Routine clinical cardiovascular magnetic resonance in paediatric and adult congenital heart disease: patients, protocols, questions asked and contributions made

CMR and Percutaneous Treatment of Pulmonary Regurgitation: Outreach the Search for the Best Candidate

Performance of cardiovascular magnetic resonance (CMR) in the planning phase of percutaneous pulmonary valve implantation (PPVI) is needed for the accurate delineation of the right ventricular outflow tract (RVOT), coronary anatomy and the quantification of right ventricular (RV) volume overload in patients with significant pulmonary regurgitation (PR). This helps to find the correct timings for the intervention and prevention of PPVI-related complications such as coronary artery compression, device embolization and stent fractures. A defined CMR study protocol should be set for all PPVI candidates to reduce acquisition times and acquire essential sequences that are determinants for PPVI success. For correct RVOT sizing, contrast-free whole-heart sequences, preferably at end-systole, should be adopted in the pediatric population thanks to their high reproducibility and concordance with invasive angiographic data. When CMR is not feasible or contraindicated, cardiac computed tomography (CCT) may be performed for high-resolution cardiac imaging and eventually the acquisition of complementary functional data. The aim of this review is to underline the role of CMR and advanced multimodality imaging in the context of pre-procedural planning of PPVI concerning its current and potential future applications.

Cardiovascular Magnetic Resonance from Fetal to Adult Life-Indications and Challenges: A State-of-the-Art Review

Cardiovascular magnetic resonance (CMR) imaging offers a comprehensive, non-invasive, and radiation-free imaging modality, which provides a highly accurate and reproducible assessment of cardiac morphology and functions across a wide spectrum of cardiac conditions spanning from fetal to adult life. It minimises risks to the patient, particularly the risks associated with exposure to ionising radiation and the risk of complications from more invasive haemodynamic assessments. CMR utilises high spatial resolution and provides a detailed assessment of intracardiac and extracardiac anatomy, ventricular and valvular function, and flow haemodynamic and tissue characterisation, which aid in the diagnosis, and, hence, with the management of patients with cardiac disease. This article aims to discuss the role of CMR and the indications for its use throughout the different stages of life, from fetal to adult life.

Detection of early signs of right ventricular systolic impairment in unoperated Ebstein's anomaly by cardiac magnetic resonance feature tracking

BACKGROUND

Cardiovascular magnetic resonance feature-tracking analysis (CMR-FT) provides a quantitative assessment of myocardial contraction with potential for diagnostic and prognostic ability in a wide spectrum of diseases. Ebstein's anomaly (EA) is a rare congenital heart disease characterized by apical displacement of the tricuspid valve. However, it is also considered a disorder of development affecting the global right ventricular myocardium. Aim of our study is to describe the complex contractile mechanics of the functional right ventricle (RV) in patients affected by EA through CMR-FT.

METHODS

Fifty surgery-free EA patients who had undergone a complete CMR protocol at our institution between January 2017 and December 2020 were selected for the retrospective study. A historical control group of twenty-five healthy subjects was also included. CMR-FT analysis was performed at a dedicated workstation by manually tracing RV endo- end epicardial borders on steady-state-free-precession (SSFP) cine images. Strain values were calculated. Apical displacement of the tricuspid valve (TV) was measured on a 4-chamber cine image from the right atrio-ventricular junction to the functional annulus of the TV.

RESULTS

EA patients presented significantly impaired RV global radial strain (GRS) and global circumferential strain (GCS) compared to controls (P<0.0001 and P=0.0008, respectively). In a subgroup analysis, GRS was significantly compromised in patients with a severely displaced TV (>16 mm/m²) compared to milder forms (P=0.03) and to controls (P<0.0001). Among EA patients with a preserved ejection fraction, 12 (48%) vs. 6 (24%) controls had reduced both GRS and GCS.

CONCLUSIONS

The contractile pattern of the functional RV in EA is characterised by prevalent alterations in the short-axis direction as indicated by reduced GRS and GCS. Strain values might be reduced prior to routine used functional parameters like RV ejection fraction (RVEF) and can possibly serve as an early predictor of myocardial dysfunction in EA patients.

