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Background: Myocardial fibrosis is a common pathophysiological process that is related to ventricular remodeling in congenital heart disease. However, the presence, characteristics, and clinical significance of myocardial fibrosis in Ebstein's anomaly have not been fully investigated. This study aimed to evaluate myocardial fibrosis using cardiovascular magnetic resonance (CMR) late gadolinium enhancement (LGE) and T1 mapping techniques, and to explore the significance of myocardial fibrosis in adolescent and adult patients with Ebstein's anomaly., Methods: Forty-four consecutive patients with unrepaired Ebstein's anomaly (34.0 ± 16.2 years; 18 males), and an equal number of age- and gender-matched controls, were included. A comprehensive CMR protocol consisted of cine, LGE, and T1 mapping by modified Look-Locker inversion recovery (MOLLI) sequences were performed. Ventricular functional parameters, native T1, extracellular volume (ECV), and LGE were analyzed. Associations between myocardial fibrosis and disease severity, ventricular function, and NYHA classification were analyzed., Results: LGE was found in 10 (22.7%) patients. Typical LGE in Ebstein's anomaly was located in the endocardium of the septum within the right ventricle (RV). The LV ECV of Ebstein's anomaly were significantly higher than those of the controls (30.0 ± 3.8% vs. 25.3 ± 2.3%, P < 0.001). An increased ECV was found to be independent of the existence of LGE. Positive LGE or higher ECV (≥30%) was associated with larger fRV volume, aRV volume, increased disease severity, and worse NYHA functional class. In addition, ECV was significantly correlated with the LV ejection fraction (P <  0.001)., Conclusions: Both focal and diffuse myocardial fibrosis were observed in adolescent and adult patients with Ebstein's anomaly. Increased diffuse fibrosis is associated with worse LV function, increased Ebstein's severity, and worse clinical status.

Purpose: To evaluate the feasibility of a proposed cardiorespiratory-resolved analysis in left ventricular (LV) function quantification from real-time cines in a cohort of cardiac patients., Materials and Methods: Electrocardiograph (ECG)-free free-breathing real-time cine imaging based on the balanced steady-state free precession technique was performed on short-axis slices of 20 cardiac patients at 3T. K-means cluster segmentation was used to delineate the endocardial contours, from which the LV centroid and cavity area were determined. Respiratory and cardiac signals were respectively resolved from the filtered LV centroid displacement and time-varied LV cavity area to identify end-expiratory end-diastolic (ED) and end-systolic (ES) images. The obtained LV cavity areas and derived volumetric function indices, including ED volume (EDV), ES volume (ESV), stroke volume (SV), and ejection fraction (EF), were compared with those measured from manual analysis using two-tailed paired Student's t-tests, linear regression analyses, and Bland-Altman plots. Interobserver variability was calculated., Results: The LV cavity area was strongly correlated between the proposed and conventional manual methods (r > 0.87) for three representative slices at the base, middle ventricle, and apex. The average differences between the two methods were 0.66 ± 3.22 mL for EDV, -0.02 ± 2.68 mL for ESV, 0.67 ± 3.73 mL for SV, and 0.17 ± 2.30% for EF. All paired measures exhibited strong correlations (r > 0.96) without significant differences (P = 0.38-0.98). Acceptable interobserver variability (0.19-3.55%) and strong correlations (r > 0.96) were shown for all measures between the two observers., Conclusion: The proposed method is feasible for efficient measurement of LV function from real-time cines., Level of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:905-914., (© 2017 International Society for Magnetic Resonance in Medicine.)

