Improved workflow for quantification of left ventricular volumes and mass using free-breathing motion corrected cine imaging

Free-Breathing Compressed Sensing Cine Cardiac MRI for Assessment of Left Ventricular Strain by Feature Tracking in Children

BACKGROUND

Cardiac MRI feature-tracking (FT) with breath-holding (BH) cine balanced steady state free precession (bSSFP) imaging is well established. It is unclear whether FT-strain measurements can be reliably derived from free-breathing (FB) compressed sensing (CS) bSSFP imaging.

PURPOSE

To compare left ventricular (LV) strain analysis and image quality of an FB CS bSSFP cine sequence with that of a conventional BH bSSFP sequence in children.

STUDY TYPE

Prospective.

SUBJECTS

40 children able to perform BHs (cohort 1 [12.1 ± 2.2 years]) and 17 children unable to perform BHs (cohort 2 [5.2 ± 1.8 years]).

FIELD STRENGTH/SEQUENCE

3T, bSSFP sequence with and without CS.

ASSESSMENT

Acquisition times and image quality were assessed. LV myocardial deformation parameters were compared between BH cine and FB CS cine studies in cohort 1. Strain indices and image quality of FB CS cine studies were also assessed in cohort 2. Intraobserver and interobserver variability of strain parameters was determined.

STATISTICAL TESTS

Paired t-test, Wilcoxon signed-rank test, intraclass correlation coefficient (ICC), and Bland-Altman analysis. A P-value <0.05 was considered statistically significant.

RESULTS

In cohort 1, the mean acquisition time of the FB CS cine study was significantly lower than for conventional BH cine study (15.6 s vs. 209.4 s). No significant difference were found in global circumferential strain rate (P = 0.089), global longitudinal strain rate (P = 0.366) and EuroCMR image quality scores (P = 0.128) between BH and FB sequences in cohort 1. The overall image quality score of FB CS cine in cohort 2 was 3.5 ± 0.5 with acquisition time of 14.7 ± 2.1 s. Interobserver and intraobserver variabilities were good to excellent (ICC = 0.810 to 0.943).

DATA CONCLUSION

FB CS cine imaging may be a promising alternative technique for strain assessment in pediatric patients with poor BH ability.

LEVEL OF EVIDENCE

1 TECHNICAL EFFICACY: Stage 1.

ESR Essentials: ten steps to cardiac MR-practice recommendations by ESCR

Cardiovascular MR imaging has become an indispensable noninvasive tool in diagnosing and monitoring a broad range of cardiovascular diseases. Key to its clinical success and efficiency are appropriate clinical indication triage, technical expertise, patient safety, standardized preparation and execution, quality assurance, efficient post-processing, structured reporting, and communication and clinical integration of findings. Technological advancements are driving faster, more accessible, and cost-effective approaches. This ESR Essentials article presents a ten-step guide for implementing a cardiovascular MR program, covering indication assessments, optimized imaging, post-processing, and detailed reporting. Future goals include streamlined protocols, improved tissue characterization, and automation for greater standardization and efficiency.

CLINICAL RELEVANCE STATEMENT

The growing clinical role of cardiovascular MR in risk assessment, diagnosis, and treatment planning highlights the necessity for radiologists to achieve expertise in this modality, advancing precision medicine and healthcare efficiency.

KEY POINTS

• Cardiovascular MR is essential in diagnosing and monitoring many acute and chronic cardiovascular pathologies. • Features such as technical expertise, quality assurance, patient safety, and optimized tailored imaging protocols, among others, are essential for a successful cardiovascular MR program. • Ongoing technological advances will push rapid multi-parametric cardiovascular MR, thus improving accessibility, patient comfort, and cost-effectiveness.

KEY POINTS

• Cardiovascular MR is essential in diagnosing and monitoring a wide array of cardiovascular pathologies (Level of Evidence: High). • A successful cardiovascular MR program depends on standardization (Level of Evidence: Low). • Future developments will increase the efficiency and accessibility of cardiovascular MR (Level of Evidence: Low).

Retrospective motion correction through multi-average k-space data elimination (REMAKE) for free-breathing cardiac cine imaging

PURPOSE

To develop a motion-robust reconstruction technique for free-breathing cine imaging with multiple averages.