Real-time CMR guidance for intracardiac and great vessel pressure mapping in patients with congenital heart disease using an MR conditional guidewire-results of 25 patients

BACKGROUND

The aim of this study was to test a CE-certified MR-conditional guidewire to facilitate blood pressure measurement in cardiovascular magnetic resonance (CMR) using fluid-filled catheters in patients with congenital heart disease (CHD). The main purpose was to determine procedural success in a post market clinical follow-up (PMCF) for routine procedure in a diagnostic and interventional workflow. Real-time CMR provides high quality imaging without the risk of exposing the patient to X-rays, especially for patients with irregular heart anatomy and patients who are susceptible to radiation and iodinated contrast media. To date, the assessment of blood pressure gradients is not a common feature of CMR, as these gradients cannot be accurately evaluated in routine CMR.

METHODS

Twenty-five CHD patients who were planned for combined clinical CMR and diagnostic and/or interventional catheterization were enrolled in the trial. Prior to inclusion, a specific procedure for catheterization in CMR was defined, encompassing the assessment of pressure and pressure gradients in the heart and great vessels.

RESULTS

By the use of an MR-conditional guidewire we successfully measured specific pressure and pressure gradients in up to 92% of cases with liquid-filled catheters which were guided exclusively under CMR guidance. There were no guidewire-related adverse events, and guidewire guidance and manipulation of catheters were successful.

CONCLUSIONS

Using a MR-conditional guidewire assists in easily reaching targets in the heart and great vessels and makes the catheter itself visible, so that invasive blood pressure assessment by CMR guidance with liquid-filled catheters can be improved.

KEYWORDS

Cardiovascular magnetic resonance (CMR); congenital heart disease (CHD); cardiac catheterization; magnetic resonance; pressure; guidewire.

Retraining Convolutional Neural Networks for Specialized Cardiovascular Imaging Tasks: Lessons from Tetralogy of Fallot

Ventricular contouring of cardiac magnetic resonance imaging is the gold standard for volumetric analysis for repaired tetralogy of Fallot (rTOF), but can be time-consuming and subject to variability. A convolutional neural network (CNN) ventricular contouring algorithm was developed to generate contours for mostly structural normal hearts. We aimed to improve this algorithm for use in rTOF and propose a more comprehensive method of evaluating algorithm performance. We evaluated the performance of a ventricular contouring CNN, that was trained on mostly structurally normal hearts, on rTOF patients. We then created an updated CNN by adding rTOF training cases and evaluated the new algorithm's performance generating contours for both the left and right ventricles (LV and RV) on new testing data. Algorithm performance was evaluated with spatial metrics (Dice Similarity Coefficient (DSC), Hausdorff distance, and average Hausdorff distance) and volumetric comparisons (e.g., differences in RV volumes). The original Mostly Structurally Normal (MSN) algorithm was better at contouring the LV than the RV in patients with rTOF. After retraining the algorithm, the new MSN + rTOF algorithm showed improvements for LV epicardial and RV endocardial contours on testing data to which it was naïve (N = 30; e.g., DSC 0.883 vs. 0.905 for LV epicardium at end diastole, p < 0.0001) and improvements in RV end-diastolic volumetrics (median %error 8.1 vs 11.4, p = 0.0022). Even with a small number of cases, CNN-based contouring for rTOF can be improved. This work should be extended to other forms of congenital heart disease with more extreme structural abnormalities. Aspects of this work have already been implemented in clinical practice, representing rapid clinical translation. The combined use of both spatial and volumetric comparisons yielded insights into algorithm errors.

Non-invasive Hemodynamic CMR Parameters Predicting Maximal Exercise Capacity in 54 Patients with Ebstein's Anomaly

BACKGROUND

Exercise capacity is a well-defined marker of outcome in congenital heart disease. We analyzed seventeen cardiovascular magnetic resonance (CMR) derived parameters and their correlation to exercise capacity in patients with Ebstein's anomaly (EA).

METHODS

Fifty-four surgery free patients, age 5 to 69 years (median 30 years) prospectively underwent CMR examination and cardiopulmonary exercise testing (CPET). The following volume/flow parameters were compared with peak oxygen uptake as the percentage of normal (peakVO₂%) using univariate and multivariate analysis: right and left ventricular ejection fraction (RVEF and LVEF), the indexed end-diastolic and end-systolic volumes (RVEDVi, RVESVi, LVEDVi, and LVESVi), the indexed stroke volumes (RVSVi and LVSVi), the total normalized right and left heart volumes; the total right to left heart volume ratio (R/L-ratio). The indexed antegrade flow (ante), indexed net flow (net) as well as cardiac index (CI) in the aorta (Ao) and pulmonary artery (PA) were used.

