Myocardial strain in healthy adults across a broad age range as revealed by cardiac magnetic resonance imaging at 1.5 and 3.0T: Associations of myocardial strain with myocardial region, age, and sex

The Interfield Strength Agreement of Left Ventricular Strain Measurements at 1.5 T and 3 T Using Cardiac MRI Feature Tracking

BACKGROUND

Left ventricular (LV) strain measurements can be derived using cardiac MRI from routinely acquired balanced steady-state free precession (bSSFP) cine images.

PURPOSE

To compare the interfield strength agreement of global systolic strain, peak strain rates and artificial intelligence (AI) landmark-based global longitudinal shortening at 1.5 T and 3 T.

STUDY TYPE

Prospective.

SUBJECTS

A total of 22 healthy individuals (mean age 36 ± 12 years; 45% male) completed two cardiac MRI scans at 1.5 T and 3 T in a randomized order within 30 minutes. FIELD STRENGTH/SEQUENCE: bSSFP cine images at 1.5 T and 3 T.

ASSESSMENT

Two software packages, Tissue Tracking (cvi42, Circle Cardiovascular Imaging) and QStrain (Medis Suite, Medis Medical Imaging Systems), were used to derive LV global systolic strain in the longitudinal, circumferential and radial directions and peak (systolic, early diastolic, and late diastolic) strain rates. Global longitudinal shortening and mitral annular plane systolic excursion (MAPSE) were measured using an AI deep neural network model.

STATISTICAL TESTS

Comparisons between field strengths were performed using Wilcoxon signed-rank test (P value < 0.05 considered statistically significant). Agreement was determined using intraclass correlation coefficients (ICCs) and Bland-Altman plots.

RESULTS

Minimal bias was seen in all strain and strain rate measurements between field strengths. Using Tissue Tracking, strain and strain rate values derived from long-axis images showed poor to fair agreement (ICC range 0.39-0.71), whereas global longitudinal shortening and MAPSE showed good agreement (ICC = 0.81 and 0.80, respectively). Measures derived from short-axis images showed good to excellent agreement (ICC range 0.78-0.91). Similar results for the agreement of strain and strain rate measurements were observed with QStrain.

CONCLUSION

The interfield strength agreement of short-axis derived LV strain and strain rate measurements at 1.5 T and 3 T was better than those derived from long-axis images; however, the agreement of global longitudinal shortening and MAPSE was good.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 2.

Recovery and prognostic values of myocardial strain in acute anterior and non-anterior wall myocardial infarction

BACKGROUND

To assess the recovery and prognostic values of myocardial strain using cardiac magnetic resonance (CMR)- feature tracking (FT) in acute anterior and non-anterior wall myocardial infarction.

METHODS

103 reperfused patients after STEMI who underwent CMR at about 4 days (baseline) and 4 months (follow-up) were included, including 48 and 55 patients with anterior wall myocardial infarction (AWMI) and non-anterior wall myocardial infarction(NAWMI). CMR-FT analysis was performed using cine images to measure LV global radial, circumferential, and longitudinal peak strains (GRS, GCS, and GLS, respectively). Infarct size (IS) and microvascular obstruction (MVO) were estimated by late-gadolinium enhancement imaging. The primary clinical endpoint was the occurrence of major adverse cardiac events (MACE) after infarction.

RESULTS

Patients with AWMI had higher IS, higher MVO, lower ejection fraction, and more significantly impaired CMR-FT strain values than patients with NAWMI (all p<0.05). Global strain significantly improved at 4 months (all p<0.01), especial in NAWMI. GLS was an independent predictor (odds ratio = 2.08, 95% confidence interval = 1.032-4.227, p = 0.04] even after adjustment for IS and MVO. The optimal cutoff of GLS was -7.9%, with sensitivity and specificity were 73.3% and 75.0%, respectively. In receiver operating characteristic analysis, IS remained the strongest predictor (area under the curve [AUC] = 0.83, p<0.01), followed by MVO (AUC = 0.81, p<0.01) and GLS (AUC = 0.78, p<0.01).

CONCLUSION

CMR-FT-derived global myocardial strains significantly improved over time, especial in NAWMI. GLS measurement independently predicted the occurrence of medium-term MACE.