METHOD

Retrospective motion correction through multiple average k-space data elimination (REMAKE) was developed using iterative removal of k-space segments (from individual k-space samples) that contribute most to motion corruption while combining any remaining segments across multiple signal averages. A variant of REMAKE, termed REMAKE+, was developed to address any losses in SNR due to k-space information removal. With REMAKE+, multiple reconstructions using different initial conditions were performed, co-registered, and averaged. Both techniques were validated against clinical "standard" signal averaging reconstruction in a static phantom (with simulated motion) and 15 patients undergoing free-breathing cine imaging with multiple averages. Quantitative analysis of myocardial sharpness, blood/myocardial SNR, myocardial-blood contrast-to-noise ratio (CNR), as well as subjective assessment of image quality and rate of diagnostic quality images were performed.

RESULTS

In phantom, motion artifacts using "standard" (RMS error [RMSE]: 2.2 ± 0.5) were substantially reduced using REMAKE/REMAKE+ (RMSE: 1.5 ± 0.4/1.0 ± 0.4, p < 0.01). In patients, REMAKE/REMAKE+ led to higher myocardial sharpness (0.79 ± 0.09/0.79 ± 0.1 vs. 0.74 ± 0.12 for "standard", p = 0.004/0.04), higher image quality (1.8 ± 0.2/1.9 ± 0.2 vs. 1.6 ± 0.4 for "standard", p = 0.02/0.008), and a higher rate of diagnostic quality images (99%/100% vs. 94% for "standard"). Blood/myocardial SNR for "standard" (94 ± 30/33 ± 10) was higher vs. REMAKE (80 ± 25/28 ± 8, p = 0.002/0.005) and tended to be lower vs. REMAKE+ (105 ± 33/36 ± 12, p = 0.02/0.06). Myocardial-blood CNR for "standard" (61 ± 22) was higher vs. REMAKE (53 ± 19, p = 0.003) and lower vs. REMAKE+ (69 ± 24, p = 0.007).

CONCLUSIONS

Compared to "standard" signal averaging reconstruction, REMAKE and REMAKE+ provide improved myocardial sharpness, image quality, and rate of diagnostic quality images.

Effect of General Anesthesia on Cardiac Magnetic Resonance-Derived Cardiac Function in Repaired Tetralogy of Fallot

Cardiac magnetic resonance imaging (CMR)-derived ejection fraction (EF) predicts adverse outcomes in repaired tetralogy of Fallot (rTOF) and drives timing of pulmonary valve replacement. Certain patient populations require sedation for successful CMR image acquisition. General anesthesia (GA) has been shown to depress EF and heart rate (HR) in animal models, however, its effect on congenital heart disease is unknown. A retrospective review was conducted of all CMR patients referred with rTOF between January 2011 and May 2019. The cohort was separated into GA and non-GA groups. Propensity score matching (PSM) adjusted for selection bias. A kernel matching algorithm was used to match subjects and the differences in mean treatment effect on the treated were computed for left ventricular (LV) and right ventricular (RV) EF, HR, and cardiac index (CI). 143 patients met criteria, 37 patients under GA (mean age 15 years, range 2-45, 59% male), and 106 patients without GA (mean age 21 years, range 10-53, 50% male). Unmatched analysis showed significant depression of LV EF (50 vs. 57%, p < 0.001) and RV EF (42 vs. 48%, p < 0.001) in the GA group compared to the non-GA group. There was no significant difference in HR or CI. After matching and PSM adjustment, the GA group had a significant decrease in LV EF (49 vs. 56%, p < 0.001), RV EF (41 vs. 48%, p < 0.001), CI (2728 vs. 3701 ml/min/m², p < 0.001), and HR (72 vs. 79 bpm, p = 0.04). General anesthesia with sevoflurane results in depressed CMR-derived EF.

Motion-corrected cardiac MRI is associated with decreased anesthesia exposure in children

BACKGROUND

The benefits of cardiac magnetic resonance imaging (MRI) in the pediatric population must be balanced with the risk and cost of anesthesia. Segmented imaging using multiple averages attempts to avoid breath-holds requiring general anesthesia; however, cardiorespiratory artifacts and prolonged scan times limit its use. Thus, breath-held imaging with general anesthesia is used in many pediatric centers. The advent of free-breathing, motion-corrected (MOCO) cines by real-time re-binned reconstruction offers reduced anesthesia exposure without compromising image quality.

OBJECTIVE

This study evaluates sedation utilization in our pediatric cardiac MR practice before and after clinical introduction of free-breathing MOCO imaging for cine and late gadolinium enhancement.

MATERIALS AND METHODS

In a retrospective study, patients referred for a clinical cardiac MR who would typically be offered sedation for their scan (n=295) were identified and divided into two eras, those scanned before the introduction of MOCO cine and late gadolinium enhancement sequences and those scanned following their introduction. Anesthesia use was compared across eras and disease-specific cohorts.

