Extracardiac vasculature in candidates for Fontan surgery: MR imaging

Cardiovascular magnetic resonance imaging of hypoplastic left heart syndrome in children

Cardiovascular magnetic resonance imaging (CMR) plays an important complementary role to echocardiography and conventional angiography in the evaluation of hypoplastic left heart syndrome. This imaging modality is particularly useful for assessing cardiovascular postsurgical changes, extracardiac vascular anatomy, ventricular and valvular function, and a variety of complications. The purpose of this article is to provide a contemporary review of the role of CMR in the management of untreated and surgically palliated hypoplastic left heart syndrome in children.

[Magnetic resonance imaging of the mediastinal vessels in pediatric patients]

The appearance of new and better magnetic resonance imaging (MRI) techniques have made the MRI a very important imaging method for the evaluation of thoracic vessels in pediatrics. The 3D angio-MRI using GD is capable of clearly demonstrating the morphology of the aorta and pulmonary vessels. The MRI may significantly reduce the number of angiographies needed and, in some patients, may even provide additional information to the angiography.

Apport de l’IRM dans l’exploration des anomalies cardiaques congénitales et des gros vaisseaux

Management of congenital heart diseases (CHD) frequently is a diagnostic challenge. MRI, as a complement to echocardiography, plays an important role in the non-invasive evaluation of these anomalies. MRI allows high resolution anatomical evaluation of these structures in multiple planes as well as functional evaluation. These features are helpful to further characterize extra-cardiac anomalies that may be difficult to assess at US and even angiography. MRI is thus a valuable imaging tool in the evaluation of CHD.

MR Findings of Spinal Muscular Atrophy Type II: Sibling Cases

We present magnetic resonance (MR) findings of siblings affected by spinal muscular atrophy (SMA) Type II. MRI of their thighs showed severe muscle atrophy and fatty infiltration. Selective preservation of the adductor longus muscle, the gracilis muscle, and the sartorius muscles was observed, suggesting a characteristic finding of SMA Type II. These findings were more severe in the older patient.

Magnetic resonance imaging of mediastinal vessels

Advances in technology have led to a changing role for MRI in the evaluation of the thoracic vasculature in children. MRI, especially with 3D gadolinium-enhanced MR angiography, can clearly demonstrate the morphology of the aortic and pulmonary vascular supply. In patients with nonvalvar obstructive lesions of the aorta (i.e., coarctation, interruption of the aortic arch, and supravalvar stenosis), MRI can reliably assess the site and extent of the obstruction. Similarly, MRI can depict the morphology of the central pulmonary arteries and aortopulmonary collateral vessels in patients with obstructive lesions of the pulmonary artery. MRI is also useful in assessing the course of the aorta and pulmonary arteries in patients with suspected vascular rings. The result is that MRI can supplement information obtained from echocardiography and angiography and reduce the need for angiography.

MR imaging and CT of vascular anomalies and connections in patients with congenital heart disease: significance in surgical planning

To plan effective management of congenital heart disease, one needs the clearest understanding of the anatomy. Although echocardiography and angiography are the dominant imaging modalities in patients with congenital heart disease, magnetic resonance (MR) imaging and computed tomography (CT) are valuable noninvasive adjuncts. MR imaging and CT are effective in demonstrating the complex cardiovascular morphology present in congenital heart disease, especially the extracardiac morphology. In patients with tetralogy of Fallot with complex pulmonary artery anatomy, MR imaging and CT are useful in demonstrating the pulmonary artery anatomy, along with the significant aortopulmonary collateral vessels. In the heterotaxy syndromes, patients often have unusual atriovenous connections. MR imaging allows accurate identification of the hepatic, systemic, and pulmonary veins and their relationships to both atria. CT and MR are the imaging modalities of choice in a patient who is thought to have a vascular ring. Treatment of aortic coarctation is usually performed on the basis of typical clinical and echocardiographic findings. In patients with atypical clinical or echocardiographic findings, MR imaging and CT yield helpful information that can change the treatment plan. The enhanced preoperative understanding of congenital heart disease provided by MR imaging and CT simplifies surgical decision making and consequently may improve outcome.

MR imaging of congenital heart diseases in adolescents and adults

Echocardiography and catheterization angiography suffer certain limitations in the evaluation of congenital heart diseases in adults, though these are overcome by MRI, in which a wide field-of view, unlimited multiplanar imaging capability and three-dimensional contrast-enhanced MR angiography techniques are used. In adults, recently introduced fast imaging techniques provide cardiac MR images of sufficient quality and with less artifacts. Ventricular volume, ejection fraction, and vascular flow measurements, including pressure gradients and pulmonary-to-systemic flow ratio, can be calculated or obtained using fast cine MRI, phase-contrast MR flow-velocity mapping, and semiautomatic analysis software. MRI is superior to echocardiography in diagnosing partial anomalous pulmonary venous connection, unroofed coronary sinus, anomalies of the pulmonary arteries, aorta and systemic veins, complex heart diseases, and postsurgical sequelae. Biventricular function is reliably evaluated with cine MRI after repair of tetralogy of Fallot, and Senning's and Mustard's operations. MRI has an important and growing role in the morphologic and functional assessment of congenital heart diseases in adolescents and adults.

