Coronary Magnetic Resonance Imaging Research Articles

Evaluation of fractional flow reserve and atherosclerotic plaque characteristics on coronary non-contrast T1-weighted magnetic resonance imaging

Background and aimsThe relationship between high-risk coronary plaque characteristics regardless of the severity of lesion stenosis and myocardial ischemia remains unsettled. High-intensity plaques (HIPs) on non-contrast T1-weighted magnetic resonance imaging (T1WI) have been characterized as high-risk coronary plaques. We sought to elucidate whether the presence of coronary HIPs on T1WI influences fractional flow reserve (FFR) in the distal segment of the vessel. MethodsWe retrospectively analyzed 281 vessels in 231 patients with chronic coronary syndrome who underwent invasive FFR measurement and coronary T1WI using a multicenter registry. The plaque-to-myocardial signal intensity ratio (PMR) of the most stenotic lesion was evaluated; a coronary plaque with PMR ≥1.4 was defined as a HIP. ResultsThe median PMR of coronary plaques on T1WI in vessels with FFR ≤0.80 was significantly higher than that of plaques with FFR >0.80 (1.17 [interquartile range (IQR): 0.99–1.44] vs. 0.97 [IQR: 0.85–1.09]; p < 0.001). Multivariable analysis showed that an increase in PMR of the most stenotic segment was associated with lower FFR (beta-coefficient, −0.050; p < 0.001). The presence of coronary HIPs was an independent predictor of FFR ≤0.80 (odds ratio (OR), 6.18; 95% confidence interval (CI), 1.93–19.77; p = 0.002). Even after adjusting for plaque composition characteristics based on computed tomography angiography, the presence of coronary HIPs was an independent predictor of FFR ≤0.80 (OR, 4.48; 95% CI, 1.19–16.80; p = 0.026). ConclusionsCoronary plaques with high PMR are associated with low FFR in the corresponding vessel, indicating that plaque morphology might influence myocardial ischemia severity.

Image and Clinical Characteristics of the Right Coronary Artery Originating From the Left Coronary Sinus: A Database Review.

This article systematically explores the imaging and clinical characteristics of a relatively rare cardiac anomaly: the right coronary artery originating from the left coronary sinus. Through a comprehensive analysis of existing literature, this study aims to provide a comprehensive understanding of the prevalence, diagnostic methods, and potential clinical implications of this anatomical variation. Anatomical classification is introduced, along with clinical imaging diagnostic methods, including coronary angiography, computed tomography, and magnetic resonance imaging. Additionally, the review delves into the clinical significance of this anomaly, including its potential associations with myocardial ischemia, arrhythmias, and acute cardiac events, outlining clinical approaches to diagnosing myocardial ischemia. The study results consolidate current knowledge about this cardiac variation, emphasizing the importance of recognizing and appropriately managing it in clinical practice.

Detection of Abnormality in Coronary Artery Magnetic Resonance Imaging using Bit Plane Slicing and Deep Learning.

This paper presents a novel approach for detecting abnormality in coronary arteries using MRI data in RGB images. The study evaluates the test accuracy of the weak classifiers and the test accuracy and F1 score of the strong classifier. The method involves separating the image into information planes, including R, G, and B color space, or bit-planes, and training a VGG-like convolutional neural network model on each plane separately, referred to as a "weak classifier." The classification results of these planes are aggregated using a proposed soft voting method, forming a "strong classifier," with the weights for the aggregation determined by the model's performance on the training set. The results indicate that the strong classifier achieves a test accuracy and F1 score of around 68% to 74% on our private coronary artery dataset. Moreover, by aggregating the top three highest bit-plane levels in a grayscale image, the accuracy is slightly lower than that of the three color spaces but requires a significantly smaller CNN model of nearly 4M parameters. The potential of bit-planes in reducing model storage costs is suggested. This approach holds promise for improving the detection of abnormalities in coronary arteries using MRI data.

