Tagged cine magnetic resonance imaging to quantify regional mechanical changes after acute myocardial infarction

Diagnostic accuracy of left atrial function and strain for differentiating between acute and chronic myocardial infarction

BACKGROUND

The cardiac magnetic resonance tissue tracking (CMR-TT) technique was used to obtain left atrial strain and strain rate in patients with myocardial infarction (MI) and to evaluate the utility of this technique in the quantitative assessment of myocardial infarction for distinguishing acute from chronic myocardial infarction.

METHODS

We retrospectively analyzed 36 consecutive patients with acute myocardial infarction (AMI) and 29 patients with chronic myocardial infarction (CMI) who underwent CMR and 30 controls. Left atrial (LA) and ventricular functions were quantified by volumetric, and CMR-TT derived strain analysis from long and short left ventricular view cines. Receiver Operating Characteristics (ROC) analysis was used to determine the diagnostic accuracy of CMR-TT strain parameters for discriminating between acute and chronic myocardial infarction.

RESULTS

AMI and CMI participants had impaired LA reservoir function, conduit function and LA booster pump dysfunction compared to the controls. LA strain was more sensitive than LV global strain for the assessment of the MI stage. Peak late-negative SR yielded the best areas under the ROC curve (AUC) of 0.879, showing differentiation between acute and chronic myocardial infarction of all the LA strain parameters obtained. The highest significant differences between chronic myocardial infarction and normal myocardium were also found in the LV strain (p < 0.001) and LA functional parameters (p < 0.001), but there was no difference between AMI and normals.

CONCLUSIONS

CMR-TT-derived LA strain is a potential and robust tool in demonstrating impaired LA mechanics and quantifying LA dynamics, which have high sensitivity and specificity in the differential diagnosis of acute versus chronic myocardial infarction. Their use is thus worth popularizing in clinical application.

Localized strain characterization of cardiomyopathy in Duchenne muscular dystrophy using novel 4D kinematic analysis of cine cardiovascular magnetic resonance

BACKGROUND

Cardiomyopathy (CMP) is the most common cause of mortality in Duchenne muscular dystrophy (DMD), though the age of onset and clinical progression vary. We applied a novel 4D (3D + time) strain analysis method using cine cardiovascular magnetic resonance (CMR) imaging data to determine if localized strain metrics derived from 4D image analysis would be sensitive and specific for characterizing DMD CMP.

METHODS

We analyzed short-axis cine CMR image stacks from 43 DMD patients (median age: 12.23 yrs [10.6-16.5]; [interquartile range]) and 25 male healthy controls (median age: 16.2 yrs [13.3-20.7]). A subset of 25 male DMD patients age-matched to the controls (median age: 15.7 yrs [14.0-17.8]) was used for comparative metrics. CMR images were compiled into 4D sequences for feature-tracking strain analysis using custom-built software. Unpaired t-test and receiver operator characteristic area under the curve (AUC) analysis were used to determine statistical significance. Spearman's rho was used to determine correlation.

RESULTS

DMD patients had a range of CMP severity: 15 (35% of total) had left ventricular ejection fraction (LVEF) > 55% with no findings of myocardial late gadolinium enhancement (LGE), 15 (35%) had findings of LGE with LVEF > 55% and 13 (30%) had LGE with LVEF < 55%. The magnitude of the peak basal circumferential strain, basal radial strain, and basal surface area strain were all significantly decreased in DMD patients relative to healthy controls (p < 0.001) with AUC values of 0.80, 0.89, and 0.84 respectively for peak strain and 0.96, 0.91, and 0.98 respectively for systolic strain rate. Peak basal radial strain, basal radial systolic strain rate, and basal circumferential systolic strain rate magnitude values were also significantly decreased in mild CMP (No LGE, LVEF > 55%) compared to a healthy control group (p < 0.001 for all). Surface area strain significantly correlated with LVEF and extracellular volume (ECV) respectively in the basal (rho = - 0.45, 0.40), mid (rho = - 0.46, 0.46), and apical (rho = - 0.42, 0.47) regions.

