ECG-gated Multidetector Computed Tomography Research Articles

Agreement between 4D transesophageal echocardiography and multi-detector computed tomography in measuring aortic root dimensions and coronary ostia heights

Multi-detector computed tomography (MDCT) is the gold standard non-invasive tool for evaluating aortic root dimensions. We assessed the agreement between 4D TEE and MDCT-derived aortic valve annular dimensions, coronary ostia height, and minor dimensions of sinuses of Valsalva (SoV) and sinotubular junction (STJ). In this prospective analytical study, we measured the annular area, annular perimeter, area-derived diameter, area-derived perimeter, left and right coronary ostial heights, and minor diameters of the SoV and the STJ using ECG-gated MDCT and 4D TEE. TEE measurements were calculated semi-automatically by the eSie valve software. We enrolled 43 adult patients (27 males, median age: 46 years). We found strong correlations and good agreement between the two modalities in annular dimensions (area, perimeter, area-derived diameter, and perimeter-derived diameter), left coronary ostial height, minimum STJ diameter, and minimum SoV diameters. Moderate correlations, and agreement, with relatively large differences between the 95% LOA, were demonstrated for the right coronary artery ostial height. 4D TEE correlates well with MDCT in measuring aortic annular dimensions, coronary ostial height, SoV minor diameter, and sinotubular junction minor diameter. Whether this can affect clinical outcomes is unknown. It could replace MDCT if the latter is unavailable or contraindicated.

Evaluation of the pulmonary vein ostia during the cardiac cycle using electrocardiography-gated cardiac computed tomography in cats.

Several studies in humans have provided detailed descriptions of the anatomy of the pulmonary veins (PVs) and their ostia for the implementation of thoracic interventions, such as radiofrequency ablation, for patients with atrial fibrillation. These studies have shown that electrocardiography (ECG)-gated multidetector computed tomography (MDCT) can evaluate the dimensional variations in the PVs or ostium according to the cardiac cycle. However, few studies have examined the PVs or ostia using MDCT in veterinary medicine. Therefore, this study investigated the variation in the diameter of the PV ostium in cats during the cardiac cycle using ECG-gated MDCT and determined the correlation between the size of the heart or left atrium (LA) and diameter of the PV ostium. This study included six cats, including five normal animals and one cat with hypertrophic cardiomyopathy. The PVs were found to drain into the LA via three ostia, i.e., the right cranial ostium, left cranial ostium, and caudodorsal ostium. Moreover, a diametric variation was observed in all PV ostia according to the cardiac cycle phase on ECG-gated MDCT: the maximal diameter was observed at the end of ventricular systole, and the minimal diameter was observed at the end of ventricular diastole for each PV ostium. There were no significant correlations between the heart or LA size and maximal or minimal diameter of each of the three PV ostia (p > 0.05); however, the enlargement of each PV ostium at the end of ventricular systole differed significantly from that at the end of ventricular diastole. This study suggested the clinical feasibility of ECG-gated MDCT in providing more detailed anatomical information about the PVs, including the dimensional changes during the cardiac cycle in cats. Based on this study, knowledge of the variations in the PV ostium offers interesting avenues for research into the effect of PV function. Furthermore, ECG-gated MDCT could allow for greater clinical application of interventional procedures in animals with various cardiac diseases.

Left atrial volume assessed by ECG-gated computed tomography: Variations according to age, gender and time during the cardiac cycle.

The purpose of this study was to retrospectively assess the accuracy of the maximal left atrial volume (LAVmax) measured at 75% of the cardiac cycle compared to the 40% measurements and to evaluate this volume according to age and gender. A total of 150 patients with a mean age of 50±17 (SD) years (range: 21-79 years) were analyzed. There were 78 men and 72 women. LAVmax were measured from retrospective triphasic cardiac-gated multi-detector computed tomography (MDCT) data at the 40% (LAV40) and 75% (LAV75) of the RR cycle phases by a semi-automatic method. LAV40was 50.7±14mL/m2 and LAV75 was 42.5±13mL/m2. The difference was statistically significant. Considering the reference range of LAVmax reported in the literature, 33% of the patients had enlarged LA with LAV40 and only 17% with LAV75. These volumes were positively influenced by age but not by gender. The relationship between LAV75 and LAV40 was: LAV75=0.908 LAV40-3.486 (r2=0.92) or LAV40=1.1×LAV75+3.8 (r2=0.92). LAVmax measured at the 75% of the cardiac cycle phase significantly underestimates actual LAV leading to reconsider normal values. LAV40 can be computed from the measured value of LAV75 obtained on prospective ECG-gated MDCT.