Background: To develop and assess an efficient method to identify end-expiratory end-diastolic (ED) and end-systolic (ES) images for accurate quantification of left ventricular (LV) function in real-time cine imaging., Methods: ECG-free free-breathing real-time cine imaging was performed on short-axis slices of thirteen healthy volunteers at 3 Tesla. K-means cluster segmentation was applied to delineate the endocardial contour, from which the LV centroid and cavity area were determined in each cine image. LV centroid displacement along the superior-inferior direction was filtered to extract respiratory motion in each slice. End-expiratory ED and ES images were then identified and used for LV function quantification. Accuracy was evaluated with that measured from the slice-matched standard ECG-gated breathhold segmented cines using two-tail paired Student's t-tests, linear regression analyses and Bland-Altman plots. Intra- and interobserver variability was calculated for each imaging technique., Results: Qualitatively, end-expiratory ED and ES images identified with the proposed method agreed with those determined by frame-by-frame visual inspection in 97.5% of cases (P > 0.05). Quantitatively, good agreement of LV function indices between the real-time cine and the standard segmented cine was observed with averaged differences of 0.1 ± 0.9 g for myocardium mass, -0.3 ± 1.0 mL for ED volume, 0.2 ± 1.2 mL for ES volume, -0.2 ± 1.3 mL for stroke volume, and -0.3 ± 0.8% for ejection fraction. Paired LV function values exhibited strong correlation (r ≥ 0.96) and no significant difference (P > 0.05). The real-time cine and the standard segmented cine showed similar intra- (1.2-3.3% and 1.1-2.8%, respectively) and interobserver variability (2.6-6.9% and 1.8-4.8%, respectively) with all P-values > 0.05. All the variability was comparable with published results., Conclusion: Compared with the laborious frame-by-frame visual inspection, as conventionally adopted, the proposed method is efficient in analyzing real-time cines for the accurate quantification of LV function without excessively manual interactions., (© 2015 Wiley Periodicals, Inc.)

Quantitative T₂ mapping was recently shown to be superior to T₂-weighted imaging in detecting T₂ changes across myocardium. Pixel-wise T₂ mapping is sensitive to misregistration between the images used to generate the parameter map. In this study, utility of two motion-compensation strategies-(i) navigator gating with prospective slice correction and (ii) nonrigid registration-was investigated for myocardial T₂ mapping in short axis and horizontal long axis views. Navigator gating provides respiratory motion compensation, whereas registration corrects for residual cardiac and respiratory motion between images; thus, the two strategies provided complementary functions. When these were combined, respiratory-motion-induced T₂ variability, as measured by both standard deviation and interquartile range, was comparable to that in breath-hold T₂ maps. In normal subjects, this combined motion-compensation strategy increased the percentage of myocardium with T₂ measured to be within normal range from 60.1% to 92.2% in short axis and 62.3% to 92.7% in horizontal long axis. The new motion-compensated T₂ mapping technique, which combines navigator gating, prospective slice correction, and nonrigid registration to provide through-plane and in-plane motion correction, enables a method for fully automatic and robust free-breathing T₂ mapping., (Copyright © 2011 Wiley Periodicals, Inc.)

Phase-contrast magnetic resonance imaging (PC-MRI) is used routinely to measure fluid and tissue velocity with a variety of clinical applications. Phase-contrast magnetic resonance imaging methods require acquisition of additional data to enable phase difference reconstruction, making real-time imaging problematic. Shared Velocity Encoding (SVE), a method devised to improve the effective temporal resolution of phase-contrast magnetic resonance imaging, was implemented in a real-time pulse sequence with segmented echo planar readout. The effect of SVE on peak velocity measurement was investigated in computer simulation, and peak velocities and total flow were measured in a flow phantom and in volunteers and compared with a conventional ECG-triggered, segmented k-space phase-contrast sequence as a reference standard. Computer simulation showed a 36% reduction in peak velocity error from 8.8 to 5.6% with SVE. A similar reduction of 40% in peak velocity error was shown in a pulsatile flow phantom. In the phantom and volunteers, volume flow did not differ significantly when measured with or without SVE. Peak velocity measurements made in the volunteers using SVE showed a higher concordance correlation (0.96) with the reference standard than non-SVE (0.87). The improvement in effective temporal resolution with SVE reconstruction has a positive impact on the precision and accuracy of real-time phase-contrast magnetic resonance imaging peak velocity measurements., (Copyright © 2011 Wiley Periodicals, Inc.)

