Cardiovascular Magnetic Resonance in Nonischemic Myocardial Inflammation: Expert Recommendations

The current landscape of imaging recommendations in cardiovascular clinical guidelines: toward an imaging-guided precision medicine

The purpose of this article is to provide an overview on the role of CT scan and MRI according to selected guidelines by the European Society of Cardiology (ESC) and the American College of Cardiology/American Heart Association (ACC/AHA). ESC and ACC/AHA guidelines were systematically reviewed for recommendations to CT and MRI use in specific cardiovascular (CV) clinical categories. All recommendations were collected in a dataset, including the class of recommendation, the level of evidence (LOE), the specific imaging technique, the clinical purpose of the recommendation and the recommending Society. Among the 43 included guidelines (ESC: n = 18, ACC/AHA: n = 25), 26 (60.4%) contained recommendations for CT scan or MRI (146 recommendations: 62 for CT and 84 for MRI). Class of recommendation IIa (32.9%) was the most represented, followed by I (28.1%), IIb (24%) and III (11.9%). MRI recommendations more frequently being of higher class (I: 36.9%, IIa: 29.8%, IIb: 21.4%, III: 11.9%) as compared to CT (I: 16.1%, IIa: 37.1%, IIb: 27.4%, III: 19.4%). Most of recommendation (55.5%) were based on expert opinion (LOE C). The use of cardiac CT and cardiac MR in the risk assessment, diagnosis, therapeutic and procedural planning is in continuous development, driven by an increasing need to evolve toward an imaging-guided precision medicine, combined with cost-effectiveness and healthcare sustainability. These developments must be accompanied by an increased availability of high-performance scanners in healthcare facilities and should emphasize the need of increasing the number of radiologists fully trained in cardiac imaging.

Management of Acute Myocarditis and Chronic Inflammatory Cardiomyopathy: An Expert Consensus Document

Myocarditis is an inflammatory disease of the heart that may occur because of infections, immune system activation, or exposure to drugs. The diagnosis of myocarditis has changed due to the introduction of cardiac magnetic resonance imaging. We present an expert consensus document aimed to summarize the common terminology related to myocarditis meanwhile highlighting some areas of controversies and uncertainties and the unmet clinical needs. In fact, controversies persist regarding mechanisms that determine the transition from the initial trigger to myocardial inflammation and from acute myocardial damage to chronic ventricular dysfunction. It is still uncertain which viruses (besides enteroviruses) cause direct tissue damage, act as triggers for immune-mediated damage, or both. Regarding terminology, myocarditis can be characterized according to etiology, phase, and severity of the disease, predominant symptoms, and pathological findings. Clinically, acute myocarditis (AM) implies a short time elapsed from the onset of symptoms and diagnosis (generally <1 month). In contrast, chronic inflammatory cardiomyopathy indicates myocardial inflammation with established dilated cardiomyopathy or hypokinetic nondilated phenotype, which in the advanced stages evolves into fibrosis without detectable inflammation. Suggested diagnostic and treatment recommendations for AM and chronic inflammatory cardiomyopathy are mainly based on expert opinion given the lack of well-designed contemporary clinical studies in the field. We will provide a shared and practical approach to patient diagnosis and management, underlying differences between the European and US scientific statements on this topic. We explain the role of histology that defines subtypes of myocarditis and its prognostic and therapeutic implications.

Myocarditis: imaging up to date

Myocarditis is an inflammatory disease of the heart muscle, diagnosed by histological, immunological, and immunohistochemical criteria. Endomyocardial biopsy represents the diagnostic gold standard for its diagnosis but is infrequently used. Due to its noninvasive ability to detect the presence of myocardial edema, hyperemia and necrosis/fibrosis, Cardiac MR imaging is routinely used in the clinical practice for the diagnosis of acute myocarditis. Recently pixel-wise mapping of T1 and T2 relaxation time have been introduced into the clinical Cardiac MR protocol increasing its accuracy. Our paper will review the role of MR imaging in the diagnosis of acute myocarditis.

Loeffler's Endocarditis: An Integrated Multimodality Approach

Loeffler's endocarditis (LE) is the cardiac manifestation of hypereosinophilic syndrome, a rare systemic disease characterized by the sustained production of eosinophils leading to organ damage. Few data, principally by case reports, are available regarding the diagnostic workup in patients with suspected LE. Thus, we have performed a systematic search of the literature dealing with imaging in LE and propose an integrated multimodality imaging approach in the cardiac diagnostics of LE patients. The aim is to provide an updated state-of-the-art review focused on noninvasive and invasive imaging modalities for this rare and underdiagnosed disease. Standard and advanced echocardiography are typically the first cardiac imaging examinations when LE is suspected and they are also used later in follow-up for prognostic stratification and assessing response to treatment. Cardiac magnetic resonance provides a more detailed anatomical and functional evaluation of cardiac chambers, tissue characterization for the presence and extension of myocardial edema and fibrosis, and ventricular thrombi identification. Computed tomography scan and [18F]-fluoro-deoxy-glucose positron emission tomography may be helpful in selected cases to evaluate the cardiac involvement of LE as well as the other noncardiac manifestations of hypereosinophilic syndrome. Endomyocardial biopsy may be considered in patients with high clinical suspicion of LE if noninvasive imaging findings are confusing or not conclusive. The appropriate use of invasive and noninvasive imaging modalities, combining the available techniques with the patients' clinical features, will hopefully lead to early diagnosis, more accurate staging of disease, and timely treatment of LE that may prevent the irreversible myocardial damage of LE and adverse cardiovascular events.

T1, T2, and Fat Fraction Cardiac MR Fingerprinting: Preliminary Clinical Evaluation

BACKGROUND

Dixon cardiac magnetic resonance fingerprinting (MRF) has been recently introduced to simultaneously provide water T₁ , water T₂ , and fat fraction (FF) maps.

PURPOSE

To assess Dixon cardiac MRF repeatability in healthy subjects and its clinical feasibility in a cohort of patients with cardiovascular disease.

POPULATION

T1MES phantom, water-fat phantom, 11 healthy subjects and 19 patients with suspected cardiovascular disease.

STUDY TYPE

Prospective.