RESULTS

The incidence of non-sedation studies performed in children nearly tripled following the introduction of MOCO imaging (25% [pre-MOCO] to 69% [post-MOCO], P<0.01), with the greatest effect in patients with simple congenital heart disease. Eleven percent of the post-MOCO cohort comprised infants younger than 3 months of age who could forgo sedation with the combination of MOCO imaging and a "feed-and-bundle" positioning technique.

CONCLUSION

Implementation of cardiac MR with MOCO cine and late gadolinium enhancement imaging in a pediatric population is associated with significantly decreased sedation utilization.

Quantitative cardiac magnetic resonance T2 imaging offers ability to non-invasively predict acute allograft rejection in children

BACKGROUND

Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection.

METHODS

Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Student's t-tests analysis.

RESULTS

Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001).

CONCLUSIONS

Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children.

A comparison of cine CMR imaging at 0.55 T and 1.5 T

BACKGROUND

There is a renewed interest in lower field magnetic resonance imaging (MRI) systems for cardiovascular magnetic resonance (CMR), due to their favorable physical properties, reduced costs, and increased accessibility to patients with implants. We sought to assess the diagnostic capabilities of high-performance low-field (0.55 T) CMR imaging for quantification of right and left ventricular volumes and systolic function in both healthy subjects and patients referred for clinical CMR.

METHODS

Sixty-five subjects underwent paired exams at 1.5 T using a clinical CMR scanner and using an identical CMR system modified to operate at 0.55 T. Volumetric coverage of the right ventricle (RV) and left ventricles (LV) was obtained using either a breath-held cine balanced steady-state free-precession acquisition or a motion-corrected free-breathing re-binned cine acquisition. Bland-Altman analysis was used to compare LV and RV end-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF), and LV mass. Diagnostic confidence was scored on a Likert-type ordinal scale by blinded readers.

RESULTS

There were no significant differences in LV and RV EDV between the two scanners (e.g., LVEDV: p = 0.77, bias = 0.40 mL, correlation coefficient = 0.99; RVEDV: p = 0.17, bias = - 1.6 mL, correlation coefficient = 0.98), and regional wall motion abnormality scoring was similar (kappa 0.99). Blood-myocardium contrast-to-noise ratio (CNR) at 0.55 T was 48 ± 7% of the 1.5 T CNR, and contrast was sufficient for endocardial segmentation in all cases. Diagnostic confidence of images was scored as "good" to "excellent" for the two field strengths in the majority of studies.

CONCLUSION

A high-performance 0.55 T system offers good bSSFP CMR image quality, and quantification of biventricular volumes and systolic function that is comparable to 1.5 T in patients.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03331380, NCT03581318.

Normal right and left ventricular volumes prospectively obtained from cardiovascular magnetic resonance in awake, healthy, 0- 12 year old children

INTRODUCTION

Pediatric z scores are necessary to describe size and structure of the heart in growing children, however, development of an accurate z score calculator requires robust normal datasets, which are difficult to obtain with cardiovascular magnetic resonance (CMR) in children. Motion-corrected (MOCO) cines from re-binned, reconstructed real-time cine offer a free-breathing, rapid acquisition resulting in cines with high spatial and temporal resolution. In combination with child-friendly positioning and entertainment, MOCO cine technique allows for rapid cine volumetry in patients of all ages without sedation. Thus, our aim was to prospectively enroll normal infants and children birth-12 years for creation and validation of a z score calculator describing normal right ventricular (RV) and left ventricular (LV) size.

METHODS

With IRB approval and consent/assent, 149 normal children successfully underwent a brief noncontrast CMR on a 1.5 T scanner including MOCO cines in the short axis, and RV and LV volumes were measured. 20% of scans were re-measured for interobserver variability analyses. A general linear modeling (GLM) framework was employed to identify and properly represent the relationship between CMR-based assessments and anthropometric data. Scatter plots of model fit and Akaike's information criteria (AIC) results were used to guide the choice among alternative models.

RESULTS

A total of 149 subjects aged 22 days-12 years (average 5.1 ± 3.6 years), with body surface area (BSA) range 0.21-1.63 m2 (average 0.8 ± 0.35 m2) were scanned. All ICC values were > 95%, reflecting excellent agreement between raters. The model that provided the best fit of volume measure to the data included BSA with higher order effects and gender as independent variables. Compared with earlier z score models, there is important additional growth inflection in early toddlerhood with similar z score prediction in later childhood.

