Eugénie Riesenkampff

Flow‐sensitive four‐dimensional cine magnetic resonance imaging for offline blood flow quantification in multiple vessels: A validation study

To further validate the quantitative use of flow‐sensitive four‐dimensional velocity encoded cine magnetic resonance imaging (4D VEC MRI) for simultaneously acquired venous and arterial blood flow in healthy volunteers and for abnormal flow in patients with congenital heart disease.

The practical clinical value of three-dimensional models of complex congenitally malformed hearts

OBJECTIVE Detailed 3-dimensional anatomic information is essential when planning strategies of surgical treatment for patients with complex congenitally malformed hearts. Current imaging techniques, however, do not always provide all the necessary anatomic information in a user-friendly fashion. We sought to assess the practical clinical value of realistic 3-dimensional models of complex congenitally malformed hearts. METHODS In 11 patients, aged from 0.8 to 27 years, all with complex congenitally malformed hearts, an unequivocal decision regarding the optimum surgical strategy had not been reached when using standard diagnostic tools. Therefore, we constructed 3-dimensional virtual computer and printed cast models of the heart on the basis of high-resolution whole-heart or cine magnetic resonance imaging or computed tomography. Anatomic descriptions were compared with intraoperative findings when surgery was performed. RESULTS Independently of age-related factors, images acquired in all patients using magnetic resonance imaging and computed tomography proved to be of sufficient quality for producing the models without major differences in the postprocessing and revealing the anatomy in an unequivocal 3-dimensional context. Examination of the models provided invaluable additional information that supported the surgical decision-making. The anatomy as shown in the models was confirmed during surgery. Biventricular corrective surgery was achieved in 5 patients, palliative surgery was achieved in 3 patients, and lack of suitable surgical options was confirmed in the remaining 3 patients. CONCLUSION Realistic 3-dimensional modeling of the heart provides a new means for the assessment of complex intracardiac anatomy. We expect this method to change current diagnostic approaches and facilitate preoperative planning.

Myocardial T1 Mapping in Pediatric and Congenital Heart Disease

In addition to the depiction of anatomy and function, tissue characterization of the myocardium has emerged as an important asset of cardiac magnetic resonance (CMR). Among the tissue properties that are quantifiable by CMR is diffuse myocardial fibrosis. Diffuse fibrosis is regarded to be the common pathological pathway toward loss of myocardial function in many cardiac conditions, including congenital heart disease.1–4 As fibrosis seems to have a major role in myocardial failure and may be reversible,5–8 its assessment by CMR has the potential to transform the way we monitor and treat our patients.9 In this review, we describe the technical aspects of fibrosis quantification with CMR and outline past and potential applications in congenital and pediatric heart disease. Diffuse myocardial fibrosis, which is present to a varying degree in children with acquired and congenital heart disease, has been attributed to abnormal loading conditions, cyanosis, and genetic predisposition.1,7,10,11 Myocardial fibrosis manifests in the pressure-loaded left ventricle of infants and children with aortic stenosis and coarctation.1 In patients with tetralogy of Fallot right ventricular myofiber disorganization and interstitial fibrosis have been demonstrated histologically.2,12 Interestingly, right ventricular fibrosis not only occurs in late adult survivors, but is already present in infants with this condition.12 The changes in myocardial architecture observed with fibrotic remodeling can be detrimental to heart function: Fibrous endocardial thickening of the right ventricular infundibulum is a predictor of poor right ventricular function in patients after tetralogy of Fallot repair.3 In patients with tricuspid atresia myocardial fibrosis is associated with systolic ventricular dysfunction early in life.4,13 In addition to being a mediator of cardiac dysfunction, diffuse fibrosis is the substrate for electric instability and a risk factor for life-threatening ventricular arrhythmia.14 Antifibrotic drugs have …

Flow-sensitive four-dimensional magnetic resonance imaging facilitates and improves the accurate diagnosis of partial anomalous pulmonary venous drainage.