FIELD STRENGTH/SEQUENCE

1.5T, inversion recovery spin echo (IRSE), multiecho spin echo (MESE), modified Look-Locker inversion recovery (MOLLI), T₂ gradient spin echo (T₂ -GRASE), 6-echo gradient rewound echo (GRE), and Dixon cardiac MRF.

ASSESSMENT

Dixon cardiac MRF precision was assessed through repeated scans against conventional MOLLI, T₂ -GRASE, and PDFF in phantom and 11 healthy subjects. Dixon cardiac MRF native T₁ , T₂ , FF, postcontrast T₁ and synthetic extracellular volume (ECV) maps were assessed in 19 patients in comparison to conventional sequences. Measurements in patients were performed in the septum and in late gadolinium enhanced (LGE) areas and assessed using mean value distributions, correlation, and Bland-Altman plots. Image quality and diagnostic confidence were assessed by three experts using 5-point scoring scales.

STATISTICAL TESTS

Paired Wilcoxon rank signed test and paired t-tests were applied. Statistical significance was indicated by *(P < 0.05).

RESULTS

Dixon cardiac MRF showed good overall precision in phantom and in vivo. Septal average repeatability was ~23 msec for T₁ , ~2.2 msec for T₂ , and ~1% for FF. Biases in healthy subjects/patients were measured at +37 msec*/+60 msec* and -8.8 msec*/-8 msec* when compared to MOLLI and T₂ -GRASE, respectively. No statistically significant differences in postcontrast T₁ (P = 0.17) and synthetic ECV (P = 0.19) measurements were observed in patients.

DATA CONCLUSION

Dixon cardiac MRF attained good overall precision in phantom and healthy subjects, while providing coregistered T₁ , T₂ , and fat fraction maps in a single breath-hold scan with similar or better image quality than conventional methods in patients.

LEVEL OF EVIDENCE

2.

TECHNICAL EFFICACY STAGE

2.

When to Use Cardiovascular Magnetic Resonance in Patients with Heart Failure

Use of cardiac magnetic resonance (CMR) to aid in diagnosis, management, and prognosis of ischemic and nonischemic cardiomyopathy has advanced tremendously in the past several decades. These advances have expanded our understanding of both ischemic and nonischemic cardiomyopathies while also allowing for new avenues of diagnosis and treatment. This review summarizes key concepts of CMR technology and CMR use in the diagnosis and prognosis in ischemic, infiltrative, inflammatory, and other nonischemic cardiomyopathies and discusses the use of CMR in the patient presenting with ventricular arrhythmia with unclear diagnosis and advances in CMR in the management cardiomyopathy.

Cardiovascular Magnetic Resonance of Myocardial Fibrosis, Edema, and Infiltrates in Heart Failure

Cardiac magnetic resonance (CMR) imaging is a unique imaging modality, which provides accurate noninvasive tissue characterization. Various CMR sequences can be utilized to identify and quantify patterns of myocardial edema, fibrosis, and infiltrates, which are important determinants for diagnosis and prognostication of heart failure. This article describes available methods of tissue characterization imaging applied in CMR. The presence and patterns of abnormal tissue characterization are related to common etiologies of heart failure and the techniques employed to demonstrate this. CMR provides the opportunity to identify the etiology of heart failure based on the recognition of different patterns of myocardial abnormalities.

Delayed acute myocarditis and COVID-19-related multisystem inflammatory syndrome

Precise descriptions of coronavirus disease 2019 (COVID‐19)‐related cardiac damage as well as underlying mechanisms are scarce. We describe clinical presentation and diagnostic workup of acute myocarditis in a patient who had developed COVID‐19 syndrome 1 month earlier. A healthy 40‐year‐old man suffered from typical COVID‐19 symptoms. Four weeks later, he was admitted because of fever and tonsillitis. Blood tests showed major inflammation. Thoracic computed tomography was normal, and RT–PCR for SARS‐CoV‐2 on nasopharyngeal swab was negative. Because of haemodynamic worsening with both an increase in cardiac troponin and B‐type natriuretic peptide levels and normal electrocardiogram, acute myocarditis was suspected. Cardiac echographic examination showed left ventricular ejection fraction at 45%. Exhaustive diagnostic workup included RT–PCR and serologies for infectious agents and autoimmune blood tests as well as cardiac magnetic resonance imaging and endomyocardial biopsies. Cardiac magnetic resonance with T2 mapping sequences showed evidence of myocardial inflammation and focal lateral subepicardial late gadolinium enhancement. Pathological analysis exhibited interstitial oedema, small foci of necrosis, and infiltrates composed of plasmocytes, T‐lymphocytes, and mainly CD163⁺ macrophages. These findings led to the diagnosis of acute lympho‐plasmo‐histiocytic myocarditis. There was no evidence of viral RNA within myocardium. The only positive viral serology was for SARS‐CoV‐2. The patient and his cardiac function recovered in the next few days without use of anti‐inflammatory or antiviral drugs. This case highlights that systemic inflammation associated with acute myocarditis can be delayed up to 1 month after initial SARS‐CoV‐2 infection and can be resolved spontaneously.

Management perspectives from the 2019 Wuhan international workshop on fulminant myocarditis

Fulminant myocarditis (FM) is a form of acute myocardial inflammation leading to rapid-onset hemodynamic instability due to cardiogenic shock or life-threatening arrhythmias. As highlighted by recent registries, FM is associated with high rates of death and heart transplantation, regardless of the underlying histology. Because of a paucity of evidence-based management strategies exists for this disease, an International workshop on FM was held in Wuhan, China, in October 2019, in order to share knowledge on the disease and identify areas of consensus. The present report highlights both agreements and controversies in FM management across the world, focusing the attention on areas of opportunity, FM definition, the use of endomyocardial biopsy and viral identification on heart specimens, treatment algorithms including immunosuppression and the timing of circulatory support escalation. This report incorporates the most recent recommendations from national and international professional societies. Main areas of interest and aims of future prospective observational registries and randomized controlled trials were finally identified and suggested.

Free-breathing simultaneous myocardial T1 and T2 mapping with whole left ventricle coverage

PURPOSE

To develop a free-breathing sequence, that is, Multislice Joint T₁ -T₂ , for simultaneous measurement of myocardial T₁ and T₂ for multiple slices to achieve whole left-ventricular coverage.