The coronary microvascular angina cardiovascular magnetic resonance imaging trial: Rationale and design

BackgroundCoronary microvascular dysfunction may cause myocardial ischemia with no obstructive coronary artery disease (INOCA). If functional testing is not performed INOCA may pass undetected. Stress perfusion cardiovascular MRI (CMR) quantifies myocardial blood flow (MBF) but the clinical utility of stress CMR in the management of patients with suspected angina with no obstructive coronary arteries (ANOCA) is uncertain. ObjectivesFirst, to undertake a diagnostic study using stress CMR in patients with ANOCA following invasive coronary angiography and, second, in a nested, double-blind, randomized, controlled trial to assess the effect of disclosure on the final diagnosis and health status in the longer term. DesignAll-comers referred for clinically indicated coronary angiography for the investigation of suspected coronary artery disease will be screened in 3 regional centers in the United Kingdom. Following invasive coronary angiography, patients with ANOCA who provide informed consent will undergo noninvasive endotyping using stress CMR within 3 months of the angiogram. Diagnostic studyStress perfusion CMR imaging to assess the prevalence of coronary microvascular dysfunction and clinically significant incidental findings in patients with ANOCA. The primary outcome is the between-group difference in the reclassification rate of the initial diagnosis based on invasive angiography versus the final diagnosis after CMR imaging. Randomized, controlled trialParticipants will be randomized to inclusion (intervention group) or exclusion (control group) of myocardial blood flow to inform the final diagnosis. The primary outcome of the clinical trial is the mean within-subject change in the Seattle Angina Questionnaire summary score (SAQSS) at 6 months. Secondary outcome assessments include the EUROQOL EQ-5D-5L questionnaire, the Brief Illness Perception Questionnaire (Brief-IPQ), the Treatment Satisfaction Questionnaire (TSQM-9), the Patient Health Questionnaire-4 (PHQ-4), the Duke Activity Status Index (DASI), the International Physical Activity Questionnaire- Short Form (IPAQ-SF), the Montreal Cognitive Assessment (MOCA) and the 8-item Productivity Cost Questionnaire (iPCQ). Health and economic outcomes will be assessed using electronic healthcare records. ValueTo clarify if routine stress perfusion CMR imaging reclassifies the final diagnosis in patients with ANOCA and whether this strategy improves symptoms, health-related quality of life and health economic outcomes. Clinicaltrials.govNCT04805814

Deep Learning-based Post Hoc CT Denoising for the Coronary Perivascular Fat Attenuation Index

Coronary inflammation related to high-risk hemorrhagic plaques can be captured by the perivascular fat attenuation index (FAI) using coronary computed tomography angiography (CCTA). Since the FAI is susceptible to image noise, we believe deep learning (DL)-based post hoc noise reduction can improve diagnostic capability. We aimed to assess the diagnostic performance of the FAI in DL-based denoised high-fidelity CCTA images compared with coronary plaque magnetic resonance imaging (MRI) delivered high-intensity hemorrhagic plaques (HIPs). We retrospectively reviewed 43 patients who underwent CCTA and coronary plaque MRI. We generated high-fidelity CCTA images by denoising the standard CCTA images using a residual dense network that supervised the denoising task by averaging three cardiac phases with nonrigid registration. We measured the FAIs as the mean CT value of all voxels (range of -190 to -30 HU) located within a radial distance from the outer proximal right coronary artery wall. The diagnostic reference standard was defined as HIPs (high-risk hemorrhagic plaques) using MRI. The diagnostic performance of the FAI in the original and denoised images was assessed using receiver operating characteristic curves. Of 43 patients, 13 had HIPs. The denoised CCTA improved the area under the curve (0.89 [95% confidence interval (CI) 0.78-0.99]) of the FAI compared with that in the original image (0.77 [95% CI, 0.62-0.91], p=0.008). The optimal cutoff value for predicting HIPs in denoised CCTA was -69 HU with 0.85 (11/13) sensitivity, 0.79 (25/30) specificity, and 0.80 (36/43) accuracy. DL-based denoised high-fidelity CCTA improved the AUC and specificity of the FAI for predicting HIPs.