Normative healthy reference values for global and segmental 3D principal and geometry dependent strain from cine cardiac magnetic resonance imaging

3-Dimensional (3D) myocardial deformation analysis (3D-MDA) enables novel descriptions of geometry-independent principal strain (PS). Applied to routine 2D cine cardiovascular magnetic resonance (CMR), this provides unique measures of myocardial biomechanics for disease diagnosis and prognostication. However, healthy reference values remain undefined. This study describes age- and sex-stratified reference values from CMR-based 3D-MDA, including 3D PS. One hundred healthy volunteers were prospectively recruited following institutional ethics approval and underwent CMR imaging. 3D-MDA was performed using validated software. Age- and sex-stratified global and segmental strain measures were derived for conventional geometry-dependent [circumferential (CS), longitudinal (LS), and radial (RS)] and geometry-independent [minimum (minPS) and maximum principal (maxPS)] directions of deformation. Layer-specific contraction angle interactions were determined using local minPS vectors. The average age was 43 ± 15 years and 55% were women. Strain measures were higher in women versus men. 3D PS-based assessment of maximum tissue shortening (minPS) and maximum tissue thickening (maxPS) were greater than corresponding geometry-dependent markers of LS and RS, consistent with improved representation of local tissue deformations. Global maxPS amplitude best discriminated both age and sex. Segmental analyses showed greater strain amplitudes in apical segments. Transmural PS contraction angles were higher in females and showed a heterogeneous distribution across segments. In this study we provided age and sex-based reference values for 3D strain from CMR imaging, demonstrating improved capacity for 3D PS to document maximal local tissue deformations and to discriminate age and sex phenotypes. Novel markers of layer-specific strain angles from 3D PS were also described.

MRI-based strain measurements reflect morphological changes following myocardial infarction: A study on the UK Biobank cohort

In a porcine experimental model of myocardial infarction, a localised, layer-specific, circumferential left ventricular strain metric has been shown to indicate chronic changes in ventricular function post-infarction more strongly than ejection fraction. This novel strain metric might therefore provide useful prognostic information clinically. In this study, existing clinical volume indices, global strains, and the novel, layer-specific strain were calculated for a large human cohort to assess variations in ventricular function and morphology with age, sex, and health status. Imaging and health data from the UK Biobank were obtained, including healthy volunteers and those with a history of cardiovascular illness. In total, 710 individuals were analysed and stratified by age, sex and health. Significant differences in all strain metrics were found between healthy and unhealthy populations, as well as between males and females. Significant differences in basal circumferential strain and global circumferential strain were found between healthy males and females, with males having smaller absolute values for both (allp ≤ 0.001). There were significant differences in the functional variables left ventricular ejection fraction, end-systolic volume, end-systolic volume index and mid-ventricular circumferential strain between healthy and unhealthy male cohorts aged 65-74 (allp ≤ 0.001). These results suggest that whilst regional circumferential strains may be useful clinically for assessing cardiovascular health, care must be taken to ensure critical values are indexed correctly to age and sex, due to the differences in these values observed here.

Age- and sex-specific reference values of biventricular strain and strain rate derived from a large cohort of healthy Chinese adults: a cardiovascular magnetic resonance feature tracking study

BACKGROUND

As a noninvasive tool, myocardial deformation imaging may facilitate the early detection of cardiac dysfunction. However, normal reference ranges of myocardial strain and strain rate (SR) based on large-scale East Asian populations are still lacking. This study aimed to provide reference values of left ventricular (LV) and right ventricular (RV) strain and SR based on a large cohort of healthy Chinese adults using cardiovascular magnetic resonance (CMR) feature tracking (FT).

METHODS

Five hundred and sixty-six healthy Chinese adults (55.1% men) free of hypertension, diabetes, and obesity were included. On cine CMR, biventricular global radial, circumferential, and longitudinal strain (GRS, GCS, and GLS), and the peak radial, circumferential, and longitudinal systolic, and diastolic SRs (PSSRR, PSSRC, PSSRL, PDSRR, PDSRC, and PDSRL), and regional radial and circumferential strain at the basal, mid-cavity, and apical levels were measured. Associations of global and regional biventricular deformation indices with age and sex were investigated.