Postoperative evaluation of congenital heart disease by magnetic resonance imaging

In the last four decades the survival of patients with corrected or palliated congenital heart disease has increased dramatically. However, post-operative abnormalities frequently occur and therefore a noninvasive imaging tool is mandatory for the timely detection of morphological as well as functional abnormalities. Magnetic resonance imaging (MRI) is ideally suited for the noninvasive diagnosis and post-operative follow-up of congenital heart disease. Spin-echo MRI is able to visualize structures that may be difficult to assess with other noninvasive image modalities and is sensitive in the detection of post-interventional stenoses or aneurysms. Because the function of the ventricles may deteriorate over time after correction or palliation of a congenital cardiac malformation, the use of gradient-echo MRI is essential in the follow-up after correction or palliation, as no other conventional technique allows such detailed evaluation of ventricular function, without geometrical assumptions. Phase-contrast MRI is well suited to assess valvular function, allowing accurate measurement of regurgitation or stenosis. Shunt quantification is another application of phase-contrast MRI. J. Magn. Reson. Imaging 1999;10:656-666.

Magnetic resonance imaging of complex congenital heart disease

Current MR techniques enable both anatomical and functional evaluations of the heart. Although it is rarely used as a primary diagnostic tool in pediatric cardiology, it can be used as a valuable adjunct to echocardiography and angiography. MRI is particularly useful in clarification of morphology of complex congenital heart diseases. It is the most accurate method of determination of visceral and atrial situs. It is easy to evaluate the systemic and pulmonary venous connections that are very important for the Fontan type of operation, especially in patients with visceral heterotaxy. It facilitates demonstration of diminutive pulmonary arteries in patients with pulmonary atresia. It clearly demonstrates juxtaposition of the atrial appendages that is often missed by echocardiography. The anatomy of the twisted atrioventricular connections is much more clear in MRI than in echocardiography. It enables en face imaging of ventricular septal defect that provides a surgical view. We find en face imaging particularly helpful in patients with double inlet left ventricle and transposition of the great arteries where the size of the ventricular septal defect governs the blood flow into the aorta. It is often advantageous to echocardiography in defining the type of univentricular atrioventricular connections by demonstrating the position and topology of the rudimentary chamber in difficult cases. In double outlet right ventricle, the spatial relationship of the ventricular septal defect to the great arterial valves can be clearly defined by visualizing the ventricular septal defect and the outlet septum in the same imaging plane.

Magnetic resonance imaging of complex congenital heart disease

Current MR techniques enable both anatomical and functional evaluations of the heart. Although it is rarely used as a primary diagnostic tool in pediatric cardiology, it can be used as a valuable adjunct to echocardiography and angiography. MRI is particularly useful in clarification of morphology of complex congenital heart diseases. It is the most accurate method of determination of visceral and atrial situs. It is easy to evaluate the systemic and pulmonary venous connections that are very important for the Fontan type of operation, especially in patients with visceral heterotaxy. It facilitates demonstration of diminutive pulmonary arteries in patients with pulmonary atresia. It clearly demonstrates juxtaposition of the atrial appendages that is often missed by echocardiography. The anatomy of the twisted atrioventricular connections is much more clear in MRI than in echocardiography. It enables en face imaging of ventricular septal defect that provides a surgical view. We find en face imaging particularly helpful in patients with double inlet left ventricle and transposition of the great arteries where the size of the ventricular septal defect governs the blood flow into the aorta. It is often advantageous to echocardiography in defining the type of univentricular atrioventricular connections by demonstrating the position and topology of the rudimentary chamber in difficult cases. In double outlet right ventricle, the spatial relationship of the ventricular septal defect to the great arterial valves can be clearly defined by visualizing the ventricular septal defect and the outlet septum in the same imaging plane.

Complex congenital heart malformation evaluated with MR imaging at 0.3 T

The aim of this study was to evaluate the efficiency of MR imaging at 0.3 T as the single modality in diagnosing complex congenital heart disease (CHD). Films from 45 cases were reviewed in two stages by four specialists and one fellow in pediatric radiology, who were unfamiliar with the patients. First a general review of CHD diagnosis was made, then a detailed study of anomalous venous return was performed. Regarding the general diagnosis of cardiovascular anomalies the results were good, with sensitivity of 80%, specificity of 96%, a positive predictive value of 88%, a negative predictive value of 93% and accuracy of 92%. As expected, the less experienced reviewer had somewhat lower figures. As for detailed evaluation of the anomalous veins, the diagnostic results were again good (sensitivity 85%), although less so when also the connection sites of the anomalous veins were considered (sensitivity 79%). The specificity of the findings was high at 97%. MR imaging at 0.3 T is valuable in the diagnosis of complex CHD, especially for anomalous vessels and their connections.