Noninvasive Plaque Imaging to Accelerate Coronary Artery Disease Drug Development.

Coronary artery disease (CAD) remains the leading cause of adult mortality globally. Targeting known modifiable risk factors has had substantial benefit, but there remains a need for new approaches. Improvements in invasive and noninvasive imaging techniques have enabled an increasing recognition of distinct quantitative phenotypes of coronary atherosclerosis that are prognostically relevant. There are marked differences in plaque phenotype, from the high-risk, lipid-rich, thin-capped atheroma to the low-risk, quiescent, eccentric, nonobstructive calcified plaque. Such distinct phenotypes reflect different pathophysiologic pathways and are associated with different risks for acute ischemic events. Noninvasive coronary imaging techniques, such as computed tomography, positron emission tomography, and coronary magnetic resonance imaging, have major potential to accelerate cardiovascular drug development, which has been affected by the high costs and protracted timelines of cardiovascular outcome trials. This may be achieved through enrichment of high-risk phenotypes with higher event rates or as primary end points of drug efficacy, at least in phase 2 trials, in a manner historically performed through intravascular coronary imaging studies. Herein, we provide a comprehensive review of the current technology available and its application in clinical trials, including implications for sample size requirements, as well as potential limitations. In its effort to accelerate drug development, the US Food and Drug Administration has approved surrogate end points for 120 conditions, but not for CAD. There are robust data showing the beneficial effects of drugs, including statins, on CAD progression and plaque stabilization in a manner that correlates with established clinical end points of mortality and major adverse cardiovascular events. This, together with a clear mechanistic rationale for using imaging as a surrogate CAD end point, makes it timely for CAD imaging end points to be considered. We discuss the importance of global consensus on these imaging end points and protocols and partnership with regulatory bodies to build a more informed, sustainable staged pathway for novel therapies.

Abstract 11041: Time Course of Recovery from Left Ventricular Systolic Dysfunction in Patients with Arrhythmia and Newly Diagnosed Heart Failure

Background: Newly diagnosed heart failure and concomitant persistent arrhythmia often is a challenging situation for clinicians, especially if left ventricular systolic dysfunction (LVSD) is otherwise not explainable. The time to recovery of arrhythmia-induced cardiomyopathy (AIC) is not well known and the prevalence of this disease is likely underestimated. Purpose: As AIC only can be diagnosed after rhythm control (RC) and thereafter recovery from LVSD (diagnosis ex juvantibus), we aimed to characterize the time course of recovery and describe the prevalence in such a specific cohort. Method and Results: We prospectively screened 95 patients hospitalized for newly diagnosed and otherwise unexplainable LVSD (left ventricular ejection fraction (LVEF) &lt;50%) and coexisting tachyarrhythmia (atrial fibrillation/flutter + heart rate (HR) &gt;100/min) in three cardiological centers. Coronary angiography and cardiac magnetic resonance imaging were performed to exclude other causes for LVSD. RC was achieved by electrocardioversion, ablation, pharmacologically or a combination of those. 50 of 68 included patients (age 69±11y, 63% male, LVEF 35.6±8%, mean±SD) were free from recurrent arrhythmia after 6 months and analyzed: AIC was diagnosed by any increase of ≥15% in absolute LVEF or an LVEF ≥50% with an improvement of ≥10% 6 months after RC; all others were diagnosed idiopathic DCM. LVEF was assessed by echocardiography at presentation and at follow-up visits 2, 4, and 6 months after RC. 9 patients did not meet the AIC-criteria, resulting in a prevalence of 82% for AIC. At presentation, AIC vs. DCM had smaller left ventricles (LVEDD 53.6±7.5 vs. 59.7±3.1mm, P&lt;0.05; LVESD 44.4±6.6 vs. 51.6±5.1mm, P&lt;0.01), biomarkers did not differ: NT-proBNP 4525±4535 vs. 4793±4076pg/mL, P=n.s., Troponin T-hs: 46.8±108.8 vs. 22.9±15.7ng/L, P=n.s.. 2 and 4 months after RC, 58% and 73% of patients fulfilled AIC criteria. Conclusion: The prevalence of AIC in patients in this specific collective with newly diagnosed and otherwise unexplainable LVSD with concomitant persistent tachycardia is surprisingly high and the time course of recovery suggests that the final diagnosis cannot be established before 6 months after rhythm restoration.

