Assessment of cardiac ischaemia and viability: role of cardiovascular magnetic resonance

Global, segmental, and layer-specific two-dimensional speckle tracking echocardiography immediately after acute myocardial infarction as a predictive tool to assess myocardial viability and scar size

AIM

The identification of myocardial scar is key in clinical decision-making after acute myocardial infarction (AMI). However, the gold standard that is cardiac magnetic resonance imaging (CMR) encounters limitations in terms of availability. Two-dimensional speckle tracking echocardiography (2D-STE) may be an accessible alternative in detecting scar and assessing scar transmurality. We aim to evaluate the predictive value of 2D-STE, encompassing measures of global, segmental and layer-specific strain, with respect to myocardial viability and scar size at 6 months follow-up.

METHODS AND RESULTS

In 43 patients admitted for primary AMI, we conducted a comparative analysis of strain parameters (including global longitudinal strain (GLS), segmental longitudinal strain (SLS), layer-specific GLS and SLS and the transmural strain gradient from endocardium to epicardium) in relation to conventional echocardiographic parameters at baseline in predicting for scar size and the transmurality index, as measured by CMR, 6 months post enrollment. We demonstrate a moderate correlation between both GLS and conventional echocardiographic parameters, and scar size as well as transmurality index. Wall motion score index exhibited superior predictive performance over GLS and left ventricular ejection fraction in anticipating scar formation. At a cut-off of - 13.3% for any scar and - 11.5% for transmural scar, SLS can predict scar formation. Layer-specific strain did not provide added predictive value.

CONCLUSION

SLS, but not layer-specific strain, during admission after AMI is an easy and accessible quantitative tool for predicting scar formation and transmurality extent at 6 months follow-up. GLS correlates well with scar size, suggesting its potential utility as a predictive tool.

Cardiovascular magnetic resonance imaging markers of ageing: a multi-centre, cross-sectional cohort study

Aims

Cardiac ageing involves a series of anatomical and physiological changes contributing to a decline in overall performance. Cardiac magnetic resonance (CMR) provides comprehensive structural and functional assessment for detecting age-related cardiovascular remodelling. We aimed to develop a fully automated CMR model to predict functional heart age.

Methods and results

This international, multi-centre, retrospective observational study enrolled 191 healthy individuals with normal body mass index (BMI), free of metabolic, cardiovascular, and respiratory disease as the derivation cohort. Left atrial (LA) end-systolic volume and LA ejection fraction were selected for the final model. The model was validated on 366 patients with BMI >25 kg/m2 and one or more comorbidities [hypertension, diabetes mellitus (DM), atrial fibrillation (AF), and obesity]. In healthy individuals [median age: 34 years, 105 (55%) female], CMR-derived functional heart age was similar to the chronological age [bias: 0.05%, 95% confidence interval (CI): 9.56-9.67%, P = 0.993]. In the validation cohort [median age: 53 years, 157 (43%) female], CMR-derived functional heart age was 4.6 years higher than chronological age (95% CI: 1.6-7.6 years, P = 0.003). Cardiac magnetic resonance-derived functional heart age was significantly higher in patients with hypertension (P < 0.001), DM (P < 0.001), and AF (P < 0.001) than age-matched healthy controls. Moreover, CMR-derived functional heart age was higher than the chronological age in obesity Class I (P = 0.07), obesity Class II (P = 0.11), and obesity Class III (P < 0.001).

Conclusion

This study highlights the time course of structural and physiological changes in the heart during healthy and unhealthy ageing. We propose simple equations that should help communicate subtle changes in heart assessment with ageing.

Registration

ClinicalTrials.gov: NCT05114785.

Feasibility and Role of Cardiac Magnetic Resonance in Intensive and Acute Cardiovascular Care

Cardiac magnetic resonance (CMR) is established as a key imaging modality in a wide range of cardiovascular diseases and has an emerging diagnostic and prognostic role in selected patients presenting acutely. Recent technical advancements have improved the versatility of this imaging technique, which has become quicker and more detailed in both functional and tissue characterization assessments. Information derived from this test has the potential to change clinical management, guide therapeutic decisions, and provide risk stratification. This review aims to highlight the evolving diagnostic and prognostic role of CMR in this setting, whilst also providing practical guidance on which patients can benefit the most from CMR and which information can be derived from this test that will impact clinical management.

Sex-Based Differences in Clinical Characteristics of Patients with Acute Myocarditis: A Cohort Study

BACKGROUND

This study investigated sex differences in acute myocarditis patients during index hospitalization.

METHODS

We included 365 patients with acute myocarditis, hospitalized with continuous monitoring at the intensive care unit from 2000-2023 into the Basel Myocarditis Cohort study. We compared sex differences in clinical presentation, the presenting electrocardiogram, prior medical history, inflammatory and cardiac biomarkers, cardiac imaging, arrhythmia occurrence, and short- to midterm outcomes.

RESULTS

Mean age was 41.3 years, and 26.3% were female. Compared with men, women were older (median 49.7 vs 38.3 years, P < .001) at the time of diagnosis and presented more frequently with dyspnea (41 vs 26%, P = .013) and a higher Killip class (P = .011). In the presenting electrocardiogram, men had a higher occurrence of diffuse ST-elevation (38 vs 9%, P < .001) and PQ-depression (31 vs 20%, P = .042), compared with women. Women had higher N-terminal pro B-type natriuretic peptide levels (1180 vs 387 ng/L, P = .015), lower cardiac troponin T levels (389 vs 726 ng/L, P = .006), and fewer segments with nonischemic late gadolinium enhancement on cardiac magnetic resonance imaging (1 vs 3, P = .005), but similar left ventricular ejection fraction (55 vs 55%, P = .629), compared with men. Overall, hospital stay was longer in women compared with men (7 vs 5 days, P = .018), with a similar length of intensive care unit stay (2.6 vs 2.7 days, P = .922). Women more often developed severe arrhythmia (8.3 vs 2.2%, P = .015) and heart failure during the hospitalization (31.3 vs 16.4%, P = .003).

CONCLUSION

Compared with men, women with acute myocarditis were older at the time of diagnosis, presented more often with heart failure, and had an increased frequency of severe arrhythmia.

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.

METHODS

In this prospective cohort study, a total of 41 patients post Coronavirus 2019 (COVID-19) infection were included. Studies were performed on a 1.5 Tesla scanner with LGE imaging acquired using a conventional inversion recovery rapid gradient echo (conventional LGE) sequence followed by the novel accelerated free-breathing (FB-LGE) sequence. Image quality was visually scored (ordinal scale from 1 to 5) and compared between conventional and free-breathing sequences using the Wilcoxon rank sum test. Presence of per-segment LGE was identified according to the American Heart Association 16-segment myocardial model and compared across both conventional LGE and FB-LGE sequences using a two-sided chi-square test. The perpatient LGE extent was also evaluated using both sequences and compared using the Wilcoxon rank sum test. Interobserver variability in detection of per-segment LGE and per-patient LGE extent was evaluated using Cohen's kappa statistic and interclass correlation (ICC), respectively.

RESULTS

The mean acquisition time for the FB-LGE sequence was 17 s compared to 413 s for the conventional LGE sequence (P < 0.001). Assessment of image quality was similar between both sequences (P = 0.19). There were no statistically significant differences in LGE assessed using the FB-LGE versus conventional LGE on a per-segment (P = 0.42) and per-patient (P = 0.06) basis. Interobserver variability in LGE assessment for FB-LGE was good for per-segment (= 0.71) and per-patient extent (ICC = 0.92) analyses.

