ACR Practice Guideline for the Performance and Interpretation of Cardiac Magnetic Resonance Imaging (MRI)

Disease- and sex-specific differences in patients with heart valve disease: a proteome study

Pressure overload in patients with aortic valve stenosis and volume overload in mitral valve regurgitation trigger specific forms of cardiac remodeling; however, little is known about similarities and differences in myocardial proteome regulation. We performed proteome profiling of 75 human left ventricular myocardial biopsies (aortic stenosis = 41, mitral regurgitation = 17, and controls = 17) using high-resolution tandem mass spectrometry next to clinical and hemodynamic parameter acquisition. In patients of both disease groups, proteins related to ECM and cytoskeleton were more abundant, whereas those related to energy metabolism and proteostasis were less abundant compared with controls. In addition, disease group-specific and sex-specific differences have been observed. Male patients with aortic stenosis showed more proteins related to fibrosis and less to energy metabolism, whereas female patients showed strong reduction in proteostasis-related proteins. Clinical imaging was in line with proteomic findings, showing elevation of fibrosis in both patient groups and sex differences. Disease- and sex-specific proteomic profiles provide insight into cardiac remodeling in patients with heart valve disease and might help improve the understanding of molecular mechanisms and the development of individualized treatment strategies.

Preliminary Study: Learning the Impact of Simulation Time on Reentry Location and Morphology Induced by Personalized Cardiac Modeling

Personalized cardiac modeling is widely used for studying the mechanisms of cardiac arrythmias. Due to the high demanding of computational resource of modeling, the arrhythmias induced in the models are usually simulated for just a few seconds. In clinic, it is common that arrhythmias last for more than several minutes and the morphologies of reentries are not always stable, so it is not clear that whether the simulation of arrythmias for just a few seconds is long enough to match the arrhythmias detected in patients. This study aimed to observe how long simulation of the induced arrhythmias in the personalized cardiac models is sufficient to match the arrhythmias detected in patients. A total of 5 contrast enhanced MRI datasets of patient hearts with myocardial infarction were used in this study. Then, a classification method based on Gaussian mixture model was used to detect the infarct tissue. For each reentry, 3 s and 10 s were simulated. The characteristics of each reentry simulated for different duration were studied. Reentries were induced in all 5 ventricular models and sustained reentries were induced at 39 stimulation sites in the model. By analyzing the simulation results, we found that 41% of the sustained reentries in the 3 s simulation group terminated in the longer simulation groups (10 s). The second finding in our simulation was that only 23.1% of the sustained reentries in the 3 s simulation did not change location and morphology in the extended 10 s simulation. The third finding was that 35.9% reentries were stable in the 3 s simulation and should be extended for the simulation time. The fourth finding was that the simulation results in 10 s simulation matched better with the clinical measurements than the 3 s simulation. It was shown that 10 s simulation was sufficient to make simulation results stable. The findings of this study not only improve the simulation accuracy, but also reduce the unnecessary simulation time to achieve the optimal use of computer resources to improve the simulation efficiency and shorten the simulation time to meet the time node requirements of clinical operation on patients.

Intra-scan inter-tissue variability can help harmonize radiomics features in CT

OBJECTIVE

We studied the repeatability and the relative intra-scan variability across acquisition protocols in CT using phantom and unenhanced abdominal series.

METHODS

We used 17 CT scans from the Credence Cartridge Radiomics Phantom database and 20 unenhanced multi-site non-pathologic abdominal patient series for which we measured spleen and liver tissues. We performed multiple measurements in extracting 9 radiomics features. We defined a "tandem" as the measurement of a given tissue (or material) by a given radiomics. For each tandem, we assessed the proportion of the variability attributable to repetitions, acquisition protocols, material, or patient. We analyzed the distribution of the intra-scan correlation between pairs of tandems and checked the impact of correlation coefficient greater than 0.90 in comparing paired and unpaired differences.

RESULTS

The repeatability of radiomics features depends on the measured material; 56% of tandems were highly repeatable. Histogram-derived radiomics were generally less repeatable. Nearly 60% of relative radiomics measurements had a correlation coefficient higher than 0.90 allowing paired measurements to improve reliability in detecting the difference between two materials. The analysis of liver and spleen tissues showed that measurement variability was negligible with respect to other variabilities. As for phantom data, we found that gray level zone length matrix (GLZLM)-derived radiomics and gray level co-occurrence matrix (GLCM)-derived radiomics were the most correlating features. For these features, relative intra-scan measurements improved the detection of different materials or tissues.