METHODS

Multislice Joint T₁ -T₂ adopts slice-interleaved acquisition to collect 10 single-shot electrocardiogram-triggered images for each slice prepared by saturation and T₂ preparation to simultaneously estimate myocardial T₁ and T₂ and achieve whole left-ventricular coverage. Prospective slice-tracking using a respiratory navigator and retrospective image registration are used to reduce through-plane and in-plane motion, respectively. Multislice Joint T₁ -T₂ was validated through numerical simulations and phantom and in vivo experiments, and compared with saturation-recovery single-shot acquisition and T₂ -prepared balanced Steady-State Free Precession (T₂ -prep SSFP) sequences.

RESULTS

Phantom T₁ and T₂ from Multislice Joint T₁ -T₂ had good accuracy and precision, and were insensitive to heart rate. Multislice Joint T₁ -T₂ yielded T₁ and T₂ maps of nine left-ventricular slices in 1.4 minutes. The mean left-ventricular T₁ difference between saturation-recovery single-shot acquisition and Multislice Joint T₁ -T₂ across healthy subjects and patients was 191 ms (1564 ± 60 ms versus 1373 ± 50 ms; P < .05) and 111 ms (1535 ± 49 ms vs 1423 ± 49 ms; P < .05), respectively. The mean difference in left-ventricular T₂ between T₂ -prep SSFP and Multislice Joint T₁ -T₂ across healthy subjects and patients was -6.3 ms (42.4 ± 1.4 ms vs 48.7 ± 2.5; P < .05) and -5.7 ms (41.6 ± 2.5 ms vs 47.3 ± 2.7; P < .05), respectively.

CONCLUSION

Multislice Joint T₁ -T₂ enables quantification of whole left-ventricular T₁ and T₂ during free breathing within a clinically feasible scan time of less than 2 minutes.

Gamut of cardiac manifestations and complications of COVID-19: a contemporary review

COVID-19 has posed an extraordinary burden on health and the economy worldwide. Patients with cardiovascular diseases are more likely to have severe illness due to COVID-19 and are at increased risk for complications and mortality. We performed a narrative literature review to assess the burden of COVID-19 and cardiovascular morbidity and mortality. Myocardial injury has been reported in 20%-30% of patients hospitalized due to COVID-19 and is associated with a worse prognosis and high mortality (~50%-60%). Proposed mechanisms of myocardial injury include inflammation within the myocardium (due to direct viral infection or cytokine storm), endotheliitis, coronary vasculitis, myocarditis, demand ischemia, plaque destabilization and right ventricular failure. The right ventricle is particularly vulnerable to injury and failure in COVID-19-infected patients, given the hypoxic pulmonary vasoconstriction, pulmonary microthrombi or pulmonary embolism. Echocardiography is an effective and accessible tool to evaluate left and right ventricular functions and risk stratify patients with COVID-19 infection. Cardiac MRI has detected and characterized myocardial injury, with changes compatible with other inflammatory cardiomyopathies. The long-term consequences of these inflammatory changes are unknown, but accumulating data will provide insight regarding the longitudinal impact of COVID-19 infection on cardiovascular morbidity and mortality.

[IRM et myocardite infectieuse]

Au cours des dix dernières années, l’IRM cardiaque est devenue un outil incontournable pour le diagnostic de myocardite aiguë. Elle peut, sous certaines conditions, permettre de surseoir à la coronarographie initiale dans de nombreuses situations. Son utilisation est préconisée en classe I, dans la situation du MINOCA, dans les recommandations de l’ESC de septembre 2020, pour permettre d’établir un diagnostic de certitude entre infarctus aigu, myocardite, Tako-Tsubo, ou autres cardiopathies en permettant d’améliorer la prise en charge thérapeutique et le suivi. Cet article reprend les principes techniques de l’IRM dans la myocardite (critères diagnostiques de Lake Louise et critères basés sur la cartographie tissulaire myocardique), les principaux diagnostics différentiels et la valeur pronostique, ainsi que la myocardite associée au COVID-19.

Myocarditis and inflammatory cardiomyopathy: current evidence and future directions

Inflammatory cardiomyopathy, characterized by inflammatory cell infiltration into the myocardium and a high risk of deteriorating cardiac function, has a heterogeneous aetiology. Inflammatory cardiomyopathy is predominantly mediated by viral infection, but can also be induced by bacterial, protozoal or fungal infections as well as a wide variety of toxic substances and drugs and systemic immune-mediated diseases. Despite extensive research, inflammatory cardiomyopathy complicated by left ventricular dysfunction, heart failure or arrhythmia is associated with a poor prognosis. At present, the reason why some patients recover without residual myocardial injury whereas others develop dilated cardiomyopathy is unclear. The relative roles of the pathogen, host genomics and environmental factors in disease progression and healing are still under discussion, including which viruses are active inducers and which are only bystanders. As a consequence, treatment strategies are not well established. In this Review, we summarize and evaluate the available evidence on the pathogenesis, diagnosis and treatment of myocarditis and inflammatory cardiomyopathy, with a special focus on virus-induced and virus-associated myocarditis. Furthermore, we identify knowledge gaps, appraise the available experimental models and propose future directions for the field. The current knowledge and open questions regarding the cardiovascular effects associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are also discussed. This Review is the result of scientific cooperation of members of the Heart Failure Association of the ESC, the Heart Failure Society of America and the Japanese Heart Failure Society.

3D free-breathing cardiac magnetic resonance fingerprinting

PURPOSE

To develop a novel respiratory motion compensated three-dimensional (3D) cardiac magnetic resonance fingerprinting (cMRF) approach for whole-heart myocardial T₁ and T₂ mapping from a free-breathing scan.

METHODS

Two-dimensional (2D) cMRF has been recently proposed for simultaneous, co-registered T₁ and T₂ mapping from a breath-hold scan; however, coverage is limited. Here we propose a novel respiratory motion compensated 3D cMRF approach for whole-heart myocardial T₁ and T₂ tissue characterization from a free-breathing scan. Variable inversion recovery and T₂ preparation modules are used for parametric encoding, respiratory bellows driven localized autofocus is proposed for beat-to-beat translation motion correction and a subspace regularized reconstruction is employed to accelerate the scan. The proposed 3D cMRF approach was evaluated in a standardized T₁ /T₂ phantom in comparison with reference spin echo values and in 10 healthy subjects in comparison with standard 2D MOLLI, SASHA and T₂ -GraSE mapping techniques at 1.5 T.

