Prenatal Diagnosis of Thoracic Ectopia Cordis by Real‐time Fetal Cardiac Magnetic Resonance Imaging and by Echocardiography

Ectopia cordis is a rare congenital defect commonly associated with intra‐ and extra‐cardiac anomalies. This report highlights the complimentary use of echocardiography and cardiac magnetic resonance imaging for detailed prenatal characterization of the anomaly at 23‐week gestation.     

Late Presentation of Pulmonary Valve Stenosis Confirmed by Cardiovascular Magnetic Resonance

We describe the case of a 70‐year‐old man who presented with increasing exertional dyspnea. He was found to have an ejection systolic murmur and evidence of right ventricular outflow tract obstruction, with a peak velocity of 4.5 m/s recorded by transthoracic Doppler echocardiography. Cardiovascular magnetic resonance showed right ventricular hypertrophy, pulmonary valve stenosis, peak recorded velocity 4.2 m/s, with thickened pulmonary valve leaflets of reduced mobility, and poststenotic dilatation of the main pulmonary artery. The case illustrates that severe pulmonary valve stenosis can present late in life and that cardiovascular magnetic resonance can be useful in clarifying nature and level of right ventricular outflow tract obstruction in an adult.     

Assessment of Right Ventricular Size and Function: Echo Versus Magnetic Resonance Imaging

Objective. The assessment of right ventricular (RV) size and function is important in the management of many patients with heart disease. Although magnetic resonance imaging (MRI) is considered the gold standard for quantitation of ventricular volumes and systolic function, subjective assessment (“eyeball”) by echocardiography is the modality most often used for the RV. The echocardiographic “eyeball” method of assessing RV size and systolic function was compared with quantitative MRI. Design. Patients with right-sided congenital heart disease who underwent an echocardiogram within 6 months of MRI formed the study group. Four echocardiographers blinded to the MRI results reviewed the echocardiograms to subjectively assess RV size and systolic function. The reliability of an echocardiographer in accurately identifying a severely dilated RV and moderately to severely diminished RV systolic function was measured using the Kappa coefficient. Inter-rater agreement was also assessed using Kappa. Results. The study group consisted of 22 patients aged 16.6 ± 7.1 years, with interval between MRI and echocardiogram of 49 ± 54 days. Using echocardiography, reliability for accurately identifying a severely dilated RV was “slight” with a prevalence-adjusted bias-adjusted Kappa (PABAK) of 0.25; and for identifying moderately to severely diminished RV systolic function was fair with a PABAK of 0.43. Inter-rater agreement analysis was poor for both with Kappas of 0.07 (P = .22) and 0.12 (P = .09), respectively. Conclusion. The usefulness of the echocardiographic “eyeball” method to estimate RV size and systolic function in patients with right heart disease has limitations when compared with MRI, specifically in regard to the variability between echocardiographers.     

Comparison between Transthoracic Echocardiography and Cardiac Magnetic Resonance Imaging in Patients Status Post Atrial Switch Procedure

Objectives. This study compares image quality, cost, right ventricular ejection fraction analysis, and baffle visualization between transthoracic echocardiography and cardiac magnetic resonance imaging in those status post atrial switch for transposition of the great arteries. Background. This population requires imaging for serial evaluations. Transthoracic echocardiography is often first line but has drawbacks, many of which are addressed by cardiac magnetic resonance imaging. Methods. Twelve patients (mean age 25 years) with relatively concurrent (mean 157 days) studies were included. Three separate echocardiography and magnetic resonance imaging physicians independently analyzed baffles, image quality, and right ventricular ejection fractions. Institutional and Medicaid charges were compared. Results. For right ventricular ejection fraction, echocardiography (36.1%) underestimated cardiac magnetic resonance imaging (47.8%, P= .002). Image quality for transthoracic echocardiography was significantly rated lower than cardiac magnetic resonance imaging (P= .002). Baffles were better seen in cardiac magnetic resonance imaging (transthoracic echocardiography vs. cardiac magnetic resonance imaging: superior vena cava 86% vs. 100% [P= .063]; inferior vena cava 33% vs. 97% [P= .002]; pulmonary vein 92% vs. 100% [P= .250]). Comparing hospital charges and Medicaid reimbursement, transthoracic echocardiography respectively costs 18% and 38% less than cardiac magnetic resonance imaging. Conclusions. In conclusion, transthoracic echocardiography underestimated right ventricular ejection fraction compared to cardiac magnetic resonance imaging. Cardiac magnetic resonance imaging had consistently higher image quality and better visualization of the baffles. Cost differences are minimal. We propose that cardiac magnetic resonance imaging be considered first line for imaging in certain patients' status post atrial switch procedure.     