Prevalence and time course of arrhythmia-induced cardiomyopathy in patients with newly diagnosed heart failure and concomitant tachyarrhythmia – the TACHY-HF pilot trial

BackgroundArrhythmias may often be a result of heart failure, but they can also cause left-ventricular systolic dysfunction (LVSD), thereby presenting as arrhythmia-induced cardiomyopathy (AIC). AIC-diagnosis is established retrospectively when LVSD normalizes or improves significantly over time following rhythm restoration. However, the prevalence and most importantly the time course of this relevant disease remain unclear and hence merit investigation to enable the correct diagnosis.PurposeTherefore, our aim was to evaluate a) the occurrence of AIC in this clinical relevant cohort of patients with newly diagnosed and otherwise unexplainable LVSD and concomitant tachycardia and b) the time needed to fulfill the diagnostic criteria of AIC in order to facilitate a diagnostic algorithm.MethodWe prospectively screened patients hospitalized for newly diagnosed and otherwise unexplainable LVSD (i.e. left ventricular ejection fraction (LVEF) <50%) and coexisting tachyarrhythmia (atrial fibrillation/flutter + heart rate (HR) >100/min) in 3 cardiological centers. Coronary angiography and cardiac magnetic resonance imaging were performed to exclude other causes for LVSD. Patients underwent a rhythm control strategy in accordance to the local clinical pathways. LVEF was assessed by echocardiography at presentation and at follow-up (FU) visits after 2, 4, and 6 months. Patients who lost sinus rhythm (SR) during FU were excluded. Patients with any increase of ≥15% in absolute EF or an EF ≥50% with an improvement of ≥10% after 6 months of FU were assigned to the AIC-group, which is a common definition of AIC. All others were assigned to an idiopathic DCM-group as final comparator.Results68 patients were eligible, 18 of them were excluded: 1 lost to follow-up, 1 PCI, 2 COVID-19, 1 diagnosed cancer, 1 withdraw consent and 12 lost SR. Thus, our sample consists of a total of 50 patients. At presentation, mean±SD HR was 121±17/min. After rhythm therapy, HR normalized (67±10/min) and LVEF increased in both groups, see fig. 1. Surprisingly, only 9 patients did not fulfill the AIC-criteria in this specific collective resulting in a prevalence of 82% (95%-CI: 68% – 92%). This high prevalence of AIC underlines the importance of the disease. 2 and 4 months after rhythm intervention, 58% and 73% of patients fulfilled AIC-criteria (fig. 2). The sensitivity for detection of AIC by echocardiographic LVEF-measurement at months 2 and 4 of FU was 65% and 86% with a specificity of 100%, emphasizing that a FU of 6 months is necessary to certainly distinguish between AIC and idiopathic DCM.ConclusionThe prevalence of AIC in patients with newly diagnosed and otherwise unexplainable LVSD with concomitant tachycardia is 82%. Analysis of the time course of AIC clearly suggests that the final diagnosis cannot be established before 6 months after successful rhythm restoration. These results may help to improve diagnosis of AIC in daily clinical practice.Funding AcknowledgementType of funding sources: None.

Velocity Encoded Cine Imaging of Mitral Valve Inflow: A novel method to determine cardiac rest periods in coronary magnetic resonance imaging

Purpose: Dual Phase Whole Heart Coronary Magnetic Resonance Angiography (CMRA) has become an invaluable addition in the evaluation of patients with congenital heart disease (CHD), as it defines detailed cardiac morphology and coronary anatomy. Image acquisition is usually performed during the cardiac rest periods, at end-systole and mid-diastole, in order to minimize cardiac motion and thus increase image sharpness. The rest periods are traditionally assessed visually using a high-temporal resolution balanced steady-state free precession (SSFP) 4-chamber (4CH) image, but this technique is limited by significant inter-observer variability. We propose that velocity encoded cine imaging of the mitral valve inflow (MVI) is a novel and more reproducible approach to determine …