Postoperative evaluation of pulmonary arteries in congenital heart surgery by magnetic resonance imaging: comparison with echocardiography

Palliative and corrective operations for the treatment of cyanotic congenital heart disease frequently involve or potentially influence the size of the pulmonary arteries. Echocardiography and magnetic resonance imaging (MRI) are two noninvasive imaging techniques currently used to assess morphologic abnormalities of the pulmonary arteries. The purpose of this study was to evaluate the role of MRI in comparison with echocardiography for defining morphologic changes of the pulmonary arteries after congenital heart surgery. The MRI scans and echocardiograms of 33 patients with surgery involving or affecting the pulmonary arteries were compared. The pulmonary outflow tract, pulmonary confluence, right and left pulmonary arteries, and surgical shunts were separately evaluated. Cineangiography and surgical reports were used to confirm findings. MRI and echocardiography were equivalent for demonstrating abnormalities of the right ventricular outflow tract, main pulmonary artery, and a variety of pulmonary shunts. MRI was superior to echocardiography in demonstrating abnormalities of the right and left pulmonary arterial branches (p < 0.001). MRI is effective for monitoring pulmonary arterial status after surgery and is superior to echocardiography for the evaluation of the right and left pulmonary arteries.

Usefulness of magnetic resonance imaging in the assessment of venoatrial connections, atrial morphology, bronchial situs, and other anomalies in right atrial isomerism

Multiple complex venous and intracardiac anomalies are frequently seen in patients with right atrial isomerism, and complete anatomic information may not always be obtained from combined echocardiography and angiography. Twenty patients with right atrial isomerism were prospectively studied with use of magnetic resonance imaging (MRI); satisfactory imaging was obtained in 18 patients, aged 6 days to 12 years (median 3 months). All patients had undergone echocardiography, cardiac catheterization, and angiocardiography. The purpose of this study was to assess the usefulness of MRI in the evaluation of venoatrial connections, atrial morphology, bronchial situs, and additional anomalies. Bilateral superior venae cavae were documented in 12 patients and anomalous hepatic venous drainage in 11. The pulmonary venous system was imaged in all 18 patients, of whom 12 had total anomalous pulmonary venous connection: 9 supracardiac, 2 infracardiac, and 1 mixed type. Some obstruction to pulmonary venous return was present in 9 of the 12 patients, and the site of obstruction was demonstrated by MRI in 6. Bilateral morphologic right atrial appendages were imaged in 7 patients. Bilateral morphologic right bronchi were identified in 17 patients, asplenia was confirmed in 17 of 18 patients by the absence of splenic tissue on imaging, and hiatal hernia was imaged in 4. Compared with angiography and echocardiography, MRI more clearly defined the pulmonary venous connections in 10 patients with pulmonary venous obstruction. Anomalous hepatic venous connections were better defined by MRI in 2. Therefore, MRI provided valuable supplementary information on the cardiovascular and visceral anomalies in these patients.

MR angiography of congenital heart disease: value of segmented two-dimensional inflow technique and maximum-intensity-projection display

Magnetic resonance (MR) angiography of the cardiovascular system was evaluated in 41 patients with congenital heart disease by using a two-dimensional (2D) inflow technique based on a magnetization-prepared gradient-echo pulse sequence with segmented k-space data acquisition and electrocardiographic gating at 0.5 T. Inversion and saturation prepulses were used to suppress stationary tissue and enhance intravascular signal. Presaturation slabs were applied where certain vascular structures had to be suppressed. Sequence parameters were optimized by evaluating signal intensity and contrast characteristics for various flip angles and inversion and saturation delay times. The heart and intrathoracic vasculature were encompassed with 40-50 overlapping sections. Both 2D angiograms and maximum-intensity-projection images were evaluated. Combining data sets acquired in the sagittal and transverse orientations provided the most satisfactory information about the pulmonary arteries. The highest signal-to-noise ratios were obtained with a flip angle of 65 degrees and short prepulse delay times. Two-dimensional MR angiography can provide useful diagnostic information but requires a thorough understanding of in-plane and hemodynamically induced signal intensity changes.

Nuclear magnetic resonance imaging of the palliative operation for hypoplastic left heart syndrome

Electrocardiographic-gated nuclear magnetic resonance (NMR) imaging has been shown to be effective for the evaluation of congenital heart disease, particularly in supracardiac regions. This study evaluated the postoperative status after a stage I palliative operation (Norwood procedure) for hypoplastic left heart syndrome. The NMR images from three patients were compared with those of angiography and depicted all components of the reconstructed supracardiac and intracardiac anatomy after this operation. Nonobstructive anastomosis of the main pulmonary artery to the proximal aorta was clearly demonstrated in each patient. The caliber of the central or branch pulmonary artery, patency and caliber of the systemic to pulmonary artery shunt and the size of the atrial communication were also depicted in each patient and these findings corresponded with angiographic results. The results suggest that NMR imaging is effective for assessing the results of initial palliative surgery for hypoplastic left heart syndrome, which seems to be important for managing patients before subsequent definitive surgery.