RESULTS

Women demonstrated greater magnitudes of LV GRS (37.6 ± 6.1% vs. 32.1 ± 5.3%), GCS (- 20.7 ± 1.9% vs. - 18.8 ± 1.9%), GLS (- 17.8 ± 1.8% vs. - 15.6 ± 1.8%), RV GRS (25.1 ± 7.8% vs. 22.1 ± 6.7%), GCS (- 14.4 ± 3.6% vs. - 13.2 ± 3.2%), GLS (- 22.4 ± 5.2% vs. - 20.2 ± 4.6%), and biventricular peak systolic and diastolic SR in all three coordinate directions (all P < 0.05). For the LV, aging was associated with increasing amplitudes of GRS, GCS, and decreasing amplitudes of PDSRR, PDSRC, PDSRL (all P < 0.05). For the RV, aging was associated with an increase in the magnitudes of GRS, GCS, GLS, PSSRR, PSSRC, PSSRL, and a decrease in the magnitude of PDSRR, PDSRC (all P < 0.05). Biventricular radial and circumferential strain measurements at the basal, mid-cavity, and apical levels were all significantly related to age and sex in both sexes (all P < 0.05).

CONCLUSIONS

We provide age- and sex-specific normal values of biventricular strain and SR based on a large sample of healthy Chinese adults with a broad age range. These results may be served as a reference standard for cardiac function assessment, especially for the Chinese population.

Impact of myocardial injury on regional left ventricular function in the course of acute myocarditis with preserved ejection fraction: insights from segmental feature tracking strain analysis using cine cardiac MRI

The aim of this study was to provide insights into myocardial adaptation over time in myocyte injury caused by acute myocarditis with preserved ejection fraction. The effect of myocardial injury, as defined by the presence of late gadolinium enhancement (LGE), on the change of left ventricular (LV) segmental strain parameters was evaluated in a longitudinal analysis. Patients with a first episode of acute myocarditis were enrolled retrospectively. Peak radial (PRS), longitudinal (PLS) and circumferential (PCS) LV segmental strain values at baseline and at follow-up were computed using feature tracking cine cardiac magnetic resonance imaging. The change of segmental strain values in LGE positive (LGE+) and LGE negative (LGE-) segments was compared over a course of 89 ± 20 days. In 24 patients, 100 LGE+ segments and 284 LGE- segments were analysed. Between LGE+ and LGE- segments, significant differences were found for the change of segmental PCS (p < 0.001) and segmental PRS (p = 0.006). LGE + segments showed an increase in contractility, indicating recovery, and LGE- segments showed a decrease in contractility, indicating normalisation after a hypercontractile state or impairment of an initially normal contracting segment. No significant difference between LGE+ and LGE- segments was found for the change in segmental PLS. In the course of acute myocarditis with preserved ejection fraction, regional myocardial function adapts inversely in segments with and without LGE. As these effects seem to counterbalance each other, global functional parameters might be of limited use in monitoring functional recovery of these patients.

Myocardial Mechanics Parameters That Predict Left Ventricular Outflow Tract Obstruction in Patients With Hypertrophic Cardiomyopathy: A Cardiovascular Magnetic Resonance Feature Tracking Analysis

OBJECTIVE

To identify left ventricular (LV) myocardial mechanics predictors of LV outflow tract obstruction (LVOTO) in patients with hypertrophic cardiomyopathy (HCM).

METHODS

Thirty-nine adults with HCM and 21 controls underwent cardiovascular magnetic resonance. The feature tracking (FT) analysis results of HCM patients with and without LVOTO and controls were compared.

RESULTS

Global radial strain measured on the short-axis slice (GRS-SAX) (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.02-1.15; P < 0.01), global longitudinal strain measured on the long-axis slice (GLS-LAX) (OR, 1.81; 95% CI, 1.21-2.73; P < 0.01) and GRS measured on the long-axis slice (GRS-LAX) (OR, 1.07; 95% CI, 1.01-1.13; P = 0.02) were independent predictors of LVOTO. The combination of GRS-SAX plus GLS-LAX and GRS-LAX showed great discriminatory power for identifying LVOTO with an area under the receiver operating characteristic curve value of 0.91 (95% CI: 0.81-1.00).

CONCLUSIONS

In adult HCM patients, GRS-SAX, GLS-LAX, and GRS-LAX were independent predictors of LVOTO. The combination of GRS-SAX plus GLS-LAX and GRS-LAX showed great discriminatory power for identifying LVOTO.

