Contrast-enhanced magnetic resonance angiography of the great arteries in patients with congenital heart disease: an accurate tool for planning catheter-guided interventions

Validity of cardiovascular magnetic resonance in pre- and post-operative evaluation of pulmonary arteries and ventricular functions in pediatric conotruncal anomalies

Background

The aim of this work is to evaluate the validity of magnetic resonance (MR) imaging in assessment of pulmonary arteries and ventricular functions with conotruncal anomalies in the pediatric population.

Results

Between March 2018 and December 2019, 42 patients ranging in age from 6 months to 18 years and diagnosed with conotruncal anomalies by echocardiographic examination were submitted for cardiac MRI followed by assessment of their morphological (intra- and extra-cardiac anatomy) and functional parameters. The most common conotruncal anomaly was tetralogy of Fallot which represented 45% of the cases. Cardiac magnetic resonance (CMR) compared to echocardiography showed 46% agreement in the assessment of right ventricular volumes and function. There was only 37% agreement between echocardiography and MRI in delineation of MAPCAS.

Conclusion

CMR provides a powerful tool, giving anatomical and physiological information that echocardiography and catheterization alone cannot provide in conotruncal anomalies.

Automated Quantitative Stress Perfusion Cardiac Magnetic Resonance in Pediatric Patients

Background: Myocardial ischemia occurs in pediatrics, as a result of both congenital and acquired heart diseases, and can lead to further adverse cardiac events if untreated. The aim of this work is to assess the feasibility of fully automated, high resolution, quantitative stress myocardial perfusion cardiac magnetic resonance (CMR) in a cohort of pediatric patients and to evaluate its agreement with the coronary anatomical status of the patients. Methods: Fourteen pediatric patients, with 16 scans, who underwent dual-bolus stress perfusion CMR were retrospectively analyzed. All patients also had anatomical coronary assessment with either CMR, CT, or X-ray angiography. The perfusion CMR images were automatically processed and quantified using an analysis pipeline previously developed in adults. Results: Automated perfusion quantification was successful in 15/16 cases. The coronary perfusion territories supplied by vessels affected by a medium/large aneurysm or stenosis (according to the AHA guidelines), induced by Kawasaki disease, an anomalous origin, or interarterial course had significantly reduced myocardial blood flow (MBF) (median (interquartile range), 1.26 (1.05, 1.67) ml/min/g) as compared to territories supplied by unaffected coronaries [2.57 (2.02, 2.69) ml/min/g, p < 0.001] and territories supplied by vessels with a small aneurysm [2.52 (2.45, 2.83) ml/min/g, p = 0.002]. Conclusion: Automatic CMR-derived MBF quantification is feasible in pediatric patients, and the technology could be potentially used for objective non-invasive assessment of ischemia in children with congenital and acquired heart diseases.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

mDixon ECG-gated 3-dimensional cardiovascular magnetic resonance angiography in patients with congenital cardiovascular disease

BACKGROUND

Cardiovascular magnetic resonance (CMR) angiography (CMRA) is an important non-invasive imaging tool for congenital heart disease (CHD) and aortopathy patients. The conventional 3D balanced steady-state free precession (bSSFP) sequence is often confounded by imaging artifacts. We sought to compare the respiratory navigated and electrocardiogram (ECG) gated modified Dixon (mDixon) CMRA sequence to conventional non-gated dynamic multi-phase contrast enhanced CMRA (CE-CMRA) and bSSFP across a variety of diagnoses.

METHODS

We included 24 patients with CHD or aortopathy with CMR performed between September 2017 to December 2017. Each patient had undergone CE-CMRA, followed by a bSSFP and mDixon angiogram. Patients with CMR-incompatible implants or contraindications to contrast were excluded. The studies were rated according to image quality at a scale from 1 (poor) to 4 (excellent) based on diagnostic adequacy, artifact burden, vascular border delineation, myocardium-blood pool contrast, and visualization of pulmonary and systemic veins and coronaries. Contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and quantitative vascular measurements were compared between the two gated sequences. Bland-Altman plots were generated to compare paired measures.