RESULTS

3D cMRF T₁ and T₂ measurements were generally in good agreement with reference spin echo values in the phantom experiments, with relative errors of 2.9% and 3.8% for T₁ and T₂ (T₂ < 100 ms), respectively. in vivo left ventricle (LV) myocardial T₁ values were 1054 ± 19 ms for MOLLI, 1146 ± 20 ms for SASHA and 1093 ± 24 ms for the proposed 3D cMRF; corresponding T₂ values were 51.8 ± 1.6 ms for T2-GraSE and 44.6 ± 2.0 ms for 3D cMRF. LV coefficients of variation were 7.6 ± 1.6% for MOLLI, 12.1 ± 2.7% for SASHA and 5.8 ± 0.8% for 3D cMRF T₁ , and 10.5 ± 1.4% for T2-GraSE and 11.7 ± 1.6% for 3D cMRF T₂ .

CONCLUSION

The proposed 3D cMRF can provide whole-heart, simultaneous and co-registered T₁ and T₂ maps with accuracy and precision comparable to those of clinical standards in a single free-breathing scan of about 7 min.

Cardiovascular disease in women: insights from magnetic resonance imaging

The presentation and identification of cardiovascular disease in women pose unique diagnostic challenges compared to men, and underrecognized conditions in this patient population may lead to clinical mismanagement.This article reviews the sex differences in cardiovascular disease, explores the diagnostic and prognostic role of cardiovascular magnetic resonance (CMR) in the spectrum of cardiovascular disorders in women, and proposes the added value of CMR compared to other imaging modalities. In addition, this article specifically reviews the role of CMR in cardiovascular diseases occurring more frequently or exclusively in female patients, including Takotsubo cardiomyopathy, connective tissue disorders, primary pulmonary arterial hypertension and peripartum cardiomyopathy. Gaps in knowledge and opportunities for further investigation of sex-specific cardiovascular differences by CMR are also highlighted.

Prevalence of Myocardial Fibrosis in Intensive Endurance Training Athletes: A Systematic Review and Meta-Analysis

Objective: To review the published literature reporting on the incidence of myocardial fibrosis (MF) in high-intensity endurance athletes measured by late gadolinium enhancement (LGE) with cardiac magnetic resonance imaging (CMR). Methods: Five databases (PubMed, Cochrane Controlled Trials Register, EMBASE, Web of Science, and SPORTDiscus) were searched to obtain case cohort studies published before November 10, 2019. From 96 abstracts or reports extracted, 18 full-text articles were reviewed. The incidence of LGE was reported as outcome measures. Subgroup analysis was performed by age (under or above 50 years). Pooled estimates were obtained using a fixed-effects model. Results: After a full-text assessment, 12 studies involving 1,359 participants were included for analysis. Among them, 163/772 participants in the endurance athletes group showed LGE positive, compared with 19/587 participants in the comparison group. The results of the meta-analysis suggested that the prevalence of LGE was higher in the athletes group with long-term endurance exercise (OR 7.20;95%CI: 4.51-11.49). In addition, the same conclusion was drawn after the stratification of age. Conclusions: The available evidence demonstrates that high-intensity endurance athletes is associated with an increased incidence of LGE positive.

Cardiac magnetic resonance in arrhythmogenic cardiomyopathies

Over the past few years, the approach to the 'arrhythmic patient' has profoundly changed. An early clinical presentation of arrhythmia is often accompanied by non-specific symptoms and followed by inconclusive electrocardiographic findings. In this scenario, cardiac magnetic resonance (CMR) has been established as a clinical tool of fundamental importance for a correct prognostic stratification of the arrhythmic patient. This technique provides a high-spatial-resolution tomographic evaluation of the heart, which allows studying accurately the ventricular volumes, identifying even segmental kinetic anomalies and properly detecting diffuse or focal tissue alterations through an excellent tissue characterization, while depicting different patterns of fibrosis distribution, myocardial edema or fatty substitution. Through these capabilities, CMR has a pivotal role for the adequate management of the arrhythmic patient, allowing the identification of those phenotypic manifestations characteristic of structural heart diseases. Therefore, CMR provides valuable information to reclassify the patient within the wide spectrum of potentially arrhythmogenic heart diseases, the definition of which remains the major determinants for both an adequate treatment and a poor prognosis. The purpose of this review study was to focus on the role of CMR in the evaluation of the main cardiac clinical entities associated with arrhythmogenic phenomena and to present a brief debate on the main pathophysiological mechanisms involved in the arrhythmogenesis process.

Cardiac magnetic resonance in hypertrophic and dilated cardiomyopathies

Cardiomyopathies are a heterogeneous entity. The progress in the field of genetics has allowed over the years to determine its origin more and more often. The classification of these pathologies has changed over the years; it has been updated with new knowledge. Imaging allows to define the phenotypic characteristics of the different forms of cardiomyopathy. Cardiac magnetic resonance (CMR) allows a morphological evaluation of the associated (and sometimes pathognomonic) cardiac findings of any form of cardiomyopathy. The tissue characterization sequences also make magnetic resonance imaging unique in its ability to detect changes in myocardial tissue. This review aims to define the features that can be highlighted by CMR in hypertrophic and dilated forms and the possible differential diagnoses. In hypertrophic forms, CMR provides: precise evaluation of wall thickness in all segments, ventricular function and size and evaluation of possible presence of areas of fibrosis as well as changes in myocardial tissue (measurement of T1 mapping and extracellular volume values). In dilated forms, cardiac resonance is the gold standard in the assessment of ventricular volumes. CMR highlights also the potential alterations of the myocardial tissue.

Advanced Nuclear Medicine and Molecular Imaging in the Diagnosis of Cardiomyopathy

OBJECTIVE. The purpose of this article is to summarize the protocol, interpretation, and diagnostic performance of nuclear medicine and molecular imaging in imaging two distinctive, underdiagnosed cardiomyopathies: cardiac amyloidosis and cardiac sarcoidosis. CONCLUSION. Emerging new radiotracers and advanced molecular imaging modalities enable us to noninvasively characterize certain types of cardiomyopathies, including cardiac amyloidosis and cardiac sarcoidosis, with great confidence. We expect to improve recognition and promote the application of such advanced techniques in the imaging and management of these potentially lethal cardiomyopathies.

