Multislice Computed Tomography for Preoperative Evaluation of Right Ventricular Volumes and Function: Comparison With Magnetic Resonance Imaging

Feasibility of Cardiac Computed Tomography for the Evaluation of Ventricular Function in Postoperative Children With Congenital Heart Disease: Comparison With Cardiac Magnetic Resonance Imaging

OBJECTIVE

We explored the feasibility of cardiac computed tomography (CCT) to evaluate postoperative ventricular function in children with congenital heart disease (CHD) and evaluated the accuracy and reproducibility of CCT using cardiac magnetic resonance (CMR) as a reference.

METHODS

Thirty-two postoperative children with CHD (20 boys and 12 girls) who underwent CMR and CCT were enrolled. Left and right ventricular ejection fraction, end-diastolic volume, end-systolic volume, stroke volume, and cardiac index were measured using cardiac function analysis software. Cardiac function data were compared between CMR and CCT. The agreement between the 2 modalities was assessed using a Bland-Altman analysis. Intraclass correlation coefficients were used to assess intraobserver and interobserver reproducibility in CCT functional measurements.

RESULTS

All functional parameters showed no significant difference (P > 0.05) and were well-correlated (r > 0.5, P < 0.05) between CMR and CCT. The mean values of all ventricular function parameters in CCT were higher compared with CMR. As indicated by 95% limits of agreement, left ventricular function parameters showed a better level of agreement compared with right ventricular function parameters between the 2 modalities. Intraobserver and interobserver reproducibility were excellent in CCT measurements for all functional parameters (intraclass correlation coefficient > 0.9).

CONCLUSIONS

Compared with the criterion standard of CMR, CCT is feasible for assessing postoperative ventricular function with sufficient diagnostic accuracy and reproducibility in children with CHD. In addition to its important role regarding anatomical characterization, CCT is a suitable alternative and convenient follow-up tool that can be used to functional evaluation in children who are intolerant with CMR or have contraindications to CMR.

Role of Computed Tomography in Postoperative Follow-up of Arterial Switch Operation

An arterial switch operation (ASO) is the standard treatment for infants and children born with D-loop transposition of the great arteries. During the ASO, the great vessels are transected from the native roots, switched and anastomosed with the opposite roots. This is accompanied by the relocation of the pulmonary artery anterior to the aorta by using the LeCompte maneuver and the translocation of coronary arteries to the neo-aorta. ASO has led to improved overall survival, and postoperative mortality is rare. Despite the improved outcomes, several postoperative sequelae may occur, and therefore patients require long-term follow-up. Computed tomography (CT) has emerged as a robust imaging modality in pre and postoperative evaluation of a variety of congenital heart disorders including ASO. Unlike echocardiography and cardiovascular magnetic resonance, CT is not hindered by a poor acoustic window, metallic devices or the need for sedation or general anesthesia. CT with advanced three-dimensional postprocessing techniques, high pitch scanning, wider detector system, electrocardiogram-dependent modulation and dose-reduction strategies is invaluable in assessing the postoperative complications after ASO.

CT compared to MRI for functional evaluation of the right ventricle: a systematic review and meta-analysis

OBJECTIVE

Right ventricular function (RVF) is a strong predictor of adverse cardiac events; however, the reference standard for RVF assessment, MRI, is limited in some patients for whom accurate evaluation of RVF is essential, like those with COPD or non-MR compatible metal implants. We conducted this meta-analysis to evaluate whether CT was as accurate as MRI for the assessment of RVF.

METHOD

We conducted a meta-analysis of studies retrieved from PubMed, Embase, and Cochrane Central searches to evaluate the differences and correlations between the following RVF parameters as measured by CT and MRI: end diastole volume (EDV), end systole volume (ESV), right ventricular ejection fraction (RVEF), and stroke volume (SV).

RESULTS

Sixteen studies that used disk summation (637 subjects) and three studies that used three-dimensional reconstruction were included. For the 16 studies, the pooled standard mean differences (95% confidence interval) were 1.04 (- 2.59, 4.67) for EDV, 1.22 (1.50, 3.95) for ESV, - 0.65 (- 2.60, 1.29) for RVEF, and - 0.37 (- 3.64, 2.90) for SV. The overall correlation coefficient (r) values were 0.98 for EDV, 0.95 for ESV, 0.98 for RVEF, and 0.97 for SV. The mean difference between the two methods was not statistically significant (overall effect Z test, p > 0.1).

CONCLUSION

CT can assess RVF with accuracy comparable to that of MRI. Thus, CT is a valid alternative to MRI.

KEY POINTS

• CT could help clinicians to assess RVF as accurately as MRI can, with satisfactory repeatability.

Temporary assist device support for the right ventricle: pre-implant and post-implant challenges

Severe right ventricular (RV) failure is more likely reversible than similar magnitudes of left ventricular (LV) failure and, because reversal of both adaptive remodeling and impaired contractility require most often only short periods of support, the use of temporary RV assist devices (t-RVADs) can be a life-saving therapy option for many patients. Although increased experience with t-RVADs and progresses made in the development of safer devices with lower risk for complications has improved both recovery rate of RV function and patient survival, the mortality of t-RVAD recipients can still be high but it depends mainly on the primary cause of RV failure (RVF), the severity of end-organ dysfunction, and the timing of RVAD implantation, and much less on adverse events and complications related to RVAD implantation, support, or removal. Reduced survival of RVAD recipients should therefore not discourage appropriate application of RVADs because their underuse further reduces the chances for RV recovery and patient survival. The article reviews and discusses the challenges related to the pre-implant and post-implant decision-making processes aiming to get best possible therapeutic results. Special attention is focused on pre-implant RV assessment and prediction of RV improvement during mechanical unloading, patient selection for t-RVAD therapy, assessment of unloading-promoted RV recovery, and prediction of its stability after RVAD removal. Particular consideration is also given to prediction of RVF after LVAD implantation which is usually hampered by the complex interactions between the different risk factors related indirectly or directly to the RV potential for reverse remodeling and functional recovery.