Objectives: The purpose of this study was to evaluate the ability of a novel cardiac magnetic resonance (CMR) real-time phase contrast (RT-PC) flow measurement technique to reveal the discordant respirophasic changes in mitral and tricuspid valve in flow indicative of the abnormal hemodynamics seen in constrictive pericarditis (CP)., Background: Definitive diagnosis of CP requires identification of constrictive hemodynamics with or without pericardial thickening. CMR to date has primarily provided morphological assessment of the pericardium., Methods: Sixteen patients (age 57 ± 13 years) undergoing CMR to assess known or suspected CP and 10 controls underwent RT-PC that acquired simultaneous mitral valve and tricuspid valve inflow velocities over 10 s of unrestricted breathing. The diagnosis of CP was confirmed via clinical history, diagnostic imaging, cardiac catheterization, intraoperative findings, and histopathology., Results: Ten patients had CP, all with increased pericardial thickness (6.2 ± 1.0 mm). RT-PC imaging demonstrated discordant respirophasic changes in atrioventricular valve inflow velocities in all CP patients, with mean ± SD mitral valve and tricuspid valve inflow velocity variation of 46 ± 20% and 60 ± 15%, respectively, compared with 16 ± 8% and 24 ± 11% in patients without CP (p < 0.004 vs. patients with CP for both) and 17 ± 5% and 31 ± 13% in controls (p < 0.001 vs. patients with CP for both). There was no difference in atrioventricular valve inflow velocity variation between patients without CP compared with controls (p > 0.3 for both). Respiratory variation exceeding 25% across the mitral valve yielded a sensitivity of 100%, a specificity of 100%, and an area under the receiver-operating characteristic curve of 1.0 to detect CP physiology. Using a cutoff of 45%, variation of transtricuspid valve velocity had a sensitivity of 90%, a specificity of 88%, and an area under the receiver-operating characteristic curve of 0.98., Conclusions: Accentuated and discordant respirophasic changes in mitral valve and tricuspid valve inflow velocities characteristic of CP can be identified noninvasively with RT-PC CMR. When incorporated into existing CMR protocols for imaging pericardial morphology, RT-PC CMR provides important hemodynamic evidence with which to make a definite diagnosis of CP., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

TSENSE and TGRAPPA are autocalibrated parallel imaging techniques that can improve the temporal resolution and/or spatial resolution in dynamic magnetic resonance imaging applications. In its original form, TSENSE uses temporal low-pass filtering of the undersampled frames to create the sensitivity map. TGRAPPA uses a sliding-window moving average when finding the autocalibrating signals. Both filtering methods are suboptimal in the least-squares sense and may give rise to mismatches between the undersampled k-space raw data and the corresponding coil sensitivities. Such mismatches may result in aliasing artifacts when imaging patients with heavy breathing, as in real-time imaging of wall motion by MRI following a treadmill exercise stress test. In this study, we demonstrate the use of an optimal linear filter, i.e., the Karhunen-Loeve transform filter, to estimate the channel sensitivity for TSENSE and acquire the autocalibration signals for TGRAPPA. Phantom experiments show that the new reconstruction method has comparable signal-to-noise ratio performance to traditional TSENSE/TGRAPPA reconstruction. In vivo real-time cardiac cine experiments performed in five healthy volunteers post-exercise during rapid respiration show that the new method significantly reduces the chest wall aliasing artifacts caused by respiratory motion (P < 0.001)., (Copyright © 2011 Wiley-Liss, Inc.)

Real-time dynamic magnetic resonance imaging (MRI) typically sacrifices the signal-to-noise ratio (SNR) to achieve higher spatial and temporal resolution. Spatial and/or temporal filtering (e.g., low-pass filtering or averaging) of dynamic images improves the SNR at the expense of edge sharpness. We describe the application of a temporal filter for dynamic MR image series based on the Karhunen-Loeve transform (KLT) to remove random noise without blurring stationary or moving edges and requiring no training data. In this paper, we present several properties of this filter and their effects on filter performance, and propose an automatic way to find the filter cutoff based on the autocorrelation of the eigenimages. Numerical simulation and in vivo real-time cardiac cine MR image series spanning multiple cardiac cycles acquired using multi-channel sensitivity-encoded MRI, i.e., parallel imaging, are used to validate and demonstrate these properties. We found that in this application, the noise standard deviation was reduced to 42% of the original with no apparent image blurring by using the proposed filter cutoff. Greater noise reduction can be achieved by increasing the length of the image series. This advantage of KLT filtering provides flexibility in the form of another scan parameter to trade for SNR.