Hemitruncus Arteriosus: Cardiac Magnetic Resonance Angiography Findings

Hemitruncus arteriosus (HA) is an uncommon congenital cardiac malformation in which one pulmonary artery branch originates from the ascending aorta. A 2‐month‐old male was referred to our hospital for failure to thrive, cyanosis, and tachypnea. A chest radiograph demonstrated moderate cardiomegaly and peribronchial thickening. Echocardiography demonstrated right atrial and ventricular enlargement and increased gradient (25 mm Hg) in the right pulmonary artery. Cardiac magnetic resonance angiography was performed and clearly revealed typical imaging findings of a right HA which had complex cardiac and vascular anatomy. This case report presents cardiac magnetic resonance angiography findings of HA.     

Evaluation of Adult Congenital Heart Disease by Cardiac Magnetic Resonance Imaging

Cardiovascular magnetic resonance (CMR) imaging plays an essential role in the evaluation and follow‐up of adult congenital heart disease (ACHD), providing safe, high‐resolution imaging of some of the most complex anatomies encountered. Unlimited by acoustic windows and capable of tissue characterization, CMR is devoid of ionizing radiation and provides superior three‐dimensional spatial resolution to transthoracic echocardiography and superior temporal resolution to computed tomography, making it the gold standard for various cardiac and great vessel imaging indications in ACHD. In this state‐of‐the art review, we provide an overview of CMR examination methods and detail the various approaches and classical findings in the more common forms of ACHD. Although this review touches upon technical aspects of CMR imaging in ACHD, it is primarily geared toward the adult congenital caregiver (i.e., clinical, interventional, or surgical), highlighting relevant practical considerations. To enhance the clinical utility of this review, numerous examples with intraoperative correlates are provided to highlight our imaging approaches for various defects. As CMR image acquisition may be time consuming and requires patient collaboration (e.g., intermittent breath holding), a systemic approach is required to maximize efficiency. A thorough knowledge of ACHD anatomy and natural history is essential in maximizing image interpretation. Proficient scanning is further enabled by clearly outlined study objectives with prior documentation of interventional and surgical procedures, where applicable.     

Pulmonary Arterial Hypertension: Use of Delayed Contrast-Enhanced Cardiovascular Magnetic Resonance in Risk Assessment

Background

Pulmonary arterial hypertension is a severe and progressive disease. Its early diagnosis is the greatest clinical challenge.

Objective

To evaluate the presence and extension of the delayed myocardial contrast-enhanced cardiovascular magnetic resonance, as well as to verify if the percentage of the myocardial fibrosis mass is a severity predictor.

Methods

Cross-sectional study with 30 patients with pulmonary arterial hypertension of groups I and IV, subjected to clinical, functional and hemodynamic evaluation, and to cardiac magnetic resonance.

Results

The mean age of patients was 52 years old, with female predominance (77%). Among the patients, 53% had right ventricular failure at diagnosis, and 90% were in functional class II/III. The mean of the 6-minute walk test was 395m. In hemodynamic study with right catheterism, the mean average pulmonary arterial pressure was 53.3mmHg, of the cardiac index of 2.1L/ min.m², and median right atrial pressure was 13.5 mmHg. Delayed myocardial contrast enhanced cardiovascular magnetic resonance was found in 28 patients. The mean fibrosis mass was 9.9 g and the median percentage of fibrosis mass was 6.17%. The presence of functional class IV, right ventricular failure at diagnosis, 6-minute walk test < 300 meters and right atrial pressure ≥ 15 mmHg, with cardiac index < 2.0 L/ min.m², there was a relevant association with the increased percentage of myocardial fibrosis.