CONCLUSIONS

We identified radiomics features for which the intra-scan measurements between tissues are linearly correlated. This property represents an opportunity to improve tissue characterization and inter-site harmonization.

KEY POINTS

• The repeatability of radiomics features on CT depends on the measured material or tissue. • Some tandems of radiomics features/tissues are linearly affected by the variability of acquisition protocols on CT. • Relative intra-scan measurements are an opportunity for improving quantitative imaging on CT.

Recommendation for Cardiac Magnetic Resonance Imaging-Based Phenotypic Study: Imaging Part

Cardiac magnetic resonance (CMR) imaging provides important biomarkers for the early diagnosis of many cardiovascular diseases and has been reported to reveal phenome-wide associations of cardiac/aortic structure and functionality in population studies. Nevertheless, due to the complexity of operation and variations among manufactural vendors, magnetic field strengths, coils, sequences, scan parameters, and image analysis approaches, CMR is rarely used in large cohort studies. Existing guidelines mainly focused on the diagnosis of cardiovascular diseases, which did not aim to basic research. The purpose of this study was to propose a recommendation for CMR based phenotype measurements for cohort study. We classify the imaging sequences of CMR into three categories according to the importance and universality of corresponding measurable phenotypes. The acquisition time and repeatability of the phenotypic measurement were also taken into consideration during the categorization. Unlike other guidelines, this recommendation focused on quantitative measurement of large amount of phenotypes from CMR.

Appropriate use criteria for cardiovascular MRI: SIC - SIRM position paper Part 2 (myocarditis, pericardial disease, cardiomyopathies and valvular heart disease)

Cardiovascular magnetic resonance (CMR) has emerged as an accurate diagnostic technique for the evaluation of patients with cardiac disease in the majority of clinical settings, thanks to an established additional diagnostic and prognostic value. This document has been developed by a joined group of experts of the Italian Society of Cardiology (SIC) and Italian Society of Radiology (SIRM) to provide a summary about the current state of technology and clinical applications of CMR, to improve the clinical diagnostic pathways and to promote its inclusion in clinical practice. The writing committee consisted of members and experts of both societies in order to develop a more integrated approach in the field of cardiac imaging. This section 2 will cover myocarditis, pericardial disease, cardiomyopathies and valvular heart disease.

Additive effect of hypertension on left ventricular structure and function in patients with asymptomatic type 2 diabetes mellitus

OBJECTIVE

We aimed to comprehensively determine the effects of hypertension on left ventricular (LV) structure, microcirculation, tissue characteristics, and deformation in type 2 diabetes mellitus (T2DM) using multiparametric cardiac magnetic resonance (CMR) imaging.

METHODS

We prospectively enrolled 138 asymptomatic patients with T2DM (80 normotensive and 58 hypertensive individuals) and 42 normal glucose-tolerant and normotensive controls and performed multiparametric CMR examination to assess cardiac geometry, microvascular perfusion, extracellular volume (ECV), and strain. Univariable and multivariable linear analysis was performed to analyze the effect of hypertension on LV deformation in patients with T2DM.

RESULTS

Compared with controls, patients with T2DM exhibited decreased strain, decreased microvascular perfusion, increased LV remodeling index, and increased ECV. Hypertension lead to greater deterioration of LV strain (peak strain-radial, P = 0.002; peak strain-longitudinal, P = 0.006) and LV remodeling index (P = 0.005) in patients with T2DM after adjustment for covariates; however, it did not affect microvascular perfusion (perfusion index, P = 0.469) and ECV (P = 0.375). In multivariable analysis, hypertension and diabetes were independent predictors of reduced LV strain, whereas hypertension is associated with greater impairment of diastolic function (P = 0.009) but not systolic function (P = 0.125) in the context of diabetes, independent of clinical factors and myocardial disorder.

CONCLUSION

Hypertension in the context of diabetes is significantly associated with LV diastolic function and concentric remodeling; however, it has little effect on systolic function, myocardial microcirculation, or fibrosis independent of covariates, which provide clinical evidence for understanding the pathogenesis of comorbidities and explaining the development of distinct heart failure phenotypes.

