Evaluation of pulmonary blood supply by nuclear magnetic resonance imaging in patients with pulmonary atresia.

Nuclear magnetic resonance (NMR) imaging defines the blood pool without the need for contrast medium. Consequently, it may be useful for defining the pulmonary circulation in patients with pulmonary atresia, in whom opacification of these vessels can be problematic. Ten patients with pulmonary atresia were evaluated by gated NMR imaging. The morphology of the right ventricular outflow tract, the size and the course of the central pulmonary vessels and the source of the collateral supply to the lung were assessed. Central pulmonary arteries were identified and measured in 9 of the 10 patients. One patient had no detectable central pulmonary arteries. Angiography confirmed the NMR findings in all but two patients, in whom NMR scanning visualized a main pulmonary artery that was not seen on angiography. Collateral arteries arising from the aorta or the arch vessels, as well as intracardiac malformations and aortic arch anomalies, were identified in all 10 patients. In six patients with palliative surgery, NMR imaging correctly demonstrated all patent shunts. Nuclear magnetic resonance imaging appears to be an effective noninvasive technique for evaluating patients with pulmonary atresia. However, tomographic thickness and spatial resolution are still limiting factors for this technique in infants.

MR imaging of congenital anomalies of the aortic arch.

Eighteen patients with congenital aortic arch anomalies were evaluated by ECG-gated MR imaging. Transverse images encompassing the heart and thoracic aorta were available in all patients; sagittal or coronal studies were available in 12 patients. Visualization of the aortic arch, its orientation, and the origin and course of the arch vessels was assessed. Associated intracardiac abnormalities were noted, and the effect of aberrant vessels on the trachea or esophagus was determined. Thirteen patients had a right aortic arch. Mirror-image branching was found in 10 cases, and an aberrant left subclavian artery was found in three of these. Three patients had a left aortic arch with aberrant right subclavian artery, and two patients had a double arch. Tracheal compression caused by vascular rings was found in two patients with respiratory symptoms. Corroborating studies (angiography, surgery, CT, and autopsy) in 16 patients confirmed the MR diagnoses in all but one. We conclude that MR could substitute for other techniques as an effective, noninvasive method for the evaluation of congenital aortic arch anomalies.

Abnormalities of the pulmonary veins: evaluation with MR imaging and comparison with cardiac angiography and echocardiography.

Seventy-seven patients underwent T1-weighted spin-echo magnetic resonance (MR) imaging. Group 1 (n = 56) consisted of patients with various types of congenital heart disease but normal pulmonary veins. Group 2 (n = 22) consisted of patients with the following conditions: partial anomalous pulmonary venous connection (n = 11), total anomalous pulmonary venous connection (n = 5), cor triatriatum (n = 4), or pulmonary vein stenosis (n = 2). In group 1, the sites of connections of all four pulmonary veins were identified with MR imaging in 88% of cases; the connections of at least three pulmonary veins were seen in all patients. In group 2, the prospective detection rate of pulmonary venous abnormalities with MR imaging was 95%. The prospective detection rates of pulmonary venous abnormalities with cardiac angiography (n = 13) and echo-cardiography (n = 13) were 69% and 38%, respectively. This study indicates that MR imaging can accurately demonstrate the normal pulmonary veins and abnormalities of the pulmonary veins.

MR imaging of the thoracic aorta in Marfan patients.

A characteristic shape of the ascending aorta has been reported in patients with Marfan syndrome. To evaluate the capability of magnetic resonance (MR) imaging to distinguish between marfanoid and other aortic aneurysms, 11 Marfan patients (group 1), eight patients with ascending aorta enlargement (group 2), and 20 normal subjects (group 3) had transverse and sagittal MR of the thoracic aorta. Aortic diameter was measured at the sinuses of Valsalva (SV), the caudal portion of the ascending aorta, the prearch region (PA), the middle arch, and the descending aorta. The ratio SV/PA was significantly greater (p less than 0.001) in group 1 compared with groups 2 and 3. The SV/PA in all Marfan patients exceeded 1.4 but was less than 1.3 in subjects of groups 2 and 3. Magnetic resonance imaging provides definitive measurements of aortic dimensions and is potentially the method of choice for establishing the diagnosis of aortic involvement in Marfan syndrome and monitoring the course of aortic enlargement.

Aortic dissection: sensitivity and specificity of MR imaging.