OBJECTIVES To assess if flow-sensitive four-dimensional velocity-encoded cine magnetic resonance imaging adds value in diagnosing patients with suspected partial anomalous pulmonary venous drainage. METHODS In six patients with echocardiographically suspected partial anomalous pulmonary venous drainage, anatomy was evaluated using standard magnetic resonance imaging including angiography. Functional analysis included shunt calculations from flow measurements. We used four-dimensional velocity-encoded cine magnetic resonance imaging for visualisation of maldraining pulmonary veins and quantification of flow via the maldraining veins and interatrial communications, if present. RESULTS In all patients, the diagnosis of partial anomalous pulmonary venous drainage was confirmed by standard magnetic resonance imaging. Shunt volumes ranged from 1.4:1 to 4.7:1. Drainage sites were the superior caval vein (n = 5) or the vertical vein (n = 1). Multiple maldraining pulmonary veins were found in three patients. Pulmonary arteries and veins could be clearly distinguished by selective visualisation using four-dimensional velocity-encoded cine magnetic resonance imaging. Flow measured individually in maldraining pulmonary veins in six patients and across the interatrial communication in three patients revealed a percentage of the overall shunt volume of 30-100% and 58-70%, respectively. CONCLUSION Selective visualisation of individual vessels and their flow characteristics by four-dimensional velocity-encoded cine magnetic resonance imaging facilitates in distinguishing adjacent pulmonary arteries and veins and thus improves the accurate diagnosis of maldraining pulmonary veins. By detailed quantification of shunt volumes, additional information for planning of treatment strategies is provided. This method adds clinical value and might replace contrast-enhanced magnetic resonance angiography in these patients in the future.

Cardiac MRI in patients with complex CHD following primary or secondary implantation of MRI-conditional pacemaker system.

OBJECTIVES In patients with CHD, cardiac MRI is often indicated for functional and anatomical assessment. With the recent introduction of MRI-conditional pacemaker systems, cardiac MRI has become accessible for patients with pacemakers. The present clinical study aims to evaluate safety, susceptibility artefacts, and image reading of cardiac MRI in patients with CHD and MRI-conditional pacemaker systems. Material and methods CHD patients with MRI-conditional pacemaker systems and a clinical need for cardiac MRI were examined with a 1.5-T MRI system. Lead function was tested before and after MRI. Artefacts and image readings were evaluated using a four-point grading scale. RESULTS A total of nine patients with CHD (mean age 34.0 years, range 19.5-53.6 years) received a total of 11 cardiac MRI examinations. Owing to clinical indications, seven patients had previously been converted from conventional to MRI-conditional pacemaker systems. All MRI examinations were completed without adverse effects. Device testing immediately after MRI and at follow-up showed no alteration of pacemaker device and lead function. Clinical questions could be addressed and answered in all patients. CONCLUSION Cardiac MRI can be performed safely with high certainty of diagnosis in CHD patients with MRI-conditional pacemaker systems. In case of clinically indicated lead and box changing, CHD patients with non-MRI-conditional pacemaker systems should be considered for complete conversion to MRI-conditional systems.

Higher extracellular volume is associated with longer bypass times at corrective surgery and reduced exercise tolerance in children late after repair of tetralogy of Fallot

Results There was no difference in ECV between 31 TOF patients (23.6 ± 3.3, age at CMR 13.9 ± 2.4 years, 19 male) and 15 controls (23.4 ± 3.0, age at CMR 13.4 ± 2.6 years, 7 male). ECV correlated with z-scores of LV end-diastolic volumes and of right ventricular (RV) enddiastolic and end-systolic volumes (r = 0.39, p < 0.05; r = 0.46, p < 0.01; and r = 0.43, p < 0.05, respectively). LV ECV did not correlate with with LV or RV ejection fraction, indexed right and left ventricular enddiastolic volumes or pulmonary regurgitation fraction or regurgitant volumes. Female TOF patients had higher ECVs as compared to males (25.7 ± 1.8% versus 22.9 ± 3.1%, p < 0.005). There were no gender differences in controls. Bypass-time during complete repair correlated with LV ECV (r = 0.46, p < 0.05). Patients who had undergone either a valve sparing repair or received a valved right ventricle to pulmonary artery conduit had a lower ECV than those after transannular patch repair (22.8 ± 2.7% versus 26.0 ± 3.0%, p < 0.05).Maximum workload on exercise testing, as a percent of predicted based on reference populations, correlated inversely with ECV (r = -0.62, p < 0.05). There were no correlations between ECV and myocardial strain, strain rate or torsion.