CONCLUSIONS

Free-breathing, MOCO cines allow for accurate, reliable RV and LV volumetry in a wide range of infants and children while awake. Equations predicting fit between LV and RV normal values and BSA are reported herein for purposes of creating z scores.

TRIAL REGISTRATION

clinicaltrials.gov NCT02892136, Registered 7/21/2016.

Complete Free-breathing Adenosine Stress Cardiac MRI Using Compressed Sensing and Motion Correction: Comparison of Functional Parameters, Perfusion, and Late Enhancement with the Standard Breath-holding Examination

PURPOSE

To compare free-breathing (FB) stress cardiac MRI examinations with the reference standard breath-holding (BH) examination.

MATERIALS AND METHODS

A total of 40 consecutive patients were enrolled prospectively and were examined with 3-T MRI. Functional imaging, perfusion, and late gadolinium enhancement (LGE) sequences were performed in BH and FB by using compressed sensing and in-line motion correction. Left ventricle (LV) and right ventricle (RV) functional parameters in BH and FB examinations were compared by using Bland-Altman plots and linear mixed models. Subjective image quality was assessed with a five-point scale (1 = nondiagnostic, 5 = very good). For perfusion and LGE imaging, diagnostic confidence was rated with a three-point scale (1 = low, 3 = high), and image quality was rated with a five-point scale (1 = nondiagnostic, 5 = very good). The Wilcoxon test was used to compare image quality and diagnostic confidence.

RESULTS

Bland-Altman plots showed good agreement for LV and RV functional parameters in BH and FB sequences. Subjective image quality was significantly better with the BH sequences in the LV (P < .01) but was comparable in the RV (P > .99). Scanning time was 218 seconds (range, 130-385 seconds) for cine BH and 16 seconds (range, 11-27 seconds) for cine FB. Extent of perfusion defects, LGE, and diagnostic confidence was comparable between groups. Scanning time was 371 seconds (range, 239-502 seconds) for the LGE BH sequence and 189 seconds (range, 122-286 seconds) for the LGE FB sequence.

CONCLUSION

FB adenosine stress cardiac MRI delivers diagnostic image quality and could represent an alternative for use in patients who are unable to meet the demands of multiple BHs and long examination times.© RSNA, 2019.

The evolving role of cardiac magnetic resonance in primary mitral regurgitation: ready for prime time?

A fifth of patients with primary degenerative mitral regurgitation continue to present with de novo ventricular dysfunction following surgery and higher rates of heart failure, morbidity, and mortality. This raises questions as to why the left ventricle (LV) might fail to recover and has led to support for better LV characterization; cardiac magnetic resonance (CMR) may play a role in this regard, pending further research and outcome data. CMR has widely acknowledged advantages, particularly in repeatability of measurements of volume and ejection fraction, yet recent guidelines relegate its use to cases where there is discordant information or poor-quality imaging from echocardiography because of the lack of data regarding the CMR-based ejection fraction threshold for surgery and CMR-based outcome data. This article reviews the current evidence regarding the role of CMR in an integrated surveillance and surgical timing programme.

Improved Workflow for Quantification of Right Ventricular Volumes Using Free-Breathing Motion Corrected Cine Imaging

Cardiac MR traditionally requires breath-holding for cine imaging. Younger or less stable patients benefit from free-breathing during cardiac MR but current free-breathing cine images can be spatially blurred. Motion corrected re-binning (MOC) is a novel approach that acquires and then reformats real-time images over multiple cardiac cycles with high spatial resolution. The technique was previously limited by reconstruction time but distributed computing has reduced these times. Using this technique, left ventricular volumetry has compared favorably to breath-held balanced steady-state free precession cine imaging (BH), the current gold-standard, however, right ventricular volumetry validation remains incomplete, limiting the applicability of MOC in clinical practice. Fifty subjects underwent cardiac MR for evaluation of right ventricular size and function by end-diastolic (EDV) and end-systolic (ESV) volumetry. Measurements using MOC were compared to those using BH. Pearson correlation coefficients and Bland-Altman plots tested agreement across techniques. Total scan plus reconstruction times were tested for significant differences using paired t-test. Volumes obtained by MOC compared favorably to BH (R = 0.9911 for EDV, 0.9690 for ESV). Combined acquisition and reconstruction time (previously reported) were reduced 37% for MOC, requiring a mean of 5.2 min compared to 8.2 min for BH (p < 0.0001). Right ventricular volumetry compares favorably to BH using MOC image reconstruction, but is obtained in a fraction of the time. Combined with previous validation of its use for the left ventricle, this novel method now offers an alternative imaging approach in appropriate clinical settings.