Image Integration to Guide Catheter Ablation in Scar‐Related Ventricular Tachycardia

Although multi-detector computed tomography (MDCT) and cardiac magnetic resonance (CMR) can assess the structural substrate of ventricular tachycardia (VT) in ischemic cardiomyopathy (ICM), non-ICM (NICM), and arrhythmogenic right ventricular cardiomyopathy (ARVC), the usefulness of systematic image integration during VT ablation remains undetermined. A total of 116 consecutive patients (67 ICM; 30 NICM; 19 ARVC) underwent VT ablation with image integration (MDCT 91%; CMR 30%; both 22%). Substrate was defined as wall thinning on MDCT and late gadolinium-enhancement on CMR in ICM/NICM, and as myocardial hypo-attenuation on MDCT in ARVC. This substrate was compared to mapping and ablation results with the endpoint of complete elimination of local abnormal ventricular activity (LAVA), and the impact of image integration on procedural management was analyzed. Imaging-derived substrate identified 89% of critical VT isthmuses and 85% of LAVA, and was more efficient in identifying LAVA in ICM and ARVC than in NICM (90% and 90% vs. 72%, P < 0.0001), and when defined from CMR than MDCT (ICM: 92% vs. 88%, P = 0.026, NICM: 88% vs. 72%, P < 0.001). Image integration motivated additional mapping and epicardial access in 57% and 33% of patients. Coronary and phrenic nerve integration modified epicardial ablation strategy in 43% of patients. The impact of image integration on procedural management was higher in ARVC/NICM than in ICM (P < 0.01), and higher in case of epicardial approach (P < 0.0001). Image integration is feasible in large series of patients, provides information on VT substrate, and impacts procedural management, particularly in ARVC/NICM, and in case of epicardial approach.

Electrocardiogram-gated 320-slice multidetector computed tomography for the measurement of pulmonary arterial distensibility in chronic thromboembolic pulmonary hypertension.

BackgroundWe aimed to study whether pulmonary arterial distensibility (PAD) correlates with hemodynamic parameters in chronic thromboembolic pulmonary hypertension (CTEPH) using electrocardiogram (ECG)-gated 320-slice multidetector computed tomography (MDCT).Methods and FindingsECG-gated 320-slice MDCT and right heart catheterization (RHC) was performed in 53 subjects (60.6±11.4 years old; 37 females) with CTEPH. We retrospectively measured the minimum and maximum values of the cross sectional area (CSA) of the main pulmonary artery (mainPA), right pulmonary artery (rtPA), and left pulmonary artery (ltPA) during one heartbeat. PAD was calculated using the following formula: PAD = [(CSAmaximum−CSAminimum)/CSAmaximum]×100(%). The correlation between hemodynamic parameters and PAD was assessed. Mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) were 40.8±8.7 mmHg and 8.3±3.0 wood units, respectively. PAD values were as follows: mainPA (14.0±5.0%), rtPA (12.8±5.6%), and ltPA (9.7±4.6%). Good correlations existed between mainPAD, with mPAP (r = −0.594, p<0.001) and PVR (r = −0.659, p<0.001). The correlation coefficients between rtPAD and ltPAD with pulmonary hemodynamics were all lower or equal than for mainPAD.ConclusionsPAD measured using ECG-gated 320-slice MDCT correlates with pulmonary hemodynamics in subjects with CTEPH. The mainPA is suitable for PAD measurement.

Preprocedural ECG-gated computed tomography for prevention of complications during lead extraction.