RESULTS

All scans were diagnostically adequate. Mean (SD) quality scores were 3.4 (0.7) for the mDixon, 3.2 (0.5) for the bSSFP and 3.4 (0.5) for the CE-CMRA. Qualitatively, the intracardiac anatomy and myocardium-blood pool definition were better in the bSSFP; however, mDixon images showed enhanced vessel wall sharpness with less blurring surrounding the anatomical borders distally. Coronary origins were identified in all cases. Pulmonary veins were visualized in 92% of mDixon sequences, 75% of bSSFP and 96% of CE-CMRA. Similarly, neck veins were identified in 92, 83 and 96% respectively. Artifacts prevented vascular measurement in 6/192 (3%) and 4/192 (2%) of total vascular measurements for the mDixon and bSSFP, respectively. However, the size of signal void and field distortion were significantly worse in the latter, particularly for flow and metal induced artifacts.

CONCLUSION

In patients with congenital heart disease, ECG gated mDixon angiography yields high fidelity vascular images including better delineation of head and neck vasculature and pulmonary veins and fewer artifacts than the comparable bSSFP sequence. It should be considered as the preferred strategy for successful CHD imaging in patients with valve stenosis, vascular stents, or metallic implants.

Cardiac Magnetic Resonance to Evaluate Percutaneous Pulmonary Valve Implantation in Children and Young Adults

Experience with cardiac magnetic resonance to evaluate coronary arteries in children and young adult patients is limited. Because noninvasive imaging has advantages over coronary angiography, we compared the effectiveness of these techniques in patients who were being considered for percutaneous pulmonary valve implantation. We retrospectively reviewed the cases of 26 patients (mean age, 12.53 ± 4.85 yr; range, 5-25 yr), all of whom had previous right ventricular-to-pulmonary artery homografts. We studied T2-prepared whole-heart images for coronary anatomy, velocity-encoded cine images for ventricular morphology, and function- and time-resolved magnetic resonance angiographic findings. Cardiac catheterization studies included coronary angiography, balloon compression testing, right ventricular outflow tract, and pulmonary artery anatomy. Diagnostic-quality images were obtained in 24 patients (92%), 13 of whom were considered suitable candidates for valve implantation. Two patients (8%) had abnormal coronary artery anatomy that placed them at high risk of coronary artery compression during surgery. Twelve patients underwent successful valve implantation after cardiac magnetic resonance images and catheterization showed no increased risk of compression. We attempted valve implantation in one patient with unsuitable anatomy but ultimately placed a stent in the homograft. Magnetic resonance imaging of coronary arteries is an important noninvasive study that may identify patients who are at high risk of coronary artery compression during percutaneous pulmonary valve implantation, and it may reveal high-risk anatomic variants that can be missed during cardiac catheterization.

Long-Term Serial Follow-Up of Pulmonary Artery Size and Wall Shear Stress in Fontan Patients

Pulmonary arterial (PA) flow is abnormal after the Fontan operation and is marked by a lack of pulsatility. We assessed the effects of this abnormal flow on the size and function of the PA's in Fontan patients in long-term serial follow-up. Twenty-three Fontan patients with serial follow-up were included. Median age was 11.1 (9.5-16.0) years at baseline and 15.5 (12.5-22.7) years at follow-up. Median follow-up duration was 4.4 (4.0-5.8) years. Flow and size of the left pulmonary artery were determined using phase-contrast MRI. From this wall shear stress (WSS), distensibility and pulsatility were determined. A group of healthy peers was included for reference. Flow and pulsatility were significantly lower in patients than in controls (p < 0.001). Mean area was comparable in patients and controls, but distensibility was significantly higher in controls (p < 0.001). Mean and peak WSS were significantly lower in Fontan patients (p < 0.001). Between baseline and follow-up, there was a significant increase in normalized flow (15.1 (14.3-19.1) to 18.7 (14.0-22.6) ml/s/m(2), p = 0.023). Area, pulsatility, distensibility and WSS did not change, but there was a trend toward a lower mean WSS (p = 0.068). Multivariable regression analysis showed that flow, area and age were important predictors for WSS. WSS in Fontan patients is decreased compared to healthy controls and tends to decrease further with age. Pulsatility and distensibility are significantly lower compared to healthy controls. Pulmonary artery size, however, is not significantly different from healthy controls and long-term growth after Fontan operation is proportionate to body size.