Validation of cardiac magnetic-resonance-derived left ventricular strain measurements from free-breathing motion-corrected cine imaging

BACKGROUND

Myocardial strain is an important measure of cardiac function and can be assessed on cardiac magnetic resonance (MR) through the current gold standard of breath-held segmented steady-state free precession (SSFP) cine imaging. Novel free-breathing techniques have been validated for volumetry and systolic function, allowing for evaluation of sicker and younger children who cannot reliably hold their breath. It is unclear whether strain measurements can be reliably performed on free-breathing, motion-corrected, re-binning cine images.

OBJECTIVE

To compare strain analysis from motion-corrected retrospective re-binning images to the breath-held SSFP cine images to explore their validity.

MATERIALS AND METHODS

Twenty-five children and young adults, ages (2.1-18.6 years) underwent breath-held and motion-corrected retrospective re-binning cine techniques during the same MR examination on a 1.5-tesla magnet. We measured endocardial end-systolic global circumferential strain and endocardial averaged segmental strain using commercial software (MEDIS QStrain 2.1). We used Pearson correlation coefficients to test agreement across techniques.

RESULTS

Analysis was possible in all 25 breath-held and motion-corrected retrospective re-binning studies. Global circumferential strain and endocardial averaged segmental strain obtained by motion-corrected retrospective re-binning compared favorably to breath-held studies. Global circumferential strain linear regression models demonstrated acceptable agreement, with coefficients of determination of 0.75 for breath-held compared to motion-corrected retrospective re-binning (P<0.001) and for endocardial averaged segmental strain comparisons yielded 0.77 for breath-held vs. motion-corrected retrospective re-binning (P<0.001). Bland-Altman assessment demonstrated minimal bias for breath-held compared to motion-corrected retrospective re-binning (mean 2.4 and 1.9, respectively, for global circumferential strain and endocardial averaged segmental strain).

CONCLUSION

Free-breathing imaging by motion-corrected retrospective re-binning cine imaging provides adequate spatial and temporal resolution to measure myocardial deformation when compared to the gold-standard breath-held SSFP cine imaging in children with normal or borderline systolic function.

Journal of Cardiovascular Magnetic Resonance 2017

There were 106 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2017, including 92 original research papers, 3 reviews, 9 technical notes, and 1 Position paper, 1 erratum and 1 correction. The volume was similar to 2016 despite an increase in manuscript submissions to 405 and thus reflects a slight decrease in the acceptance rate to 26.7%. The quality of the submissions continues to be high. The 2017 JCMR Impact Factor (which is published in June 2018) was minimally lower at 5.46 (vs. 5.71 for 2016; as published in June 2017), which is the second highest impact factor ever recorded for JCMR. The 2017 impact factor means that an average, each JCMR paper that were published in 2015 and 2016 was cited 5.46 times in 2017.In accordance with Open-Access publishing of Biomed Central, the JCMR articles are published on-line in continuus fashion and in the chronologic order of acceptance, with no collating of the articles into sections or special thematic issues. For this reason, over the years, the Editors have felt that it is useful to annually summarize the publications into broad areas of interest or theme, so that readers can view areas of interest in a single article in relation to each other and other contemporary JCMR articles. In this publication, the manuscripts are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought within the journal. In addition, I have elected to use this format to convey information regarding the editorial process to the readership.I hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your very best, high quality manuscripts to JCMR for consideration. I thank our very dedicated Associate Editors, Guest Editors, and Reviewers for their efforts to ensure that the review process occurs in a timely and responsible manner and that the JCMR continues to be recognized as the forefront journal of our field. And finally, I thank you for entrusting me with the editorship of the JCMR as I begin my 3rd year as your editor-in-chief. It has been a tremendous learning experience for me and the opportunity to review manuscripts that reflect the best in our field remains a great joy and highlight of my week!

A framework for constraining image SNR loss due to MR raw data compression

INTRODUCTION

Computationally intensive image reconstruction algorithms can be used online during MRI exams by streaming data to remote high-performance computers. However, data acquisition rates often exceed the bandwidth of the available network resources creating a bottleneck. Data compression is, therefore, desired to ensure fast data transmission.

METHODS

The added noise variance due to compression was determined through statistical analysis for two compression libraries (one custom and one generic) that were implemented in this framework. Limiting the compression error variance relative to the measured thermal noise allowed for image signal-to-noise ratio loss to be explicitly constrained.