Evaluation of the CT imaging findings in patients newly diagnosed with chronic thromboembolic pulmonary hypertension

PURPOSE

The aim of this study was to evaluate the vascular and parenchymal CT imaging findings, including vessel and cardiac chamber diameter measurements, in patients newly diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH). The CT imaging findings were correlated with hemodynamic measurements and patient outcome.

METHODS

Vascular and parenchymal CT findings were assessed on retrospectively ECG-gated MDCT angiography scans in 76 patients newly diagnosed with CTEPH. The diameters of the right and left ventricle (dRV, dLV), the right and left atrium (dRA, dLA), the ascending aorta (dAA), the right and left pulmonary arteries (drPA, dlPA), and the main pulmonary artery (dPA) were measured on axial CT scans. The CT imaging findings were correlated with demographic and hemodynamic data and adverse patient outcome due to right heart failure (RHF).

RESULTS

The majority of patients showed chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals in CT. Mean pulmonary artery pressure (mPAP) was not significantly different in patients with and those without chronic PE, mosaic perfusion, disparity in segmental vessel size, parenchymal densities, bronchial dilatation, and bronchial collaterals. Mean PAP showed significant correlations with the CT metrics of dRV/dLV ratio, dRA, dRV, dPA and dPA/dAA ratio, but no correlation with the central thrombi score. By backward linear regression, the dPA/dAA ratio independently correlated with mPAP. Patients who died of RHF tended to have a higher frequency of exclusively chronic peripheral PE and greater dRV/dLV ratios on presenting CT scans compared with survivors.

CONCLUSION

The majority of patients newly diagnosed with CTEPH show vascular signs of chronic PE, mosaic perfusion, parenchymal densities, disparity in segmental vessel size, bronchial dilatation, and bronchial collaterals on presenting CT scans. Particularly CTEPH patients with exclusively chronic peripheral PE and increased dRV/dLV ratios seem to be at risk of adverse outcome due to RHF.

Evaluation of right ventricular function by coronary computed tomography angiography using a novel automated 3D right ventricle volume segmentation approach: a validation study

OBJECTIVES

To evaluate right ventricle (RV) function by coronary computed tomography angiography (CTA) using a novel automated three-dimensional (3D) RV volume segmentation tool in comparison with clinical reference modalities.

METHODS

Twenty-six patients with severe end-stage heart failure [left ventricle (LV) ejection fraction (EF) <35%] referred to CTA were enrolled. A specific individually tailored biphasic contrast agent injection protocol was designed (80%/20% high/low flow) was designed. Measurement of RV function [EF, end-diastolic volume (EDV), end-systolic volume (ESV)] by CTA was compared with tricuspid annular plane systolic excursion (TAPSE) by transthoracic echocardiography (TTE) and right heart invasive catheterisation (IC).

RESULTS

Automated 3D RV volume segmentation was successful in 26 (100%) patients. Read-out time was 3 min 33 s (range, 1 min 50s-4 min 33s). RV EF by CTA was stronger correlated with right atrial pressure (RAP) by IC (r = -0.595; p = 0.006) but weaker with TAPSE (r = 0.366, p = 0.94). When comparing TAPSE with RAP by IC (r = -0.317, p = 0.231), a weak-to-moderate non-significant inverse correlation was found. Interobserver correlation was high with r = 0.96 (p < 0.001), r = 0.86 (p < 0.001) and r = 0.72 (p = 0.001) for RV EDV, ESV and EF, respectively. CT attenuation of the right atrium (RA) and right ventricle (RV) was 196.9 ± 75.3 and 217.5 ± 76.1 HU, respectively.

CONCLUSIONS

Measurement of RV function by CTA using a novel 3D volumetric segmentation tool is fast and reliable by applying a dedicated biphasic injection protocol. The RV EF from CTA is a closer surrogate of RAP than TAPSE by TTE.

KEY POINTS

• Evaluation of RV function by cardiac CTA by using a novel 3D volume segmentation tool is fast and reliable. • A biphasic contrast agent injection protocol ensures homogenous RV contrast attenuation. • Cardiac CT is a valuable alternative modality to CMR for the evaluation of RV function.

Imaging in patients after cardiac transplantation and in patients with ventricular assist devices

The field of cardiac imaging and the management of patients with severe heart failure have advanced substantially during the past 10 years. Cardiac transplantation offers the best long-term survival with high quality of life for the patients with end stage heart failure. However, acute cardiac rejection and cardiac allograft vasculopathy (CAV) can occur post cardiac transplantation and these problems necessitate regular surveillance. The short-term success of mechanical circulatory support devices (MCSD), such as ventricular assist devices (VADs), in improving survival and quality of life has led to a dramatic growth of the patient population with these devices. The development of optimal imaging techniques and algorithms to evaluate these advanced heart failure patients is evolving and multimodality non-invasive imaging approaches and invasive techniques are commonly employed. Most of the published studies done in the transplant and VAD population are small, and biased based on the strength of the particular program, and there is a relative lack of published protocols to evaluate these patient groups. Moreover, the techniques of echocardiography, computed tomography (CT), magnetic resonance imaging, and nuclear cardiology have all progressed rapidly in recent years. There is thus a knowledge gap for cardiologists, radiologists, and clinicians, especially regarding surveillance for CAV and ideal imaging approaches for patients with VADs. The purpose of this review article is to provide an overview of different noninvasive imaging modalities used to evaluate patients after cardiac transplantation and for patients with VADs. The review focuses on the role of echocardiography, CT, and nuclear imaging in surveillance for CAV and rejection and on the assessment of ventricular structure and function, myocardial remodeling and complications for VAD patients.