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.

MR and CT imaging of pulmonary valved conduits in children and adolescents: normal appearance and complications

BACKGROUND

The Contegra® is a conduit made from the bovine jugular vein and then interposed between the right ventricle and the pulmonary artery. It is used for cardiac malformations in the reconstruction of right ventricular outflow tract.

OBJECTIVE

To describe both normal and pathological appearances of the Contegra® in radiological imaging, to describe imaging of complications and to define the role of CT and MRI in postoperative follow-up.

MATERIALS AND METHODS

Forty-three examinations of 24 patients (17 boys and 7 girls; mean age: 10.8 years old) with Contegra® conduits were reviewed. Anatomical description and measurements of the conduits were performed. Pathological items examined included stenosis, dilatation, plicature or twist, thrombus or vegetations, calcifications and valvular regurgitation. Findings were correlated to the echographic gradient through the conduit when available.

RESULTS

CT and MR work-up showed Contegra® stenosis (n = 12), dilatation (n = 9) and plicature or twist (n = 7). CT displayed thrombus or vegetations in the Contegra® in three clinically infected patients. Calcifications of the conduit were present at CT in 12 patients and valvular regurgitation in three patients. The comparison between CT and/or MR results showed a good correlation between the echographic gradient and the presence of stenosis in the Contegra®.

CONCLUSION

CT and MR bring additional information about permeability and postoperative anatomy especially when echocardiography is inconclusive. Both techniques depict the normal appearance of the conduit, and allow comparison and precise evaluation of changes in the postoperative follow-up.

Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0.9) and sagittal oblique MRA of left pulmonary artery (LPA) (Δ 0.2 ± 1.1 mm, ICC 0.9). CMR PA measurements were compared to surgical measurements in 25 children (5.4 ± 4.8 years). All MRI sequences demonstrated good agreement (ICC > 0.8) with the best (ICC 0.9) from axial cine bSSFP for both RPA and LPA. Maximal cross sectional and angulated oblique reformatted MRA provide the best correlation to catheterization for measurement of branch PA's and stenosis diameter. This is likely due to similar angiographic methods based on reformatting techniques that transect the central axis of the arteries. Axial cine bSSFP CMR was the best surgically measured correlate of PA branch size due to this being a measure of stretched diameter. Knowledge of these differences provides more precise PA measurements and may aid catheter or surgical interventions for RVOTO lesions.

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.

Comparison between proximal thoracic vascular measurements obtained by contrast-enhanced magnetic resonance angiography and by transthoracic echocardiography in infants and children with congenital heart disease