RESULTS

Achievable compression ratios are dependent on image SNR, user-defined SNR loss tolerance, and acquisition type. However, a 1% reduction in SNR yields approximately four to ninefold compression ratios across MRI acquisition strategies. For free-breathing cine data reconstructed in the cloud, the streaming bandwidth was reduced from 37 to 6.1 MB/s, alleviating the network transmission bottleneck.

CONCLUSION

Our framework enabled data compression for online reconstructions and allowed SNR loss to be constrained based on a user-defined SNR tolerance. This practical tool will enable real-time data streaming and greater than fourfold faster cloud upload times.

Motion-Corrected Real-Time Cine Magnetic Resonance Imaging of the Heart: Initial Clinical Experience

OBJECTIVES

Free-breathing real-time (RT) imaging can be used in patients with difficulty in breath-holding; however, RT cine imaging typically experiences poor image quality compared with segmented cine imaging because of low resolution. Here, we validate a novel unsupervised motion-corrected (MOCO) reconstruction technique for free-breathing RT cardiac images, called MOCO-RT. Motion-corrected RT uses elastic image registration to generate a single heartbeat of high-quality data from a free-breathing RT acquisition.

MATERIALS AND METHODS

Segmented balanced steady-state free precession (bSSFP) cine images and free-breathing RT images (Cartesian, TGRAPPA factor 4) were acquired with the same spatial/temporal resolution in 40 patients using clinical 1.5 T magnetic resonance scanners. The respiratory cycle was estimated using the reconstructed RT images, and nonrigid unsupervised motion correction was applied to eliminate breathing motion. Conventional segmented RT and MOCO-RT single-heartbeat cine images were analyzed to evaluate left ventricular (LV) function and volume measurements. Two radiologists scored images for overall image quality, artifact, noise, and wall motion abnormalities. Intraclass correlation coefficient was used to assess the reliability of MOCO-RT measurement.

RESULTS

Intraclass correlation coefficient showed excellent reliability (intraclass correlation coefficient ≥ 0.95) of MOCO-RT with segmented cine in measuring LV function, mass, and volume. Comparison of the qualitative ratings indicated comparable image quality for MOCO-RT (4.80 ± 0.35) with segmented cine (4.45 ± 0.88, P = 0.215) and significantly higher than conventional RT techniques (3.51 ± 0.41, P < 0.001). Artifact and noise ratings for MOCO-RT (1.11 ± 0.26 and 1.08 ± 0.19) and segmented cine (1.51 ± 0.90, P = 0.088 and 1.23 ± 0.45, P = 0.182) were not different. Wall motion abnormality ratings were comparable among different techniques (P = 0.96).

CONCLUSIONS

The MOCO-RT technique can be used to process conventional free-breathing RT cine images and provides comparable quantitative assessment of LV function and volume measurements to conventional segmented cine imaging while providing improved image quality and less artifact and noise. The free-breathing MOCO-RT reconstruction method may have considerable clinical utility in cardiac magnetic resonance imaging for patients with difficulty breath-holding.

Myocardial Strain Using Cardiac MR Feature Tracking and Speckle Tracking Echocardiography in Duchenne Muscular Dystrophy Patients

Duchenne muscular dystrophy (DMD) is an inherited X-linked disorder with an incidence of 1 in 3500 male births, and cardiomyopathy is becoming the leading cause of death. While Cardiac MRI (CMR) and late gadolinium enhancement (LGE) are important tools in recognizing myocardial involvement, myocardial strain imaging may demonstrate early changes and allow patients to avoid gadolinium contrast. We performed CMR feature tracking (FT) and echo-based speckle tracking (STE) strain measures on DMD patients and age/sex matched controls who had received a CMR with contrast and transthoracic echocardiogram. Data were collected for longitudinal strain in the apical four-chamber view and circumferential strain in the mid-papillary parasternal short axis. Segmental wall analysis was performed and compared with the presence of LGE. Data were analyzed using student's t tests or one-way ANOVA adjusting for multiple comparisons. We measured 24 subjects with DMD and 8 controls. Thirteen of 24 DMD subjects were LGE positive only in the lateral segments in short-axis views. Average circumferential strain (CS) measured by FT was significantly decreased in DMD compared to controls (- 18.8 ± 6.1 vs. - 25.5 ± 3.2; p < 0.001) and showed significant differences in the anterolateral, inferolateral, and inferior segments. Average CS by STE trended towards significance (p = 0.06) but showed significance in only the inferior segment. FT showed significant differences in the inferolateral segment between LGE positive (- 15.5 ± 9.0) and LGE negative (- 18.2 ± 8.3) in DMD subjects compared to controls (- 28.6 ± 7.3; p ≤ 0.04). FT also showed significant differences between anteroseptal and inferolateral segments within LGE-positive (p < 0.003) and LGE-negative (p < 0.03) DMD subjects while STE did not. There were no significant differences in longitudinal strain measures. CMR-FT-derived myocardial strain was able to demonstrate differences between subjects with DMD and controls not detected by STE. FT was also able to demonstrate differences in LGE-positive and LGE-negative segments within patients with DMD. FT may be able to predict LGE-positive segments in DMD without the use of gadolinium contrast.