Guideline for Cardiovascular Magnetic Resonance Imaging from the Korean Society of Cardiovascular Imaging-Part 1: Standardized Protocol

Cardiac magnetic resonance (CMR) imaging is widely used in many areas of cardiovascular disease assessment. This is a practical, standard CMR protocol for beginners that is designed to be easy to follow and implement. This protocol guideline is based on previously reported CMR guidelines and includes sequence terminology used by vendors, essential MR physics, imaging planes, field strength considerations, MRI-conditional devices, drugs for stress tests, various CMR modules, and disease/symptom-based protocols based on a survey of cardiologists and various appropriate-use criteria. It will be of considerable help in planning and implementing tests. In addressing CMR usage and creating this protocol guideline, we particularly tried to include useful tips to overcome various practical issues and improve CMR imaging. We hope that this document will continue to standardize and simplify a patient-based approach to clinical CMR and contribute to the promotion of public health.

Clinical outcomes meta-analysis: measuring subendocardial perfusion and efficacy of transmyocardial laser revascularization with nuclear imaging

INTRODUCTION

Randomized and nonrandomized clinical trials have tried to assess whether or not TMR patients experience an increase in myocardial perfusion. However there have been inconsistencies reported in the literature due to the use of different nuclear imaging modalities to test this metric. The primary purpose of this meta-analysis was to determine whether SPECT, MUGA and PET scans demonstrate changes in myocardial perfusion between lased and non-lased subjects and whether laser type affects myocardial perfusion. The secondary purpose was to examine the overall effect of laser therapy on clinical outcomes including survival, hospital re-admission and angina reduction.

METHODS

Sixteen studies were included in the primary endpoint analysis after excluding all other non-imaging TMR papers. Standardized mean difference was used as the effect size for all quantitative outcomes and log odds ratio was used as the effect size for all binary outcomes.

RESULTS

Statistically significant improvements in myocardial perfusion were observed between control and treatment groups in myocardial perfusion at 6-month follow up using PET imaging with a porcine model. However non-significant differences were observed in patients at 3 and 12 months using SPECT, PET or MUGA scans. Both CO₂ and Ho:YAG laser systems demonstrated an increase in myocardial perfusion however this effect was not statistically significant. In addition both laser types displayed statistically significant decreases in patient angina at 3, 6 and 12 months but non-significant increases in survival rates and decreases in hospital re-admissions.

CONCLUSION

In order to properly assess myocardial perfusion in TMR subjects, subendocardial perfusion needs to be analyzed via nuclear imaging. PET scans can provide this level of sensitivity and should be utilized in future studies to monitor and detect perfusion changes in lased and non-lased subjects.

Usefulness of Electrocardiographic Voltage to Determine Myocardial Fibrosis in Hypertrophic Cardiomyopathy

Classic electrocardiographic (ECG) voltage indexes have been applied to screen for left ventricular (LV) hypertrophy in hypertrophic cardiomyopathy (HC). However, it is unclear whether low ECG voltage reflects deteriorated electrical forces because of replacement of the myocardium by fibrotic tissues in HC. We investigated correlations between classic ECG voltage indexes (Cornell, total QRS voltage, and Sokolow-Lyon) and cardiac magnetic resonance (CMR) parameters focusing on the impact of low ECG voltage on the LV ejection fraction (LVEF) and myocardial fibrosis in HC. We studied 108 consecutive patients with HC who underwent CMR imaging with late gadolinium enhancement (LGE). Nineteen patients with complete right or left bundle branch block were excluded, leaving 89 patients for analysis (age 61.0 ± 13.9 years; 58 men). Of the 3 voltage indexes, the total QRS voltage and Sokolow-Lyon indexes were positively correlated with LVEF. For discriminating patients with end-stage HC (LVEF <50%) from patients with HC and preserved LVEF (≥ 50%), receiver-operating characteristic analysis revealed an excellent area under the curve of 0.87 for the total QRS voltage index and 0.90 for the Sokolow-Lyon index, whereas the area under the curve for the Cornell index was only 0.54 (p <0.01). Moreover, these 2 voltage indexes were negatively correlated with the extent of LGE-determined myocardial fibrosis when adjusted by the LV maximal wall thickness. In conclusion, low ECG voltage indexes may reflect increased myocardial fibrosis in patients with HC.