CONCLUSIONS

The accelerated FB-LGE sequence performed comparably to the conventional standard-of-care LGE sequence in a cohort of patients post COVID-19 infection in a fraction of the time and without the need for breath-holding. Such a sequence could impact clinical practice by increasing cardiac MRI throughput and accessibility for frail or acutely ill patients unable to perform breath-holding.

Prospective Comparison of Free-Breathing Accelerated Cine Deep Learning Reconstruction Versus Standard Breath-Hold Cardiac MRI Sequences in Patients With Ischemic Heart Disease

BACKGROUND. Cine cardiac MRI sequences require repeated breath-holds, which can be difficult for patients with ischemic heart disease (IHD). OBJECTIVE. The purpose of the study was to compare a free-breathing accelerated cine sequence using deep learning (DL) reconstruction and a standard breath-hold cine sequence in terms of image quality and left ventricular (LV) measurements in patients with IHD undergoing cardiac MRI. METHODS. This prospective study included patients undergoing 1.5- or 3-T cardiac MRI for evaluation of IHD between March 15, 2023, and June 21, 2023. Examinations included an investigational free-breathing cine short-axis sequence with DL reconstruction (hereafter, cine-DL sequence). Two radiologists (reader 1 [R1] and reader 2 [R2]), in blinded fashion, independently assessed left ventricular ejection fraction (LVEF), left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and subjective image quality for the cine-DL sequence and a standard breath-hold balanced SSFP sequence; R1 assessed artifacts. RESULTS. The analysis included 26 patients (mean age, 64.3 ± 11.7 [SD] years; 14 men, 12 women). Acquisition was shorter for the cine-DL sequence than the standard sequence (mean ± SD, 0.6 ± 0.1 vs 2.4 ± 0.6 minutes; p < .001). The cine-DL sequence, in comparison with the standard sequence, showed no significant difference for LVEF for R1 (mean ± SD, 51.7% ± 14.3% vs 51.3% ± 14.7%; p = .56) or R2 (53.4% ± 14.9% vs 52.8% ± 14.6%; p = .53); significantly greater LVEDV for R2 (mean ± SD, 171.9 ± 51.9 vs 160.6 ± 49.4 mL; p = .01) but not R1 (171.8 ± 53.7 vs 165.5 ± 52.4 mL; p = .16); and no significant difference in LVESV for R1 (mean ± SD, 88.1 ± 49.3 vs 86.0 ± 50.5 mL; p = .45) or R2 (85.2 ± 48.1 vs 81.3 ± 48.2 mL; p = .10). The mean bias between the cine-DL and standard sequences by LV measurement was as follows: LVEF, 0.4% for R1 and 0.7% for R2; LVEDV, 6.3 mL for R1 and 11.3 mL for R2; and LVESV, 2.1 mL for R1 and 3.9 mL for R2. Subjective image quality was better for cine-DL sequence than the standard sequence for R1 (mean ± SD, 2.3 ± 0.5 vs 1.9 ± 0.8; p = .02) and R2 (2.2 ± 0.4 vs 1.9 ± 0.7; p = .02). R1 reported no significant difference between the cine-DL and standard sequences for off-resonance artifacts (3.8% vs 23.1% examinations; p = .10) and parallel imaging artifacts (3.8% vs 19.2%; p = .19); blurring artifacts were more frequent for the cine-DL sequence than the standard sequence (42.3% vs 7.7% examinations; p = .008). CONCLUSION. A free-breathing cine-DL sequence, in comparison with a standard breath-hold cine sequence, showed very small bias for LVEF measurements and better subjective quality. The cine-DL sequence yielded greater LV volumes than the standard sequence. CLINICAL IMPACT. A free-breathing cine-DL sequence may yield reliable LVEF measurements in patients with IHD unable to repeatedly breath-hold. TRIAL REGISTRATION. ClinicalTrials.gov NCT05105984.

CMR Mapping: The 4th-Era Revolution in Cardiac Imaging

Cardiac magnetic resonance (CMR) imaging has witnessed substantial progress with the advent of parametric mapping techniques, most notably T1 and T2 mapping. These advanced techniques provide valuable insights into a wide range of cardiac conditions, including ischemic heart disease, cardiomyopathies, inflammatory cardiomyopathies, heart valve disease, and athlete's heart. Mapping could be the first sign of myocardial injury and oftentimes precedes symptoms, changes in ejection fraction, and irreversible myocardial remodeling. The ability of parametric mapping to offer a quantitative assessment of myocardial tissue properties addresses the limitations of conventional CMR methods, which often rely on qualitative or semiquantitative data. However, challenges persist, especially in terms of standardization and reference value establishment, hindering the wider clinical adoption of parametric mapping. Future developments should prioritize the standardization of techniques to enhance their clinical applicability, ultimately optimizing patient care pathways and outcomes. In this review, we endeavor to provide insights into the potential contributions of CMR mapping techniques in enhancing the diagnostic processes across a range of cardiac conditions.

Cardiovascular Follow-up of Patients Treated for MIS-C

OBJECTIVES

To assess the prevalence of residual cardiovascular pathology by cardiac MRI (CMR), ambulatory rhythm monitoring, and cardiopulmonary exercise testing (CPET) in patients ∼6 months after multisystem inflammatory disease in children (MIS-C).

METHODS

Patients seen for MIS-C follow-up were referred for CMR, ambulatory rhythm monitoring, and CPET ∼6 months after illness. Patients were included if they had ≥1 follow-up study performed by the time of data collection. MIS-C was diagnosed on the basis of the Centers for Disease Control and Prevention criteria. Myocardial injury during acute illness was defined as serum Troponin-I level >0.05 ng/mL or diminished left ventricular systolic function on echocardiogram.

RESULTS

Sixty-nine of 153 patients seen for MIS-C follow-up had ≥1 follow-up cardiac study between October 2020-June 2022. Thirty-seven (54%) had evidence of myocardial injury during acute illness. Of these, 12 of 26 (46%) had ≥1 abnormality on CMR, 4 of 33 (12%) had abnormal ambulatory rhythm monitor results, and 18 of 22 (82%) had reduced functional capacity on CPET. Of the 37 patients without apparent myocardial injury, 11 of 21 (52%) had ≥1 abnormality on CMR, 1 of 24 (4%) had an abnormal ambulatory rhythm monitor result, and 11 of 15 (73%) had reduced functional capacity on CPET. The prevalence of abnormal findings was not statistically significantly different between groups.

CONCLUSIONS

The high prevalence of abnormal findings on follow-up cardiac studies and lack of significant difference between patients with and without apparent myocardial injury during hospitalization suggests that all patients treated for MIS-C warrant cardiology follow-up.

Comprehensive review of ST-segment elevation myocardial infarction: Understanding pathophysiology, diagnostic strategies, and current treatment approaches

ST-Segment Elevation Myocardial Infarction (STEMI) is a life-threatening medical emergency characterized by complete coronary artery occlusion, leading to myocardial ischemia and subsequent necrosis. Over the years, STEMI has remained a significant cause of morbidity and mortality worldwide, necessitating a comprehensive understanding of its pathophysiology, accurate diagnostic strategies, and effective treatment approaches. This review article aims to thoroughly analyze the current knowledge surrounding STEMI, emphasizing key aspects crucial for optimizing patient outcomes. Firstly, the pathophysiology of STEMI will be explored, elucidating the sequence of events from coronary artery plaque rupture to thrombus formation and occlusion. This section will also cover the underlying risk factors contributing to STEMI development, including atherosclerosis, hypertension, and diabetes. Secondly, the diagnostic modalities for STEMI will be critically evaluated. Traditional electrocardiography remains the cornerstone of STEMI diagnosis. Still, advancements in imaging techniques such as cardiac magnetic resonance imaging and coronary angiography have enhanced accuracy and allow for better risk stratification. Furthermore, the review will delve into the latest treatment approaches for STEMI. Prompt reperfusion therapy through primary percutaneous coronary intervention or thrombolytic therapy is essential in restoring blood flow and salvaging the jeopardized myocardium. The role of adjunctive medical treatment, including antiplatelet agents, beta-blockers, and statins, will also be discussed in post-STEMI management.