Cardiac Magnetic Resonance in Nonischemic Cardiomyopathies

Cardiovascular magnetic resonance (CMR) has emerged as a key modality to assess nonischemic cardiomyopathies. Its ability to detect cardiac morphology and function with fast cine imaging, myocardial edema with T2-based techniques, and fibrosis with late gadolinium enhancement techniques has enabled noninvasive characterization of cardiac tissue, thus helping clinicians assess cardiovascular risk and determine the most effective management strategy. Active investigations into parametric imaging techniques will further expand the potential clinical applications of CMR for cardiac tissue characterization. This review discusses the use of CMR techniques in characterizing the major morphofunctional phenotypes of nonischemic cardiomyopathies.

Influence of hydration status on cardiovascular magnetic resonance myocardial T1 and T2 relaxation time assessment: an intraindividual study in healthy subjects

BACKGROUND

Myocardial native T1 and T2 relaxation time mapping are sensitive to pathological increase of myocardial water content (e.g. myocardial edema). However, the influence of physiological hydration changes as a possible confounder of relaxation time assessment has not been studied. The purpose of this study was to evaluate, whether changes in myocardial water content due to dehydration and hydration might alter myocardial relaxation times in healthy subjects.

METHODS

A total of 36 cardiovascular magnetic resonance (CMR) scans were performed in 12 healthy subjects (5 men, 25.8 ± 3.2 years). Subjects underwent three successive CMR scans: (1) baseline scan, (2) dehydration scan after 12 h of fasting (no food or water), (3) hydration scan after hydration. CMR scans were performed for the assessment of myocardial native T1 and T2 relaxation times and cardiac function. For multiple comparisons, repeated measures ANOVA or the Friedman test was used.

RESULTS

There was no change in systolic blood pressure or left ventricular ejection fraction between CMR scans (P > 0.05, respectively). T1 relaxation times were significantly reduced with dehydration (987 ± 27 ms [baseline] vs. 968 ± 29 ms [dehydration] vs. 986 ± 28 ms [hydration]; P = 0.006). Similar results were observed for T2 relaxation times (52.9 ± 1.8 ms [baseline] vs. 51.5 ± 2.0 ms [dehydration] vs. 52.2 ± 1.9 ms [hydration]; P = 0.020).

CONCLUSIONS

Dehydration may lead to significant alterations in relaxation times and thereby may influence precise, repeatable and comparable assessment of native T1 and T2 relaxation times. Hydration status should be recognized as new potential confounder of native T1 and T2 relaxation time assessment in clinical routine.

Applications of PET-MR Imaging in Cardiovascular Disorders

Cardiac PET/MR imaging is an integrated imaging approach that requires less radiation than PET/computed tomography and combines the high spatial resolution and morphologic data from MR imaging with the physiologic information from PET. This hybrid approach has the potential to improve the diagnostic and prognostic evaluation of several cardiovascular conditions, such as ischemic heart disease, infiltrative diseases such as sarcoidosis, acute and chronic myocarditis, and cardiac masses. Herein, the authors discuss the strengths of PET and MR imaging in several cardiovascular conditions; the challenges and potential; and the current data on the application of this powerful hybrid imaging modality.

COVID-19 Myocardial Pathology Evaluated Through scrEening Cardiac Magnetic Resonance (COMPETE CMR)

Background

Myocarditis is a leading cause of sudden cardiac death among competitive athletes and may occur without antecedent symptoms. COVID-19-associated myocarditis has been well-described, but the prevalence of myocardial inflammation and fibrosis in young athletes after COVID-19 infection is unknown.

Objectives

This study sought to evaluate the prevalence and extent of cardiovascular involvement in collegiate athletes that had recently recovered from COVID-19.

Methods

We conducted a retrospective cohort analysis of collegiate varsity athletes with prior COVID-19 infection, all of whom underwent cardiac magnetic resonance (CMR) prior to resumption of competitive sports in August 2020.

Results

Twenty-two collegiate athletes with prior COVID-19 infection underwent CMR. The median time from SARS-CoV-2 infection to CMR was 52 days. The mean age was 20.2 years. Athletes represented 8 different varsity sports. This cohort was compared to 22 healthy controls and 22 tactical athlete controls. Most athletes experienced mild illness (N=17, 77%), while the remainder (23%) were asymptomatic. No athletes had abnormal troponin I, electrocardiograms, or LVEF < 50% on echocardiography. Late gadolinium enhancement was found in 9% of collegiate athletes and one athlete (5%) met formal criteria for myocarditis.

Conclusions

Our study suggests that the prevalence of myocardial inflammation or fibrosis after an asymptomatic or mild course of ambulatory COVID-19 among competitive athletes is modest (9%), but would be missed by ECG, Ti, and strain echocardiography. Future investigation is necessary to further phenotype cardiovascular manifestations of COVID-19 in order to better counsel athletes on return to sports participation.

COVID-19-associated myocarditis has been well-described, but the prevalence of myocardial inflammation and fibrosis in athletes after COVID-19 is unknown. We conducted a retrospective cohort analysis of 22 collegiate athletes with prior COVID-19 infection who underwent electrocardiography, troponin I, echocardiography with strain, and CMR. The median time from SARS-CoV-2 infection to CMR was 52 days. All athletes experienced mild illness or were asymptomatic. Late gadolinium enhancement was found in 9%. This suggests the prevalence of myocardial inflammation or fibrosis after an asymptomatic or mild course of COVID-19 among competitive athletes is modest, but would be missed without CMR screening.

Cardiovascular Complications of Novel Anti-Cancer Immunotherapy: Old Problems from New Agents?

Many novel anti-cancer therapies have dramatically improved outcomes of various cancer patients. However, it also poses a risk for cardiovascular complications as well. For the novel anti-cancer agent with which physicians does not have enough clinical experiences to determine the characteristics of cardiovascular complications, it is important to assess risk factors for cardiotoxicity before starting anti-cancer therapy. High-risk patient should be consulted to cardiologist before initiating anti-cancer therapy and pre-emptive cardiac function monitoring plan might be prepared in advance. The biomarkers, electrocardiography and echocardiography are useful tools for the detection of subclinical cardiotoxicity during anti-cancer therapy. This review article tried to suggest the cardiac function monitoring strategies for newly encountered potential cardiotoxic anti-cancer agents and to summarize the cardiovascular complications of novel anti-cancer immunotherapies including immune checkpoint inhibitor (ICI) and chimeric antigen receptor (CAR) T-cell therapy. ICIs can cause fatal myocarditis, which usually occurs early after initiation, and prompt treatment with high-dose corticosteroid is necessary. CAR T-cell therapy can cause cytokine release syndrome, which may result in circulatory collapse. Supportive treatment as well as tocilizumab, an anti-interleukin-6 receptor antibody are cornerstones of treatment.