Accurate assessment of the proximal thoracic vasculature in infants and children with congenital heart disease (CHD) is vital for deciding the appropriate surgical or interventional procedure and predicting outcomes. This information usually is obtained by transthoracic echocardiography (TTE). Contrast-enhanced magnetic resonance angiography (CE-MRA) frequently is used to obtain diagnostic data when the image quality by TTE is limited. Calculation of z-scores for measurements obtained by CE-MRA in this population currently is not possible due to the lack of normative data. A reasonable agreement between vessel dimensions by CE-MRA and TTE will allow the use of TTE-based z-scores on measurements from CE-MRA. This study examines the accuracy and agreement of proximal thoracic vascular measurements obtained by CE-MRA versus TTE. Infants and children younger than 3 years with CHD who had a CE-MRA between August 2006 and May 2011 were retrospectively identified. Main and branch pulmonary arteries, ascending aorta, distal transverse arch, and aortic isthmus were measured from CE-MRA and TTE in analogous imaging planes and locations by two investigators blinded to each other. The study enrolled 35 subjects with CHD. The median age was 129 days (range, 0-1077 days), and the median weight was 5.8 kg (range, 2.16-17 kg). The median interval between the two imaging methods was 9 days (range, 0-60 days). Data analysis was performed with 129 of the 210 possible paired measurements. The remaining 81 paired measurements could not be performed due to inaccurate visualization of vessel borders or an unavailable imaging plane from TTE, CE-MRA, or both. The range of vessel sizes measured from 2.8 to 23.4 mm. There was excellent correlation between CE-MRA and TTE (r = 0.94, p < 0.001). The mean difference between the measurements was -0.1 ± 1.2 mm, and the limits of agreement were -2.5 to 2.3 mm. Proximal thoracic vascular measurements obtained by CE-MRA and TTE in infants and children with CHD have a strong correlation. The agreement between these two imaging methods is adequate. Until normative data for vessel size measurements obtained from CE-MRA are available for this population, TTE-based z-scores can be applied to the measurements obtained by CE-MRA.

Imaging the right heart: the use of integrated multimodality imaging

During recent years, right ventricular (RV) structure and function have been found to be an important determinant of outcome in different cardiovascular and also pulmonary diseases. Currently, echocardiography and cardiac magnetic resonance (CMR) imaging are the two imaging modalities most commonly used to visualize the RV. Most structural abnormalities of the RV can be reliably described by echocardiography but due its complex geometrical shape, echocardiographic assessment of RV function is more challenging. Newer promising echocardiographic techniques are emerging but lack of validation and limited normal reference data influence their routine clinical application. Cardiac magnetic resonance is generally considered the clinical reference technique due to its unlimited imaging planes, superior image resolution, and three-dimensional volumetric rendering. The accuracy and reliability of CMR measurements make it the ideal tool for serial examinations of RV function. Multidetector computed tomography (MDCT) plays an important role in the diagnosis of pulmonary emboli but can also be used for assessing RV ischaemic disease or as an alternative for CMR if contra-indicated. Radionuclide techniques have become more obsolete in the current era. The different imaging modalities should be considered complimentary and each plays a role for different indications.

Detection of pulmonary arterial morphology in tetralogy of Fallot with pulmonary atresia by computed tomography: 12 years of experience

Our aim was to evaluate the feasibility of using computed tomography (CT) to define the pulmonary artery anatomy in patients with tetralogy of Fallot and pulmonary atresia (TOF-PA). We retrospectively reviewed 110 patients with TOF-PA between 1995 and 2008. Those who received cardiac catheterization and surgery within 3 months of their CT examinations were enrolled. Based on Dr. Somerville's classification, the pulmonary arterial pattern was determined, including identifiable pulmonary trunk (type I), the presence of both left and right pulmonary arteries without trunk (II), only left or right pulmonary artery present (III), and absent intrapericardial pulmonary arteries (IV). The accuracy of both imaging modalities was evaluated with operation findings as the golden standard. The effective radiation doses and adverse events were also recorded. In the 64 eligible patients (median age, 23 months), CT and catheterization demonstrated accurate pulmonary arterial morphology in 60 (60/64) and 53 (53/64) TOF-PA patients, respectively. Thirty-two of 35 type I patients were correctly identified by CT, whereas 26 were correctly identified by catheterization (p = 0.03). Of the 20 type II TOF-PA patients, 19 were diagnosed by CT, whereas 18 were diagnosed by catheterization. CT and catheterization both successfully defined six type III and three type IV patients. The median calculated radiation doses caused by CT and catheterization were 4.5 and 5.6 mSv, respectively (p > 0.05).

CONCLUSIONS

For patients with TOF-PA, CT could accurately delineate pulmonary arterial morphology with the same level of accuracy as cardiac catheterization. Therefore, CT can be considered a reasonable diagnostic alternative for such patients.