The Role of Non-Invasive Multimodality Imaging in Chronic Coronary Syndrome: Anatomical and Functional Pathways

Coronary artery disease (CAD) is one of the major causes of mortality and morbidity worldwide, with a high socioeconomic impact. Currently, various guidelines and recommendations have been published about chronic coronary syndromes (CCS). According to the recent European Society of Cardiology guidelines on chronic coronary syndrome, a multimodal imaging approach is strongly recommended in the evaluation of patients with suspected CAD. Today, in the current practice, non-invasive imaging methods can assess coronary anatomy through coronary computed tomography angiography (CCTA) and/or inducible myocardial ischemia through functional stress testing (stress echocardiography, cardiac magnetic resonance imaging, single photon emission computed tomography-SPECT, or positron emission tomography-PET). However, recent trials (ISCHEMIA and REVIVED) have cast doubt on the previous conception of the management of patients with CCS, and nowadays it is essential to understand the limitations and strengths of each imaging method and, specifically, when to choose a functional approach focused on the ischemia versus a coronary anatomy-based one. Finally, the concept of a pathophysiology-driven treatment of these patients emerged as an important goal of multimodal imaging, integrating 'anatomical' and 'functional' information. The present review aims to provide an overview of non-invasive imaging modalities for the comprehensive management of CCS patients.

Cardiovascular Magnetic Resonance from Fetal to Adult Life-Indications and Challenges: A State-of-the-Art Review

Cardiovascular magnetic resonance (CMR) imaging offers a comprehensive, non-invasive, and radiation-free imaging modality, which provides a highly accurate and reproducible assessment of cardiac morphology and functions across a wide spectrum of cardiac conditions spanning from fetal to adult life. It minimises risks to the patient, particularly the risks associated with exposure to ionising radiation and the risk of complications from more invasive haemodynamic assessments. CMR utilises high spatial resolution and provides a detailed assessment of intracardiac and extracardiac anatomy, ventricular and valvular function, and flow haemodynamic and tissue characterisation, which aid in the diagnosis, and, hence, with the management of patients with cardiac disease. This article aims to discuss the role of CMR and the indications for its use throughout the different stages of life, from fetal to adult life.

[Ischemic heart disease : More than just chronic CAD]

CLINICAL/METHODOLOGICAL ISSUE

Myocardial ischemia as a reduction in perfusion with therefore oxygen deficiency of vital cardiomyocytes. Thus primary and secondary prophylaxis of myocardial infarction and it's complications.

STANDARD RADIOLOGICAL METHODS

Adenosine-regadenoson stress magnetic resonance imaging (AR-stress MRI), computed tomography coronary angiography (CTCA).

METHODOLOGICAL INNOVATIONS

Non-invasive stress testing using AR-stress MRI to exclude relevant obstructive coronary artery disease (CAD).

PERFORMANCE

Meta-analysis: The diagnosis of obstructive CAD at the coronary artery level has a pooled sensitivity of 87.7% and a specificity of 88.6%. Diagnostic accuracy is better than single photon emission computed tomography (SPECT; AUC 0.89 vs. 0.74).

ACHIEVEMENTS

AR-stress MRI can be used to assess myocardial ischemia in the setting of obstructive CAD. Current clinical guidelines for myocardial revascularization have strengthened the use of stress MRI in patients with intermediate risk of CAD and stable symptoms. Cardiac MR imaging using late gadolinium enhancement (LGE) is considered gold standard for myocardial viability assessment in vivo. Both viability and ischemia are considered prognostic factors for major adverse cardiac events.

PRACTICAL RECOMMENDATIONS

AR-stress MRI is used to diagnose myocardial ischemia in combination with viability imaging (LGE). Dobutamine-atropine (DoA) stress MRI is an alternative in the setting of contraindications for AR or specific clinical questions.

COVID-19 Vaccine-Induced Myocarditis: A Systemic Review and Literature Search

Myocarditis is one of the complications reported with COVID-19 vaccines, particularly both Pfizer-BioNTech and Moderna vaccines. Most of the published data about this association come from case reports and series. Integrating the geographical data, clinical manifestations, and outcomes is therefore important in patients with myocarditis to better understand the disease. A thorough literature search was conducted in Cochrane library, PubMed, ScienceDirect, and Google Scholar for published literature till 30 March 2022. We identified 26 patients eligible from 29 studies; the data were pooled from these qualifying case reports and case series. Around 94% of patients were male in this study, the median age for onset of myocarditis was 22 years and 85% developed symptoms after the second dose. The median time of admission for patients to hospitals post-vaccination was three days and chest pain was the most common presenting symptom in these patients. Most patients had elevated troponin on admission and about 90% of patients had cardiac magnetic resonance imaging (CMR) that showed late gadolinium enhancement. All patients admitted with myocarditis were discharged home after a median stay of four days. Results from this current analysis show that post-mRNA vaccination myocarditis is mainly seen in young males after the second dose of vaccination. The pathophysiology of vaccine-induced myocarditis is not entirely clear and late gadolinium enhancement is a common finding on CMR in these patients that may indicate myocardial fibrosis or necrosis. Prognosis remains good and all patients recovered from myocarditis, however further studies are advisable to assess long-term prognosis of myocarditis.

Determination of scar area using native and post-contrast T1 mapping: Agreement with late gadolinium enhancement

The purpose of this study is to ascertain agreement in measurements of the scar area between late gadolinium enhancement (LGE), native and post-contrast T1 mapping in patients with known ischemic heart disease. 132 patients (age 60 ± 11 yrs, male 82%) were included in the study. Corresponding 3 short axis slices images of LGE, native and post contrast T1 mapping were used. Scar area was evaluated semi- quantitatively with FWHM methods, in which scar is automatically determined by specialized post-processing software. Agreement per culprit vessel was also assessed. Concordance and inter- intraobserver reproducibility were assessed with Bland-Altman analysis. The results show that scar area amounted to 12.6% of myocardium for LGE, 9.1% for native (p < 0.05) and 19.4% (p < 0.05) for post-contrast T1 mapping. LAD and RCA territory infarcts showed statistical discrepancy for both T1 acquisitions. Intraobserver differences in infarct size were comparable at 0.39% ± 0.28, 2.93% ± 0.03 and 0.97% ± 0.01 respectively (p≫0.05). Interobserver differences were 5.56% ± 0.91 for LGE, 11.87% ± 3.21 (p < 0.05) for native and 5.55% ± 2.87 (p≫0.05) for post-contrast T1 mapping. In conclusion, native T1 acquisitions systematically underestimated infarct size in comparison to LGE, while post-contrast T1 overestimated it. Variances in measurements were most pronounced for LAD and RCA territory infarcts. Intraobserver reproducibility was similar with both methods, whereas interobserver variability for native T1 mapping acquisition was worse.

Feasibility of fast cardiovascular magnetic resonance strain imaging in patients presenting with acute chest pain

Background

Cardiovascular magnetic resonance (CMR) is the current reference standard for the quantitative assessment of ventricular function. Fast Strain-ENCoded (fSENC)-CMR imaging allows for the assessment of myocardial deformation within a single heartbeat. The aim of this pilot study was to identify obstructive coronary artery disease (oCAD) with fSENC-CMR in patients presenting with new onset of chest pain.