Preprocedural multidetector computed tomography (MDCT) may identify patients at risk for mechanical complications during lead extraction. To describe the use and feasibility of computed tomography scanning for preprocedural planning of lead extraction, we conducted a retrospective study of high-risk patients, who underwent electrocardiogram (ECG)-gated MDCT before planned lead extraction between January 1, 2012, and March 30, 2013. Among 30 patients the mean age was 63 ± 15 years, 60% were male, and 20% had prior sternotomy. Most devices were left sided (93%) and 24 had implantable defibrillators (80%). Indications for extraction included lead malfunction (n = 15; 50%), class I lead advisories (n = 11; 37%), and infection (n = 10; 33%). Overall, there were 65 leads extracted (mean 2.1 leads per patient). One extraction procedure was deferred due to MDCT evidence of significant myocardial perforation with the lead tip > 1 cm beyond the epicardium (n = 1, 3%). MDCT suggestion of lead adherence to central venous structures (n = 13, 43%) was associated with significantly longer laser times (88 ± 71 seconds vs 30 ± 37 seconds, P = 0.02) and larger sheath size (14.9 ± 1.3 vs 13.5 ± 1.2 French, P = 0.02). MDCT evidence of central venous occlusion or stenosis was not associated with increased laser times. Excluding the patient with MDCT evidence of significant perforation, clinical success was achieved in all patients (n = 29/29). ECG-gated MDCT scanning before lead extraction may facilitate the identification of significant perforation and patients at high risk for mechanical complication.

The prevalence of coronary anomalies in a single center of Korea: origination, course, and termination anomalies of aberrant coronary arteries detected by ECG-gated cardiac MDCT.

BackgroundCoronary anomalies are rare congenital abnormalities often found incidentally on conventional coronary angiography (CCA) or coronary CT angiography (CTA). They may result in various clinical outcomes. CCA is invasive and not able to demonstrate all coronary anomalies in detail, especially those with complex courses. Multidetector computed tomography (MDCT) enables visualization of the origin and course of coronary arteries. The objective of this study was to investigate the prevalence of origin and termination coronary artery anomalies and the course of these anomalies in patients in a single center in Korea.MethodsTo diagnose coronary anomalies, the angiographic data of 8,864 consecutive patients undergoing 64- or 320-MDCT from September 2005 to November 2011 were analyzed retrospectively.ResultsAmong the 8,864 patients, 103 (1.16%) had coronary anomalies. Ninety (87.4%) patients had origin and distribution anomalies, and 13 (12.6%) patients had a coronary artery fistula. The most common anomaly (41, 39.8%) was an anomalous origin of the right coronary artery (RCA). Of these, three patients received a coronary artery bypass graft.ConclusionsThe prevalence of coronary anomalies in a single center of Korea was 1.16%. The incidence and patterns of coronary artery anomalies in our patient population were similar to those of previous studies.

Visualization of thrombosis on a prosthetic pulmonary valve using electrocardiogram-gated multidetector computed tomography.

We report a case of prosthetic valve thrombosis in an 18-year-old man. Total surgical repair of tetralogy of Fallot was performed at 3 years of age. At the age of 18, he underwent pulmonary valve replacement because of exacerbating pulmonary trunk obstruction. After surgery, valve malfunction was suspected. We attempted to employ electrocardiogram (ECG)-gated multidetector computed tomography (MDCT). The stuck valve was clearly visualized together with a thrombus within. Thrombolytic therapy was undertaken on these findings. ECG-gated MDCT allowed us to make a definitive diagnosis of valve thrombosis as the cause of valve malfunction, which led us to avoid surgical reintervention.

Experience with multidetector computed tomography changes in acute myocardiatis

Background: Acute myocarditis can present as an ACS with elevated ST segment and elevated level of troponin mimicking myocardial infarction. Aim: To determine the potential diagnostic value of ECG-gated multidetector computed tomography (MDCT) in the setting of suspected acute myocarditis. Patients and methods: The study group consisted of 12 consecutive patients admitted for suspected acute myocarditis less than 5 days after onset of symptoms. All patients had clinical, electrocardiographic signs, and laboratory findings consistent with the diagnosis. ECGgated MDCT was performed in all patients and included a first-pass contrast-enhanced acquisition and a delayed low dose acquisition performed 5 min later without reinjection of contrast medium. 3 patients underwent cardiac MRI with injection of gadolinium. Results: The first-pass MDCT acquisition showed absence of coronary stenosis in all patients. Delayed MDCT acquisition, revealed multiple areas of sub epicardial myocardial hyperenhancement in 9 patients. This hyperhencement was confirmed in the 3 MRI examinations. Conclusion: ECG-gated MDCT could be a useful alternative non-invasive diagnostic test in the early phase of acute myocarditis, especially in the context of emergency and when MRI is unavailable.