Secundum atrial septal defect in adults: a practical review and recent developments

Secundum atrial septal defect (ASDII) is a common congenital heart defect that causes shunting of blood between the systemic and pulmonary circulations. Patients with an isolated ASDII often remain asymptomatic during childhood and adolescence. If the defect remains untreated, however, the rates of exercise intolerance, supraventricular arrhythmias, right ventricular dysfunction and pulmonary arterial hypertension (PAH) increase with patient age, and life expectancy is reduced. Transcatheter and surgical techniques both provide valid options for ASDII closure, the former being the preferred method. With the exception of those with severe and irreversible PAH, closure is beneficial to, and thus indicated in all patients with significant shunts, regardless of age and symptoms. The symptomatic and survival benefits conferred by defect closure are inversely related to patient age and the presence of PAH, supporting timely closure after diagnosis. In this paper we review the management of adult patients with an isolated ASDII, with a focus on aspects of importance to the decision regarding defect closure and medical follow-up.

Is cardiac CT a reproducible alternative for cardiac MR in adult patients with a systemic right ventricle?

OBJECTIVE

20 % of patients with a systemic RV are pacemaker dependent, and unsuitable to undergo cardiac magnetic resonance (CMR). Multidetector row computed tomography (MDCT) could provide a reproducible alternative to CMR in these patients. The aim of this study was to compare variability of MDCT with CMR.

METHODS

Thirty-five patients with systemic RV underwent either MDCT (n = 15) or CMR (n = 20). Systemic RV volumes and ejection fraction were obtained, and intra- and interobserver variability for both modalities were assessed and compared.

RESULTS

We found the intra- and interobserver variability of volumes and function measurements of the systemic RV obtained with MDCT to be higher compared with those obtained with CMR. However, these differences in variability were not significant, the only exception being the interobserver variability of systemic RV stroke volume.

CONCLUSIONS

MDCT provides a reproducible alternative to CMR for volumes and function assessment in patients with a systemic RV.

Pulmonary artery and right ventricle assessment in pulmonary hypertension: correlation between functional parameters of ECG-gated CT and right-side heart catheterization

BACKGROUND

Right ventricular function predicts outcome in patients with pulmonary hypertension (PH). Therefore accurate assessment of right ventricular function is essential to graduate severity, assess follow-up, and response to therapy.

PURPOSE

To evaluate whether PH severity could be assessed using electrocardiography-gated CT (ECG-gated CT) functional parameters. A further objective was to evaluate cardiac output (CO) using two ECG-gated CT methods: the reference Simpson technique and the fully automatic technique generated by commercially available cardiac software.

MATERIAL AND METHODS

Our institutional review board approved this study; patient consent was not required. Twenty-seven patients who had undergone ECG-gated CT and right heart catheterization (RHC) were included. Two independent observers measured pulmonary artery (PA) diameter, PA distensibility, aorta diameter, right ventricular cardiac output (CT-RVCO) and right ventricular ejection fraction (CT-RVEF) with automatic and Simpson techniques on ECG-gated CT. RHC-CO and mean pulmonary arterial pressure (mPAP) were measured on RHC. Relationship between ECG-gated CT and RHC measurements was tested with linear regression analysis.

RESULTS

Inter-observer agreement was good for all measurements (r > 0.7) except for CT-RVCO calculated with Simpson's technique (r = 0.63). Pulmonary artery (PA) distensibility was significantly correlated to mPAP (r = -0.426, P = 0.027). CT-RVEF was correlated with mPAP only when issued from Simpson technique (r = -0.417, P = 0.034). CT-RVEF was not significantly correlated to RHC-CO (P > 0.2). CT-RVCO measured with Simpson technique (r = 0.487, P = 0.010) and automatic segmentation (r = 0.549, P = 0.005) correlated equally with RHC-CO.

CONCLUSION

CT-RVEF and CT-RVCO measured on ECG-gated CT are significantly correlated, respectively, to mPAP and RHC-CO in this population with severe reduction of the right ventricular ejection fraction and could be useful for evaluating and following patients with PH.

Right heart on multidetector CT

Right ventricular function plays an integral role in the pathogenesis and outcome of many cardiovascular diseases. Imaging the right ventricle has long been a challenge because of its complex geometry. In recent years there has been a tremendous expansion in multidetector row CT (MDCT) and its cardiac applications. By judicious modification of contrast medium protocol, it is possible to achieve good opacification of the right-sided cardiac chambers, thereby paving the way for exploring the overshadowed right heart. This article will describe the key features of right heart anatomy, review MDCT acquisition techniques, elaborate the various morphological and functional information that can be obtained, and illustrate some important clinical conditions associated with an abnormal right heart.

Coronary CT and the coronary calcium score, the future of ED risk stratification?

Accurate and efficient evaluation of acute chest pain remains clinically challenging because traditional diagnostic modalities have many limitations. Recent improvement in non-invasive imaging technologies could potentially improve both diagnostic efficiency and clinical outcomes of patients with acute chest pain while reducing unnecessary hospitalizations. However, there is still controversy regarding much of the evidence for these technologies. This article reviews the role of coronary artery calcium score and the coronary computed tomography in the assessment of individual coronary risk and their usefulness in the emergency department in facilitating appropriate disposition decisions. The evidence base and clinical applications for both techniques are also described, together with cost- effectiveness and radiation exposure considerations.

Left and right ventricle assessment with Cardiac CT: validation study vs. Cardiac MR

Objectives

To compare Magnetic Resonance (MR) and Computed Tomography (CT) for the assessment of left (LV) and right (RV) ventricular functional parameters.

Methods

Seventy nine patients underwent both Cardiac CT and Cardiac MR. Images were acquired using short axis (SAX) reconstructions for CT and 2D cine b-SSFP (balanced-steady state free precession) SAX sequence for MR, and evaluated using dedicated software.