Methods and results

In 108 patients presenting with acute chest pain, we performed fSENC-CMR after initial clinical assessment in the emergency department. The final clinical diagnosis, for which cardiology-trained physicians used clinical information, serial high-sensitive Troponin T (hscTnT) values and—if necessary—further diagnostic tests, served as the standard of truth. oCAD was defined as flow-limiting CAD as confirmed by coronary angiography with typical angina or hscTnT dynamics. Diagnoses were divided into three groups: 0: non-cardiac, 1: oCAD, 2: cardiac, non-oCAD. The visual analysis of fSENC bull´s eye maps (blinded to final diagnosis) resulted in a sensitivity of 82% and specificity of 87%, as well as a negative predictive value of 96% for identification of oCAD. Both, global circumferential strain (GCS) and global longitudinal strain (GLS) accurately identified oCAD (area under the curve/AUC: GCS 0.867; GLS 0.874; p<0.0001 for both), outperforming ECG, hscTnT dynamics and EF. Furthermore, the fSENC analysis on a segmental basis revealed that the number of segments with impaired strain was significantly associated with the patient´s final diagnosis (p<0.05 for all comparisons).

Conclusion

In patients with acute chest pain, myocardial strain imaging with fSENC-CMR may serve as a fast and accurate diagnostic tool for ruling out obstructive coronary artery disease.

CMR for myocardial characterization in ischemic heart disease: state-of-the-art and future developments

Ischemic heart disease and its sequelae are one of the major contributors to morbidity and mortality worldwide. Over the last decades, technological developments have strengthened the role of noninvasive imaging for detection, risk stratification, and management of patients with ischemic heart disease. Cardiac magnetic resonance (CMR) imaging incorporates both functional and morphological characterization of the heart to determine presence, acuteness, and severity of ischemic heart disease by evaluating myocardial wall motion and function, the presence and extent of myocardial edema, ischemia, and scarring. Currently established clinical protocols have already demonstrated their diagnostic and prognostic value. Nevertheless, there are emerging imaging technologies that provide additional information based on advanced quantification of imaging biomarkers and improved diagnostic accuracy, therefore potentially allowing reduction or avoidance of contrast and/or stressor agents. The aim of this review is to summarize the current state of the art of CMR imaging for ischemic heart disease and to provide insights into promising future developments.

Cardiac MRI in Patients with Acute Chest Pain

Acute chest pain is a common reason for visits to the emergency department. It is important to distinguish among the various causes of acute chest pain, because treatment and prognosis are substantially different among the various conditions. It is critical to exclude acute coronary syndrome (ACS), which is a major cause of hospitalization, death, and health care costs worldwide. Myocardial ischemia is defined as potential myocyte death secondary to an imbalance between oxygen supply and demand due to obstruction of an epicardial coronary artery. Unobstructed coronary artery disease can have cardiac causes (eg, myocarditis, myocardial infarction with nonobstructed coronary arteries, and Takotsubo cardiomyopathy), and noncardiac diseases can manifest with acute chest pain and increased serum cardiac biomarker levels. In the emergency department, cardiac MRI may aid in the identification of patients with non-ST-segment elevation myocardial infarction or unstable angina or ACS with unobstructed coronary artery disease, if the patient's clinical history is known to be atypical. Also, cardiac MRI is excellent for risk stratification of patients for adverse left ventricular remodeling or major adverse cardiac events. Cardiac MRI should be performed early in the course of the disease (<2 weeks after onset of symptoms). Steady-state free-precession T2-weighted MRI with late gadolinium enhancement is the mainstay of the cardiac MRI protocol. Further sequences can be used to analyze the different pathophysiologic subjacent mechanisms of the disease, such as microvascular obstruction or intramyocardial hemorrhage. Finally, cardiac MRI may provide several prognostic biomarkers that help in follow-up of these patients. Online supplemental material is available for this article. ^©RSNA, 2020.

SCMR Position Paper (2020) on clinical indications for cardiovascular magnetic resonance

The Society for Cardiovascular Magnetic Resonance (SCMR) last published its comprehensive expert panel report of clinical indications for CMR in 2004. This new Consensus Panel report brings those indications up to date for 2020 and includes the very substantial increase in scanning techniques, clinical applicability and adoption of CMR worldwide. We have used a nearly identical grading system for indications as in 2004 to ensure comparability with the previous report but have added the presence of randomized controlled trials as evidence for level 1 indications. In addition to the text, tables of the consensus indication levels are included for rapid assimilation and illustrative figures of some key techniques are provided.

Comorbidity of chronic heart failure and chronic obstructive pulmonary disease: features of pathogenesis, clinic and diagnostics

This article discusses the epidemiology of chronic heart failure (CHF) and chronic obstructive pulmonary disease (COPD). CHF and COPD are characterized by high prevalence and high mortality, especially when they are combined. The article analyzes the general mechanisms of formation of these diseases: the relationship of COPD with cardiovascular diseases is explained by common risk factors, including smoking, physical inactivity, improper feeding and genetic predisposition. The leading role in the pathogenesis of pathologies is played by the activation and maintenance of systemic inflammation. Article presents the features of the clinical picture and the direction of the diagnostics in case of suspected combined pathology, the possibilities of modern laboratory and instrumental research methods. Diagnostics of comorbidity of CHF and COPD may be difficult, given the above common risk factors, some common pathogenesis mechanisms and similar clinical symptoms. However the caution regarding the comorbidity of the studied conditions, as well as a thorough clinical examination and the appointment of the necessary additional research methods, can reduce the number of diagnostic mistakes and improve the prognosis in such patients.

Cardiac Magnetic Resonance in Stable Coronary Artery Disease: Added Prognostic Value to Conventional Risk Profiling

Aims

Cardiovascular magnetic resonance (CMR) permits a comprehensive evaluation of stable coronary artery disease (CAD). We sought to assess whether, in a large contemporaneous population receiving optimal medical therapy, CMR independently predicts prognosis beyond conventional cardiovascular risk factors (RF).

Methods

We performed a single centre, observational prospective study that enrolled 465 CAD patients (80% males; 63±11 years), optimally treated with ACE-inhibitors/ARB, aspirin, and statins (76-85%). Assessments included conventional evaluation (clinical history, atherosclerosis RF, electrocardiography, and echocardiography) and a comprehensive CMR with LV dimensions/function, late gadolinium enhancement (LGE), and stress perfusion CMR (SPCMR).

Results

During a median follow-up of 62 months (IQR 23-74) there were 50 deaths and 92 major adverse cardiovascular events (MACE). CMR variables improved multivariate model prediction power of mortality and MACE over traditional RF alone (F-test p<0.05 and p<0.001, respectively). LGE was an independent prognostic factor of mortality (hazard ratio [95% CI]: 3.4 [1.3−8.8]); moreover, LGE (3.3 [1.7−6.3]) and SPCMR (2.1 [1.4−3.2]) were the best predictors of MACE.

Conclusion

LGE is an independent noninvasive marker of mortality in the long term in patients with stable CAD and optimized medical therapy. Furthermore, LGE and SPCMR independently predict MACE beyond conventional risk stratification.