Impact of iterative reconstruction on CNR and SNR in dynamic myocardial perfusion imaging in an animal model

To evaluate a new iterative reconstruction (IR) algorithm for radiation dose, image quality (IQ), signal-to-noise-ratio (SNR), and contrast-to-noise-ratio (CNR) in multidetector computed tomography (MDCT) dynamic myocardial perfusion imaging (MPI). ECG-gated 256-slice MDCT dynamic MPI was performed in six pigs after subtotal balloon occlusion of one artery. Two 100 kVp protocols were compared: high dose (HD): 150 mAs; low dose (LD): 100 mAs. HD images were reconstructed with filtered back projection (FBP), LD images with FBP and different strengths of IR (L1, L4, and L7). IQ (5-point scale), SNR, and CNR (ischemic vs. normal myocardium) values derived from the HD (FBP) images and the different LD images were compared. Mean SNR values for myocardium were 16.3, 11.3, 13.1, 17.1, and 28.9 for the HD, LD (FBP), LD (L1), LD (L4), and LD (L7) reconstructions, respectively. Mean CNR values were 8.9, 6.3, 7.8, 9.3, and 12.8. IQ was scored as 4.6, 3.3, 4.4, 4.7, and 3.4, respectively. A significant loss of IQ was observed for the LD (L7) images compared to the HD (FBP) images (P < 0.05). Appropriate levels of iterative reconstruction can improve SNR and CNR, facilitating radiation dose savings in CT-MPI without influencing diagnostic quality. Iterative reconstruction (IR) can reduce radiation dose in myocardial perfusion CT. Our study also demonstrated improvements in image quality (noise, SNR, and CNR). Dynamic CT-MPI could help determine the hemodynamic significance of coronary artery disease. With dynamic CT MPI, myocardial blood flow can be determined quantitatively.

Assessment of Coronary Vasoreactivity by Multidetector Computed Tomography - Feasibility Study With Rubidium-82 Cardiac Positron Emission Tomography -

Positron emission tomography (PET) during the cold pressor test (CPT) has been used to assess endothelium-dependent coronary vasoreactivity, a surrogate marker of cardiovascular events. However, its use remains limited by cardiac PET availability. As multidetector computed tomography (MDCT) is more widely available, we aimed to develop a measurement of endothelium-dependent coronary vasoreactivity with MDCT and similar radiation burden as with PET. A study group of 18 participants without known cardiovascular risk factor (9F/9M; age 60±6 years) underwent cardiac PET with (82)Rb and unenhanced ECG-gated MDCT within 4h, each time at rest and during CPT. The relation between absolute myocardial blood flow (MBF) response to CPT by PET (ml·min(-1)·g(1)) and relative changes in MDCT-measured coronary artery surface were assessed using linear regression analysis and Spearman's correlation. MDCT and PET/CT were analyzed in all participants. Hemodynamic conditions during CPT at MDCT and PET were similar (P>0.3). Relative changes in coronary artery surface because of CPT (2.0-21.2%) correlated to changes in MBF (-0.10-0.52ml·min(-1)·g(1)) (ρ=0.68, P=0.02). Effective dose was 1.3±0.2mSv for MDCT and 3.1mSv for PET/CT. Assessment of endothelium-dependent coronary vasoreactivity using MDCT CPT appears feasible. Because of its wider availability, shorter examination time and similar radiation burden, MDCT could be attractive in clinical research for coronary status assessment.

Multi detector computed tomography (MDCT) of the aortic root; ECG-gated verses non-ECG-gated examinations

Purpose Motion artifacts may degrade a conventional CT examination of the ascending aorta and hinder accurate diagnosis. We quantitatively compared retrospectively electrocardiographic (ECG) -gated multi detector computed tomography (MDCT) with non-ECG-gated MDCT in order to demonstrate whether or not one of the methods should be preferred. Method The study included seventeen patients with surgically reconstructed aortic root and reimplanted coronary arteries. All patients had undergone both non-gated MDCT and retrospectively ECG-gated MDCT employing a stringently modulated tube current with single phase image reconstruction. The incidence of motion artifacts in the left main coronary artery (LM), proximal right coronary artery (RCA), and aortic root and ascending aorta were rated using a four point scale. The effective dose for each scan was calculated and normalized to a 15 cm scan length. Statistical analysis of motion artifacts and radiation dose was performed using Wilcoxon matched pairs signed rank sum test. Results A significant reduction in motion artifacts was found in all three vessels in images from the retrospectively ECG-gated scans (LM: P = 0.005, RCA: P = 0.015, aorta: P = 0.003). The mean normalized effective radiation dose was 3.69 mSv (±1.03) for the non-ECG-gated scans and 16.37 mSv (±2.53) for the ECG-gated scans. Conclusion Retrospective ECG-gating with single phase reconstruction significantly reduces the incidence of motion artifacts in the aortic root and the proximal portion of the coronary arteries but at the expense of a fourfold increase in radiation dose.