Hemodynamic in Aortic Coarctation Using MRI-Based Inflow Condition

Image-based CFD can support diagnosis, treatment decision and planning. The ability of CFD to calculate pressure drop across the aortic coarctation is the focus of the 2013 STACOM Challenge. The focus of our study was inflow conditions. We compared a MRI-based inlet velocity profile with a swirl and an often used plug velocity profile without swirl. The unsteady flow simulations were performed using the solver FLUENT with consideration of the challenge specifications. For outflows, the constant outflow ratios of the supra-aortic vessels were set. The consideration of a secondary flow swirl at the inlet of the ascending aorta significantly affect reduce the calculated pressure drop across the aortic coarctation and hence the treatment decision. Furthermore, using MRI-measured flow rates at the ascending and the descending aorta without a proof of data consistency could result in an overestimated pressure drop due to overestimated flow into the supra-aortic vessels.

Magnetic resonance imaging of the transplanted pediatric heart as a potential predictor of rejection

AIM To evaluate cardiac magnetic resonance imaging (CMR) as a non-invasive tool to detect acute cellular rejection (ACR) in children after heart transplant (HT). METHODS Thirty pediatric HT recipients underwent CMR at the time of surveillance endomyocardial biopsy (EMB) and results were compared to 14 non-transplant controls. Biventricular volumes, ejection fractions (EFs), T2-weighted signal intensities, native T1 times, extracellular volumes (ECVs) and presence of late gadolinium enhancement (LGE) were compared between patients and controls and between patients with International Society of Heart and Lung Transplantation (ISHLT) grade ≥ 2R rejection and those with grade 0/1R. Heart rate (HR) and brain natriuretic peptide (BNP) were assessed as potential biomarkers. RESULTS Significant ACR (ISHLT grade ≥ 2R) was an infrequent event in our population (5/30, 17%). Ventricular volumes, EFs, LGE prevalence, ECVs, native T1 times, T2 signal intensity ratios, HR and BNP were not associated with the presence of ≥ 2R ACR. CONCLUSION In this pilot study CMR did not reliably identify ACR-related changes in pediatric HT patients.

Diffuse myocardial fibrosis using native T1 mapping in children with repaired Tetralogy of Fallot: correlation with surgical factors and exercise capacity

Background Regional myocardial scarring in adults following Tetralogy of Fallot (TOF) repair is associated with adverse clinical outcomes. This is the largest study to date assessing native T1 times as a marker for diffuse myocardial fibrosis in children after TOF repair. The aim of the study was to describe native T1 times patients post-TOF repair and to evaluate its relationship to clinical status and surgical factors.

Diffuse myocardial fibrosis in patients after Fontan operation: a T1 relaxometry magnetic resonance pilot study

Background Patients with single ventricle (SV) circulations are at risk for heart failure, frequently burdened by both systolic and diastolic cardiac dysfunction. The mechanisms of adverse remodeling of functionally univentricular hearts are incompletely understood. Diffuse myocardial fibrosis is one of the candidate morphological substrates, for which cardiac magnetic resonance (CMR) derived native T1 times and extracellular volume fraction (ECV) have been used as markers. The purpose of this pilot study was to explore whether there is evidence of accelerated myocardial fibrosis in young children after the Fontan operation using CMR.