Right ventricular segmentation in cardiac MRI with moving mesh correspondences

This study investigates automatic propagation of the right ventricle (RV) endocardial and epicardial boundaries in 4D (3D+time) magnetic resonance imaging (MRI) sequences. Based on a moving mesh (or grid generation) framework, the proposed algorithm detects the endocardium and epicardium within each cardiac phase via point-to-point correspondences. The proposed method has the following advantages over prior RV segmentation works: (1) it removes the need for a time-consuming, manually built training set; (2) it does not make prior assumptions as to the intensity distributions or shape; (3) it provides a sequence of corresponding points over time, a comprehensive input that can be very useful in cardiac applications other than segmentation, e.g., regional wall motion analysis; and (4) it is more flexible for congenital heart disease where the RV undergoes high variations in shape. Furthermore, the proposed method allows comprehensive RV volumetric analysis over the complete cardiac cycle as well as automatic detections of end-systolic and end-diastolic phases because it provides a segmentation for each time step. Evaluated quantitatively over the 48-subject data set of the MICCAI 2012 RV segmentation challenge, the proposed method yielded an average Dice score of 0.84±0.11 for the epicardium and 0.79±0.17 for the endocardium. Further, quantitative evaluations of the proposed approach in comparisons to manual contours over 23 infant hypoplastic left heart syndrome patients yielded a Dice score of 0.82±0.14, which demonstrates the robustness of the algorithm.

Right ventricular hypertrophy is associated with cardiovascular events in hypertrophic cardiomyopathy: evidence from study with magnetic resonance imaging

BACKGROUND

Although left ventricular (LV) morphology and function have been well studied in hypertrophic cardiomyopathy (HCM), few data exist regarding the right ventricle. Accordingly, we studied right ventricular (RV) morphology and function and their effect on cardiovascular events in HCM using cardiac magnetic resonance (CMR) imaging.

METHODS

This retrospective study included 106 HCM patients (age 61.6 ± 14.5 years) examined using CMR imaging during January 2008 to September 2014. RV hypertrophy (RVH) was defined as RV maximal wall thickness > 5 mm.

RESULTS

RVH was observed in 30 of the 106 patients (RVH group), with the remaining 76 patients assigned to the non-RVH group. The RVH group had higher brain natriuretic peptide levels (461.6 ± 699.8 pg/mL vs. 225.3 ± 254.5 pg/mL; P = 0.01) and also showed a reduced RV end-diastolic volume index (43.4 ± 16.0 mL/m2 vs. 56.6±15.2 mL/m2; P = 0.0001), in keeping with a greater LV mass index (109.1 ± 24.9 g/m2 vs. 78.6 ± 23.0 g/m2; P < 0.0001). The RVH group was prominently associated with RV late gadolinium enhancement compared with the non-RVH group (33.3% vs. 0%; P < 0.0001). After CMR imaging, 15 patients developed cardiovascular events that included admission for heart failure, ventricular tachyarrhythmia/fibrillation, stroke, and sudden cardiac death. Cox proportional hazard analysis revealed that RVH was an independent predictor of the occurrence of cardiovascular events after adjustments by sex, age, LV mass index, LV ejection fraction, and LV outflow tract obstruction (hazard ratio, 5.42; 95% confidence interval, 1.16-25.3; P = 0.03).

CONCLUSIONS

These results suggest that HCM patients with RVH on CMR images have a greater incidence of cardiovascular events than non-RVH patients. Further work is needed to confirm this observation and assess its clinical importance.

Cardiovascular magnetic resonance activity in the United Kingdom: a survey on behalf of the British Society of Cardiovascular Magnetic Resonance

BACKGROUND

The indications, complexity and capabilities of cardiovascular magnetic resonance (CMR) have rapidly expanded. Whether actual service provision and training have developed in parallel is unknown.

METHODS

We undertook a systematic telephone and postal survey of all public hospitals on behalf of the British Society of Cardiovascular Magnetic Resonance to identify all CMR providers within the United Kingdom.

RESULTS

Of the 60 CMR centres identified, 88% responded to a detailed questionnaire. Services are led by cardiologists and radiologists in equal proportion, though the majority of current trainees are cardiologists. The mean number of CMR scans performed annually per centre increased by 44% over two years. This trend was consistent across centres of different scanning volumes. The commonest indication for CMR was assessment of heart failure and cardiomyopathy (39%), followed by coronary artery disease and congenital heart disease. There was striking geographical variation in CMR availability, numbers of scans performed, and distribution of trainees. Centres without on site scanning capability refer very few patients for CMR. Just over half of centres had a formal training programme, and few performed regular audit.