Evaluating a Thrombosed Azygous Vein Aneurysm Combined with Pulmonary Arterial Thromboembolism by ECG-Gated Multidetector CT: a Case Report

Azygous vein aneurysm is a rare congenital lesion that needs to be differentiated from mediastinal mass lesions. Although almost of these anomalies are asymptomatic lesions, we experienced an interesting case in which a thrombus within an azygous vein aneurysm in a 75-year-old woman caused pulmonary thromboembolism. The patient was managed by medical treatment for one month and then the thrombus within both the azygous vein aneurysm and the pulmonary arteries completely resolved.

Coronary artery and thoracic calcium on noncontrast thoracic CT scans: Comparison of ungated and gated examinations in patients from the COPD Gene cohort

Coronary artery calcification (CAC) and thoracic aortic calcification, (TAC) are frequently detected on ungated multidetector computed tomography (MDCT) performed for lung evaluations. We sought to evaluate concordance of CAC and TAC scores on ungated (thoracic) and electrocardiogaphically (ECG)-gated (cardiac) MDCT scans. Fifty patients, enrolled in the Genetic Epidemiology of COPD study (COPDGene), were recruited to undergo gated CAC scans with 64-detector row CT, in addition to the ungated thoracic studies already being obtained as part of their study evaluation. Coronary and thoracic calcium were measured similarly (Agatston score, requiring 3 contiguous voxels of >130 Hounsfield units) with low-dose ungated studies and ECG-gated MDCT performed at the same scanning session. Intertechnique scoring variability and concordance were calculated. Correlations between gated and ungated CAC and TAC were excellent (r = 0.96). The relative differences (median variability) measured by ECG-gated versus ungated MDCT were relatively high for CAC (44%) but not for TAC (8%). Prevalence of depicted CAC (n = 33; 66%) and TAC (n = 21; 42%) were coincident between ECG-gated and ungated MDCT, respectively (intertechnique concordance, 100%). Bland-Altman plots for CAC showed mean differences of 354 (confidence interval, 169-538) and 16.1 (confidence interval, -89 to 121). Low-dose ungated MDCT is reliable for prediction of the presence of CAC and assessment of Agatston score. Concordance between methods and between TAC and CAC is high. This technique should allow for atherosclerotic disease risk stratification among patients undergoing ungated lung CT evaluation without requiring additional scanning. Measurement of TAC is almost as accurate from gated CT, and CAC scores are highly concordant.

Evaluation of Reperfused Myocardial Infarction by Low-Dose Multidetector Computed Tomography Using Prospective Electrocardiography (ECG)-Triggering: Comparison with Magnetic Resonance Imaging

PurposeTo evaluate the potential of prospective electrocardiography (ECG)-gated 64-slice multidetector computed tomography (MDCT) for evaluation of myocardial enhancement, infarct size, and stent patency after percutaneous coronary intervention (PCI) with stenting in patients with myocardial infarction.Materials and MethodsSeventeen patients who were admitted with acute myocardial infarction were examined with prospective ECG-gated 64-slice cardiac MDCT and magnetic resonance (MR) imaging after reperfusion using PCI with stenting. Cardiac MDCT was performed with two different phases: arterial and delayed phases. We evaluated the stent patency on the arterial phase, and nonviable myocardium on the delayed phase of computed tomography (CT) image, and they were compared with the results from the delayed MR images.ResultsTotal mean radiation dose was 7.7 ± 0.5 mSv on the two phases of CT images. All patients except one showed good patency of the stent at the culprit lesion on the arterial phase CT images. All patients had hyperenhanced area on the delayed phase CT images, which correlated well with those on the delayed phase MR images, with a mean difference of 1.6% (20 ± 10% vs. 22 ± 10%, r = 0.935, p = 0.10). Delayed MR images had a better contrast-to-noise ratio (CNR) than delayed CT images (27.1 ± 17.8% vs. 4.3 ± 2.1%, p < 0.001).ConclusionProspective ECG-gated 64-slice MDCT provides the potential to evaluate myocardial viability on delayed phase as well as for stent patency on arterial phase with an acceptable radiation dose after PCI with stenting in patients with myocardial infarction.