Results

CT and MR images showed good agreement: LV EF (Ejection Fraction) (52 ± 14% for CT vs. 52 ± 14% for MR; r = 0.73; p > 0.05); RV EF (47 ± 12% for CT vs. 47 ± 12% for MR; r = 0.74; p > 0.05); LV EDV (End Diastolic Volume) (74 ± 21 ml/m² for CT vs. 76 ± 25 ml/m² for MR; r = 0.59; p > 0.05); RV EDV (84 ± 25 ml/m² for CT vs. 80 ± 23 ml/m² for MR; r = 0.58; p > 0.05); LV ESV (End Systolic Volume)(37 ± 19 ml/m² for CT vs. 38 ± 23 ml/m² for MR; r = 0.76; p > 0.05); RV ESV (46 ± 21 ml/m² for CT vs. 43 ± 18 ml/m² for MR; r = 0.70; p > 0.05). Intra- and inter-observer variability were good, and the performance of CT was maintained for different EF subgroups.

Conclusions

Cardiac CT provides accurate and reproducible LV and RV volume parameters compared with MR, and can be considered as a reliable alternative for patients who are not suitable to undergo MR.

Key Points

• Cardiac-CT is able to provide Left and Right Ventricular function.

• Cardiac-CT is accurate as MR for LV and RV volume assessment.

• Cardiac-CT can provide accurate evaluation of coronary arteries and LV and RV function.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-011-2345-6) contains supplementary material, which is available to authorized users.

Evaluation of right ventricular function and post-operative findings using cardiac computed tomography in patients with left ventricular assist devices

BACKGROUND

Right ventricular (RV) failure is a major contributor to morbidity and mortality after left ventricular assist device (LVAD) implantation. Accurate evaluation of RV function in patients with LVAD remains challenging. We hypothesized that, after LVAD implantation, electrocardiographic-gated cardiac computed tomography (CCT) allows RV evaluation with higher feasibility and reproducibility compared with echocardiography.

METHODS

Thirty-six patients with an implanted LVAD who had 2-dimensional echocardiography and CCT evaluation were studied. RV end-diastolic and end-systolic volumes and ejection fraction were quantified using CCT. RV fractional area change, tricuspid annular plane systolic excursion and RV end-diastolic short-to-long axis ratio were calculated by echocardiography. Intraclass correlation coefficients (ICCs) and Bland-Altman analysis were used to assess intra- and interobserver reproducibility for all measurements.

RESULTS

The quality of CCT studies was good in all cases except for one. Intra- and interobserver reproducibility for all CCT measurements was high (interobserver ICC for RV ejection fraction = 0.89, 95% confidence interval 0.74 to 0.95). Echocardiographic indices of RV function and geometry had lower reproducibility. The echocardiographic index that best correlated with the CCT-determined RV ejection fraction was RV fractional area change (r = 0.80, p < 0.001). In addition, CCT detected relevant post-operative findings in 50% of the patients.

CONCLUSIONS

CCT is highly effective and reproducible compared with echocardiography for the evaluation of RV function in patients with LVAD support and provides relevant information on post-operative findings. Our results suggest that CCT should be considered as a useful imaging modality in this clinical setting.

Late tricuspid surgery: predicting outcome with computed tomography

Tricuspid regurgitation can progressively worsen years after left-sided heart valve surgery, requiring surgical intervention for which the prognostic factors are unclear. This study aimed to assess the prediction of surgical outcome using right ventricular function obtained from computed tomography. We prospectively enrolled 24 patients who underwent isolated tricuspid repair or replacement from 2005 to 2008. Right ventricular computed tomography was carried out before surgery. The primary endpoint was survival with symptomatic improvement after one year. Twelve patients survived with improvement of at least one New York Heart Association functional class, and 12 died or had no symptomatic improvement. All baseline characteristics, echocardiogram data, and surgical details were similar in both groups. Right ventricular computed tomography parameters including end-systolic volume, indexed end-systolic volume, end-diastolic volume, and indexed end-diastolic volume were significantly different between the two groups. We concluded that right ventricular function assessed by computed tomography can predict the surgical outcome in patients undergoing surgery for isolated late tricuspid regurgitation.

Assessment of right ventricular function in acute pulmonary embolism using ECG-synchronized MDCT

OBJECTIVE

The purpose of this article is to determine the independent predictors of right ventricular (RV) dysfunction in patients with acute pulmonary embolism (PE) and to assess the relationship between RV ejection fraction (EF) and PE load.

SUBJECTS AND METHODS

Breath-hold CT of the chest was performed for 64 patients with PE (33 men and 31 women; mean [± SD] age, 58.6 ± 16.5 years). In addition, ECG-synchronized cardiac CT was performed to determine the RV and left ventricular (LV) EFs. PE load was determined using the Qanadli obstruction index. Multivariable regression analysis was performed to determine independent predictors of RV dysfunction (defined as EF < 35%). In addition, the relationship between RV EF and PE load was assessed by receiver operating characteristic (ROC) curves.

RESULTS

RV dysfunction was independently predicted by a PE load greater than 50% (odds ratio, 40.17; 95% CI, 4.22-382.67) and an LV EF less than 45% (odds ratio, 31.18; 95% CI, 2.00-487.09; p < 0.05 for both). Curve analysis revealed that a PE load greater than 50% had a sensitivity of 82% and a specificity of 85% to identify an RV EF less than 35%. Conversely, an RV EF less than 35% had a sensitivity of 93% and a specificity of 67% to predict a PE load greater than 50%.

CONCLUSION

RV dysfunction (defined as RV EF < 35%) in patients with acute PE is highly sensitive to define a PE load greater than 50%. Furthermore, RV dysfunction is independently predicted by an obstruction index greater than 50% or an LV EF less than 45%. Assessment of RV function by ECG-synchronized CT may become useful for guiding therapy.