CONCLUSION

Strain analysis of 3D cine CMR images in DMD CMP patients generates localized kinematic parameters that strongly differentiate disease from control and correlate with LVEF and ECV.

Echocardiographic and Cardiac MRI Comparison of Longitudinal Strain and Strain Rate in Cancer Patients Treated with Immune Checkpoint Inhibitors

Background: Immune checkpoint inhibitor (ICI)-induced cardiac side effects in cancer patients are increasingly being recognized and can be fatal. There is no standardized cardiac imaging test to examine the effects of ICIs in myocardial morphology and function. Objective: To study the utility of echocardiography and cardiac MRI in examining regional and global changes arising from ICI-induced myocarditis and cardiomyopathy in high-risk subjects suspected to have developed ICI cardiomyopathy. Methods: We studied eight consecutive patients referred for cardiac MRI (CMR) from a comprehensive cancer center for suspected ICI-induced myocarditis and compared the data with sixteen age-matched controls. Using newly developed strain analysis algorithms, we measured myocardial strain and strain rates using echocardiography and CMR. Then, we compared the mean longitudinal strain and strain rates derived from echocardiography and CMR in the same ICI-treated cohort of patients (n = 8). They underwent both of these imaging studies with images taken 24−48 h apart and followed up prospectively within the same hospital course. Results: All our cases had preserved ejection fraction (EF) > 50%. Echocardiogram showed reduced mean systolic longitudinal strain (LS, %) (ICI: −12.381 ± 4.161; control: −19.761 ± 1.925; p < 0.001), peak systolic strain rate (SRS, s−1) (ICI: −0.597 ± 0.218; control: −0.947 ± 0.135; p = 0.002) and early diastolic strain rate (SRE, s−1) (ICI: 0.562 ± 0.295; control: 1.073 ± 0.228; p = 0.002) in ICI-treated cases. Direct comparison between the echocardiogram vs. CMR obtained within the same hospital course demonstrated strong a correlation of LS scores (r = 0.83, p = 0.012) and SRS scores (r = 0.71, p = 0.048). The Bland−Altman plots showed that 95% of the data points fitted within the ±1.96 SD of the mean difference, suggesting an agreement among these two imaging modalities. Conclusion: In this feasibility cohort study, both echocardiography- and CMR-based strain indices illustrate changes in myocardial contractility and relaxation suggestive of ICI-induced cardiomyopathy. Our data, after validation in a larger cohort, can form the basis of myocardial imaging in cancer patients treated with ICIs.

Modified GAN Augmentation Algorithms for the MRI-Classification of Myocardial Scar Tissue in Ischemic Cardiomyopathy

Contrast-enhanced cardiac magnetic resonance imaging (MRI) is routinely used to determine myocardial scar burden and make therapeutic decisions for coronary revascularization. Currently, there are no optimized deep-learning algorithms for the automated classification of scarred vs. normal myocardium. We report a modified Generative Adversarial Network (GAN) augmentation method to improve the binary classification of myocardial scar using both pre-clinical and clinical approaches. For the initial training of the MobileNetV2 platform, we used the images generated from a high-field (9.4T) cardiac MRI of a mouse model of acute myocardial infarction (MI). Once the system showed 100% accuracy for the classification of acute MI in mice, we tested the translational significance of this approach in 91 patients with an ischemic myocardial scar, and 31 control subjects without evidence of myocardial scarring. To obtain a comparable augmentation dataset, we rotated scar images 8-times and control images 72-times, generating a total of 6,684 scar images and 7,451 control images. In humans, the use of Progressive Growing GAN (PGGAN)-based augmentation showed 93% classification accuracy, which is far superior to conventional automated modules. The use of other attention modules in our CNN further improved the classification accuracy by up to 5%. These data are of high translational significance and warrant larger multicenter studies in the future to validate the clinical implications.

