Evaluating a novel accelerated free-breathing late gadolinium enhancement imaging sequence for assessment of myocardial injury.

Introduction: Cardiac magnetic resonance imaging (MRI), including late gadolinium enhancement (LGE), plays an important role in the diagnosis and prognostication of ischemic and non-ischemic myocardial injury. Conventional LGE sequences require patients to perform multiple breath-holds and require long acquisition times. In this study, we compare image quality and assessment of myocardial LGE using an accelerated free-breathing sequence to the conventional standard-of-care sequence.

Estimating Uncertainty in Neural Networks for Cardiac MRI Segmentation: A Benchmark Study.

Objective: Convolutional neural networks (CNNs) have demonstrated promise in automated cardiac magnetic resonance image segmentation. However, when using CNNs in a large real-world dataset, it is important to quantify segmentation uncertainty and identify segmentations which could be problematic. In this work, we performed a systematic study of Bayesian and non-Bayesian methods for estimating uncertainty in segmentation neural networks.

Low Prevalence of Late Myocardial Injury on Cardiac MRI Following COVID-19 Infection.

Background: The prevalence of abnormal cardiac magnetic resonance imaging (MRI) findings indicative of myocardial injury in patients who recovered from coronavirus disease 2019 (COVID-19) is currently unclear, with a high variability in the reported prevalence.

Purpose: To assess the prevalence of myocardial injury after a COVID-19 infection.

Study Type: Prospective, bicentric study.

A Deep Learning Segmentation Pipeline for Cardiac T1 Mapping Using MRI Relaxation-based Synthetic Contrast Augmentation.

Purpose: To design and evaluate an automated deep learning method for segmentation and analysis of cardiac MRI T1 maps with use of synthetic T1-weighted images for MRI relaxation-based contrast augmentation.

Materials And Methods: This retrospective study included MRI scans acquired between 2016 and 2019 from 100 patients (mean age ± SD, 55 years ± 13; 72 men) across various clinical abnormalities with use of a modified Look-Locker inversion recovery, or MOLLI, sequence to quantify native T1 (T1), postcontrast T1 (T1), and extracellular volume (ECV). Data were divided into training ( = 60) and internal ( = 40) test subsets.

Vendor-neutral sequences and fully transparent workflows improve inter-vendor reproducibility of quantitative MRI.

Purpose: We developed an end-to-end workflow that starts with a vendor-neutral acquisition and tested the hypothesis that vendor-neutral sequences decrease inter-vendor variability of T1, magnetization transfer ratio (MTR), and magnetization transfer saturation-index (MTsat) measurements.

Methods: We developed and deployed a vendor-neutral 3D spoiled gradient-echo (SPGR) sequence on three clinical scanners by two MRI vendors. We then acquired T1 maps on the ISMRM-NIST system phantom, as well as T1, MTR, and MTsat maps in three healthy participants.

MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute Lesions and Associated Electrophysiologic Voltage Reductions.

Objective: Radiofrequency (RF) energy delivered to cardiac tissue produces a core ablation lesion with surrounding edema, the latter of which has been implicated in acute procedural failure of Ventricular Tachycardia (VT) ablation and late arrhythmia recurrence. This study sought to investigate the electrophysiological characteristics of acute RF lesions in the left ventricle (LV) visualized with native-contrast Magnetic Resonance Imaging (MRI).

Methods: An MR-guided electrophysiology system was used to deliver RF ablation in the LV of 8 swine (9 RF lesions in total), then perform MRI and electroanatomic mapping.

Suspected subclinical myocarditis detected by cardiac magnetic resonance imaging late post COVID-19 recovery.

There is growing evidence of the potential for cardiac involvement in patients who have been infected with COVID-19. In this case study, we present a patient with no history of cardiovascular disease, who was hospitalized for COVID-19 pneumonia and subsequently recovered. Despite normal serum troponin levels and left ventricular structure and function, multi-parametric cardiac magnetic resonance imaging revealed a classic myocarditis-like pattern of injury approximately 6 months after his convalescence.

Technical Note: Fully automatic segmental relaxometry (FASTR) for cardiac magnetic resonance T1 mapping.

Purpose: Cardiac relaxometry techniques, particularly T1 mapping, have recently gained clinical importance in various cardiac pathologies. Myocardial T1 and extracellular volume are usually calculated from manual identification of left ventricular epicardial and endocardial regions. This is a laborious process, particularly for large volume studies.

Evaluating a novel free-breathing accelerated cardiac MRI cine sequence in patients with cardiomyopathy.