The role of cardiovascular magnetic resonance in pediatric congenital heart disease

Cardiovascular magnetic resonance (CMR) has expanded its role in the diagnosis and management of congenital heart disease (CHD) and acquired heart disease in pediatric patients. Ongoing technological advancements in both data acquisition and data presentation have enabled CMR to be integrated into clinical practice with increasing understanding of the advantages and limitations of the technique by pediatric cardiologists and congenital heart surgeons. Importantly, the combination of exquisite 3D anatomy with physiological data enables CMR to provide a unique perspective for the management of many patients with CHD. Imaging small children with CHD is challenging, and in this article we will review the technical adjustments, imaging protocols and application of CMR in the pediatric population.

What is the clinical utility of routine cardiac catheterization before a Fontan operation?

Patients with single-ventricle circulation presenting for Fontan completion routinely undergo cardiac catheterization despite ongoing debate concerning its additive value. Increasing interest in noninvasive preoperative evaluation alone led the authors to analyze the utility of routine pre-Fontan catheterization and to determine whether a subset of patients could avoid this invasive procedure. Patients younger than 5 years referred for pre-Fontan evaluation were retrospectively reviewed. Medical records and catheter angiograms were examined, and catheterizations were categorized as "additive" based on predetermined criteria. Associations between precatheterization variables, catheterization findings, and short-term postoperative outcomes were evaluated. Cardiac catheterization was clinically nonadditive for 89 of 175 patients undergoing pre-Fontan evaluation (51%). There were no robust precatheterization predictors of a nonadditive catheterization. Echocardiography did not fully demonstrate the relevant anatomy of 115 patients (66%), most frequently due to inadequate visualization of the pulmonary arteries, and 22 patients had additive catheterizations due to new diagnostic findings alone. Interventions at catheterization were frequent and deemed "important" for 64 patients (37%). Catheterization hemodynamic data were not associated with early postoperative outcomes. Minor catheterization complications occurred for 51 patients (29%) and major complications for 4 patients (2%). Although at least 50% of the patients presenting for Fontan completion may be able to avoid routine catheterization safely, an echocardiography-based imaging strategy alone is insufficient to allow proper identification of those who could be evaluated noninvasively. A more comprehensive imaging strategy not based solely on echocardiography should be considered.

Magnetic resonance imaging findings in Loeys-Dietz syndrome

Loeys-Dietz syndrome is a newly described entity characterised by a constellation of arterial tortuosity, cranial malformations, and hypertelorism. We report a case of a 7-year old boy with confirmed Loeys-Dietz syndrome and discuss magnetic resonance imaging as a complete technique for assessment and follow-up of aggressive vascular pathology in the brain, thorax, and abdomen, which may dictate early surgical intervention.

Normal values for aortic diameters in children and adolescents--assessment in vivo by contrast-enhanced CMR-angiography

BACKGROUND

Contrast-enhanced CMR angiography (CE-CMRA) is being increasingly used for diagnosing aortic arch anomalies, planning interventions and follow-up assessment. We sought to establish normal values for the diameters of the thoracic aorta and reference curves related to body growth in children using CE-CMRA.

RESULTS

CE-CMRA was performed in 53 children without cardiovascular disease. The median age was 9 years (range 2 - 20 years), weight 30 kg (range 12 - 75 kg), height 131 cm (range 81 - 184 cm), body surface area (BSA) 1.05 m2 (range 0.52-1.9 m2). Aortic diameters were measured at nine standardized sites on oblique maximum-intensity projection (MIP) images. Regression analysis of diameters in relation to BSA demonstrated linear relationship between the cross-sectional aortic diameters and the square root of BSA (BSA0.5). Normative diameters were (0.57 + 19.37*BSA0.5) mm for the aortic sinus, (-3.52 + 18.66*BSA0.5) mm for the first segment of the aortic arch, (-3.37 + 16.52*BSA0.5) mm for the isthmic region and (-1.27 + 9.89*BSA0.5) mm for the descending aorta at the level of the diaphragm. Normative curves are presented.