Velocity Encoded Cine Imaging of Mitral Valve Inflow: A novel method to determine cardiac rest periods in coronary magnetic resonance imaging

Velocity Encoded Cine Imaging of Mitral Valve Inflow: A novel method to determine cardiac rest periods in coronary magnetic resonance imaging

Noncontrast free-breathing respiratory self-navigated coronary artery cardiovascular magnetic resonance angiography at 3\u2009T using lipid insensitive binomial off-resonant excitation (LIBRE)

BackgroundRobust and homogeneous lipid suppression is mandatory for coronary artery cardiovascular magnetic resonance (CMR) imaging since the coronary arteries are commonly embedded in epicardial fat. However, effective large volume lipid suppression becomes more challenging when performing radial whole-heart coronary artery CMR for respiratory self-navigation and the problem may even be exacerbated at increasing magnetic field strengths. Incomplete fat suppression not only hinders a correct visualization of the coronary vessels and generates image artifacts, but may also affect advanced motion correction methods. The aim of this study was to evaluate a recently reported lipid insensitive CMR method when applied to a noncontrast self-navigated coronary artery CMR acquisitions at 3 T, and to compare it to more conventional fat suppression techniques.MethodsLipid insensitive binomial off resonant excitation (LIBRE) radiofrequency excitation pulses were included into a self-navigated 3D radial GRE coronary artery CMR sequence at 3 T. LIBRE was compared against a conventional CHESS fat saturation (FS) and a binomial 1–180°-1 water excitation (WE) pulse. First, fat suppression of all techniques was numerically characterized using Matlab and experimentally validated in phantoms and in legs of human volunteers. Subsequently, free-breathing self-navigated coronary artery CMR was performed using the LIBRE pulse as well as FS and WE in ten healthy subjects. Myocardial, arterial and chest fat signal-to-noise ratios (SNR), as well as coronary vessel conspicuity were quantitatively compared among those scans.ResultsThe results obtained in the simulations were confirmed by the experimental validations as LIBRE enabled near complete fat suppression for 3D radial imaging in vitro and in vivo. For self-navigated whole-heart coronary artery CMR at 3 T, fat SNR was significantly attenuated using LIBRE compared with conventional FS. LIBRE increased the right coronary artery (RCA) vessel sharpness significantly (37 ± 9% (LIBRE) vs. 29 ± 8% (FS) and 30 ± 8% (WE), both p < 0.05) and led to a significant increase in the measured RCA vessel length to (83 ± 31 mm (LIBRE) vs. 56 ± 12 mm (FS) and 59 ± 27 (WE) p < 0.05).ConclusionsApplied to a respiratory self-navigated noncontrast 3D radial whole-heart sequence, LIBRE enables robust large volume fat suppression and significantly improves coronary artery image quality at 3 T compared to the use of conventional FS and WE.

Rationale and design of the Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) diagnostic study: the CorMicA CMR sub-study.

IntroductionAngina with no obstructive coronary artery disease (ANOCA) is a common syndrome with unmet clinical needs. Microvascular and vasospastic angina are relevant but may not be diagnosed without measuring coronary vascular function. The relationship between cardiovascular magnetic resonance (CMR)-derived myocardial blood flow (MBF) and reference invasive coronary function tests is uncertain. We hypothesise that multiparametric CMR assessment will be clinically useful in the ANOCA diagnostic pathway.Methods/analysisThe Stratified Medical Therapy Using Invasive Coronary Function Testing In Angina (CorMicA) trial is a prospective, blinded, randomised, sham-controlled study comparing two management approaches in patients with ANOCA. We aim to recruit consecutive patients with stable angina undergoing elective invasive coronary angiography. Eligible patients with ANOCA (n=150) will be randomised to invasive coronary artery function-guided diagnosis and treatment (intervention group) or not (control group). Based on these test results, patients will be stratified into disease endotypes: microvascular angina, vasospastic angina, mixed microvascular/vasospastic angina, obstructive epicardial coronary artery disease and non-cardiac chest pain. After randomisation in CorMicA, subjects will be invited to participate in the Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) substudy. Patients will undergo multiparametric CMR and have assessments of MBF (using a novel pixel-wise fully quantitative method), left ventricular function and mass, and tissue characterisation (T1 mapping and late gadolinium enhancement imaging). Abnormalities of myocardial perfusion and associations between MBF and invasive coronary artery function tests will be assessed. The CorCMR substudy represents the largest cohort of ANOCA patients with paired multiparametric CMR and comprehensive invasive coronary vascular function tests.Ethics/disseminationThe CorMicA trial and CorCMR substudy have UK REC approval (ref.16/WS/0192).Trial registration numberNCT03193294.