RESULTS

RVEF (R² 0.2788), indexed flow PA net (R² 0.2330), and PA ante (R² 0.1912) showed the best correlation with peakVO₂% (all p < 0.001) in the univariate model. Further significant correlation could also be demonstrated with CI-PA, LVEF, LVSVi, Aorta net, RVESVi, and Aorta ante. Multivariate analysis for RVEF and indexed net flow PA revealed a R² of 0.4350.

CONCLUSION

Functional CMR parameters as RVEF and LVEF and flow data of cardiac forward flow correlate to peakVO₂%. Evaluation of the indexed net flow in the pulmonary artery and the overall function of the right ventricle best predicts the maximal exercise capacity in patients with EA.

Aortopulmonary collateral flow quantification by MR at rest and during continuous submaximal exercise in patients with total cavopulmonary connection

BACKGROUND

Aortopulmonary collateral flow is considered to have significant impact on the outcome of patients with single ventricle circulation and total cavopulmonary connection (TCPC). There is little information on collateral flow during exercise.

PURPOSE

To quantify aortopulmonary collateral flow at rest and during continuous submaximal exercise in clinical patients doing well with TCPC.

STUDY TYPE

Prospective, case controlled.

POPULATION

Thirteen patients with TCPC (17 (11-37) years) and 13 age and sex-matched healthy controls (18 (11-38) years).

FIELD STRENGTH

1.5T; free breathing; phase sensitive gradient echo sequence.

ASSESSMENT

Blood flow in the ascending and descending aorta and superior vena cava were measured at rest and during continuous submaximal physical exercise in patients and controls. Systemic blood flow (Q_s ) was assumed to be represented by the sum of flow in the superior caval vein (Q_svc ) and the descending aorta (Q_AoD ) at the diaphragm level. Aortopulmonary collateral flow (Q_coll ) was calculated by subtracting Q_s from flow in the ascending aorta (Q_AoA ).

STATISTICS

Mann-Whitney U-test and Wilcoxon test for comparison between groups and between rest and exercise.

RESULTS

Absolute collateral flow in TCPC patients at rest was 0.4 l/min/m² (-0.1-1.2), corresponding to 14% (-2-42) of Q_s . Collateral flow did not change during exercise (difference -0.01 (-0.7-1.0) l/min/m² , P = 0.97). TCPC patients had significantly lower Q_s at rest (2.5 (1.6-4.1) vs. 3.5 (2.6-4.8) l/min/m² , P = 0.001) and during submaximal exercise (3.2 (2.0-6.0) vs. 4.8 (3.3-6.9) l/min/m² , P = 0.001), compared to healthy controls. The increase in Q_s with exercise was also significantly lower in patients than in healthy controls (median 0.6 vs. 1.2 l/min/m² , P < 0.02).

DATA CONCLUSION

Clinical patients doing well with TCPC have significant aortopulmonary collateral flow at rest (14% of Q_s ) compared to healthy controls, which does not change during submaximal exercise.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1509-1516.

Cardiovascular magnetic resonance is successfully feasible in many patients aged 3 to 8years without general anesthesia or sedation

OBJECTIVES

Patients younger than 8 years are usually examined by cardiovascular magnetic resonance (CMR) under general anesthesia (GA) or sedation without intubation. Therefore, we sought to study the feasibility of CMR in patients aged 3 to 8years without GA or sedation.

PATIENTS

Data sets of 71 consecutive patients aged 3 to 8years were studied retrospectively.

DESIGN

The total cohort was divided into 2 groups: a no-GA or sedation without intubation group (no-GA or sedation) and a GA or sedation without intubation group (GA or sedation).

MEASUREMENTS

The patients' age, scan durations for each group, successfully answered clinical question, and number of sequences per study were compared between both groups.

MAIN RESULTS

Scan duration in the no-GA or sedation group (n=44) was 35± 20minutes, and that in the GA or sedation group (n=27) was 60± 31minutes (P<.001). The percentage of successful reports was 95% (42/44) in the no-GA or sedation group and 89% (24 of 27) in the GA or sedation group (P=.29).