Review of Journal of Cardiovascular Magnetic Resonance (JCMR) 2015-2016 and transition of the JCMR office to Boston

The Journal of Cardiovascular Magnetic Resonance (JCMR) is the official publication of the Society for Cardiovascular Magnetic Resonance (SCMR). In 2016, the JCMR published 93 manuscripts, including 80 research papers, 6 reviews, 5 technical notes, 1 protocol, and 1 case report. The number of manuscripts published was similar to 2015 though with a 12% increase in manuscript submissions to an all-time high of 369. This reflects a decrease in the overall acceptance rate to <25% (excluding solicited reviews). The quality of submissions to JCMR continues to be high. The 2016 JCMR Impact Factor (which is published in June 2016 by Thomson Reuters) was steady at 5.601 (vs. 5.71 for 2015; as published in June 2016), which is the second highest impact factor ever recorded for JCMR. The 2016 impact factor means that the JCMR papers that were published in 2014 and 2015 were on-average cited 5.71 times in 2016.In accordance with Open-Access publishing of Biomed Central, the JCMR articles are published on-line in the order that they are accepted with no collating of the articles into sections or special thematic issues. For this reason, over the years, the Editors have felt that it is useful to annually summarize the publications into broad areas of interest or themes, so that readers can view areas of interest in a single article in relation to each other and other recent JCMR articles. The papers are presented in broad themes with previously published JCMR papers to guide continuity of thought in the journal. In addition, I have elected to open this publication with information for the readership regarding the transition of the JCMR editorial office to the Beth Israel Deaconess Medical Center, Boston and the editorial process.Though there is an author publication charge (APC) associated with open-access to cover the publisher's expenses, this format provides a much wider distribution/availability of the author's work and greater manuscript citation. For SCMR members, there is a substantial discount in the APC. I hope that you will continue to send your high quality manuscripts to JCMR for consideration. Importantly, I also ask that you consider referencing recent JCMR publications in your submissions to the JCMR and elsewhere as these contribute to our impact factor. I also thank our dedicated Associate Editors, Guest Editors, and reviewers for their many efforts to ensure that the review process occurs in a timely and responsible manner and that the JCMR continues to be recognized as the leading publication in our field.

Radiation-free CMR diagnostic heart catheterization in children

BACKGROUND

Children with heart disease may require repeated X-Ray cardiac catheterization procedures, are more radiosensitive, and more likely to survive to experience oncologic risks of medical radiation. Cardiovascular magnetic resonance (CMR) is radiation-free and offers information about structure, function, and perfusion but not hemodynamics. We intend to perform complete radiation-free diagnostic right heart catheterization entirely using CMR fluoroscopy guidance in an unselected cohort of pediatric patients; we report the feasibility and safety.

METHODS

We performed 50 CMR fluoroscopy guided comprehensive transfemoral right heart catheterizations in 39 pediatric (12.7 ± 4.7 years) subjects referred for clinically indicated cardiac catheterization. CMR guided catheterizations were assessed by completion (success/failure), procedure time, and safety events (catheterization, anesthesia). Pre and post CMR body temperature was recorded. Concurrent invasive hemodynamic and diagnostic CMR data were collected.

RESULTS

During a twenty-two month period (3/2015 - 12/2016), enrolled subjects had the following clinical indications: post-heart transplant 33%, shunt 28%, pulmonary hypertension 18%, cardiomyopathy 15%, valvular heart disease 3%, and other 3%. Radiation-free CMR guided right heart catheterization attempts were all successful using passive catheters. In two subjects with septal defects, right and left heart catheterization were performed. There were no complications. One subject had six such procedures. Most subjects (51%) had undergone multiple (5.5 ± 5) previous X-Ray cardiac catheterizations. Retained thoracic surgical or transcatheter implants (36%) did not preclude successful CMR fluoroscopy heart catheterization. During the procedure, two subjects were receiving vasopressor infusions at baseline because of poor cardiac function, and in ten procedures, multiple hemodynamic conditions were tested.