Defining the Reference Range for Left Ventricular Strain in Healthy Patients by Cardiac MRI Measurement Techniques: Systematic Review and Meta-Analysis

BACKGROUND. Echocardiography is the primary noninvasive technique for left ventricular (LV) strain measurement. MRI has potential advantages, although reference ranges and thresholds to differentiate normal from abnormal left ventricular global longitudinal strain (LVGLS), left ventricular global circumferential strain (LVGCS), and left ventricular global radial strain (LVGRS) are not yet established. OBJECTIVE. The purpose of our study was to determine the mean and lower limit of normal (LLN) of MRI-derived LV strain measurements in healthy patients and explore factors potentially influencing these measurements. EVIDENCE ACQUISITION. PubMed, Embase, and Cochrane Library databases were searched for studies published through January 1, 2020, that reported MRI-derived LV strain measurements in at least 30 healthy individuals. Mean and LLN measurements of LV strain were pooled using random-effects models overall and for studies stratified by measurement method (feature tracking [FT] or tagging). Additional subgroup and meta-regression analyses were performed. EVIDENCE SYNTHESIS. Twenty-three studies with a total of 1782 healthy subjects were included. Pooled means and LLNs for all studies were -18.6% (95% CI, -19.5% to -17.6%) and -13.3% (-13.9% to 12.7%) for LVGLS, -21.0% (-22.4% to -19.6%) and -15.6% (-17.0% to -14.3%) for LVGCS, and 38.7% (30.5-46.9%) and 20.6% (15.1-26.1%) for LVGRS. Pooled means and LLNs for LVGLS by strain measurement method were -19.4% (95% CI, -20.6% to -18.1%) and -13.1% (-14.2% to -12.0%) for FT and -15.6% (-16.2% to -15.1%) and -13.1% (-14.1% to -12.2%) for tagging. A later year of study publication, increasing patient age, and increasing body mass index were associated with more negative mean LVGLS values. An increasing LV end-diastolic volume index was associated with less negative mean LVGLS values. No factor was associated with LLN of LVGLS. CONCLUSION. We determined the pooled means and LLNs, with associated 95% CIs, for LV strain by cardiac MRI to define thresholds for normal, abnormal, and borderline strain in healthy patients. The method of strain measurement by MRI affected the mean LVGLS. No factor affected the LLN of LVGLS. CLINICAL IMPACT. This meta-analysis lays a foundation for clinical adoption of MRI-derived LV strain measurements, with management implications in both healthy patients and patients with various disease states.

In vivo estimation of normal left ventricular stiffness and contractility based on routine cine MR acquisition

Post-myocardial infarction remodeling process is known to alter the mechanical properties of the heart. Biomechanical parameters, such as tissue stiffness and contractility, would be useful for clinicians to better assess the severity of the diseased heart. However, these parameters are difficult to obtain in the current clinical practice. In this paper, we estimated subject-specific in vivo myocardial stiffness and contractility from 21 healthy volunteers, based on left ventricle models constructed from data acquired from routine cardiac MR acquisition only. The subject-specific biomechanical parameters were quantified using an inverse finite-element modelling approach. The personalized models were evaluated against relevant clinical metrics extracted from the MR data, such as circumferential strain, wall thickness and fractional thickening. We obtained the ranges of healthy biomechanical indices of 1.60 ± 0.22 kPa for left ventricular stiffness and 95.13 ± 14.56 kPa for left ventricular contractility. These reference normal values can be used for future model-based investigation on the stiffness and contractility of ischemic myocardium.

Tissue-tracking in the assessment of late gadolinium enhancement in myocarditis and myocardial infarction

PURPOSE

To test the diagnostic performance of cardiovascular magnetic resonance (CMR) tissue-tracking (TT) to detect the presence of late gadolinium enhancement (LGE) in patients with a diagnosis of myocardial infarction (MI) or myocarditis (MYO), preserved left ventricular ejection fraction (LVEF) and no visual regional wall motion abnormalities (RWMA).

METHODS

We selected consecutive CMR studies of 50 MI, 50 MYO and 96 controls. Receiving operating characteristic (ROC) curve and net reclassification index (NRI) analyses were used to assess the predictive ability and the incremental diagnostic yield of 2D and 3D TT-derived strain parameters for the detection of LGE and to measure the best cut-off values of strain parameters.