CONCLUSION

CMR in patients aged 3 to 8years is usually successfully feasible without GA or sedation.

Cardiovascular magnetic resonance: Diagnostic utility and specific considerations in the pediatric population

Cardiovascular magnetic resonance is a non-invasive imaging modality which is emerging as important tool for the investigation and management of pediatric cardiovascular disease. In this review we describe the key technical and practical differences between scanning children and adults, and highlight some important considerations that must be taken into account for this patient population. Using case examples commonly seen in clinical practice, we discuss the important clinical applications of cardiovascular magnetic resonance, and briefly highlight key future developments in this field.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

Indications for cardiovascular magnetic resonance in children with congenital and acquired heart disease: an expert consensus paper of the Imaging Working Group of the AEPC and the Cardiovascular Magnetic Resonance Section of the EACVI

This article provides expert opinion on the use of cardiovascular magnetic resonance (CMR) in young patients with congenital heart disease (CHD) and in specific clinical situations. As peculiar challenges apply to imaging children, paediatric aspects are repeatedly discussed. The first section of the paper addresses settings and techniques, including the basic sequences used in paediatric CMR, safety, and sedation. In the second section, the indication, application, and clinical relevance of CMR in the most frequent CHD are discussed in detail. In the current era of multimodality imaging, the strengths of CMR are compared with other imaging modalities. At the end of each chapter, a brief summary with expert consensus key points is provided. The recommendations provided are strongly clinically oriented. The paper addresses not only imagers performing CMR, but also clinical cardiologists who want to know which information can be obtained by CMR and how to integrate it in clinical decision-making.

Remote delivery of congenital cardiac magnetic resonance imaging services: a unique telemedicine model

Cardiac magnetic resonance imaging (CMRI) is increasingly utilized in the management of patients with congenital heart disease. Unfortunately, the expertise to perform and interpret these studies is not universally available, despite an increasing population of congenital heart survivors. This retrospective analysis describes our experience providing on-site CMRI services compared with providing the same services over a geographic distance of 250 miles. There were 83 local scans with both physician and patient on-site compared with 91 scans controlled by a physician geographically remote from the patients. The patients were well-matched for age, sex, study duration, scan type, and history of prior cardiac intervention. There was no difference in use of deep sedation or diazepam for anxiolysis, or use of atropine for arrhythmia suppression. There were no patient safety issues and there was satisfaction on the part of the referring physicians who were able to obtain more timely studies, as well as the remote-scanning physicians who had a workflow comparable with the local scans, but no lost travel time. This experience suggests that remote delivery of cardiac MRI services for the congenital heart population is feasible and can be done with comparable success and safety to a traditional "local" model. We also suggest the configuration to provide such remote CMRI services with commercially available hardware and software.

Baseline correction does not improve flow quantification in phase-contrast velocity measurement for routine clinical practice

INTRODUCTION

Velocity offset errors may influence flow measurement in phase-contrast cardiovascular magnetic resonance (CMR). By using a stationary gel phantom, offset errors probably may be corrected. We tested its impact on flow measurement and, in particular, on shunt calculation in patients proven not to have any shunt.

METHODS

Flow measurements were carried out in 24 patients with congenital heart disease. Baseline correction was performed by using a stationary gel phantom.

RESULTS

Significantly more patients without shunts incorrectly showed a calculated shunt after baseline correction.

CONCLUSIONS

Baseline correction did not improve flow measurement and was clinically not relevant for routine CMR.

Cardiac MRI findings of endomyocardial fibrosis (Loeffler's endocarditis) in a patient with rheumatoid arthritis

Loeffler’s endocarditis and cardiac manifestations of the hypereosinophilic syndrome (HES) are rare and difficult to diagnose. We report a case of in a 36 year-old female with a history of rheumatoid arthritis with disabling dyspnea. The transthoracic echocardiogram demonstrated normal systolic cardiac functions and a left ventricular apical thrombus. However, using cardiovascular magnetic resonance (CMR) with inversion-recovery (IR) delayed enhancement, and cine steady-state free precession (SSFP) sequences, we were able to clearly demonstrate endocardial fibrosis, tissue inflammation, apical ventricular hypertrophy, and LV thrombus that correlate with clinical findings. We believe cardiac MRI is more useful than transthoracic echocardiography in the diagnosis and management of HES and ultimately it obviated the need for biopsy to confirm the diagnosis.

Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease

Cardiovascular magnetic resonance (CMR) has taken on an increasingly important role in the diagnostic evaluation and pre-procedural planning for patients with congenital heart disease. This article provides guidelines for the performance of CMR in children and adults with congenital heart disease. The first portion addresses preparation for the examination and safety issues, the second describes the primary techniques used in an examination, and the third provides disease-specific protocols. Variations in practice are highlighted and expert consensus recommendations are provided. Indications and appropriate use criteria for CMR examination are not specifically addressed.

Demonstration of value of optimizing ECG triggering for cardiovascular magnetic resonance in patients with congenital heart disease

BACKGROUND

Optimal ECG triggering is of paramount importance for correct blood flow quantification during cardiovascular magnetic resonance (CMR). However, optimal ECG triggering and therefore blood flow quantification is impaired in many patients with congenital heart disease (CHD) due to complex QRS patterns. Therefore, a new ECG-trigger algorithm was developed to address triggering problems due to complex QRS patterns.The aim of this study was to test this new ECG-trigger algorithm in routine patients with CHD and its impact on blood flow quantification.

METHODS

35 consecutive routine patients with CHD undergoing CMR were included in the study. (40% Fallot's Tetralogy, 20% aortic arch pathology, 14% transposition of the great arteries, 26% others; age 26+/-11 yrs).In all patients, blood flow in the ascending aorta was quantified using the old ECG-trigger algorithm and the new ECG-trigger algorithm in random order. Blood flow quantified using the old or new ECG-trigger algorithm was compared by Bland-Altman analysis.Three blinded investigators evaluated the vector clouds and trigger points of both ECG-trigger methods. Evaluation criteria were false positive and false negative triggered QRS complexes (specificity and sensitivity), and accuracy of detection. Accuracy of detection was defined as time scatter of the trigger around the correct trigger point.

RESULTS

Specificity, sensitivity, and accuracy of detection significantly increased using the new ECG-trigger algorithm compared to the old ECG-trigger algorithm.Blood flow quantification using the old or new ECG-trigger algorithm differed more than 5% in 31% of the cases.

CONCLUSIONS

Our results suggest that optimizing ECG triggering during CMR using our new algorithm can avoid errors of >5% in approximately 1/3 of routine patients with congenital heart disease (CHD). We furthermore suggest that incorrect ECG triggering appears to be problematic for blood flow quantification of many patients with CHD undergoing routine CMR.

The functional right ventricle and tricuspid regurgitation in Ebstein's anomaly

BACKGROUND

The size of the functional right ventricle of patients with Ebstein's anomaly is, according to contemporary opinion, small. However, the in vivo size of the functional right ventricle in patients with Ebstein's anomaly is unknown. Furthermore, it is unknown how the apical displacement and regurgitant fraction of the tricuspid valve in Ebstein's anomaly affects the size of the functional right ventricle. Therefore the primary aim of this study was to determine the volume of the functional right ventricle in patients with Ebstein's anomaly. The secondary aim of this study was to assess correlation of the volume of the functional right ventricle to the apical displacement and regurgitant fraction of the tricuspid valve.

METHODS

Thirty-two consecutive patients with Ebstein's anomaly without previous cardiac surgery or shunts were studied prospectively by cardiovascular magnetic resonance. Functional right ventricle, left ventricle, and atrialized right ventricle volumes and tricuspid valve regurgitation were measured.

RESULTS

Functional right ventricle end diastolic volumes were median 127 ml/m² (range: 76-339 ml/m²) and were median 2.5 (range: 1.3-8.8) times larger than the left ventricle volumes. Furthermore, functional right ventricle volumes correlated in a strong positive fashion with tricuspid valve regurgitation (p<0.001, R(2)=0.65) and modestly with the atrialized right ventricle volumes (p=0.027, R(2)=0.16).

CONCLUSION

Patients with untreated Ebstein's anomaly have large functional right ventricles. The size of the enlarged functional right ventricle seems to depend on the degree of tricuspid valve regurgitation and not on the size of the atrialized right ventricle or the age of the patient.