CONCLUSION

The number of CMR scans performed in the UK has increased dramatically in just two years. Trainees are mainly located in large volume centres and enrolled in cardiology as opposed to radiology training programmes.

Diagnostic contributions of cardiac magnetic resonance imaging in patients presenting with elevated troponin, acute chest pain syndrome and unobstructed coronary arteries

AIMS

Myocardial infarction with unobstructed coronary artery disease represents a serious diagnostic challenge. The role of cardiac magnetic resonance in the management of cardiomyopathies is increasing. We examined the diagnostic contributions of cardiac magnetic resonance in patients presenting with acute chest pain syndrome, elevated serum cardiac troponin concentrations and no significant coronary artery stenoses.

METHODS

Over a 3-year period, 107 consecutive patients (mean age 43.5 years; 62% men) presented to our institution with acute onset of chest pain, elevated serum troponin concentration and unobstructed coronary arteries, and underwent 3-tesla cardiac magnetic resonance at a mean delay of 6.9 days. A diagnosis was made based on: wall motion abnormalities and pericardial effusion on cine mode; myocardial oedema on T2-weighted imaging; abnormalities on first-pass perfusion imaging; and late gadolinium enhancement on T1-weighted imaging.

RESULTS

Cardiac magnetic resonance was normal in 10.3% of patients and contributed a diagnosis in 89.7%, including myocarditis in 59.9%, stress cardiomyopathy (takotsubo syndrome) in 14% and myocardial infarction in 15.8%. Patients with normal cardiac magnetic resonance had a significantly lower mean peak troponin concentration (2.6ng/mL) than patients with diagnostic cardiac magnetic resonance (9.7ng/mL; P=0.01).

CONCLUSION

Cardiac magnetic resonance contributed a diagnosis in nearly 90% of patients presenting with acute chest pain, elevated serum troponin and unobstructed coronary arteries.

Coronary computed tomography and magnetic resonance imaging

Cardiac computed tomography and magnetic resonance are relatively new imaging modalities that can exceed the ability of established imaging modalities to detect present pathology or predict patient outcomes. Coronary calcium scoring may be useful in asymptomatic patients at intermediate risk. Computed tomographic coronary angiography is a first-line indication to evaluate congenitally abnormal coronary arteries and, along with stress magnetic resonance myocardial perfusion imaging, is useful in symptomatic patients with nondiagnostic conventional stress tests. Cardiac magnetic resonance is indicated for visualizing cardiac structure and function, and delayed enhancement magnetic resonance is a first-line indication for assessing myocardial viability. Imaging plaque and molecular mechanisms related to plaque rupture holds great promise for the presymptomatic detection of patients at risk for coronary events but is not yet suitable for routine clinical use.

White matter lesions and cognitive performance: the role of cognitively complex leisure activity

BACKGROUND

Among persons with white matter lesions (WMLs), there is a range of cognitive function. We examine whether participation in leisure activities modifies the effect of WML load on cognitive function.

METHODS

Data are from 2300 men and women (aged 66-92 years) participating in the population-based Age Gene/Environment Susceptibility-Reykjavik Study. Subcortical WML load was calculated as a weighted sum, based on size of lesions in the four lobes. Periventricular WML load was calculated as the sum of lesion scores, based on size, for the frontal caps, occipitoparietal caps and bands. The upper quartile of lesion load in either area was compared to the lower three quartiles. Composite scores of memory (MEM), speed of processing (SP), and executive function (EF) were constructed from a battery of neuropsychological tests. Frequency of participation in nine cognitively stimulating leisure activities was assessed via questionnaire; the upper quartile was compared to the lower three quartiles. Multiple regression, controlling for demographic and health factors and brain infarcts, was used to test the main effects and interaction of WMLs and leisure activity on cognitive function.

RESULTS

High leisure activity was associated with higher performance in all three cognitive abilities: MEM beta = 0.20, 95% confidence interval [CI], 0.11-0.29; SP beta = 0.37, 95% CI, 0.29-0.45; and EF beta = 0.23, 95% CI, 0.15-0.29. High WML load was associated with significantly lower performance in SP (beta = -0.06, 95% CI, -0.13 to -0.01). The effect of WMLs on SP performance was modified by high leisure activity (p for interaction <.05).

CONCLUSION

Participation in cognitively stimulating leisure activity may attenuate the effect of WML pathology on cognitive performance.