Coronary Artery Disease: Analysis of Diagnostic Performance of CT Perfusion and MR Perfusion Imaging in Comparison with Quantitative Coronary Angiography and SPECT-Multicenter Prospective Trial

Purpose To compare the diagnostic performance of stress myocardial computed tomography (CT) perfusion with that of stress myocardial magnetic resonance (MR) perfusion imaging in the detection of coronary artery disease (CAD). Materials and Methods All patients gave written informed consent prior to inclusion in this institutional review board-approved study. This two-center substudy of the prospective Combined Noninvasive Coronary Angiography and Myocardial Perfusion Imaging Using 320-Detector Row Computed Tomography (CORE320) multicenter trial included 92 patients (mean age, 63.1 years ± 8.1 [standard deviation]; 73% male). All patients underwent perfusion CT and perfusion MR imaging with either adenosine or regadenoson stress. The predefined reference standards were combined quantitative coronary angiography (QCA) and single-photon emission CT (SPECT) or QCA alone. Results from coronary CT angiography were not included, and diagnostic performance was evaluated with the Mantel-Haenszel test stratified by disease status. Results The prevalence of CAD was 39% (36 of 92) according to QCA and SPECT and 64% (59 of 92) according to QCA alone. When compared with QCA and SPECT, per-patient diagnostic accuracy of perfusion CT and perfusion MR imaging was 63% (58 of 92) and 75% (69 of 92), respectively (P = .11); sensitivity was 92% (33 of 36) and 83% (30 of 36), respectively (P = .45); and specificity was 45% (25 of 56) and 70% (39 of 56), respectively (P < .01). When compared with QCA alone, diagnostic accuracy of CT perfusion and MR perfusion imaging was 82% (75 of 92) and 74% (68 of 92), respectively (P = .27); sensitivity was 90% (53 of 59) and 69% (41 of 59), respectively (P < .01); and specificity was 67% (22 of 33) and 82% (27 of 33), respectively (P = .27). Conclusion This multicenter study shows that the diagnostic performance of perfusion CT is similar to that of perfusion MR imaging in the detection of CAD. ^© RSNA, 2017 Online supplemental material is available for this article.

Image Quality of Cardiac Magnetic Resonance Imaging in Patients With an Implantable Cardioverter Defibrillator System Designed for the Magnetic Resonance Imaging Environment

BACKGROUND

Recently, magnetic resonance (MR)-conditional implantable cardioverter defibrillator (ICD) systems have become available. However, associated cardiac MR image (MRI) quality is unknown. The goal was to evaluate the image quality performance of various cardiac MR sequences in a multicenter trial of patients implanted with an MR-conditional ICD system.

METHODS AND RESULTS

The Evera-MRI trial enrolled 275 patients in 42 centers worldwide. There were 263 patients implanted with an Evera-MRI single- or dual-chamber ICD and randomized to controls (n=88) and MRI (n=175), 156 of whom underwent a protocol-required MRI (9-12 weeks post implant). Steady-state-free-precession (SSFP) and fast-gradient-echo (FGE) sequences were acquired in short-axis and horizontal long-axis orientations. Qualitative and quantitative assessment of image quality was performed by using a 7-point scale (grades 1-3: good quality, grades 6-7: nondiagnostic) and measuring ICD- and lead-related artifact size. Good to moderate image quality (grades 1-5) was obtained in 53% and 74% of SSFP and FGE acquisitions, respectively, covering the left ventricle, and in 69% and 84%, respectively, covering the right ventricle. Odds for better image quality were greater for right ventricle versus left ventricle (odds ratio, 1.8; 95% confidence interval, 1.5-2.2; P<0.0001) and greater for FGE versus SSFP (odds ratio, 3.5; 95% confidence interval, 2.5-4.8; P<0.0001). Compared with SSFP, ICD-related artifacts on FGE were smaller (141±65 versus 75±57 mm, respectively; P<0.0001). Lead artifacts were much smaller than ICD artifacts (P<0.0001).

CONCLUSIONS

FGE yields good to moderate quality in 74% of left ventricle and 84% of right ventricle acquisitions and performs better than SSFP in patients with an MRI-conditional ICD system. In these patients, cardiac MRI can offer diagnostic information in most cases.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02117414.

Utility of stress perfusion-cardiac magnetic resonance in follow-up of patients undergoing percutaneous coronary interventions of the left main coronary artery

To assess the accuracy of cardiac magnetic resonance (CMR) for the diagnosis of angiographic stenosis after percutaneous coronary intervention (PCI) of left main coronary artery (LMCA). Patients undergone in the last year PCI of unprotected LMCA and scheduled for conventional X-ray coronary angiography (CXA) were evaluated with stress perfusion CMR within 2 weeks before CXA. Main contraindications to CMR were exclusion criteria. Stress perfusion CMR was performed to follow a bolus of contrast Gadobutrol after 3 min of adenosine infusion. Between the 50 patients enrolled, only 1 did not finish the CMR protocol and 49 patients with median age 71 (65-75) years (38 male, 11 female) were analyzed. Between 784 coronary angiographic segments evaluated we found 75 stenosis or occlusions (prevalence 9.5%), but only 13 stenosis or occlusions in proximal segments (prevalence 6.6%). Patients with coronary stenosis (n = 12, 24%) showed a significantly (p = 0.002) higher prevalence of diabetes (7 of 12, 58%). At CMR examination, late gadolinium enhancement was present in 25 (51%), reversible perfusion defects in 12 (24%), and fixed perfusion defects in 6 subjects (12%). The only patient with LMCA restenosis resulted positive at perfusion CMR. The accuracy of stress perfusion CMR in diagnosis of coronary stenosis was higher when the analysis was performed only in proximal coronary arteries (95%, CI 86-99) compared to overall vessels (84%, CI 70-92). Stress perfusion CMR could strongly reduce the need for elective CXA in follow up of LMCA PCI and should be validated in further multicenter prospective studies.

Cardiovascular magnetic resonance in systemic sclerosis: "Pearls and pitfalls"

Systemic sclerosis (SSc) is an autoimmune disease characterized by vascular dysfunction and excessive fibrosis, involving internal organs including the heart. The estimated prevalence of cardiac involvement in SSc is high and remains subclinical until the late stages. It is either primary, related to myocardial inflammation and fibrosis, or secondary, due to pulmonary arterial hypertension (SSc-PAH) or systemic hypertension, in those patients with renal involvement. Cardiovascular magnetic resonance (CMR) is a useful tool for the early assessment of cardiac involvement in SSc. It is the gold standard technique to assess ventricular volumes,ejection fraction, and in particular is very useful to reliably and non-invasively detect myocardial inflammation, early perfusion defects, and myocardial fibrosis. However, the CMR evaluation in SSc may be problematic, because of cardiac and respiratory artefacts, commonly found in these patients. Therefore, a high level of expertise is necessary for both acquisition and interpretation of CMR images in SSc.

Role of cardiovascular magnetic resonance in acute and chronic ischemic heart disease

Cardiovascular magnetic resonance (CMR) is a multi-parametric, multi-planar, non-invasive imaging technique, which allows accurate determination of biventricular function and precise myocardial tissue characterization in a one-stop-shop technique, free from the use of ionizing radiations. Though CMR has been increasingly applied over the last two decades in every-day clinical practice, its widest application has been in the assessment of ischemic cardiomyopathy.

Suppression of ghost artifacts arising from long T1 species in segmented inversion-recovery imaging

PURPOSE

We demonstrate an improved segmented inversion-recovery sequence that suppresses ghost artifacts arising from tissues with long T₁ ( > 1.5 s).

THEORY AND METHODS

Long T₁ species such as pericardial fluid can create bright ghost artifacts in segmented, inversion-recovery MRI because of oscillations in longitudinal magnetization between segments. A single dummy acquisition at the beginning of the sequence can reduce oscillations; however, its effectiveness in suppressing long T₁ artifacts is unknown. In this study, we systematically evaluated several test sequences, including a prototype (saturation post-pulse readout to eliminate spurious signal: SPPRESS) in simulations, phantoms, and patients.

RESULTS

SPPRESS reduced artifact signal 90% ± 25% and 74% ± 28% compared with Control and Single-Dummy methods in phantoms. SPPRESS performed well at 1.5 Tesla (T) and 3T, with steady-state free precession (SSFP) and fast low-angle shot (FLASH) readout, with conventional and phase-sensitive reconstruction, and over a range of physiologic heart rates. A review of 100 consecutive clinical cardiac MRI scans revealed large fluid collections (eg, regions with long T₁ ) in 14% of patients. In a prospectively enrolled cohort of 16 patients with visible long T₁ fluids, SPPRESS appreciably reduced artifacts in all cases compared with Control and Single-Dummy methods.