Introduction: Cardiac magnetic resonance imaging (CMR) is the gold standard for the assessment of left ventricular (LV) function. However, traditional sequences are time-consuming and require breath-holding. Our aim was to evaluate the image quality of LV functional assessment with a novel, accelerated, free-breathing cine sequence and to compare LV functional parameters between it and a traditional sequence.

Omnipolarity applied to equi-spaced electrode array for ventricular tachycardia substrate mapping.

Aims: Bipolar electrogram (BiEGM)-based substrate maps are heavily influenced by direction of a wavefront to the mapping bipole. In this study, we evaluate high-resolution, orientation-independent peak-to-peak voltage (Vpp) maps obtained with an equi-spaced electrode array and omnipolar EGMs (OTEGMs), measure its beat-to-beat consistency, and assess its ability to delineate diseased areas within the myocardium compared against traditional BiEGMs on two orientations: along (AL) and across (AC) array splines.

Methods And Results: The endocardium of the left ventricle of 10 pigs (three healthy and seven infarcted) were each mapped using an Advisor™ HD grid with a research EnSite Precision™ system.

Cardiovascular magnetic resonance guided ablation and intra-procedural visualization of evolving radiofrequency lesions in the left ventricle.

Background: Radiofrequency (RF) ablation has become a mainstay of treatment for ventricular tachycardia, yet adequate lesion formation remains challenging. This study aims to comprehensively describe the composition and evolution of acute left ventricular (LV) lesions using native-contrast cardiovascular magnetic resonance (CMR) during CMR-guided ablation procedures.

Methods: RF ablation was performed using an actively-tracked CMR-enabled catheter guided into the LV of 12 healthy swine to create 14 RF ablation lesions.

Feasibility Study of Respiratory Motion Modeling Based Correction for MRI-Guided Intracardiac Interventional Procedures.

Goal: The purpose of this study is to improve the accuracy of interventional catheter guidance during intracardiac procedures. Specifically, the use of preprocedural magnetic resonance roadmap images for interventional guidance has limited anatomical accuracy due to intraprocedural respiratory motion of the heart. Therefore, we propose to build a novel respiratory motion model to compensate for this motion-induced error during magnetic resonance imaging (MRI)-guided procedures.

Distribution of abnormal potentials in chronic myocardial infarction using a real time magnetic resonance guided electrophysiology system.

Background: Identification of viable slow conduction zones manifested by abnormal local potentials is integral to catheter ablation of ventricular tachycardia (VT) sites. The relationship between contrast patterns in cardiovascular magnetic resonance (CMR) and local electrical mapping is not well characterized. The purpose of this study was to identify regions of isolated, late and fractionated diastolic potentials in sinus rhythm and controlled-paced rhythm in post-infarct animals relative to regions detected by late gadolinium enhancement CMR (LGE-CMR).

Postinfarction ventricular tachycardia substrate characterization: a comparison between late enhancement magnetic resonance imaging and voltage mapping using an MR-guided electrophysiology system.

Catheter ablation of ventricular tachycardia (VT) is preceded by characterization of the myocardial substrate via electroanatomical voltage mapping (EAVM). The purpose of this study was to characterize the relationship between chronic myocardial fibrotic scar detected by multicontrast late enhancement (MCLE) MRI and by EAVM obtained using an MR-guided electrophysiology system, with a final aim to better understand how these measures may improve identification of potentially arrhythmogenic substrates. Real-time MR-guided EAVM was performed in six chronically infarcted animals in a 1.

The feasibility of endocardial propagation mapping using magnetic resonance guidance in a Swine model, and comparison with standard electroanatomic mapping.

The introduction of electroanatomic mapping (EAM) has improved the understanding of the substrate of ventricular tachycardia. EAM systems are used to delineate scar regions responsible for the arrhythmia by creating voltage or activation time maps. Previous studies have identified the benefits of creating MR-guided voltage maps; however, in some cases voltage maps may not identify regions of slow propagation that can cause the reentrant tachycardia.

Free-breathing, nongated real-time delayed enhancement MRI of myocardial infarcts: a comparison with conventional delayed enhancement.

Purpose: To compare a free-breathing, nongated, and black-blood real-time delayed enhancement (RT-DE) sequence to the conventional inversion recovery gradient echo (IR-GRE) sequence for delayed enhancement MRI.

Materials And Methods: Twenty-three patients with suspected myocardial infarct (MI) were examined using both the IR-GRE and RT-DE imaging sequences. The sensitivity and specificity of RT-DE for detecting MI, using IR-GRE as the gold standard, was determined.