RESULTS

Overall, cases showed significantly reduced 2D global longitudinal strain (2D-GLS) values compared with controls (-20.1 ± 3.1% vs -21.6 ± 2.7%; p = 0.0008). 2D-GLS was also significantly reduced in MYO patients compared with healthy controls (-19.7 ± 2.9% vs -21.9 ± 2.4%; p = 0.0001). 3D global radial strain (3D-GRS) was significantly reduced in MI patients compared with controls with risk factors (34.3 ± 11.8% vs 40.3 ± 12.5%, p = 0.024) Overall, 2D-GLS yielded good diagnostic accuracy for the detection of LGE in the MYO subgroup (AUROC 0.79; NRI (95% CI) = 0.6 (0.3, 1.02) p = 0.0004), with incremental predictive value beyond risk factors and LV function parameters (p for AUROC difference = 0.048). In the MI subgroup, 2D-GRS (AUROC 0.81; NRI (95% CI) = 0.56 (0.17, 0.95) p = 0.004), 3D-GRS (AUROC 0.82; NRI (95% CI) = 0.57 (0.17, 0.97) p = 0.006) and 3D global circumferential strain (3D-GCS) (AUROC 0.81; NRI (95% CI) = 0.62 (0.22, 1.01) p = 0.002) emerged as potential markers of disease. The best cut-off for 2D-GLS was -21.1%, for 2D- and 3D-GRS were 39.1% and 37.7%, respectively, and for 3D-GCS was -16.4%.

CONCLUSIONS

At CMR-tissue tracking analysis, 2D-GLS was a significant predictor of LGE in patients with myocarditis but preserved LVEF and no visual RWMA. Both 2D- and 3D-GRS and 2D-GCS yielded good diagnostic accuracy for LGE detection in patients with previous MI but preserved LVEF and no visual RWMA.

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.

Non-contrast enhanced diagnosis of acute myocarditis based on the 17-segment heart model using 2D-feature tracking magnetic resonance imaging

PURPOSE

The aim of this study was to investigate the diagnostic value of myocardial deformation analysis based on the 17-segment heart model using non-contrast enhanced (CE) 2D tissue feature tracking (2D-FT) technique.

MATERIAL AND METHODS

Seventy patients with suspected myocarditis underwent a cardiovascular magnetic resonance (CMR) examination at 1.5 Tesla. A contrast-agent-free part of this CMR protocol was additionally performed in forty healthy volunteers (HV). Besides standard CMR data sets, 2D-FT derived segmental and global longitudinal, radial, and circumferential deformation parameters were analyzed. The 2D-FT results were compared to the combined findings from CMR imaging and endomyocardial biopsy (EMB).

RESULTS

Patients were assigned to three groups depending on their ejection fraction (EF) (<40%, 40-55%, ≥55%). Compared to HV, impaired EF (<55%) was significantly correlated to reduced segmental and global strain and strain rate values. The circumferential deformation analysis was more sensitive to myocardial changes than longitudinal and radial analysis. The segmental strain/strain rate had an accuracy of 84.3%/70.0% for the diagnosis of an acute myocarditis, stated by EMB and CMR in 42 of 70 patients. In patients with preserved EF, acute myocarditis could be ruled out using only segmental strain analysis with a negative predictive value of 87.5%.

CONCLUSION

In patients with suspected myocarditis, the deformation analysis based on the 17-segment heart model provides valuable information about functional myocardial inhomogeneity. This quantitative approach could be used in addition to the clinical standard CMR protocol and represents a promising tool in the framework of a prospective automatized multiparametric CMR imaging analysis.

MRI in cardio-oncology: A review of cardiac complications in oncologic care

From detailed characterization of cardiac abnormalities to the assessment of cancer treatment-related cardiac dysfunction, cardiac MRI is playing a growing role in the evaluation of cardiac pathology in oncology patients. Current guidelines are now incorporating the use of MRI for the comprehensive multidisciplinary approach to cancer management, and innovative applications of MRI in research are expanding its potential to provide a powerful noninvasive tool in the arsenal against cancer. This review focuses on the application of cardiac MRI to diagnose and manage cardiovascular complications related to cancer and its treatment. Following an introduction to current cardiac MRI methods and principles, this review is divided into two sections: functional cardiovascular analysis and anatomical or tissue characterization related to cancer and cancer therapeutics. Level of Evidence: 5 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:1349-1366.

CMR feature tracking in cardiac asymptomatic systemic sclerosis: Clinical implications

Background

Impaired myocardial deformation has been sporadically described in cardiac asymptomatic systemic sclerosis (SSc). We aimed to study myocardial deformation indices in cardiac asymptomatic SSc patients using cardiac magnetic resonance feature tracking (CMR-FT) and correlate these findings to the phenotypic and autoimmune background.