Accuracy and reproducibility of assessing right ventricular function with 64-section multi-detector row CT: comparison with magnetic resonance imaging

BACKGROUND

Right ventricular (RV) function is very important for those patients with respiratory and cardiovascular disorders that can result in RV impairments. Because of complex geometry of the chamber, it is difficult to accurately measure the RV volumetric parameters with conventional imaging modalities. The purpose of this study was to evaluate whether the 64-MDCT can assess RV function with high accuracy and reproducibility when compared to the results with those of MRI.

METHODS

Forty-seven consecutive subjects underwent retrospectively ECG-gated 64-MDCT and MRI for assessing the ventricular function. Right ventricular end diastolic and end-systolic volume, stroke volume, and ejection fraction were measured with dedicated cardiac analysis software on 64-MDCT and compared with values measured on MRI which served as the reference standard. Agreement between two modalities was assessed with Bland and Altman analysis and linear regression analysis. Repeated measurements were performed to determine intraobserver and interobserver variability.

RESULTS

No significant differences were revealed in calculated RV volumes and EF between the two modalities. Agreement and correlation were similar for RV-EDV (0.4 ± 8.2 ml; r=0.95), RV-ESV (-0.6 ± 4.8; r=0.95), RV-SV (1.1 ± 6.7 ml; r=0.93), and RV-EF (0.9 ± 4.4; r=0.88). The difference of SV of right and left ventricle with 64-MDCT was not statistically significant (p=0.40) and good correlation was obtained (r=0.96). The variability in 64-MDCT measurements was lower than those in MRI.

CONCLUSIONS

ECG-gated 64-MDCT can assess the RV function with high accuracy and reproducibility without geometric assumptions about right ventricle.

Evaluation of right ventricular function with multidetector computed tomography: comparison with magnetic resonance imaging and analysis of inter- and intraobserver variability

This study was performed to prospectively compare multidetector computed tomography (MDCT) with 16 simultaneous sections and magnetic resonance imaging (MRI) for the assessment of global right ventricular function in 50 patients. MDCT using a semiautomatic analysis tool showed good correlation with MRI for end-diastolic volume (EDV, r=0.83, p<0.001), end-systolic volume (ESV, r=0.86, p<0.001) and stroke volume (SV, r=0.74, p<0.001), but only a moderate correlation for the ejection fraction (EF, r=0.67, p<0.001). Bland Altman analysis revealed a slight, but insignificant overestimation of EDV (4.0 ml, p=0.08) and ESV (2.4 ml, p=0.07), and underestimation of EF (0.1%, p=0.92) with MDCT compared with MRI. All limits of agreement between both modalities (EF: +/-15.7%, EDV: +/-31.0 ml, ESV: +/-18.0 ml) were in a moderate but acceptable range. Interobserver variability of MDCT was not significantly different from that of MRI. For MDCT software, the post-processing time was significantly longer (19.6+/-5.8 min) than for MRI (11.8+/-2.6 min, p<0.001). Accurate assessment of right ventricular volumes by 16-detector CT is feasible but still rather time-consuming.

A single, comprehensive non-invasive cardiovascular assessment in pulmonary arterial hypertension: combined computed tomography pulmonary and coronary angiography

BACKGROUND

Comprehensive assessment of pulmonary arterial hypertension (PAH) should identify structural causes and subsequent cardiopulmonary consequences of PAH. This currently requires the use of several imaging modalities. Computed tomography (CT) is routinely used for pulmonary angiography (CTPA). Our aim was to assess whether combined pulmonary and coronary angiography (CTPCA) using ECG-gated, multi-detector CT (MDCT) would allow satisfactory pulmonary angiography, coronary angiography and ventriculography to be combined into a single acquisition using a single imaging modality.

METHODS

We assessed CTPCA in 30 consecutive adult patients (mean age 41+/-11 years) with a diagnosis of PAH. In addition to the standard assessment of lung parenchyma and pulmonary vasculature, we assessed the ability of CT to satisfactorily visualise coronary vessels and biventricular function. Functional analysis included: end-diastolic volume (EDV), end-systolic volume (EDV), stroke volume (SV) and ejection fraction (EF) and mass and these parameters were correlated with same day cardiovascular magnetic resonance (CMR).

RESULTS

Lung parenchyma, pulmonary and coronary vessels were fully visualised in all cases. Ventriculography correlated well with same day CMR (RVEDV r=0.94, +19.5+/-49.2 ml, RVESV r=0.93, +11.1+/-46.4 ml, RVSV r=0.60, +8.5+/-41.6 ml, RVEF r=0.77, -0.5+/-21.3% and RV mass r=0.73, -17.3+/-60.4 g, LVEDV r=0.68, +12.2+/-110 ml, LVESV r=0.69, +7.5+/-59.7 ml, LVSV r=0.54, +2.5+/-40.6 ml, LVEF r=0.73, -1.9+/-20.8% and LV mass r=0.87, -20.5+/-22.5 g (all p<0.001)). Associated congenital cardiovascular malformations were characterised in 22/30 cases.

CONCLUSIONS

A CTPCA protocol allows safe, fast, comprehensive, non-invasive assessment of the possible anatomical causes and cardiopulmonary sequelae of PAH in adult patients, demonstrating congenital heart abnormalities, coronary artery disease and cardiac function.

Comparison of ECG-gated versus non-gated CT ventricular measurements in thirty patients with acute pulmonary embolism

OBJECTIVE

To prospectively compare cardiac ventricular measurements from non-gated CT and end-diastolic ECG-gated CT in patients with acute pulmonary embolism (PE).