Conclusion

The percentage of the myocardial fibrosis mass indicates a non-invasive marker with promising perspectives in identifying patients with high risk factors for pulmonary hypertension.     

Magnetic Resonance Imaging Evaluation of Cardiac Masses

Background

Cardiac tumors are extremely rare; however, when there is clinical suspicion, proper diagnostic evaluation is necessary to plan the most appropriate treatment. In this context, cardiovascular magnetic resonance imaging (CMRI) plays an important role, allowing a comprehensive characterization of such lesions.

Objective

To review cases referred to a CMRI Department for investigation of cardiac and paracardiac masses. To describe the positive case series with a brief review of the literature for each type of lesion and the role of cardiovascular magnetic resonance imaging in evaluation.

Methods

Between August 2008 and December 2011, all cases referred for CMRI with suspicion of tumor involving the heart were reviewed. Cases with positive histopathological diagnosis, clinical evolution or therapeutic response compatible with the clinical suspicion and imaging findings were selected.

Results

Among the 13 cases included in our study, eight (62%) had histopathological confirmation. We describe five benign tumors (myxomas, rhabdomyoma and fibromas), five malignancies (sarcoma, lymphoma, Richter syndrome involving the heart and metastatic disease) and three non-neoplastic lesions (pericardial cyst, intracardiac thrombus and infectious vegetation).

Conclusion

CMRI plays an important role in the evaluation of cardiac masses of non-neoplastic and neoplastic origin, contributing to a more accurate diagnosis in a noninvasive manner and assisting in treatment planning, allowing safe clinical follow-up with good reproducibility.     

Total Anomalous Pulmonary Venous Connection in an Adult: Comprehensive Multimodality Evaluation

An unusual case of total anomalous pulmonary venous connection surviving to adulthood without surgical correction is presented. Transthoracic echocardiography first led to this diagnosis and magnetic resonance imaging refined the anatomic diagnosis leading to successful surgical correction.     

Magnetic Resonance Imaging Outcomes From a Comprehensive Magnetic Resonance Study of Children With Fetal Alcohol Spectrum Disorders

Background: Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities. Methods: A comprehensive neuropsychological/psychiatric battery, coupled with MR imaging, (MRI), MR spectroscopy (MRS), and functional MRI (fMRI) assessments, were administered to children with fetal alcohol spectrum disorders (FASD) to determine if global and/or focal abnormalities could be identified, and distinguish diagnostic subclassifications across the spectrum. The 4 study groups included: (i) fetal alcohol syndrome (FAS)/partial FAS (PFAS); (ii) static encephalopathy/alcohol exposed (SE/AE); (iii) neurobehavioral disorder/alcohol exposed (ND/AE) as diagnosed with the FASD 4‐Digit Code; and (iv) healthy peers with no prenatal alcohol exposure. Presented here are the MRI assessments that were used to compare the sizes of brain regions between the 4 groups. The neuropsychological/behavioral, MRS, and fMRI outcomes are reported separately. Results: Progressing across the 4 study groups from Controls to ND/AE to SE/AE to FAS/PFAS, the mean absolute size of the total brain, frontal lobe, caudate, putamen, hippocampus, cerebellar vermis, and corpus callosum length decreased incrementally and significantly. The FAS/PFAS group (the only group with the 4‐Digit FAS facial phenotype) had disproportionately smaller frontal lobes relative to all other groups. The FAS/PFAS and SE/AE groups [the 2 groups with the most severe central nervous system (CNS) dysfunction] had disproportionately smaller caudate regions relative to the ND/AE and Control groups. The prevalence of subjects in the FAS/PFAS, SE/AE, and ND/AE groups that had 1 or more brain regions, 2 or more SDs below the mean size observed in the Control group was 78, 58, and 43%, respectively. Significant correlations were observed between size of brain regions and level of prenatal alcohol exposure, magnitude of FAS facial phenotype, and level of CNS dysfunction. Conclusions: Magnetic resonance imaging provided further validation that ND/AE, SE/AE, and FAS/PFAS as defined by the FASD 4‐Digit Code are 3 clinically distinct and increasingly more affected diagnostic subclassifications under the umbrella of FASD. Neurostructural abnormalities are present across the spectrum. MRI could importantly augment diagnosis of conditions under the umbrella of FASD, once population‐based norms for structural development of the human brain are established.     