CONCLUSION

We developed and validated a new robust method, SPPRESS, for reducing artifacts due to long T₁ species across a wide range of imaging and physiologic conditions. Magn Reson Med 78:1442-1451, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Chest pain: coronary CT in the ER

Cardiac CT has developed into a robust clinical tool during the past 15 years. Of the fields in which the potential of cardiac CT has raised more interest is chest pain in acute settings. In fact, the possibility to exclude with high reliability obstructive coronary artery disease (CAD) in patients at low-to-intermediate risk is of great interest both from the clinical standpoint and from the management standpoint. Several other modalities, with or without imaging, have been used during the past decades in the settings of new onset chest pain or in acute chest pain for both diagnostic and prognostic assessment of CAD. Each one has advantages and disadvantages. Most imaging modalities also focus on inducible ischaemia to guide referral to invasive coronary angiography. The advent of cardiac CT has introduced a new practice diagnostic paradigm, being the most accurate non-invasive method for identification and exclusion of CAD. Furthermore, the detection of subclinical CAD and plaque imaging offer the opportunity to improve risk stratification. Moreover, recent advances of the latest generation CT scanners allow combining both anatomical and functional imaging by stress myocardial perfusion. The role of cardiac CT in acute settings is already important and will become progressively more important in the coming years.

Relationship of T2-Weighted MRI Myocardial Hyperintensity and the Ischemic Area-At-Risk

RATIONALE

After acute myocardial infarction (MI), delineating the area-at-risk (AAR) is crucial for measuring how much, if any, ischemic myocardium has been salvaged. T2-weighted MRI is promoted as an excellent method to delineate the AAR. However, the evidence supporting the validity of this method to measure the AAR is indirect, and it has never been validated with direct anatomic measurements.

OBJECTIVE

To determine whether T2-weighted MRI delineates the AAR.

METHODS AND RESULTS

Twenty-one canines and 24 patients with acute MI were studied. We compared bright-blood and black-blood T2-weighted MRI with images of the AAR and MI by histopathology in canines and with MI by in vivo delayed-enhancement MRI in canines and patients. Abnormal regions on MRI and pathology were compared by (a) quantitative measurement of the transmural-extent of the abnormality and (b) picture matching of contours. We found no relationship between the transmural-extent of T2-hyperintense regions and that of the AAR (bright-blood-T2: r=0.06, P=0.69; black-blood-T2: r=0.01, P=0.97). Instead, there was a strong correlation with that of infarction (bright-blood-T2: r=0.94, P<0.0001; black-blood-T2: r=0.95, P<0.0001). Additionally, contour analysis demonstrated a fingerprint match of T2-hyperintense regions with the intricate contour of infarcted regions by delayed-enhancement MRI. Similarly, in patients there was a close correspondence between contours of T2-hyperintense and infarcted regions, and the transmural-extent of these regions were highly correlated (bright-blood-T2: r=0.82, P<0.0001; black-blood-T2: r=0.83, P<0.0001).

CONCLUSION

T2-weighted MRI does not depict the AAR. Accordingly, T2-weighted MRI should not be used to measure myocardial salvage, either to inform patient management decisions or to evaluate novel therapies for acute MI.

Meta-analysis of trials on mortality after percutaneous coronary intervention compared with medical therapy in patients with stable coronary heart disease and objective evidence of myocardial ischemia

Outcomes of percutaneous coronary intervention (PCI) versus medical therapy (MT) in the management of stable ischemic heart disease (SIHD) remain controversial, with some but not all studies showing improved results in patients with ischemia. We sought to elucidate whether PCI improves mortality compared to MT in patients with objective evidence of ischemia (assessed using noninvasive imaging or its invasive equivalent). We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing PCI to MT in patients with SIHD. To maintain a high degree of specificity for ischemia, studies were only included if ischemia was defined on the basis of noninvasive stress imaging or abnormal fractional flow reserve. The primary outcome was all-cause mortality. We identified 3 RCTs (Effects of Percutaneous Coronary Interventions in Silent Ischemia After Myocardial Infarction II, Fractional Flow Reserve versus Angiography for Multivessel Evaluation 2, and a substudy of the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation trial) enrolling a total of 1,557 patients followed for an average of 3.0 years. When compared with MT in this population of patients with objective ischemia, PCI was associated with lower mortality (hazard ratio 0.52, 95% confidence interval 0.30 to 0.92, p=0.02). There was no evidence of study heterogeneity or bias among included trials. In this meta-analysis of published RCTs, PCI was shown to have a mortality benefit over MT in patients with SIHD and objective assessment of ischemia using noninvasive imaging or its invasive equivalent. In conclusion, this study provides insight into the management of a higher-risk SIHD population that is the focus of the ongoing International Study of Comparative Health Effectiveness with Medical and Invasive Approaches trial.

Feasibility of high-resolution quantitative perfusion analysis in patients with heart failure

BACKGROUND

Cardiac magnetic resonance (CMR) is playing an expanding role in the assessment of patients with heart failure (HF). The assessment of myocardial perfusion status in HF can be challenging due to left ventricular (LV) remodelling and wall thinning, coexistent scar and respiratory artefacts. The aim of this study was to assess the feasibility of quantitative CMR myocardial perfusion analysis in patients with HF.

METHODS

A group of 58 patients with heart failure (HF; left ventricular ejection fraction, LVEF ≤ 50%) and 33 patients with normal LVEF (LVEF >50%), referred for suspected coronary artery disease, were studied. All subjects underwent quantitative first-pass stress perfusion imaging using adenosine according to standard acquisition protocols. The feasibility of quantitative perfusion analysis was then assessed using high-resolution, 3 T kt perfusion and voxel-wise Fermi deconvolution.

RESULTS

30/58 (52%) subjects in the HF group had underlying ischaemic aetiology. Perfusion abnormalities were seen amongst patients with ischaemic HF and patients with normal LV function. No regional perfusion defect was observed in the non-ischaemic HF group. Good agreement was found between visual and quantitative analysis across all groups. Absolute stress perfusion rate, myocardial perfusion reserve (MPR) and endocardial-epicardial MPR ratio identified areas with abnormal perfusion in the ischaemic HF group (p = 0.02; p = 0.04; p = 0.02, respectively). In the Normal LV group, MPR and endocardial-epicardial MPR ratio were able to distinguish between normal and abnormal segments (p = 0.04; p = 0.02 respectively). No significant differences of absolute stress perfusion rate or MPR were observed comparing visually normal segments amongst groups.

CONCLUSIONS

Our results demonstrate the feasibility of high-resolution voxel-wise perfusion assessment in patients with HF.

Is the diagnostic yield of myocardial stress perfusion MRI impaired by three-vessel coronary artery disease?

BACKGROUND

Three-vessel coronary artery disease (CAD) comes along with globally reduced myocardial perfusion potentially restricting the demarcation of regional hypoperfusion in stress perfusion cardiac magnetic resonance imaging (MRI).

PURPOSE

To evaluate whether stress perfusion cardiac MRI is capable of detecting myocardial hypoperfusion in patients with 3-vessel CAD reliably.

MATERIAL AND METHODS

Two hundred and five patients with symptoms of CAD were included. The examination protocol comprised imaging of myocardial perfusion at stress (0.14 mg/kg/min adenosine for 4 min) using a 2D saturation recovery gradient echo sequence after administration of gadobutrol (0.1 mmol/kg body weight). Perfusion sequences were assessed qualitatively by two experienced observers. Coronary angiography served as standard of reference.