MATERIALS AND METHODS

With institutional review board approval, 30 adult patients (16 female, mean age = 56 years, range = 26-77 years) underwent ECG-gated cardiac CT within 36 h of their CT diagnosis of acute PE to assess the right ventricle (RV). The axial and reformatted four-chamber ventricular diameters, areas and volumes were measured for both the non-gated CT and the ECG-gated CT in end-diastole and end-systole. Spearman's rank correlation coefficient (RCC) was calculated to compare measurements from the non-gated CT to the gated end-diastolic measurements. The median absolute differences between the gated and non-gated measurements relative to the gated measurements were provided to summarize the degree to which the two measurements differ. A statistical model was constructed to test for potential improvement in specificity for the prediction of 30-day mortality after acute PE using right ventricular measurements from ECG-gated CT versus non-gated CT.

RESULTS

The RCC (0.90 confidence interval) for non-gated and ECG-gated end-diastolic four-chamber and axial RV/LV diameter ratios were 0.83 (0.68-0.90) and 0.88 (0.74-0.95). The median absolute percent differences suggested a high degree of concordance between gated and non-gated measurements. The statistical model predicted that measuring the RV/LV diameter ratio from end-diastole using ECG-gated CT rather than non-gated CT would yield a potential improvement in specificity for death after PE of 0.035 (0.020-0.060) for axial diameter ratios and 0.035 (0.020-0.055) for four-chamber diameter ratios.

CONCLUSION

The benefit from a separate ECG-gated CT scan for the evaluation of RV ventricular diameter, area, and volume measurements is minimal and does not justify its routine clinical use.

Mid-Term Clinical Results Using a Tissue-Engineered Pulmonary Valve to Reconstruct the Right Ventricular Outflow Tract During the Ross Procedure

BACKGROUND

The Ross procedure is mainly limited by the durability of the valve prostheses used to reconstruct the right ventricular outflow tract. This study was performed to collect prospective safety and effectiveness data of the Ross procedure using a tissue-engineered heart valve to reconstruct the right ventricular outflow tract.

METHODS

Between May 2000 and February 2003, 23 patients received tissue-engineered heart valves. Two to four weeks before the Ross operation, a piece of forearm or saphenous vein was harvested to isolate, characterize, and expand endothelial cells. A pulmonary allograft (n = 11) or xenograft (n = 12) was decellularized, coated with fibronectin, and seeded with autologous vascular endothelial cells, using a specially developed bioreactor. Follow-up was performed by clinical evaluation, transthoracic echocardiography, magnetic resonance imaging, and multislice computed tomography.

RESULTS

The patient mean age was 44.0 +/- 13.7 years. Cell seeding density was 1.1 x 10(5) +/- 0.5 x 10(5) cells/cm2, with a viability of 90.2% +/- 8.9%. All patients survived the operation. One patient died during follow-up, and 1 patient required reoperation. All surviving patients are currently in New York Heart Association functional class I. Transthoracic echocardiographic evaluation of the tissue-engineered heart valve showed a mean flow velocity of 0.9 +/- 0.4 m/s at 5 years. Multislice computed tomography showed no calcification up to 5 years postoperatively.

CONCLUSIONS

Tissue-engineered heart valves showed excellent hemodynamic performance during mid-term follow-up. Decellularization of heart valves and seeding with autologous vascular endothelial cells may prevent tissue degeneration and improve valve durability.

Assessment of adult congenital heart disease with multi-detector computed tomography – beyond coronary lumenography

Adult congenital heart disease is an increasingly prevalent condition with more than 135,000 patients affected in England alone. With this increased patient population and an increase in interventional procedures being performed on them, traditional imaging techniques such as cardiac magnetic resonance (CMR) may be unavailable locally or contra-indicated. Cardiac multidetector computed tomography (MDCT) is rapidly emerging as an alternative imaging method for the investigation of these patients and this review highlights the broad application of cardiac MDCT to this population and makes recommendations on the standardized reporting of complex congenital heart disease.

Gated-SPECT equilibrium radionuclide angiography in right ventricular assessment of patients with repaired tetralogy of Fallot

BACKGROUND

The long-term prognosis of patients with tetralogy of Fallot (TF) who have undergone repair is determined by right ventricular dilatation resulting from residual pulmonary insufficiency. We have studied the values of right and left ventricle systolic function obtained by gated single photon emission computed tomography (SPECT) equilibrium radionuclide angiography (ERNA) in these patients.

METHODS

A study population of 62 patients with surgically repaired TF underwent gated-SPECT ERNA to determine ejection fraction of the right and left ventricle and dimensions of the right ventricle and pulmonary infundibulum. Results were compared with those of a group of 11 patients without heart disease.

RESULTS

RVEF (34% vs. 40%, P=0.02) and LVEF (49% vs. 54%, P=0.03) were significantly lower in patients with TF than in the control group. The RVEF and LVEF variation coefficients were 9% and 6.2%, respectively. Volumes of the right ventricle (P=0.003) were significantly greater than those of the control group, although variation coefficients were 15%.

CONCLUSIONS

Gated-SPECT ERNA is a non-invasive method of assessing ejection fraction in patients with repaired TF. In these patients, the ejection fraction is decreased in both ventricles, whereas size of the right ventricle is significantly increased. Reproducibility of the RVEF calculation is good, but in the case of volumes it is suboptimal.

Right Ventricular Function in Patients with Acute Pulmonary Embolism: Analysis with Electrocardiography-synchronized Multi–Detector Row CT

PURPOSE

To prospectively assess electrocardiography (ECG)-synchronized multi-detector row computed tomography (CT) for the evaluation of right ventricular (RV) function in patients suspected of having pulmonary embolism (PE).

