investigate causes for discordance between the two. The protocol was approved by the local ethics committee. Patients gave informed consent. The study included 114 patients (103 men, 11 women; mean age, 63 years +/- 8.2 [standard deviation]) with potential myocardial ischemia. Multisection CT images were interpreted independently by two radiologists with unequal experience in reading coronary CT angiograms. Diagnostic performance of 64-section CT in detection of stenoses of 50% or more was assessed per patient, per artery, and per segment. Interrater agreement was assessed by using the Cohen kappa coefficient. Agreement between 64-section CT and coronary angiography for assigning grades to stenoses was assessed by using Bland-Altman analysis. Sixty-eight percent of patients had stenoses of 50% or more. Good interrater agreement was found, with kappa values of 0.77-0.85. For the most experienced radiologist, the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were 73.4%, 95.0%, 14.7, and 0.28 per segment, 95.2%, 94.7%, 18.0, and 0.05 per artery, and 100%, 89.2%, 9.26, and zero per patient, respectively. Discordance between 64-section CT and coronary angiography was related to either under- or overestimation of the degree of stenosis, anatomic misclassification, and coronary artery segments that were not assessable at 64-section CT. Bland-Altman analysis showed poor agreement, especially for intermediate stenosis (mean bias, 1.3%; 95% limits of agreement: -27.3%, 29.9%). Despite excellent sensitivity and negative likelihood ratios in a per-patient or per-vessel analysis, some coronary artery stenosis remained misdiagnosed with 64-section CT, resulting in limited sensitivity on a per-segment basis owing to anatomic discordance and failure to accurately quantify intermediate stenosis.

Imaging of Patent Foramen Ovale with 64-Section Multidetector CT

To investigate the feasibility of 64-section multidetector computed tomography (CT) by using CT angiography (a) to demonstrate anatomic detail of the interatrial septum pertinent to the patent foramen ovale (PFO), and (b) to visually detect left-to-right PFO shunts and compare these findings in patients who also underwent transesophageal echocardiography (TEE). In this institutional review board-approved HIPAA-compliant study, electrocardiographically gated coronary CT angiograms in 264 patients (159 men, 105 women; mean age, 60 years) were reviewed for PFO morphologic features. The length and diameter of the opening of the PFO tunnel, presence of atrial septal aneurysm (ASA), and PFO shunts were evaluated. A left-to-right shunt was assigned a grade according to length of contrast agent jet (grade 1, <or=1 cm; grade 2, >1 cm to 2 cm; grade 3, >2 cm). In addition, 23 patients who underwent both modalities were compared (Student t test and linear regression analysis). A difference with P < .05 was significant. A flap valve, seen in 101 (38.3%) patients, was patent at the entry into the right atrium (PFO) in 62 patients (61.4% of patients with flap valve, 23.5% of total patients). A left-to-right shunt was detected in 44 (16.7% of total) patients (grade 1, 61.4%; grade 2, 34.1%; grade 3, 4.5%). No shunt was seen in patients without a flap valve. Mean length of PFO tunnel was 7.1 mm in 44 patients with a shunt and 12.1 mm in 57 patients with a flap valve without a shunt (P < .0001). In patients with a tunnel length of 6 mm or shorter, 92.6% of the shunts were seen. ASA was seen in 11 (4.2%) patients; of these patients, a shunt was seen in seven (63.6%). In 23 patients who underwent CT angiography and TEE, both modalities showed a PFO shunt in seven. Multidetector CT provides detailed anatomic information about size, morphologic features, and shunt grade of the PFO. Shorter tunnel length and septal aneurysms are frequently associated with left-to-right shunts in patients with PFO.

Bachmann Bundle and Its Arterial Supply: Imaging with Multidetector CT—Implications for Interatrial Conduction Abnormalities and Arrhythmias

To retrospectively investigate anatomy of Bachmann Bundle (BB) and its vascular supply at 64-section multidetector computed tomography (CT) in healthy patients and patients with abnormalities. The institutional review board approved this HIPAA-compliant study and waived informed consent. Clinical histories, electrocardiograms (ECGs), and coronary 64-section multidetector CT angiograms in 317 patients were reviewed (healthy group, 164; group with abnormalities, 153). Among patients with abnormalities, 68 had atrial fibrillation (AF) or interatrial conduction block (IAB) (P wave duration, >or=120 msec), 46 had severe coronary artery disease (CAD) (>or=70% stenosis of coronary artery giving rise to sinuatrial node [SAN] artery), and 39 had severe CAD and an abnormal ECG (AF or IAB). Length, anteroposterior and superoinferior diameters, attenuation, and vascular supply of BB were studied. Student t test for continuous variables and contingency tables for categorical variables were used. BB was visualized, to greater degree, in the healthy group (90.2% vs 73.9% for group with abnormalities, P < .001). Visualization of BB was similar among subgroups with abnormalities: 71.7% in patients with severe CAD, 73.5% in patients with abnormal ECG, and 76.9% in patients with severe CAD and abnormal ECG. BB measurements were similar for both groups. Patients with nonvisualized BB displayed lower overall mean attenuation in the region, with -30.6 HU +/- 33.4 (standard deviation), but mean attenuation in healthy patients was 51.3 HU +/- 59.9 (P < .001). This finding suggests fatty infiltration. BB and BB region were mainly supplied by the right SAN artery (55.5%), followed by the left SAN artery (39.6%) and both SAN arteries (4.9%). In the group with abnormalities, there was a significant difference for SAN artery nonvisualization between those with and without identifiable BB (P = .001). BB and its vascular supply can easily be demarcated on cardiac CT images. BB was visualized less in patients with severe CAD and abnormal ECG, a finding that suggests that disease of BB fibers may play a role in development of atrial arrhythmias.

Pitfalls in 16–Detector Row CT of the Coronary Arteries

Recently developed 16-detector row computed tomography (CT) has been introduced as a reliable noninvasive imaging modality for evaluating the coronary arteries. In most cases, with appropriate premedication that includes beta-blockers and nitroglycerin, ideal data sets can be acquired from which to obtain excellent-quality coronary CT angiograms, most often with multiplanar reformation, thin-slab maximum intensity projection, and volume rendering. However, various artifacts associated with data creation and reformation, postprocessing methods, and image interpretation can hamper accurate diagnosis. These artifacts can be related to pulsation (nonassessable segments, pseudostenosis) as well as rhythm disorders, respiratory issues, partial volume averaging effect, high-attenuation entities, inappropriate scan pitch, contrast material enhancement, and patient body habitus. Some artifacts have already been resolved with technical advances, whereas others represent partially inherent limitations of coronary CT angiography. Familiarity with the pitfalls of coronary angiography with 16-detector row CT, coupled with the knowledge of both the normal anatomy and anatomic variants of the coronary arteries, can almost always help radiologists avoid interpretive errors in the diagnosis of coronary artery stenosis.