高ヘリカルピッチを用いた前向き心電図同期ヘリカルスキャンによる冠動脈MDCTの被ばく低減効果

High radiation dose of conventional retrospective ECG-gated coronary MDCT (multidetector computed tomography) with regular helical pitch (HP) continuous scan has disturbed wide clinical use. The purpose was to estimate the radiation dose reduction effects of FlashScan, which was a prospective ECG-gated helical scan with high HP. Coronary MDCT was performed by Aquilion 64 Super Heart (Toshiba) in 474 patients (M/F=280/194, mean age: 65+/-11 years old, mean height: 161+/-10 cm, body weight: 62+/-13 kg, BMI: 23.9+/-3.4) with HR<or=60 and without arrhythmia before scan. Mean HP (BP) which was automatically decided by the FlashScan system was 15.3+/-1.0 (0.239+/-0.016) when the gantry rotation speed was 0.35 s/rot. In 6 patients, arrhythmias occurred during scan and data deficits were observed on their images. In the remaining 468 patients, image quality was excellent. Mean DLP of the FlashScan (499+/-119 mGy.cm) was significantly (P<0.0001) lower than that of retrospective continuous scan with regular HP (1281+/-286 mGy.cm) or than that of modulation scan (927+/-202 mGy.cm), and mean scan time of the FlashScan (6.9+/-0.6 s) was also significantly (P<0.0001) shorter than that of retrospective continuous scan with regular HP (8.8+/-0.6 s). The FlashScan was a useful method to reduce patients' radiation dose and scan time in patients with HR<or=60 and without arrhythmia.

ECG-gated multidetector computed tomography for the assessment of the postoperative ascending aorta

This study was undertaken to define the role of electrocardiographically (ECG)-gated multidetector computed tomography (MDCT) in the assessment of the postoperative ascending aorta. From November 2006 to June 2007, 21 patients, [11 men, ten women; age +/- standard deviation (SD): 62.7+/-10.8 years] with a history of ascending aorta replacement underwent ECG-gated MDCT and were prospectively included in our study. Ascending aorta replacement had been performed with different surgical techniques: Bentall-De Bono (four patients, 19%), Tirone-David (five patients, 23%), and modified Tirone-David with creation of aortic neosinuses (12 patients, 57%). Two patients were excluded from MDCT evaluation because they failed to fulfil the inclusion criteria. Transthoracic echocardiography was used as the reference standard. All patients provided informed consent. In all patients, ECG-gated MDCT provided a clear depiction of the aortic annulus, aortic root and ascending aorta, enabling accurate measurements in all cases. The aortic valve area (3.4+/-0.2 cm(2)), the diameter of the sinotubular junction (31.6+/-1.8 mm), the diameter of the neosinuses in the case of modified Tirone-David procedures (37.3+/-2.1 mm) and the distance between the cusps and the graft wall during systole (3.1+/-0.7 mm) fell within standard ranges and showed a good correlation (r=0.89) with the values obtained with transthoracic echocardiography. MDCT is currently considered a compulsory diagnostic step in patients with suspected or known aortic pathology. MDCT is a reliable technique for anatomical and functional assessment of the postoperative aortic root and provides cardiac surgeons with new and detailed information, enabling them to formulate a prognostic opinion regarding the outcome of the surgical procedure.

CT and MR Imaging Findings in Patients with Acquired Heart Disease at Risk for Sudden Cardiac Death

Noninvasive imaging is an important screening and diagnostic tool in conditions associated with sudden cardiac death. The most common cause of sudden cardiac death is coronary artery disease, with myocarditis, cardiac sarcoidosis, and dilated and infiltrative cardiomyopathies being less common acquired causes. Common risk factors for sudden cardiac death, regardless of the disease process, include severe ventricular dysfunction and the presence of macroscopic scar seen at delayed contrast material-enhanced imaging. Recent advances in electrocardiographically (ECG) gated cardiac magnetic resonance (MR) imaging and multidetector computed tomography (CT) have led to increased referrals for cross-sectional imaging; thus, cardiac radiologists should be familiar with the disease entities associated with sudden cardiac death. Inflammatory processes and cardiomyopathies are best depicted with cardiac MR imaging. Steady-state free precession cine sequences coupled with inversion-recovery prepared gradient-echo T1-weighted sequences performed after the intravenous administration of gadolinium-based contrast material should form the basis of cardiac MR imaging protocols for cardiomyopathy. A clinical history that is suggestive of myocardial ischemia, specific requests to exclude coronary artery disease, or contraindications for MR imaging may imply that multidetector CT would be more appropriate. Nevertheless, both cardiac MR imaging and ECG-gated multidetector CT offer robust diagnosis and risk stratification for individual disease processes associated with sudden cardiac death.