Gated transverse magnetic resonance (MR) images of 54 patients (35 male, 19 female; aged 16-90 years) with suspected or known aortic dissection were reviewed by three cardiac radiologists without knowledge of clinical details. The reviewers independently determined the presence or absence and the type of aortic dissection. A confidence level was assigned for each diagnosis, and receiver operating characteristic curves were generated. The reviewer with extensive MR experience correctly identified 96% of the proved aortic dissections and all of the normal cases; the reviewer with moderate experience identified 96% and 84%, respectively; and the reviewer with minimal experience, 78% and 94%. The sensitivity at a specificity level of 90% was determined for each reviewer (100%, 96%, and 83%, respectively). MR imaging is highly sensitive and specific in the diagnosis of aortic dissection but does require considerable experience because of the need to recognize flow artifacts.

Evaluation of surgical procedures for cyanotic congenital heart disease by using MR imaging.

ECG-gated MR imaging has been shown to be effective for the diagnosis of congenital heart disease. In this study, we assessed its role in the postoperative evaluation of surgical procedures in patients with complex congenital heart disease. MR images of 26 patients with Rastelli (five), Fontan (three), Senning (three), Damus (one), Jatene (eight), Waterston (four), and Potts (two) procedures were evaluated retrospectively. The accuracy of MR imaging was compared with that of angiography in 20 patients. The surgical anastomoses were identified in all patients. Patency, atresia, or hypoplasia of central pulmonary arteries and postoperative complications (focal stenoses of pulmonary arteries, thrombosed conduit, peri-conduit abscess) were shown. Narrowing of the right ventricular outflow tract and focal compression of the proximal pulmonary arteries were recognized as specific complications of the Jatene procedure. MR imaging appears to be effective in the postoperative evaluation of surgical procedures used for congenital heart disease. It should be considered as an alternative to repeated catheterization and angiography for the postoperative examination of children with complex congenital heart disease.

Magnetic resonance imaging of congenital heart disease: sensitivity and specificity using receiver operating characteristic curve analysis.

MRI has shown promise for the evaluation of various congenital heart lesions. The current study was designed to assess the sensitivity and specificity of the technique for the evaluation of all major anatomic elements of the heart affected in simple and complex congenital heart disease. MR images of 51 patients (31 males and 20 females, ages 3 to 69 years) with a total of 110 congenital heart lesions were reviewed by a panel of two cardiac radiologists and one pediatric cardiologist, who assessed the cardiac pathoanatomy without knowledge of clinical details and assigned a confidence level to each diagnosis. The true diagnosis was established independently by the findings of angiocardiography and catheterization as well as by surgery, where applicable. ROC curves were generated from the responses, and the sensitivity at a specificity level of 90% was determined. MRI was shown to have a high sensitivity in evaluating great vessel relationships (100%), thoracic aorta abnormalities (94%), ASDs (91%) and VSDs (100%), visceroatrial situs (100%), and loop (100%). Three of five anomalies of the pulmonary and systemic veins were diagnosed by MRI. Right ventricular outflow obstructions (95%) were detected with a much higher sensitivity than lesions of the other valves (aortic valve 52%, mitral valve 62%, tricuspid valve 76%). Spin-echo MRI is a sensitive and specific method for the noninvasive assessment of congenital heart disease, with limitations in the evaluation of some valvular anomalies.

Evaluation of complex congenital ventricular anomalies with magnetic resonance imaging.

Complex ventricular anomalies are frequently associated with abnormalities of thoracic and abdominal situs, arterioventricular connection, and venous connection. The definition of all components of these anomalies is difficult to accomplish with imaging techniques. This study compared the effectiveness of electrocardiographic (ECG) gated spin-echo magnetic resonance imaging (MRI) with cardiac angiography for the evaluation of all components of central cardiovascular anatomy in patients with the clinical diagnosis of single or common ventricle or complete atrioventricular (AV) septal (canal) defect. MRI studies and angiograms of 29 patients were evaluated independently. A sequential approach was used to define cardiac anatomy assessing nine anatomic features in each patient. MRI provided 261 observations and angiography provided 209 observations. In the mutual 209 observations, only 17 discrepancies were found. Comparison of MRI and angiography in individual cases showed that MRI was as effective as angiography in the depiction of ventricular anomalies, including determination of morphology and evaluation of the size of the ventricles, the orientation of the ventricular septum relative to the AV valves, as well as the origins and spatial relationships of the great arteries. MRI was more informative for the determination of thoracic and abdominal situs and systemic and pulmonary venoatrial connections, but was not as effective for the evaluation of semilunar valves. Thus MRI provides complete evaluation of central cardiovascular anatomy and is effective in the anatomic assessment of most components of complex ventricular anomalies.