T2 Relaxation Times at Cardiac MRI in Healthy Adults: A Systematic Review and Meta-Analysis

Background T2 mapping is an important cardiac MRI technique with applications in various conditions. However, a comprehensive evaluation of the T2 literature for normal values is lacking. Purpose To characterize the ranges of normal values and variability of myocardial T2 relaxation times using a systematic review and meta-analysis of the T2 literature. Materials and Methods PubMed and Cochrane Central were searched from June 2019 to January 2020 for myocardial T2 measurements in healthy adults. Studies quantifying T2 relaxation times conducted at 1.5 T or 3.0 T using gradient and spin-echo (GRASE) or T2-prepared balanced steady-state free precession sequences were included. Summary means were generated using a random-effects model. Subgroup analysis and meta-regression were performed to assess factors causing heterogeneity. Results Of the 2481 articles retrieved, 42 studies were included with 954 healthy adults (mean age, 42.4 years ± 10.5 [standard deviation]; 538 men). The pooled mean of T2 across studies was 52 msec at 1.5 T (95% confidence interval [CI]: 51 msec, 53 msec) and 46 msec at 3.0 T (95% CI: 44 msec, 48 msec) (P ≤ .001). I² was 98% at 1.5 T and 3.0 T. Meta-regression at 1.5 T and 3.0 T identified vendor (β at 1.5 T = -4 msec [with Philips as reference], P < .001; β at 3.0 T = -5 msec, P = .02) and pulse sequence (β at 1.5 T = -5 msec [with GRASE as reference], P < .001; β at 3.0 T = -6 msec, P = .002) as significant covariates, but it did not identify any association with covariates of age (β at 1.5 T = 0 msec per year, P = .70; β at 3.0 T = 0 msec per year, P = .83) or sex (β at 1.5 T = -1 msec, P = .88; β at 3.0 T = 6 msec, P = .42). Conclusion The pooled mean of T2 relaxation times in healthy adults had marked heterogeneity across studies with field strength, vendor, and pulse sequence identified as covariates associated with T2. T2-prepared measurements were similar between vendors at each field strength. © RSNA, 2020 Online supplemental material is available for this article.

Coronary and aortic calcification are associated with cardiovascular events on immune checkpoint inhibitor therapy

BACKGROUND

Although the incidence of immune checkpoint inhibitor (ICI)-related cardiovascular (CV) toxicity is low, the overall burden of CV events after ICI is unknown. Risk factors for CV events after ICI have yet to be identified.

OBJECTIVES

We sought to evaluate the association between vascular calcification on routine baseline computed tomography (CT) imaging and CV events following ICI.

METHOD

This was a single-center, retrospective cohort study of 76 patients referred to Cardio-Oncology with prior ICI treatment. Coronary and aortic calcification on non-gated chest and abdominal CT imaging were qualitatively assessed. The association of baseline clinical parameters and vascular calcification with symptomatic heart failure (HF), acute coronary syndrome, myocarditis, symptomatic arrhythmia, or pericardial effusion after ICI was evaluated.

RESULTS

Over 11 months of follow-up, there were 80 CV events that occurred in 49 patients. Worse coronary and aortic calcification on pre-treatment CT imaging was seen in patients with a CV event (p = .018 and p = .014, respectively). There were no differences in traditional CV risk factors between those with and without a CV event. Eighteen patients (37%) were restarted on ICI therapy after a non- myocarditis or symptomatic systolic HF CV event without recurrent events or mortality over 13 months of follow-up.

CONCLUSIONS

Symptomatic HF was the most common CV event seen after ICI therapy. Worse coronary and aortic calcification on baseline CT imaging was associated with CV events following ICI. With careful clinical evaluation, selected patients may be re-treated with ICI following a non- myocarditis or symptomatic systolic HF CV event.

Predictors of Mortality in Patients With Biopsy-Proven Viral Myocarditis: 10-Year Outcome Data

Background

There is scarce data about the long‐term mortality as well as the prognostic value of cardiovascular magnetic resonance and late gadolinium enhancement (LGE) in patients with biopsy‐proven viral myocarditis. We sought to investigate: (1) mortality and (2) prognostic value of LGEcardiovascular magnetic resonance (location, pattern, extent, and distribution) in a >10‐year follow‐up in patients with biopsy‐proven myocarditis.

Methods and Results

Two‐hundred three consecutive patients with biopsy‐proven viral myocarditis and cardiovascular magnetic resonance were enrolled; 183 patients were eligible for standardized follow‐up. The median follow‐up was 10.1 years. End points were all‐cause death, cardiac death, and sudden cardiac death (SCD). We found substantial long‐term mortality in patients with biopsy‐proven myocarditis (39.3% all cause, 27.3% cardiac, and 10.9% SCD); 101 patients (55.2%) demonstrated LGE. The presence of LGE was associated with a more than a doubled risk of death (hazard ratio [HR], 2.40; 95% CI], 1.30–4.43), escalating to a HR of 3.00 (95% CI, 1.41–6.42) for cardiac death, and a HR of 14.79 (95% CI, 1.95–112.00) for SCD; all P≤0.009. Specifically, midwall, (antero‐) septal LGE, and extent of LGE were highly associated with death, all P<0.001. Septal LGE was the best independent predictor for SCD (HR, 4.59; 95% CI, 1.38–15.24; P=0.01).

Conclusions

In patients with biopsy‐proven viral myocarditis, the presence of midwall LGE in the (antero‐) septal segments is associated with a higher rate of mortality (including SCD) compared with absent LGE or other LGE patterns, underlining the prognostic benefit of a distinct LGE analysis in these patients.