The Right Sided Great Vessels by Cardiac Multidetector Computed Tomography: Normative Reference Values among Healthy Adults Free of Cardiopulmonary Disease, Hypertension, and Obesity

We sought to derive normative reference values for the thoracic great vessels using multidetector computed tomography (MDCT) in a healthy normotensive non-obese population free of cardiovascular disease. Non-gated axial computed tomography (CT) of the chest has traditionally been used to evaluate normal great vessel anatomy for prognosis and management. However, non-gated axial chest CT cannot account for the obliquity, systolic expansion, and non-axial motion of the great vessels during the cardiac cycle and may misclassify patients as normal or abnormal for prognostic and management purposes. To date, normative reference values for double-oblique, short-axis great vessel diameters have not been established using current generation electrocardiogram (ECG)-gated 64-detector row MDCT. A total of 103 (43% women, age 51 +/- 14 years) consecutive normotensive, non-obese adults free of cardiopulmonary or great vessel structural disease, arrhythmias, or significant coronary artery disease were studied by MDCT. Individuals underwent examination for determination of end-diastolic (ED) pulmonary artery (PA) and superior vena cava (SVC) dimensions in double-oblique short axes for comparison with the ascending aorta and the right-sided cardiac chambers. For right sided great vessels, the 5th to 95th interval was 1.89-3.03 cm for ED PA diameter and 1.08-4.42 cm(2) for SVC cross-sectional area. The pulmonary artery to ascending aortic (PA-to-Ao) ratio was 0.66-1.13. In multivariate analysis, the PA was significantly associated with weight, whereas the PA-to-Ao ratio was inversely associated with age. Axial PA measurements were significantly higher and PA-to-Ao measurements significantly lower than corresponding short axis measurements (P = .04 and P < .001, respectively). This study establishes ECG-gated MDCT reference values for right-sided great vessel dimensions derived from a healthy population of individuals free of cardiovascular disease, hypertension, and obesity. The traditional axial PA-to-Ao discriminant value of 1 for pulmonary hypertension is a poor diagnostic tool because it encompasses normal patients and is negatively affected by age. Thoracic great vessels should be measured by CT in ECG-gated double-oblique short-axis for accurate quantitation. These data may serve as a reference to identify right-sided great vessel pathology in individuals being referred for ECG-gated MDCT imaging.

Clinical evaluation of a fully automated model-based algorithm to calculate left ventricular volumes and ejection fraction using multidetector computed tomography

To evaluate feasibility and accuracy of a fully automatic algorithm (FAA) for calculating left ventricular volumes and ejection fraction (LVEF) from multidetector computed tomography (MDCT) studies versus a previously validated method based on Simpson's method serving as our reference standard (RS), and left ventriculography (LVG), in patients with acute chest pain (ACP). 23 patients admitted with ACP underwent ECG-gated MDCT, as well as LVG during their hospitalization. MDCT based end-diastolic, end-systolic and stroke volumes (EDV, ESV, SV) and LVEF were calculated using the RS and the FAA. One patient was excluded after FAA failure to detect contours. In the remaining 22 patients, mean+/-SD LVEF measurements were RS 61+/-11%, FAA 59+/-11% (r = 0.91 versus RS), LVG 57+/-16% (r = 0.6 versus RS). In comparison to RS, FAA overestimated EDV by 10.1+/-8.5 ml, ESV by 7.3+/-6.4 ml and SV by 3.6+/-8.6 ml, and underestimated LVEF measurements by 2.7+/-4.6%, related to contour smoothing. LVEF by FAA was within 8% of RS for all patients except one. In contrast, LVG differed significantly from RS. The evaluated FAA obtained accurate, clinically relevant results for left ventricular volumes and LVEF relative to the RS.