RESULTS

Sensitivity and specificity for hemodynamically relevant stenoses in patients with 0-, 1-, 2-, 3-vessel coronary artery disease were 100%/91%, 91%/73%, 90%/71%, 92%/64%; positive/negative predictive value, 67%/100%, 91%/73%, 83%/81%, 93%/58%; diagnostic accuracy, 93%/87%/83%/87%, respectively. The negative predictive value in patients with 3-vessel CAD was lower than in patients with 0- and 2-vessel CAD and the specificity lower than in patients with no CAD whereas the positive predictive value was higher than in patients with no CAD. The other proportions did not differ significantly between the groups.

CONCLUSION

The diagnostic value of stress perfusion cardiac MRI in patients with 3-vessel CAD is comparable to results in patients with 1- or 2-vessel CAD. In the rare event that stress perfusion images do not depict regional hypoperfusion in patients with severe 3-vessel CAD, myocardial ischemia could be identified by reduced semi-quantitative perfusion parameters.

Appropriateness criteria for cardiovascular imaging use in heart failure: report of literature review

The Imaging Task Force appointed by the European Society of Cardiology (ESC) and the European Association of Cardiovascular Imaging (EACVI) identified the need to develop appropriateness criteria for the use of cardiovascular imaging in heart failure as a result of continuously increasing demand for imaging in diagnosis, definition of aetiology, follow-up, and treatment planning. This article presents the report of literature review performed in order to inform the process of definition of clinical indications and to aid the decisions of the appropriateness criteria voting panel. The report is structured according to identified common heart failure clinical scenarios.

Myocardial edema after ischemia/reperfusion is not stable and follows a bimodal pattern: imaging and histological tissue characterization

BACKGROUND

It is widely accepted that edema occurs early in the ischemic zone and persists in stable form for at least 1 week after myocardial ischemia/reperfusion. However, there are no longitudinal studies covering from very early (minutes) to late (1 week) reperfusion stages confirming this phenomenon.

OBJECTIVES

This study sought to perform a comprehensive longitudinal imaging and histological characterization of the edematous reaction after experimental myocardial ischemia/reperfusion.

METHODS

The study population consisted of 25 instrumented Large-White pigs (30 kg to 40 kg). Closed-chest 40-min ischemia/reperfusion was performed in 20 pigs, which were sacrificed at 120 min (n = 5), 24 h (n = 5), 4 days (n = 5), and 7 days (n = 5) after reperfusion and processed for histological quantification of myocardial water content. Cardiac magnetic resonance (CMR) scans with T2-weighted short-tau inversion recovery and T2-mapping sequences were performed at every follow-up stage until sacrifice. Five additional pigs sacrificed after baseline CMR served as controls.

RESULTS

In all pigs, reperfusion was associated with a significant increase in T2 relaxation times in the ischemic region. On 24-h CMR, ischemic myocardium T2 times returned to normal values (similar to those seen pre-infarction). Thereafter, ischemic myocardium-T2 times in CMR performed on days 4 and 7 after reperfusion progressively and systematically increased. On day 7 CMR, T2 relaxation times were as high as those observed at reperfusion. Myocardial water content analysis in the ischemic region showed a parallel bimodal pattern: 2 high water content peaks at reperfusion and at day 7, and a significant decrease at 24 h.

CONCLUSIONS

Contrary to the accepted view, myocardial edema during the first week after ischemia/reperfusion follows a bimodal pattern. The initial wave appears abruptly upon reperfusion and dissipates at 24 h. Conversely, the deferred wave of edema appears progressively days after ischemia/reperfusion and is maximal around day 7 after reperfusion.

Three-dimensional whole-heart T2 mapping at 3T

PURPOSE

Detecting variations in myocardial water content with T2 mapping is superior to conventional T2 -weighted MRI since quantification enables direct observation of complicated pathology. Most commonly used T2 mapping techniques are limited in achievable spatial and/or temporal resolution, both of which reduce accuracy due to partial-volume averaging and misregistration between images. The goal of this study was to validate a novel free breathing T2 mapping sequence that overcomes these limitations.

METHODS

The proposed technique was made insensitive to heart rate variability through the use of a saturation prepulse to reset magnetization every heartbeat. Respiratory navigator-gated, differentially T2 -weighted volumes were interleaved per heartbeat, guaranteeing registered images and robust voxel-by-voxel T2 maps. Free breathing acquisitions removed limits on spatial resolution and allowed short diastolic windows. Accuracy was quantified with simulations and phantoms.

RESULTS

Homogeneous three-dimensional (3D) T2 maps were obtained from normal human subjects and swine. Normal human and swine left ventricular T2 values were 42.3 ± 4.0 and 43.5 ± 4.3 ms, respectively. The T2 value for edematous myocardium obtained from a swine model of acute myocardial infarction was 59.1 ± 7.1 ms.

CONCLUSION

Free-breathing accurate 3D T2 mapping is feasible and may be applicable in myocardial assessment in lieu of current clinical black blood, T2 -weighted techniques.

Role of cardiovascular magnetic resonance in assessment of acute coronary syndrome

Cardiovascular disease (CVD) is the leading cause of death in the western world and is becoming more important in the developing world. Recently, advances in monitoring, revascularisation and pharmacotherapy have resulted in a reduction in mortality. However, although mortality rates have declined, the burden of disease remains large resulting in high direct and indirect healthcare costs related to CVDs. In Australia, acute coronary syndrome (ACS) accounts for more than 300000 years of life lost due to premature death and a total cost exceeding eight billion dollars annually. It is also the main contributor towards the discrepancy in life expectancy between indigenous and non-indigenous Australians. The high prevalence of CVD along with its associated cost urgently requires a reliable but non-invasive and cost-effective imaging modality. The imaging modality of choice should be able to accelerate the diagnosis of ACS, aid in the risk stratification of de novo coronary artery disease and avail incremental information of prognostic value such as viability which cardiovascular magnetic resonance (CMR) allows. Despite its manifold benefits, there are limitations to its wider use in routine clinical assessment and more studies are required into assessing its cost-effectiveness. It is hoped that with greater development in the technology and imaging protocols, CMR could be made less cumbersome, its imaging protocols less lengthy, the technology more inexpensive and easily applied in routine clinical practice.

Extra cardiac findings in cardiovascular MR: why cardiologists and radiologists should read together

PURPOSE

To assess prevalence and significance of extra cardiac findings (ECF) in clinical routine cardiovascular magnetic resonance (CMR) studies reported by cardiologists alone versus cardiologist and radiologist working together.

METHODS

One-thousand-seventy-four consecutive patients presenting at our institution for CMR work-up of multiple cardiovascular disease entities were enrolled retrospectively in two groups (cardiologists reading alone vs. cardiologists and radiologist reading together).

RESULTS

In 1,074 routine CMR studies a total of 357 ECF's were identified in 235 patients yielding a prevalence of 21.9 %. Of these 357 ECF's more than one-third were previously known. In the remaining 223 previously unknown findings 118 (52.9 %) were considered as major ECF's (92 patients), and 105 (47.1 %) were considered as minor ECF's (69 patients). Cardiologists reading alone reported 23 previously unknown ECF's in 23 patients, versus 200 previously unknown ECF in 138 patients by cardiologists and radiologists working together, p < 0.0001. Nevertheless, highly significant ECF's with major prognostic implications, such as the initial diagnosis of malignancy in an individual with no history of cancer, are extremely rare (n = 3, 0.3 %). Cardiologists alone, as well as cardiologists and radiologists working together seem to do well with reporting of such extremely important ECF's.