MATERIALS AND METHODS

All patients gave informed consent after the study details, including radiation exposure, were explained; institutional ethical committee approval was obtained. Nonsynchronized multi-detector row CT of the chest was performed in 66 consecutive patients (29 men, 37 women; mean age, 58 years+/-15 [standard deviation]) who were suspected of having PE. ECG-synchronized cardiac multi-detector row CT was performed to assess cardiac function. Dimension ratios for the RV and left ventricle (LV) were measured on nonsynchronized transverse and angulated four-chamber views. Furthermore, the RV end-diastolic and end-systolic volumes were measured on ECG-synchronized multi-detector row CT scans. An independent samples t test was performed to compare the mean value of different groups. An analysis of variance post hoc test was performed to investigate whether the values of the variables varied between groups.

RESULTS

PE was detected in 29 of 66 patients. The location of PE was categorized as central (n=17) or peripheral (n=12). The RV/LV dimension ratio was larger on the four-chamber view (P=.002), and RV end-systolic volume was larger (P=.01) and ejection fraction was lower (P=.01) in patients with PE. The RV end-systolic volumes and RV/LV volume ratios, as assessed by using ECG-synchronized multi-detector row CT, showed significant differences (P<.005) between patients with central PE and those with peripheral PE. However, the RV/LV dimensions on nonsynchronized images revealed no significant differences.

CONCLUSION

Retrospective ECG-synchronized multi-detector row CT facilitates detection of RV dysfunction, depending on pulmonary embolus location.

MDCT of Right Ventricular Function: Impact of Methodologic Approach in Estimation of Right Ventricular Ejection Fraction, Part 2

OBJECTIVE

The purpose of this study was to evaluate the impact of the methodologic approach for MDCT estimation of right ventricular ejection fraction (RVEF).

MATERIALS AND METHODS

In 49 consecutive patients (30 men, 19 women; mean age, 59 years) known to have or suspected of having right ventricular (RV) dysfunction secondary to pulmonary disease, 16-MDCT of the heart was performed after standard CT angiographic examination of the entire thorax, with determination of RVEF by two reviewers who had limited experience in cardiac CT. The reconstruction windows were determined using the ECG tracing (reviewer 1) or using transverse test images obtained in 5% steps through the entire R-R interval showing the largest and smallest RV cavity areas (reviewer 2). After manual segmentation of the ventricular cavity on diastolic and systolic short-axis reformations by each reviewer, the end-diastolic and end-systolic RV volumes were calculated, with subsequent determination of the RVEF. CT results were compared with those of equilibrium radionuclide ventriculography.

RESULTS

Agreement between the two methods for determining the end-systolic and end-diastolic phases was observed in 61% of cases (n = 30) for the systole and 59% of cases (n = 29) for the diastole. Discordant selections were observed in 39% of cases (n = 19) for determination of the systole and in 41% of cases (n = 20) for determination of the diastole, ranging from 5% to 15% of the R-R interval, suggesting that selection of the reconstruction window on the ECG tracing does not differ significantly from that obtained by the visual analysis of transverse test images. Focusing on the 59 common selections of the reconstruction windows made by the two reviewers, no statistically significant differences were found in the determination of mean (+/- SD) end-diastolic volumes (reviewer 1, 176.21 +/- 67 mL vs reviewer 2, 175.55 +/- 71.24 mL; p = 0.98) and end-systolic (reviewer 1, 97.3 +/- 26.49 mL vs reviewer 2, 96.33 +/- 65.72 mL; p = 0.65), suggesting the lack of operator dependence in the manual-contour drawing process. No significant difference was found between the mean values of RVEF obtained by each reviewer with MDCT and equilibrium radionuclide ventriculography, and there was excellent interobserver agreement with MDCT (intraclass correlation coefficient, 0.86). Using a Bland-Altman approach, the limits of concordance between the two reviewers ranged between -10.2 and 10.9. The mean absolute percentage error for measuring RVEF between the two reviewers was 9.7%. A moderate agreement was found between RVEFs obtained on CT by each reviewer and scintigraphy (intraclass correlation coefficients, 0.76 for reviewer 1 and 0.64 for reviewer 2).

CONCLUSION

These results show that RVEF can be accurately assessed with ECG-gated MDCT using commercially available software.

MDCT of Right Ventricular Function: Comparison of Right Ventricular Ejection Fraction Estimation and Equilibrium Radionuclide Ventriculography, Part 1

OBJECTIVE

The aim of this study was to calculate right ventricular ejection fraction by use of ECG-gated MDCT and to compare the results with those of equilibrium radionuclide ventriculography.

SUBJECTS AND METHODS

Forty-nine consecutively examined patients (30 men, 19 women; mean age, 59 years) with known or suspected right ventricular dysfunction secondary to bronchopulmonary (n = 30) or pulmonary vascular (n = 19) disease underwent ECG-gated 16-MDCT angiography of the heart (rotation time, 0.42 second; 120 kV; 300 mAs; collimation, 12 x 0.75 mm; pitch, 0.2) after CT angiographic examination of the entire thorax according to a standard protocol. Biphasic administration of a 30% contrast agent was systematically performed (phase 1, 90 mL at 3 mL/s; phase 2, 30 mL at 1.5 mL/s); no patient received additional medication. Right ventricular ejection fraction was calculated after two reviewers in consensus determined the reconstruction windows and segmentation of the right ventricular cavity on a series of diastolic and systolic short-axis images. The results were compared with those of equilibrium radionuclide ventriculography.

RESULTS

At data acquisition, the mean (+/- SD) heart rate of the study group was 82 +/- 13.87 beats per minute (BPM) (range, 51-115 BPM). ECG showed a sinus rhythm in 30 (61%) of the patients and irregular cardiac rhythm in 19 (39%) of the patients. Agreement between the two techniques was estimated by intraclass correlation coefficient (0.77), the method of Bland and Altman (limits of concordance, -14.9 and 13.7), and percentage of variability between two measurements expressed by mean absolute percentage error (12.1%). The estimated effective dose for heart examination was 7.48 mSv with CT and 5 mSv with scintigraphy. The mean effective dose for the chest and heart CT examinations was 11.64 mSv.