Late sodium channel blockade improves angina and myocardial perfusion in patients with severe coronary microvascular dysfunction: Women's Ischemia Syndrome Evaluation–Coronary Vascular Dysfunction ancillary study

BackgroundIn a prior trial of late sodium channel inhibition (ranolazine) among symptomatic subjects without obstructive coronary artery disease (CAD) and limited myocardial perfusion reserve index (MPRI), we observed no improvement in angina or MPRI, overall. Here we describe the clinical characteristics and myocardial perfusion responses of a pre-defined subgroup who had coronary flow reserve (CFR) assessed invasively. MethodsSymptomatic patients without obstructive CAD and limited MPRI in a randomized, double-blind, crossover trial of ranolazine vs. placebo were subjects of this prespecified substudy. Because we had previously observed that adverse outcomes and beneficial treatment responses occurred in those with lower CFR, patients were subgrouped by CFR <2.5 vs ≥2.5. Symptoms were assessed using the Seattle Angina Questionnaire and the SAQ-7, and left-ventricular volume and MPRI were assessed by magnetic resonance imaging (MRI). Coronary angiograms, CFR, and MRI data were analyzed by core labs masked to treatment and patient characteristics. ResultsDuring qualifying coronary angiography, 81 patients (mean age 55 years, 98% women) had invasively determined CFR 2.69 ± 0.65 (mean ± SD; range 1.4–5.5); 43% (n = 35) had CFR <2.5. Demographic and symptomatic findings did not differ comparing CFR subgroups. Those with low CFR had improved angina (p = 0.04) and midventricular MPRI (p = 0.03) with ranolazine vs placebo. Among patients with low CFR, reduced left-ventricular end-diastolic volume predicted a beneficial angina response. ConclusionsSymptomatic patients with CFR <2.5 and no obstructive CAD had improved angina and myocardial perfusion with ranolazine, supporting the hypothesis that the late sodium channel is important in management of coronary microvascular dysfunction. Trial registrationclinicaltrials.gov Identifier NCT01342029

Coronary magnetic resonance imaging after routine implantation of bioresorbable vascular scaffolds allows non-invasive evaluation of vascular patency.

BackgroundEvaluation of recurrent angina after percutaneous coronary interventions is challenging. Since bioresorbable vascular scaffolds (BVS) cause no artefacts in magnetic resonance imaging (MRI) due to their polylactate-based backbone, evaluation of vascular patency by MRI might allow for non-invasive assessment and triage of patients with suspected BVS failure.MethodsPatients with polylactate-based ABSORB-BVS in proximal coronary segments were examined with 3 Tesla MRI directly (baseline) and one year after implantation. For assessment of coronary patency, a high-resolution 3D spoiled gradient echo pulse sequence with fat-saturation, T2-preparation (TE: 40 ms), respiratory and end-diastolic cardiac gating, and a spatial resolution of (1.08 mm)3 was positioned parallel to the course of the vessel for bright blood imaging. In addition, a 3D navigator-gated T2-weighted variable flip angle turbo spin echo (TSE) sequence with dual-inversion recovery black-blood preparation and elliptical k-space coverage was applied with a voxel size of (1.14 mm)3. For quantitative evaluation lumen diameters of the scaffolded areas were measured in reformatted bright and black blood MR angiography data.Results11 patients with implantation of 16 BVS in the proximal coronary segments were included, of which none suffered from major adverse cardiac events during the one year follow up. Vascular patency in all segments implanted with BVS could be reliably assessed by MRI at baseline and after one year, whereas segments with metal stents could not be evaluated due to artefacts. Luminal diameter within the BVS remained constant during the one year period. One patient with atypical angina after BVS implantation was noninvasively evaluated showing a patent vessel, also confirmed by coronary angiography.ConclusionsCoronary MRI allows contrast-agent free and non-invasive assessment of vascular patency after ABSORB-BVS implantation. This approach might be supportive in the triage and improvement of diagnostic workflows in patients with postinterventional angina and scaffold implantation.Trial registrationGerman Register of Clinical Studies DRKS00007456