Background: The purpose of this article is to describe a steady-state free precession (SSFP) sequence for fat suppressed cine cardiovascular magnetic resonance (CMR). A rapid phase-modulated binomial water excitation (WE) pulse is utilized to minimize repetition time and acquisition time., Methods: Three different water-excitation pulses were combined with cine-SSFP for evaluation. The frequency response of each sequence was simulated and examined in phantom imaging studies. The ratio of fat to water signal amplitude was measured in phantoms to evaluate the fat suppression capabilities of each method. Six volunteers underwent CMR of the heart at 1.5T to compare retrospectively-gated cine-SSFP with and without water excitation. The ratio of fat to myocardium signal amplitude was measured for conventional cine-SSFP and phase-modulated WE-SSFP. The proposed WE-SSFP method was tested in one patient referred for CMR to characterize a cardiac mass., Results and Discussion: The measured frequency response in a phantom corresponded to the numerical Bloch equation simulation demonstrating the widened stop-band around the fat resonant frequency for all water-excitation pulses tested. In vivo measurements demonstrated that a rapid, phase-modulated water excitation pulse significantly reduced the signal amplitude ratio of fat to myocardium from 6.92 +/- 2.9 to 0.8 +/- 0.13 (mean +/- SD) without inducing any perceptible artifacts in SSFP cine CMR., Conclusion: Fat suppression can be achieved in SSFP cine CMR while maintaining steady-state equilibrium using rapid, phase modulated, binomial water-excitation pulses.

This study was performed by using an institutional review board-approved protocol, with waived informed consent and HIPAA compliance. The purpose of this study was to preliminarily evaluate a cine delayed-enhancement (DE) pulse sequence for depiction of wall motion and myocardial scar extent during a single acquisition. The technique is based on inversion-recovery single-shot balanced steady-state free precession magnetic resonance imaging. Cine DE images were acquired in 26 patients (18 men, eight women; age range, 25-84 years; mean age, 61 years+/-13 [standard deviation]). Image contrast was consistent throughout each series. Overall (ie, with both readers' scores averaged), the cine DE imaging-depicted wall motion was scored correctly in 71% of myocardial segments. Scar extent was scored correctly in 76% of segments; in no patient was scarring missed. Cine DE imaging is a promising technique for simultaneous visualization of wall motion and myocardial scar extent., (Copyright (c) RSNA, 2006.)

Purpose: To evaluate the consistency and inversion time (TI) independence of phase-sensitive reconstruction (PSIR) delayed-enhancement (DE) MRI in a clinical setting., Materials and Methods: Mid-ventricular short-axis DE images were acquired in 25 patients using three TIs: 1) optimized to null viable myocardium, 2) 50 msec less than optimal TI, and 3) 50 msec greater than optimal TI. At each TI, images were acquired with PSIR and without magIR. In each image, percent scar was computed as the ratio of nonviable to total pixels in the left ventricle (LV)., Results: In the magIR images, percent scar was 23% +/- 15% (optimal), 11% +/- 11% (short), and 22% +/- 15% (long). In PSIR images, percent scar was 25% +/- 15% (optimal), 22% +/- 15% (short), and 22% +/- 14% (long). Percent scar was significantly underestimated in magIR images with short TI, but no statistically significant difference in percent scar was observed at the optimal or long TIs., Conclusion: DE-MRI is a robust imaging technique for clinical use. PSIR provided consistent image quality independently of TI, at least over the range of TIs evaluated in this study. However, neither image quality nor scar appearance in the PSIR images was significantly different from that in the magIR images when TI was at or above the null point of viable myocardium.

Seventeen patients underwent magnetic resonance (MR) imaging for myocardial viability with a protocol approved by the institutional review board and gave written informed consent. Breath-hold cine inversion-recovery segmented k-space true fast imaging with steady-state precession sequence, referred to as inversion time (TI) mapping, was performed to determine optimal TI for myocardial infarction inversion-recovery imaging. From TI mapping, optimal TI was 180-315 msec 10-15 minutes after administration of 0.15 mmol/kg of gadolinium-based contrast material. At that optimal TI, relative signal intensity of infarcted myocardium compared with uninfarcted myocardium was maximal (mean +/- standard deviation, 297.8% +/- 86.5), whereas signal-to-noise ratio of uninfarcted myocardium was minimal (4.5 +/- 1.2). When applied to conventional myocardial infarction inversion-recovery imaging, optimal TI resulted in nulling of signal intensity of uninfarcted myocardium in all patients and in excellent conspicuity of infarcted myocardium in all nine patients with visible infarction., ((c) RSNA, 2004)