Comparison of 3D and 2D late gadolinium enhancement magnetic resonance imaging in patients with acute and chronic myocarditis

We compared a fast, single breath-hold three dimensional LGE sequence (3D LGE) with an established two dimensional multi breath-hold sequence (2D LGE) and evaluated image quality and the amount of myocardial fibrosis in patients with acute and chronic myocarditis. 3D LGE and 2D LGE (both spatial resolution 1.5 × 1.5 mm², slice-thickness 8 mm, field of view 350 × 350 mm²) were acquired in 25 patients with acute myocarditis (mean age 40 ± 18 years, 7 female) and 27 patients with chronic myocarditis (mean age 44 ± 22 years, 9 female) on a 1.5 T MR system. Image quality was evaluated by two independent, blinded readers using a 5-point Likert scale. Total myocardial mass, fibrotic mass and total fibrotic tissue percentage were quantified for both sequences in both groups. There was no significant difference in image quality between 3D und 2D acquisitions in patients with acute (p = 0.8) and chronic (p = 0.5) myocarditis. No significant differences between 3D and 2D acquisitions could be shown for myocardial mass (acute p = 0.2; chronic p = 0.3), fibrous tissue mass (acute p = 0.7; chronic p = 0.1) and total fibrous percentage (acute p = 0.4 and chronic p = 0.2). Inter-observer agreement was substantial to almost perfect. Acquisition time was significantly shorter for 3D LGE (24 ± 5 s) as compared to 2D LGE (350 ± 58 s, p < 0.001). In patients with acute and chronic myocarditis 3D LGE imaging shows equal diagnostic quality compared to standard 2D LGE imaging but with significantly reduced acquisition time.

Troponin-Positive Non-Obstructive Coronary Arteries and Myocardial Infarction with Non-Obstructive Coronary Arteries: Definition, Etiologies, and Role of CT and MR Imaging

In approximately 10% of patients with acute myocardial infarction (MI), angiography does not reveal an obstructive coronary stenosis. This is known as myocardial infarction with non-obstructive coronary arteries (MINOCA), which has complex and multifactorial causes. However, this term can be confusing and open to dual interpretation, because MINOCA is also used to describe patients with acute myocardial injury caused by ischemia-related myocardial necrosis. Therefore, with regards to this specific context of MINOCA, the generic term for MINOCA should be replaced with troponin-positive with non-obstructive coronary arteries (TpNOCA). The causes of TpNOCA can be subcategorized into epicardial coronary (causes of MINOCA), myocardial, and extracardiac disorders. Cardiac magnetic resonance imaging can confirm MI and differentiate various myocardial causes, while cardiac computed tomography is useful to diagnose the extracardiac causes.

Molecular magnetic resonance imaging of activated platelets allows noninvasive detection of early myocarditis in mice

MRI sensitivity for diagnosis and localization of early myocarditis is limited, although it is of central clinical interest. The aim of this project was to test a contrast agent targeting activated platelets consisting of microparticles of iron oxide (MPIO) conjugated to a single-chain antibody directed against ligand-induced binding sites (LIBS) of activated glycoprotein IIb/IIIa (= LIBS-MPIO). Myocarditis was induced by subcutaneous injection of an emulsion of porcine cardiac myosin and complete Freund’s adjuvant in mice. 3D 7 T in-vivo MRI showed focal signal effects in LIBS-MPIO injected mice 2 days after induction of myocarditis, whereas in control-MPIO injected mice no signal was detectable. Histology confirmed CD41-positive staining, indicating platelet involvement in myocarditis in mice as well as in human specimens with significantly higher LIBS-MPIO binding compared to control-MPIO in both species. Quantification of the myocardial MRI signal confirmed a signal decrease after LIBS-MPIO injection and significant less signal in comparison to control-MPIO injection. These data show, that platelets are involved in inflammation during the course of myocarditis in mice and humans. They can be imaged non-invasively with LIBS-MPIO by molecular MRI at an early time point of the inflammation in mice, which is a valuable approach for preclinical models and of interest for both diagnostic and prognostic purposes.

Heart and Lung Multimodality Imaging in COVID-19

The severe acute respiratory syndrome-coronavirus-2 outbreak has rapidly reached pandemic proportions and has become a major threat to global health. Although the predominant clinical feature of coronavirus disease-2019 (COVID-19) is an acute respiratory syndrome of varying severity, ranging from mild symptomatic interstitial pneumonia to acute respiratory distress syndrome, the cardiovascular system can be involved in several ways. As many as 40% of patients hospitalized with COVID-19 have histories of cardiovascular disease, and current estimates report a proportion of myocardial injury in patients with COVID-19 of up to 12%. Multiple pathways have been suggested to explain this finding and the related clinical scenarios, encompassing local and systemic inflammatory responses and oxygen supply-demand imbalance. From a clinical point of view, cardiac involvement during COVID-19 may present a wide spectrum of severity, ranging from subclinical myocardial injury to well-defined clinical entities (myocarditis, myocardial infarction, pulmonary embolism, and heart failure), whose incidence and prognostic implications are currently largely unknown because of a significant lack of imaging data. Integrated heart and lung multimodality imaging plays a central role in different clinical settings and is essential in the diagnosis, risk stratification, and management of patients with COVID-19. The aims of this review are to summarize imaging-oriented pathophysiological mechanisms of lung and cardiac involvement in COVID-19 and to provide a guide for integrated imaging assessment in these patients.

Nuclear cardiology in the context of multimodality imaging to detect cardiac toxicity from cancer therapeutics: Established and emerging methods

The complexity of cancer therapies has vastly expanded in the last decade, along with type and severity of cardiac toxicities associated with these treatments. Prevention of pre-clinical cardiotoxicity may improve cardiovascular outcomes and circumvent the decision to place life-sustaining chemotherapeutic agents on hold, making the early detection of cancer therapeutic related cardiac toxicity with non-invasive imaging essential to the care of these patients. There are several established methods of cardiac imaging in the areas of nuclear cardiology, echocardiography, computed tomography, and cardiac magnetic resonance imaging that are used to assess for cardiovascular toxicity of cancer treatments, with several methods under development. The following review will provide an overview of current and emerging imaging techniques in these areas.