P547Non-invasive evaluation of vascular patency after routine implantation of bioresorbable vascular scaffolds using coronary magnetic resonance imaging

P547Non-invasive evaluation of vascular patency after routine implantation of bioresorbable vascular scaffolds using coronary magnetic resonance imaging

Accelerated 3D Coronary Vessel Wall MR Imaging Based on Compressed Sensing with a Block-Weighted Total Variation Regularization

Coronary vessel wall magnetic resonance (MR) imaging is important for heart disease diagnosis but often suffers long scan time. Compressed sensing (CS) has been previously used to accelerate MR imaging by reconstructing an MR image from undersampled k-space data using a regularization framework. However, the widely used regularizations in the current CS methods often lead to smoothing effects and thus are unable to reconstruct the coronary vessel walls with sufficient resolution. To address this issue, a novel block-weighted total variation regularization is presented to accelerate the coronary vessel wall MR imaging. The proposed regularization divides the image into two parts: a region-of-interest (ROI) which contains the coronary vessel wall, and the other region with less concerned features. Different penalty weights are given to the two regions. As a result, the small details within ROI do not suffer from over-smoothing while the noise outside the ROI can be significantly suppressed. Results with both numerical simulations and in vivo experiments demonstrated that the proposed method can reconstruct the coronary vessel wall from undersampled k-space data with higher qualities than the conventional CS with the total variation or the edge-preserved total variation.

Follow-up of coronary artery patency after implantation of bioresorbable coronary scaffolds: The emerging role of magnetic coronary artery imaging.

Bioresorbable vascular scaffolds (BVSs) represent the newest tool in the treatment of coronary artery disease (CAD). Conversely to the previous metal stents and thanks to the polylactate-based backbone, BVSs could be visualized by magnetic resonance imaging (MRI) without artifacts. These properties allow a potential non-invasive assessment of coronary artery patency after percutaneous coronary intervention (PCI), avoiding cardiac catheterization included iodine contrast and radiation exposure, and potentially more sophisticated imaging tool as the optical coherence tomography (OCT). We reviewed the available medical literature on the coronary MRI evaluation of BVS after PCI, also discussing its potential diagnostic role in the long-term follow-up of these patients.

Coronary atherosclerosis and dilation in hyper IgE syndrome patients: Depiction by magnetic resonance vessel wall imaging and pathological correlation

Background and aimsAutosomal dominant hyper-IgE (AD-HIES) is a primary immunodeficiency caused by mutations in STAT3. Elevated levels of IgE, an ineffective immune response, connective tissue abnormalities, and coronary arterial dilation and tortuosity characterize AD-HIES. To date, coronary artery evaluation in AD-HIES patients has been limited to lumenography measurements. Direct in vivo coronary vessel wall (VW) imaging may allow for better interrogation of coronary vessel abnormalities. The goal of this prospective study was to evaluate the coronary VW of AD-HIES patients using Magnetic Resonance Imaging (MRI) and histology. VW image findings were compared in healthy subjects and subjects with coronary atherosclerotic disease (CAD). MethodsA total of 28 subjects (10 with AD-HIES, 8 healthy, 10 with CAD) were studied by coronary VW MRI imaging. Additionally, a post-mortem coronary artery from one VW imaged AD-HIES patient was examined. ResultsCoronary VW in AD-HIES was thicker than in healthy controls but not significantly different from VW thickness in CAD subjects. AD-HIES coronaries showed increased VW area compared to healthy controls and CAD subjects. On histology, the AD-HIES coronary artery had findings consistent with atherosclerotic plaque, but had minimal luminal narrowing, deficient adventitia thickening and absence of both internal and external elastic laminae. ConclusionsThis is the first study to demonstrate subclinical coronary atherosclerosis in AD-HIES patients on VW imaging by MRI. Histologic evaluation confirmed the presence of atherosclerosis with lack of supportive adventitial thickening and elastic components. These findings suggest mechanisms for coronary dilation in AD-HIES and thereby help direct clinical management.