CONCLUSIONS

Comprehensive CMR fluoroscopy guided right heart catheterization was feasible and safe in this small cohort of pediatric subjects. This includes subjects with previous metallic implants, those requiring continuous vasopressor medication infusions, and those requiring pharmacologic provocation. Children requiring multiple, serial X-Ray cardiac catheterizations may benefit most from radiation sparing. This is a step toward wholly CMR guided diagnostic (right and left heart) cardiac catheterization and future CMR guided cardiac intervention.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02739087 registered February 17, 2016.

CMR fluoroscopy right heart catheterization for cardiac output and pulmonary vascular resistance: results in 102 patients

BACKGROUND

Quantification of cardiac output and pulmonary vascular resistance (PVR) are critical components of invasive hemodynamic assessment, and can be measured concurrently with pressures using phase contrast CMR flow during real-time CMR guided cardiac catheterization.

METHODS

One hundred two consecutive patients underwent CMR fluoroscopy guided right heart catheterization (RHC) with simultaneous measurement of pressure, cardiac output and pulmonary vascular resistance using CMR flow and the Fick principle for comparison. Procedural success, catheterization time and adverse events were prospectively collected.

RESULTS

RHC was successfully completed in 97/102 (95.1%) patients without complication. Catheterization time was 20 ± 11 min. In patients with and without pulmonary hypertension, baseline mean pulmonary artery pressure was 39 ± 12 mmHg vs. 18 ± 4 mmHg (p < 0.001), right ventricular (RV) end diastolic volume was 104 ± 64 vs. 74 ± 24 (p = 0.02), and RV end-systolic volume was 49 ± 30 vs. 31 ± 13 (p = 0.004) respectively. 103 paired cardiac output and 99 paired PVR calculations across multiple conditions were analyzed. At baseline, the bias between cardiac output by CMR and Fick was 5.9% with limits of agreement -38.3% and 50.2% with r = 0.81 (p < 0.001). The bias between PVR by CMR and Fick was -0.02 WU.m2 with limits of agreement -2.6 and 2.5 WU.m2 with r = 0.98 (p < 0.001). Correlation coefficients were lower and limits of agreement wider during physiological provocation with inhaled 100% oxygen and 40 ppm nitric oxide.

CONCLUSIONS

CMR fluoroscopy guided cardiac catheterization is safe, with acceptable procedure times and high procedural success rate. Cardiac output and PVR measurements using CMR flow correlated well with the Fick at baseline and are likely more accurate during physiological provocation with supplemental high-concentration inhaled oxygen.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01287026 , registered January 25, 2011.

Cardiac Computed Tomography and Magnetic Resonance Imaging in the Evaluation of Mitral and Tricuspid Valve Disease

Transcatheter interventions to treat mitral and tricuspid valve disease are becoming increasingly available because of the growing number of elderly patients with significant comorbidities or high operative risk. Thorough clinical and imaging evaluation in these patients is essential. The latter involves both characterization of the mechanism and severity of valvular disease as well as determining the hemodynamic consequences and extent of ventricular remodeling, which is an important predictor of future outcomes. Moreover, an assessment of the suitability and risk of complications associated with device-specific therapies is also an important component of the preprocedural evaluation in this cohort. Although echocardiography including 2-dimensional and 3-dimensional methods has an important role in the initial assessment and procedural guidance, cross-sectional imaging, including both computed tomographic imagning and cardiac magnetic resonance imaging, is increasingly being integrated into the evaluation of mitral and tricuspid valve disease. In this review, we discuss the role of cross-sectional imaging in mitral and tricuspid valve disease, primarily valvular regurgitation assessment, with an emphasis on the preprocedural evaluation and implications for transcatheter interventions.

Update on the Role of Cardiac Magnetic Resonance Imaging in Congenital Heart Disease

OPINION STATEMENT

Cardiac magnetic resonance imaging (CMR) is an important imaging modality in the evaluation of congenital heart diseases (CHD). CMR has several strengths including good spatial and temporal resolutions, wide field-of-view, and multi-planar imaging capabilities. CMR provides significant advantages for imaging in CHD through its ability to measure function, flow and vessel sizes, create three-dimensional reconstructions, and perform tissue characterization, all in a single imaging study. Thus, CMR is the most comprehensive imaging modality available today for the evaluation of CHD. Newer MRI sequences and post-processing tools will allow further development of quantitative methods of analysis, and opens the door for risk stratification in CHD. CMR also can interface with computer modeling, 3D printing, and other methods of understanding the complex anatomic and physiologic relationships in CHD.