[Progress in pediatric cardiology, congenital heart disease in adults, and heart surgery for congenital heart disease]

The field of pediatric cardiology is continually developing and now covers not only congenital and acquired heart disease in children but also congenital heart disease in adults and the prenatal diagnosis and prevention of heart disease. This review highlights new findings in the field of genetics, selected articles on the use of magnetic resonance imaging and multislice CT in diagnosis, and recent publications on electrophysiology and the surgical treatment of children and adults with congenital heart disease. In addition, the increasingly advanced use of mechanical assist devices as a bridge to heart transplantation in children is also discussed.

Recommendations for cardiovascular magnetic resonance in adults with congenital heart disease from the respective working groups of the European Society of Cardiology

This paper aims to provide information and explanations regarding the clinically relevant options, strengths, and limitations of cardiovascular magnetic resonance (CMR) in relation to adults with congenital heart disease (CHD). Cardiovascular magnetic resonance can provide assessments of anatomical connections, biventricular function, myocardial viability, measurements of flow, angiography, and more, without ionizing radiation. It should be regarded as a necessary facility in a centre specializing in the care of adults with CHD. Also, those using CMR to investigate acquired heart disease should be able to recognize and evaluate previously unsuspected CHD such as septal defects, anomalously connected pulmonary veins, or double-chambered right ventricle. To realize its full potential and to avoid pitfalls, however, CMR of CHD requires training and experience. Appropriate pathophysiological understanding is needed to evaluate cardiovascular function after surgery for tetralogy of Fallot, transposition of the great arteries, and after Fontan operations. For these and other complex CHD, CMR should be undertaken by specialists committed to long-term collaboration with the clinicians and surgeons managing the patients. We provide a table of CMR acquisition protocols in relation to CHD categories as a guide towards appropriate use of this uniquely versatile imaging modality.

Review of Journal of Cardiovascular Magnetic Resonance 2009

There were 56 articles published in the Journal of Cardiovascular Magnetic Resonance in 2009. The editors were impressed with the high quality of the submissions, of which our acceptance rate was about 40%. In accordance with open-access publishing, the articles go on-line as they are accepted with no collating of the articles into sections or special thematic issues. We have therefore chosen to briefly summarise the papers in this article for quick reference for our readers in broad areas of interest, which we feel will be useful to practitioners of cardiovascular magnetic resonance (CMR). In some cases where it is considered useful, the articles are also put into the wider context with a short narrative and recent CMR references. It has been a privilege to serve as the Editor of the JCMR this past year. I hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your quality manuscripts to JCMR for publication.

Comparison of accuracy of axial slices versus short-axis slices for measuring ventricular volumes by cardiac magnetic resonance in patients with corrected tetralogy of fallot

The best method to measure right (RV) and left (LV) ventricle volumes of patients with corrected tetralogy of Fallot is considered cardiac magnetic resonance (CMR). However, to date, no standard protocol to measure RV volumes by CMR exists. RV volumes can be measured from a stack of short-axis slices or a stack of axial slices through the patient's chest. Therefore, the aim of this study was to determine whether short-axis or axial slices are more reliable for routine measurement of RV and LV volumes in patients with corrected tetralogy of Fallot. We studied consecutive patients with corrected tetralogy of Fallot (n = 46) undergoing routine CMR. The end-diastolic and end-systolic RV and LV volumes were measured by 2 investigators unaware of the results of the other measurements using short-axis and axial slices, and the inter- and intraobserver variances were compared. The design of the study was based on the Standards for Reporting of Diagnostic Accuracy. Interobserver variance was significantly smaller using axial slices than using short-axis slices for the RV end-systolic volumes (127.9%(2) vs 315.1%(2); p = 0.003), LV end-diastolic volumes (11.4%(2) vs 36.1%(2); p <0.001), and LV end-systolic volumes (31.9%(2) vs 176.1%(2); p <0.001). Intraobserver variance was significantly smaller using axial slices than using short-axis slices for the RV end-diastolic volumes (26.7%(2) vs 51.1%(2); p = 0.032), LV end-diastolic volumes (11.0%(2) vs 23.5%(2); p = 0.012), and LV end-systolic volumes (34.3%(2) vs 86.1%(2); p = 0.003). In conclusion, axial slices are more reproducible than short-axis slices for measuring ventricular volumes of patients with corrected tetralogy of Fallot by CMR.