Correlation of Myocardial Strain and Late Gadolinium Enhancement by Cardiac Magnetic Resonance After a First Anterior ST-Segment Elevation Myocardial Infarction

Objectives: To investigate the correlation of cardiac magnetic resonance (CMR) feature-tracking with conventional CMR parameters in patients with a first anterior ST-segment elevation myocardial infarction (STEMI).

Methods: This sub-analysis of OCTAMI (Optical Coherence Tomography Examination in Acute Myocardial Infarction) registry included 129 patients who finished a CMR examination 1 month after a first anterior STEMI. Cine images were applied to calculate both global and segmental left ventricular peak strain parameters. The patients were divided into two groups by left ventricular ejection fraction (LVEF) and compared with 42 healthy controls. Segmental late gadolinium enhancement (LGE) was graded according to LGE transmurality as follows: (1) >0 to ≤ 25%; (2) >25 to ≤ 50%; (3) >50 to ≤ 75%; (4) >75%. Left ventricle was divided into infarcted, adjacent, and remote regions to assess regional function.

Results: Compared with controls, global radial (28.39 ± 5.08% vs. 38.54 ± 9.27%, p < 0.05), circumferential (−16.91 ± 2.11% vs. −20.77 ± 2.78%, p < 0.05), and longitudinal (−13.06 ± 2.15 vs. −15.52 ± 2.69, p < 0.05) strains were impaired in STEMI patients with normal LVEF (≥55%). Strain parameters were strongly associated with LGE (radial: r = 0.65; circumferential: r = 0.69; longitudinal: r = 0.61; all p < 0.05). A significant and stepwise impairment of global strains was observed in groups divided by LGE tertiles. Furthermore, segmental strain was different in various degrees of LGE transmurality especially for radial and circumferential strain. Strains of adjacent region were better than infarcted region in radial and circumferential directions and worse than remote region in all three directions.

Conclusion: Global and regional strain could stratify different extent and transmurality of LGE, respectively. Although without LGE, adjacent region had impaired strains comparing with remote region.

Biventricular Strain Imaging with Cardiac MRI in Genotyped and Histology Validated Amyloid Cardiomyopathy

Cardiac amyloidosis (CA) is a common and potentially fatal infiltrative cardiomyopathy. Contrast-enhanced cardiac MRI (CMR) is used as a diagnostic tool. However, utility of CMR for the comprehensive analysis of biventricular strains and strain rates is not reported as extensively as echocardiography. In addition, RV strain analysis using CMR has not been described previously.

Objectives

We sought to study the global and regional indices of biventricular strain and strain rates in endomyocardial biopsy (EMB)-proven, genotyped cases of CA.

Methods

A database of 80 EMBs was curated from 2012 to 2019 based on histology. A total of 19 EMBs positive for CA were subjected to further tissue-characterization with histology, and compared with four normal biopsy specimens. Samples were genotyped for ATTR- or AL-subtypes. Five patients, with both echocardiography and contrast-enhanced CMR performed 72-h apart, were subjected to comprehensive analysis of biventricular strain and strain-rates.

Results

Histology confirmed that the selected samples were indeed positive for cardiac amyloid. Echocardiography showed reduced global and regional left-ventricular (LV) longitudinal strain indices. CMR with tissue-characterization of LV showed global reductions in circumferential, radial and longitudinal strains and strain-rates, following a general trend with the echocardiographic findings. The basal right-ventricular (RV) segments had reduced circumferential strains with no changes in longitudinal strain.

Conclusions

In addition to providing a clinical diagnosis of CA based on contrast clearance-dynamics, CMR can be a potent tool for accurate functional assessment of global and regional changes in strain and strain-rates involving both LV and RV. Further studies are warranted to validate and curate the strain imaging capacity of CMR in CA.

Elevated myocardial wall stress after percutaneous coronary intervention in acute ST elevation myocardial infraction is associated with increased mortality

BACKGROUND

Despite early attempts to salvage myocardium-at-risk with percutaneous coronary intervention (PCI), changes in myocardial wall stress (MWS) leads to ventricular dilatation and dysfunction after acute ST-elevation myocardial infraction (STEMI). Whether this is transient or leads to long-term adverse outcomes major adverse cardiovascular events (MACE) is not known. We studied the association between MWS and MACE in patients after a successful PCI for acute STEMI.