Coronary Artery PET/MR Imaging: Feasibility, Limitations, and Solutions

ObjectivesThe aims of this study were to describe the authors’ initial experience with combined coronary artery positron emission tomographic (PET) and magnetic resonance (MR) imaging using 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF) radiotracers, describe common problems and their solutions, and demonstrate the feasibility of coronary PET/MR imaging in appropriate patients. BackgroundRecently, PET imaging has been applied to the aortic valve and regions of atherosclerosis. 18F-FDG PET imaging has become established for imaging inflammation in atherosclerosis in the aorta and carotid arteries. Moreover, 18F-NaF has emerged as a novel tracer of active microcalcification in the aortic valve and coronary arteries. Coronary PET imaging remains challenging because of the small caliber of the vessels and their complex motion. Currently, most coronary imaging uses combined PET and computed tomographic imaging, but there is increasing enthusiasm for PET/MR imaging because of its reduced radiation, potential to correct for motion, and the complementary information available from cardiac MR in a single scan. MethodsTwenty-three patients with diagnosed or documented risk factors for coronary artery disease underwent either 18F-FDG or 18F-NaF PET/MR imaging. Standard breath-held MR-based attenuation correction was compared with a novel free-breathing approach. The impact on PET image artifacts and the interpretation of vascular uptake were evaluated semiquantitatively by expert readers. Moreover, PET reconstructions with more algorithm iterations were compared visually and by target-to-background ratio. ResultsImage quality was significantly improved by novel free-breathing attenuation correction. Moreover, conspicuity of coronary uptake was improved by increasing the number of algorithm iterations from 3 to 6. Elevated radiotracer uptake could be localized to individual coronary lesions using both 18F-FDG (n = 1, maximal target-to-background ratio = 1.61) and 18F-NaF (n = 7, maximal target-to-background ratio = 1.55 ± 0.37), including in 1 culprit plaque post–myocardial infarction confirmed by myocardial late gadolinium enhancement. ConclusionsThe authors provide the first demonstration of successful, low-radiation (7.2 mSv) PET/MR imaging of inflammation and microcalcification activity in the coronary arteries. However, this requires specialized approaches tailored to coronary imaging for both attenuation correction and PET reconstruction.

Magnetic Resonance Imaging of Coronary Arteries: Latest Technical Innovations and Clinical Experiences

Cardiovascular disease (CVD) is the leading cause of death and a major health care challenge globally. Coronary artery disease (CAD) is a primary underlying pathological process in the majority of cardiovascular disease cases. Magnetic resonance imaging (MRI) can play a potentially important role in the management of CAD as a noninvasive imaging modality without ionizing radiation, although its early promise has not been delivered because of several crucial technical limitations. However, recent innovations in MRI have reopened the door, with tremendous opportunities for multiparametric assessment of CAD including luminal stenosis, plaque burden and composition, and disease activities such as inflammation and hemorrhage. Novel MRI acquisition and reconstruction strategies now offer much increased spatial resolution and image quality and shortened examination times compared with conventional approaches. Recent clinical experiences of coronary MRI indicated the potential to improve the current management of coronary atherosclerosis, such as identifying the patients at the highest risk and evaluating therapeutic responses. In this review we discuss the latest technical advances and clinical insights in coronary MRI.