Magnetic Resonance Spectroscopic Imaging of Ethanol in the Human Brain: A Feasibility Study

The in vivo distribution of ethanol in normal human brain following the consumption of a moderate amount of alcohol was measured using magnetic resonance spectroscopic imaging. Three subjects were studied, and the spatial distribution of brain ethanol, 60-min postingestion and measured at a spatial resolution of 1.5 cm, was found to be highly nonuniform with the relative ethanol signal in cerebral spinal fluid, gray matter, and white matter determined to be 1.00, 0.72, and 0.37, respectively. These spectroscopic imaging results indicate that whereas in vivo magnetic resonance studies of ethanol are feasible, quantitative studies of alcohol need to account carefully for the various tissue types within the observed volume.     

Resonant Mode Reduction in Radiofrequency Volume Coils for Ultrahigh Field Magnetic Resonance Imaging

In a multimodal volume coil, only one mode can generate homogeneous Radiofrequency (RF) field for Magnetic Resonance Imaging. The existence of other modes may increase the volume coil design difficulties and potentially decreases coil performance. In this study, we introduce common-mode resonator technique to high and ultrahigh field volume coil designs to reduce the resonant mode while maintain the homogeneity of the RF field. To investigate the design method, the common-mode resonator was realized by using a microstrip line which was split along the central to become a pair of parallel transmission lines within which common-mode currents exist. Eight common-mode resonators were placed equidistantly along the circumference of a low loss dielectric cylinder to form a volume coil. Theoretical analysis and comparison between the 16-strut common-mode volume coil and a conventional 16-strut volume coil in terms of RF field homogeneity and efficiency was performed using Finite-Difference Time-Domain (FDTD) method at 298.2 MHz. MR imaging experiments were performed by using a prototype of the common-mode volume coil on a whole body 7 Tesla scanner. FDTD simulation results showed the reduced number of resonant modes of the common-mode volume coil over the conventional volume coil, while the RF field homogeneity of the two type volume coils was kept at the same level. MR imaging of a water phantom and a kiwi fruit showing the feasibility of the proposed method for simplifying the volume coil design is also presented.     

Alcoholic Myopathy: Evaluation with Magnetic Resonance Imaging—A Case Study

Magnetic resonance imaging (MRI) of thigh and leg muscles was performed in a patient with alcoholic myopathy showing myalgia, hypercreatine kinasemia, and hypermyoglobinemia. High signal intensities in both T₁- and T₂-weighted images were widely distributed in the affected muscle groups, which most likely reflected lipid accumulation. Although he had hypermyoglobinemia, MRI and muscle biopsy did not show findings of rhabdomyolysis, such as necrosis, regeneration, and edema. We suggest that the high signal intensities in this case may have indicated „prerhabdomyolysis” related to alcohol abuse and that muscle MRI is useful in the evaluation of alcoholic myopathy, mainly predicting the onset of rhabdomyolysis.     

The Use of Magnetic Resonance Methods in Translational Cardiovascular Research

Magnetic resonance methods are widely applicable to research questions posed in translational cardiovascular studies. The main intent of this review was to offer the cardiovascular translational research scientist a “menu” of magnetic resonance (MR) approaches that can be applied to answering research questions posed in a variety of experimental situations including those involving the use of human subjects. Obviously, this menu is not comprehensive and many other topics could have been selected for emphasis. However, we hope that the material presented encompasses a broad enough slice of the field to stimulate thinking about the possible applications of MR methods to specific research questions.