OBJECTIVES

To study the MWS in percutaneously revascularized STEMI patients in relation to all-cause mortality and MACE.

METHODS

We prospectively enrolled 142 patients who presented to our tertiary care hospital with acute STEMI requiring emergent PCI. In addition to the standard clinical biomarkers, both end-systolic and end-diastolic MWS was calculated using our recently validated Echocardiographic indices. Patients were then prospectively followed up to an average of 16.5 (± 12.0) months to assess all-cause mortality and MACE.

RESULTS

During the follow-up period, 9% of the patients died and 17% developed MACE. Patients who died had significantly elevated end-systolic WS compared to those who survived (mean ESWS, 80.01 ± 36.86 vs 59.28 ± 27.68). There was no significant difference in end-diastolic WS, left ventricular systolic function and peak troponin levels among survivors versus non-survivors. Elevated ESWS (>62.5 Kpa) and age remained the significant predictors of mortality on multivariate logistic analysis (OR 7.75, CI 1.33-73.86, P = .03; OR 1.16, CI 1.06-1.31, P = .002).

CONCLUSION

Elevated ESWS measured by echocardiogram is associated with increased odds of long-term mortality in STEMI patients who have undergone emergent PCI. This finding can help clinicians to risk stratify high-risk patients.

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.

Immune Checkpoint Inhibitors: Cardiotoxicity in Pre-clinical Models and Clinical Studies

Since the approval of the first immune checkpoint inhibitor (ICI) 9 years ago, ICI-therapy have revolutionized cancer treatment. Lately, antibodies blocking the interaction of programmed cell death protein (PD-1) and ligand (PD-L1) are gaining momentum as a cancer treatment, with multiple agents and cancer types being recently approved for treatment by the US Food and Drug Administration (FDA). Unfortunately, immunotherapy often leads to a wide range of immune related adverse events (IRAEs), including several severe cardiac effects and most notably myocarditis. While increased attention has been drawn to these side effects, including publication of multiple clinical observational data, the underlying mechanisms are unknown. In the event of IRAEs, the most widely utilized clinical solution is administration of high dose corticosteroids and in severe cases, discontinuation of these ICIs. This is detrimental as these therapies are often the last line of treatment options for many types of advanced cancer. In this review, we have systematically described the pathophysiology of the PD-1/PD-L1 axis (including a historical perspective) and cardiac effects in pre-clinical models, clinical trials, autoimmune mechanisms, and immunotherapy in combination with other cancer treatments. We have also reviewed the current challenges in the diagnosis of cardiac events and future directions in the field. In conclusion, this review will delve into this expanding field of cancer immunotherapy and the emerging adverse effects that should be quickly detected and prevented.

[A review on motion tracking methods for left myocardium based on cardiac cine magnetic resonance image]

Due to the high spatiotemporal resolution , cardiac cine magnetic resonance imaging (CCMRI) has been widely used to evaluate the cardiac function of cardiovascular diseases such as myocardial ischemia and so on. Segmentation-based motion tracking of left myocardium is very important for comprehensive evaluation of cardiac function in the diagnosis and treatment of cardiovascular diseases. However, it is a challenge to track motion of left myocardium, which is homogeneous and cannot provide effective motion information. In this paper, CCMRI imaging techniques for myocardial motion tracking are introduced firstly. Then approaches for motion tracking of left myocardium based on CCMRI image are described in details and are summarized and prospected at the end, which not only helps beginners to have a quick and comprehensive understanding on this topic, but also provides theoretical reference to related researchers for further optimization of approaches for motion tracking of left myocardium. From the current study, motion tracking approaches for left myocardium based on CCMRI image make comprehensive use of the spatiotemporal motion characteristics of CCMRI image, the motion and structures of myocardium of left ventricle and so on, which can make up for the shortcomings of sparse motion information of CCMRI image. However, it still needs improved constraint framework, verification methods and so on.