CONCLUSION

Right ventricular ejection fraction can be reliably estimated with 16-MDCT in unselected patients.

Coronary artery imaging during preoperative CT staging: preliminary experience with 64-slice multidetector CT in 99 consecutive patients

The purpose of this study was to evaluate the clinical feasibility of coronary artery imaging during routine preoperative 64-slice MDCT scans of the chest. Ninety-nine consecutive patients in sinus rhythm underwent a biphasic multidetector-row spiral CT examination of the chest without the administration of beta-blockers, including an ECG-gated acquisition over the cardiac cavities, followed by a non-gated examination of the upper third of the thorax. Data were reconstructed to evaluate coronary arteries and to obtain presurgical staging of the underlying disease. The percentage of assessable segments ranged from 65.4% (972/1,485) when considering all coronary artery segments to 88% (613/693) for the proximal and mid segments, reaching 98% (387/396) for proximal coronary artery segments. The 387 interpretable proximal segments included 97 (97%) LM, 99 (100%) LAD, 96 (97%) LCX and 95 (96%) RCA with a mean attenuation of 280.70+/-52.93 HU. The mean percentage of assessable segments was significantly higher in patients with a heart rate <or=80 bpm (n=48) than in patients with a heart rate greater than 80 bpm (n=35) (80+/-11% vs. 72+/-13%; P=0.0008). Diagnostic image quality was achieved in all patients for preoperative staging of the underlying disorder. The mean estimated effective dose was 12.06+/-3.25 mSv for ECG-gated scans and 13.88+/-3.49 mSv for complete chest examinations. Proximal and mid-coronary artery segments can be adequately evaluated during presurgical CT examinations of the chest obtained with 64-slice MDCT without the administration of beta-blockers.

Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients

The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without beta-blockers using the following parameters: (1) collimation: 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., "morphologic scans") and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., "functional scans"). The mean heart rate was 73 bpm (range: 42-120) and the mean scan time was 18.11 +/- 2.67 s (range: 10-27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n = 4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n = 6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88-97%). For these 124 examinations, the mean RVEF was 46.10% (+/- 9.5; range: 20-72) and the mean LVEF was 58.23% (+/- 10.88; range: 20-83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end-diastolic ventricular volumes. The mean (+/- SD) DLP value of the examinations was 279.86 (+/- 117.50) mGy.cm. Assessment of underlying respiratory disease and cardiac function from the same data set was achievable in 92% of the patients with ECG-gated 64-slice MDCT.

Portopulmonary hypertension: hemodynamics, pulmonary angiography, and configuration of the heart

BACKGROUND

The goal of the present study was to examine the cardiac configuration and pulmonary vascular changes in patients with portopulmonary hypertension (PPHTN) and compare them with those of idiopathic pulmonary arterial hypertension (IPAH).

METHODS AND RESULTS

The subjects were 10 patients with PPHTN and 18 with IPAH. In PPHTN, the increases in the right ventricular end-diastolic volume index (89+/-19 vs 128+/-50 ml/m2; p=0.04), right end-systolic volume index (50+/-19 vs 95+/-47 ml/m 2; p=0.02) and right ventricular mass index (47+/-18 g/m2 vs 79+/-31; p=0.04) were low compared with IPAH. The decrease in the right ventricular ejection fraction was also low in PPHTN (45+/-10 vs 28+/-13%; p=0.01). The degree of sparse arborization and abrupt narrowing on wedged pulmonary angiography was moderate in PPHTN compared with IPAH. In PPHTN, the proximal pulmonary arteries were dilated near the segmental arteries, which were narrow in IPAH.

CONCLUSION

Changes in the configuration of the heart were moderate in PPHTN compared with those in IPAH. The degree of sparse arborization and abrupt narrowing were also moderate in PPHTN.

Relation of systemic ventricular function quantified by myocardial performance index (Tei) to cardiopulmonary exercise capacity in adults after Mustard procedure for transposition of the great arteries

After Mustard repair for transposition of the great arteries, the right ventricle serves as a chronically overloaded systemic ventricle (SV). Thus, during long-term follow-up, dysfunction of the right ventricle with consecutive heart failure (HF) is not unusual. Early signs and symptoms of HF are depressed parameters of right ventricular (RV) function at rest and exercise intolerance. It was hypothesized that the measurement of RV function parameters, N-terminal pro-brain natriuretic peptide (NT-pro-BNP), and peak oxygen uptake (VO2max) during exercise testing were suitable for the early detection of subclinical HF. In 33 asymptomatic adolescents and adults who had undergone Mustard repair, RV function was analyzed by the myocardial performance index (Tei index). NT-pro-BNP and VO2max were also determined. The corresponding data from 52 patients operated on for left-to-right shunt defects without residual lesions served as reference data. In patients who underwent the Mustard procedure, the Tei index and NT-pro-BNP were elevated (mean Tei index of the SV 0.63 +/- 0.17 vs 0.34 +/- 0.05, p <0.002; mean NT-pro-BNP 240 +/- 230 vs 57 +/- 39 pg/ml, p <0.0001), and VO2max was reduced (27 +/- 6 vs 32 +/- 6 ml x kg(-1) x min(-1), p <0.002). A good correlation was found between the Tei index and VO2max (r = -0.83, p <0.0001). In conclusion, RV function is depressed in most patients with Mustard repair. Ventricular dysfunction in such asymptomatic or minimally symptomatic patients can be detected by measurement of the Tei index, NT-pro-BNP, and VO2max. These parameters are simple and reliable screening methods to stratify patients with impaired cardiac dysfunction before they become symptomatic.