A Case-Based Review of Vaping-Induced Injury-Pulmonary Toxicity and Beyond

The last 10 years has seen a steady rise in the use of electronic cigarettes ("e-cigarettes" or ECIGs) or "vape pens." Though initially developed to assist with smoking cessation, use among adolescents has been particularly high. A concomitant rise in ECIG-related injuries disproportionately affecting young patients has been recognized. This unique case series highlights both pulmonary and extra-pulmonary ECIG-induced injuries including vape tip ingestion, maxillofacial fractures after vape pen explosion, myocarditis, and several different manifestations of vaping-associated lung injury. Becoming familiar with expected imaging findings in the wide array of ECIG-induced complications will help radiologists recognize these findings, recommend further imaging as needed, facilitate early diagnosis by help referring clinicians elicit the relevant history from patients, and expedite appropriate treatment.

Diagnostic Value of Global Cardiac Strain in Patients With Myocarditis

BACKGROUND

Cardiac strain represents an imaging biomarker of contractile dysfunction.

PURPOSE

The purpose of this study was to investigate the diagnostic value of cardiac strain obtained by feature-tracking cardiac magnetic resonance (MR) in acute myocarditis.

MATERIALS AND METHODS

Cardiac MR examinations of 46 patients with myocarditis and preserved ejection fraction at acute phase and follow-up were analyzed along with cardiac MR of 46 healthy age- and sex-matched controls. Global circumferential strain and global radial strain were calculated for each examination, along with myocardial edema and late gadolinium enhancement, and left ventricle functional parameters, through manual contouring of the myocardium. Correlations were assessed using Spearman ρ. Wilcoxon and Mann-Whitney U test were used to assess differences between data. Receiver operating characteristics curves and reproducibility were obtained to assess the diagnostic role of strain parameters.

RESULTS

Global circumferential strain was significantly lower in controls (median, -20.4%; interquartile range [IQR], -23.4% to -18.7%) than patients in acute phase (-18.4%; IQR, -21.0% to -16.1%; P = 0.001) or at follow-up (-19.2%; IQR, -21.5% to -16.1%; P = 0.020). Global radial strain was significantly higher in controls (82.4%; IQR, 62.8%-104.9%) than in patients during the acute phase (65.8%; IQR, 52.9%-79.5%; P = 0.001). Correlations were found between global circumferential strain and global radial strain in all groups (acute, ρ = -0.580, P < 0.001; follow-up, ρ = -0.399, P = 0.006; controls, ρ = -0.609, P < 0.001), and between global circumferential strain and late gadolinium enhancement only in myocarditis patients (acute, ρ = 0.035, P = 0.024; follow-up, ρ = 0.307, P = 0.038).

CONCLUSIONS

Cardiac strain could potentially have a role in detecting acute myocarditis in low-risk acute myocarditis patients where cardiac MR is the main diagnosing technique.

Cardiovascular Imaging in Infective Endocarditis: A Multimodality Approach

Multimodality imaging plays a pivotal role in the evaluation and management of infective endocarditis (IE)-a condition with high morbidity and mortality. The diagnosis of IE is primarily based on the modified Duke criteria with echocardiography as the first-line imaging modality. Both transthoracic and transesophageal echocardiography delineate vegetation location and size, assess for paravalvular extension of infection, and have the added advantage of defining the hemodynamic effects of valvular or device infection. Native and prosthetic valve IE, infections relating to cardiac implantable electronic devices, and indwelling catheters are effectively evaluated with echocardiography. However, complementary imaging is occasionally required when there remains diagnostic uncertainty following transesophageal echocardiography. Multidetector computed tomography and nuclear imaging techniques such as positron emission tomography and white blood cell scintigraphy have been shown to reduce the rate of misdiagnosed IE particularly in the setting of prosthetic valve endocarditis, paravalvular extension of infection, and cardiac implantable electronic devices. In this review, we describe a modern approach to cardiac imaging in native and prosthetic valve endocarditis, as well as cardiac implantable electronic devices including pacing devices and left ventricular assist devices. Current guidelines addressing the role of multimodality imaging in IE are discussed. The utility of imaging in the assessment of local and distant endocarditis complications such as pericardial sequelae, myocarditis, and embolic events is also addressed.

Letter to the editor: is it time for imaging to level with pathology?

CMR provides pathology-like insights of myocardial abnormality, such as hyperemia, edema, necrosis and fibrosis, which is in-vivo, non-invasive and real-time. Hence, it is most likely to become one alternative tool for mimicking pathology, so-called pathologicalized imaging due to its extraordinary tissue characteristics. This article aims to call for a wider clinical application of CMR with more attention on its tissue characterization value.

Feature Tracking Myocardial Strain Incrementally Improves Prognostication in Myocarditis Beyond Traditional CMR Imaging Features

OBJECTIVES

This study investigated the association of cardiovascular cardiac magnetic resonance (CMR) feature tracking (FT) with outcome in a patient cohort with myocarditis and evaluated the possible incremental prognostic benefit beyond clinical features and traditional CMR features.

BACKGROUND

CMR is used to diagnose and risk stratify patients with myocarditis. CMR-FT allows quantitative strain analysis of myocardial function; however, its prognostic benefit in myocarditis is unknown.

METHODS

Consecutive patients with clinically suspected myocarditis and presence of midmyocardial or epicardial late gadolinium enhancement (LGE) and/or myocardial edema in CMR were included. Clinical and CMR features were analyzed with regard to major adverse cardiovascular events (MACE) (i.e., hospitalization for heart failure, sustained ventricular tachycardia, and all-cause mortality).

RESULTS

Of 740 patients with clinically suspected myocarditis, 455 (61%) met our final diagnostic criteria based on CMR tissue characterization. At a median follow-up of 3.9 years, MACE occurred in 74 (16%) patients. In the univariable analysis, CMR-FT global longitudinal peak strain (GLS) was significantly associated with MACE. In a multivariable model adjusting for clinical variables (age, sex, body mass index, and acuteness of symptoms) and traditional CMR features (left ventricular ejection fraction [LVEF] and LGE extent), GLS remained independently associated with outcome (GLS hazard ratio: 1.21; 95% confidence interval: 1.08 to 1.36; p = 0.001) and incrementally improved prognostication (chi-square increases from 42.6 to 79.8 to 88.5; p < 0.001).

CONCLUSIONS

Myocardial strain using CMR-FT provides independent and incremental prognostic value over clinical features, LVEF, and LGE in patients with myocarditis. CMR-FT may serve as a novel marker to improve risk stratification in myocarditis. (CMR Features in Patients With Suspected Myocarditis [CMRMyo]; NCT03470571).