CONCLUSION

This study provides normative values for aortic diameters in children measured by CE-CMRA. These data may serve for making the diagnosis of pediatric arch anomalies, assessing the need for treatment and planning interventions.

Cardiovascular magnetic resonance of pulmonary artery growth and ventricular function after Norwood procedure with Sano modification

For hypoplastic left heart syndrome (HLHS), there have been concerns regarding pulmonary artery growth and ventricular dysfunction after first stage surgery consisting of the Norwood procedure modified with a right ventricle-to-pulmonary artery conduit. We report our experience using cardiovascular magnetic resonance (CMR) to determine and follow pulmonary arterial growth and ventricular function in this cohort. Following first stage palliation, serial CMR was performed at 1 and 10 weeks post-operatively, followed by cardiac catheterization at 4-6 months. Thirty-four of 47 consecutive patients with HLHS (or its variations) underwent first stage palliation. Serial CMR was performed in 20 patients. Between studies, ejection fraction decreased (58 +/- 9% vs. 50 +/- 5%, p < 0.05). Pulmonary artery growth occurred on the left (6 +/- 1 mm vs. 4 +/- 1 mm at baseline, p < 0.05) but not significantly in the right. This trend continued to cardiac catheterization 4-6 months post surgery, with the left pulmonary artery of greater size than the right (8.8 +/- 2.2 mm vs. 6.7 +/- 1.9 mm, p < 0.05). By CMR, 5 had pulmonary artery stenoses initially, and at 2 months, 9 had stenoses. Three of the 9 underwent percutaneous intervention prior to the second stage procedure. In this cohort, reasonable growth of pulmonary arteries occurred following first stage palliation with this modification, although that growth was preferential to the left. Serial studies demonstrate worsening of ventricular function for the cohort. CMR was instrumental for detecting pulmonary artery stenosis and right ventricular dysfunction.

Cardiovascular MR imaging in neonates and infants with congenital heart disease

Cardiovascular magnetic resonance (MR) imaging has become an important alternative to echocardiography and angiocardiography in the evaluation of patients with congenital heart disease (CHD). It is increasingly being used in neonates and infants for the initial investigation of CHD or as follow-up after surgery or catheter-guided intervention. Specific indications for cardiovascular MR imaging in neonates and infants include investigation of the thoracic vasculature, quantification of the ventricular volumes, and evaluation of primary cardiac tumors. To obtain good-quality MR images in neonates and infants, it is essential to adjust the technical parameters of the pulse sequences to the small size and fast heart rates of the patients. Various MR imaging techniques are available that are effective in demonstrating the complex morphologic features of the cardiovascular system and that provide additional functional and hemodynamic information. The information provided by cardiovascular MR imaging is useful for treatment planning and, in many cases, may obviate potentially harmful cardiac catheterization.

Using multidetector-row CT in neonates with complex congenital heart disease to replace diagnostic cardiac catheterization for anatomical investigation: initial experiences in technical and clinical feasibility

BACKGROUND

Echocardiography is the first-line modality for the investigation of neonatal congenital heart disease. Diagnostic cardiac catheterization, which has a small but recognized risk, is usually performed if echocardiography fails to provide a confident evaluation of the lesions.

OBJECTIVE

To verify the technical and clinical feasibilities of replacing diagnostic cardiac catheterization with multidetector-row CT (MDCT) in neonatal complex congenital heart disease.

MATERIALS AND METHODS

Over a 1-year period we prospectively enrolled all neonates with complex congenital heart disease referred for diagnostic cardiac catheterization after initial assessment by echocardiography. MDCT was performed using a 40-detector-row CT scanner with dual syringe injection. A multidisciplinary congenital heart disease team evaluated the MDCT images and decided if further diagnostic cardiac catheterization was necessary. The accuracy of MDCT in detecting separate cardiovascular anomalies and bolus geometry of contrast enhancement were calculated.