CONCLUSIONS

The prevalence of all ECF's was 21.9 %, and 14.9 % of previously unknown ECF's, respectively. However, the prevalence of highly significant ECF's was low. Joint reading with cardiologists and radiologists may increase the number of ECF's detected in CMR studies, but it remains unclear if this could result in an improved long-term outcome of patients undergoing routine CMR.

A technique for in vivo mapping of myocardial creatine kinase metabolism

ATP derived from the conversion of phosphocreatine to creatine by creatine kinase provides an essential chemical energy source that governs myocardial contraction. Here, we demonstrate that the exchange of amine protons from creatine with protons in bulk water can be exploited to image creatine through chemical exchange saturation transfer (CrEST) in myocardial tissue. We show that CrEST provides about two orders of magnitude higher sensitivity compared to (1)H magnetic resonance spectroscopy. Results of CrEST studies from ex vivo myocardial tissue strongly correlate with results from (1)H and (31)P magnetic resonance spectroscopy and biochemical analysis. We demonstrate the feasibility of CrEST measurement in healthy and infarcted myocardium in animal models in vivo on a 3-T clinical scanner. As proof of principle, we show the conversion of phosphocreatine to creatine by spatiotemporal mapping of creatine changes in the exercised human calf muscle. We also discuss the potential utility of CrEST in studying myocardial disorders.

Myocardial oxygenation is maintained during hypoxia when combined with apnea - a cardiovascular MR study

Oxygenation-sensitive (OS) cardiovascular magnetic resonance (CMR) is used to noninvasively measure myocardial oxygenation changes during pharmacologic vasodilation. The use of breathing maneuvers with OS CMR for diagnostic purposes has been recently proposed based on the vasodilatory effect of Co₂, which can be enhanced by the additive effect of mild hypoxia. This study seeks to investigate this synergistic concept on coronary arteriolar resistance with OS CMR. In nine anesthetized swine, normoxemic and mild hypoxemic arterial partial pressure of oxygen (Pao₂) levels (100 and 80 mmHg) were targeted with three arterial partial pressure of carbon dioxide (Paco₂) levels of 30, 40, and 50 mmHg. During a 60-sec apnea from the set baselines, OS T2*-weighted gradient echo steady-state free precession (SSFP) cine series were obtained in a clinical 1.5T magnetic resonance imaging (MRI) system. Arterial blood gases were acquired prior to and after apnea. Changes in global myocardial signal intensity (SI) were measured. Although a greater drop in arterial oxygen saturation (SaO₂) was observed in the hypoxemic baselines, myocardial SI increased or was maintained during apnea in all levels (n = 6). An observed decrease in left ventricular blood pool SI was correlated with the drop in SaO₂. Corrected for the arterial desaturation, the calculated SI increase attributable to the increase in myocardial blood flow was greater in the hypoxemic levels. Both the changes in Paco₂ and Pao₂ were correlated with myocardial SI changes at normoxemia, yet not at hypoxemic levels. Using OS CMR, we found evidence that myocardial oxygenation is preserved during hypoxia when combined with Co₂-increasing maneuvers, indicating synergistic effects of hypoxemia and hypercapnia on myocardial blood flow.

Iterative k-t principal component analysis with nonrigid motion correction for dynamic three-dimensional cardiac perfusion imaging

PURPOSE

In this study, an iterative k-t principal component analysis (PCA) algorithm with nonrigid frame-to-frame motion correction is proposed for dynamic contrast-enhanced three-dimensional perfusion imaging.

METHODS

An iterative k-t PCA algorithm was implemented with regularization using training data corrected for frame-to-frame motion in the x-pc domain. Motion information was extracted using shape-constrained nonrigid image registration of the composite of training and k-t undersampled data. The approach was tested for 10-fold k-t undersampling using computer simulations and in vivo data sets corrupted by respiratory motion artifacts owing to free-breathing or interrupted breath-holds. Results were compared to breath-held reference data.

RESULTS

Motion-corrected k-t PCA image reconstruction resolved residual aliasing. Signal intensity curves extracted from the myocardium were close to those obtained from the breath-held reference. Upslopes were found to be more homogeneous in space when using the k-t PCA approach with motion correction.

CONCLUSIONS

Iterative k-t PCA with nonrigid motion correction permits correction of respiratory motion artifacts in three-dimensional first-pass myocardial perfusion imaging.

Is myocardial stress perfusion MR-imaging suitable to predict the long term clinical outcome after revascularization?

INTRODUCTION

Aim of our study was to evaluate, whether myocardial ischemia or myocardial infarction (MI) depicted by myocardial stress perfusion MR imaging (SP CMR) can predict the clinical outcome in patients with coronary artery disease (CAD).

MATERIALS AND METHOD

220 patients were included. Myocardial perfusion was assessed at stress and at rest, using a 2D saturation recovery gradient echo sequence (SR GRE) and myocardial viability by late gadolinium enhancement magnetic resonance images (LGE CMR). MR-images were assessed in regard of presence and extent of MI and ischemia. Patients were monitored for major adverse cardiac events (MACE) (monitoring period: 5-7 years). MACE were correlated with the initial results of SP CMR.

RESULTS

Ischemia was found in 143 patients, MI in 107 patients. Number of MACE was in patients with normal SP CMR 0 (51 patients), with ischemia 21 (62 patients), with MI 14 (26 patients), with ischemia and MI 52 (81 patients). In all patients with severe MACE (MI, death) and in 63 of those with recurring symptoms LGE CMR revealed MI at baseline.

CONCLUSION

Negative SP CMR indicates low risk for MACE. In patients with stress induced ischemia, MACE might occur even after myocardial revascularization. The presence of MI proved by LGE CMR is associated with a significantly increased risk for MACE.

Combined delivery of bone marrow-derived mononuclear cells in chronic ischemic heart disease: rationale and study design

BACKGROUND

Treatment with bone marrow-derived mononuclear cells (BM-MNC) may improve left ventricular (LV) function in patients with chronic ischemic heart disease (IHD). Delivery method of the cell product may be crucial for efficacy.

HYPOTHESIS

We aimed to demonstrate that the combination of intramyocardial and intracoronary injection of BM-MNC is safe and improves LV function in patients with chronic IHD.

METHODS

After a safety/feasibility phase of 10 patients, 54 patients will be randomly assigned in a 1:1:1 pattern to 1 control and 2 BM-MNC treatment groups. The control group will be treated with state-of-the-art medical management. The treatment groups will receive either exclusively intramyocardial injection or a combination of intramyocardial and intracoronary injection of autologous BM-MNC. Left ventricular function as well as scar size, transmural extension, and regional wall-motion score will be assessed by cardiac magnetic resonance imaging studies at baseline and after 6 months. The primary endpoint is the change in global LV ejection fraction by cardiac magnetic resonance from 6 months to baseline.

RESULTS

The results, it is hoped, will have important clinical impact and provide essential information to improve the design of future regenerative-medicine protocols in cardiology.

CONCLUSIONS

As cell delivery may play an important role in chronic IHD, we aim to demonstrate feasibility and efficacy of a combined cell-delivery approach in patients with decreased LV function.

Cardiac MRI of acute coronary syndrome

Acute coronary syndrome (ACS) is a major cause of morbidity and mortality worldwide. New serological biomarkers, such as troponins, have improved the diagnosis of ACS; however, the diagnosis of ACS can still be difficult as there is marked heterogeneity in its presentation and significant overlap with other disorders presenting with chest pain. Evidence is accumulating that cardiac MRI provides information that can aid the detection and differential diagnosis of ACS, guide clinical decision-making and improve risk-stratification after an event. In this review, we present the relevant cardiac MRI techniques that can be used to detect ACS accurately, provide differential diagnosis, identify the sequelae of ACS, and determine prognostication after ACS.