RESULTS

A total of 14 neonates were included in the study. No further diagnostic cardiac catheterization was needed in any neonate. The accuracy of MDCT in diagnosing separate cardiovascular anomalies was 98% (53/54) with only one atrial septal defect missed in a patient with coarctation syndrome. The average cardiovascular enhancement in evaluated chambers was 471 HU. No obvious beam-hardening artefact was observed.

CONCLUSION

The technical and clinical feasibility of MDCT in complex congenital heart disease in neonates is confirmed. After initial assessment with echocardiography, MDCT could probably replace diagnostic cardiac catheterization for further anatomical clarification in neonates.

Isolated left pulmonary artery stenosis due to extrinsic compression by intra thoracic tumor: recognition of unusual Doppler flow pattern and correlation with computed tomography

Pulmonary artery compression in adults resulting from tumors is an uncommon condition often associated with poor prognosis. Among the imaging modalities used for diagnosis, the role of trans thoracic echocardiography in identifying secondary pulmonic stenosis due to extrinsic or intrinsic compression and more importantly the physiologic significance has been increasingly recognized. We describe here a case of isolated left pulmonary artery stenosis which was initially suspected based on classic echocardiographic features of obstruction of pulmonary artery and subsequently confirmed by CT imaging. This case illustrates the versatility of trans thoracic echocardiography in diagnosing incidental abnormalities with potential significant consequences.

Clinical feasibility of free-breathing, gadolinium-enhanced magnetic resonance angiography for assessing extracardiac thoracic vascular abnormalities in young children with congenital heart diseases

OBJECTIVE

Congenital heart diseases in pediatric patients are associated with a wide variety of extracardiac thoracic vascular abnormalities. This study analyzed the value of gadolinium-enhanced magnetic resonance angiography during quiet free breathing for assessing extracardiac thoracic vascular abnormalities in young children with congenital heart diseases.

METHODS

Fifty-three children with congenital heart diseases (age range, 1 day-40 months; mean, 10.9 months) associated with extracardiac thoracic vascular abnormalities who had undergone both free-breathing, gadolinium-enhanced magnetic resonance angiography and cardiac catheterization, surgical intervention, or both within 2 weeks were reviewed. Diagnostic findings on gadolinium-enhanced magnetic resonance angiography among patients grouped according to 3 major conditions of conotruncal abnormalities (n = 33), aortic or venous abnormalities (n = 11), and pulmonary vascular abnormalities (n = 9), as well as associated extracardiac thoracic vascular abnormality findings, were compared with findings made by using cardiac catheterization, surgical intervention, or both.

RESULTS

Extracardiac thoracic vascular abnormality findings on gadolinium-enhanced magnetic resonance angiography were similar to those on catheterization, surgical intervention, or both in patients with conotruncal abnormalities (124 vs 127, P = .083), aortic or venous abnormalities (36 vs 33, P = .083), and pulmonary vascular abnormalities (24 vs 25, P = .317). The overall sensitivity of gadolinium-enhanced magnetic resonance angiography for detection of these lesions identified by means of catheterization, surgical intervention, or both was 97.9%. However, gadolinium-enhanced magnetic resonance angiography revealed 11 additional extracardiac thoracic vascular abnormalities that were not found on cardiac catheterization. The kappa coefficient for the correlation of image quality and diagnostic value of gadolinium-enhanced magnetic resonance angiography by using a 4-point-scale (1 = nondiagnostic to 4 = excellent) assessed by 2 independent reviewers was excellent (mean score = 3.66), with superb interobserver agreement (kappa = 0.727-0.874).

CONCLUSIONS

Free-breathing, gadolinium-enhanced magnetic resonance angiography is clinically feasible for detailed anatomic delineation and treatment planning of various extracardiac thoracic vascular abnormalities in young children with congenital heart diseases.