Methods

Fifty-four cardiac asymptomatic SSc patients (44 females, 56±13 years), with normal routine cardiac assessment and CMR evaluation, including cine and late gadolinium enhancement (LGE) images, were included. SSc patients were compared to 21 sex- and age- matched healthy controls (17 females; 54±19 years). For CMR-FT analysis, a mid-ventricular slice for LV peak systolic radial and circumferential strain and a 4-chamber view for LV/RV peak systolic longitudinal strain were used.

Results

Twenty-four patients had diffuse cutaneous SSc and 30 limited cutaneous SSc. Thirteen patients had digital ulcers. Median disease duration was 3.6 years. LV ejection fraction was higher in SSc patients compared to controls (62±6% vs. 59±5%, p = 0.01). Four patients had no LGE examination; in the remaining patients LGE was absent in 74%, while 18% had RV insertion fibrosis and 8% evidence of subendocardial infarction. LV longitudinal strain differed in those with insertion fibrosis (-18.0%) and infarction (-16.7%) compared to no fibrosis (-20.3%, p = 0.04). Patients with SSc had lower RV longitudinal strain and strain rate compared to controls (p<0.001 and p = 0.01, respectively). All other strain and strain rate measurements were non-significant between patients and controls.

Conclusions

In cardiac asymptomatic SSc patients with normal routine functional indices, CMR-FT identifies subclinical presence of insertion fibrosis and/or myocardial infarction by impaired LV longitudinal strain. RV derived longitudinal indices were impaired in the patient group. CMR FT indices did not correlate to the patients’ phenotypic and autoimmune features.

Feature-tracking myocardial strain in healthy adults- a magnetic resonance study at 3.0 tesla

We analyzed feature-tracking derived circumferential and longitudinal strain in healthy volunteers who underwent cardiac magnetic resonance imaging (CMR) at 3.0 T. 88 healthy adults (44.6 ± 18.0 years old, 49% male), without prior cardiovascular disease, underwent CMR at 3.0 T including cine, and late gadolinium enhancement in subjects >45 years. LV functional analysis and feature-tracking strain analyses were carried out. Global strain had better reproducibility than segmental strain. There was a sex specific difference global longitudinal strain (mean ± SD, -18.48 ± 3.65% (male), -21.91 ± 3.01% (female), p < 0.001), but not global circumferential strain (mean ± SD, -25.41 ± 4.50% (male), -27.94 ± 3.48% (female), p = 0.643). There was no association of strain with ageing after accounting for sex for both global longitudinal and circumferential strain. Feature-tracking strain analysis is feasible at 3.0 T. Healthy female volunteers demonstrated higher magnitudes of global longitudinal strain when compared to male counterparts. Whilst global cine-strain has good reproducibility, segmental strain does not.

Left Ventricular Strain Is Abnormal in Preclinical and Overt Hypertrophic Cardiomyopathy: Cardiac MR Feature Tracking

Purpose To evaluate myocardial strain and circumferential transmural strain difference (cTSD; the difference between epicardial and endocardial circumferential strain) in a genotyped cohort with hypertrophic cardiomyopathy (HCM) and to explore correlations between cTSD and other anatomic and functional markers of disease status. Left ventricular (LV) dysfunction may indicate early disease in preclinical HCM (sarcomere mutation carriers without LV hypertrophy). Cardiac MRI feature tracking may be used to evaluate myocardial strain in carriers of HCM sarcomere mutation. Materials and Methods Participants with HCM and their family members participated in a prospective, multicenter, observational study (HCMNet). Genetic testing was performed in all participants. Study participants underwent cardiac MRI with temporal resolution at 40 msec or less. LV myocardial strain was analyzed by using feature-tracking software. Circumferential strain was measured at the epicardial and endocardial surfaces; their difference yielded the circumferential transmural strain difference (cTSD). Multivariable analysis to predict HCM status was performed by using multinomial logistic regression adjusting for age, sex, and LV parameters. Results Ninety-nine participants were evaluated (23 control participants, 34 participants with preclinical HCM [positive for sarcomere mutation and negative for LV hypertrophy], and 42 participants with overt HCM [positive for sarcomere mutation and negative for LV hypertrophy]). The average age was 25 years ± 11 and 44 participants (44%) were women. Maximal LV wall thickness was 9.5 mm ± 1.4, 9.8 mm ± 2.2, and 16.1 mm ± 5.3 in control participants, participants with preclinical HCM (P = .496 vs control participants), and participants with overt HCM (P < .001 vs control participants), respectively. cTSD for control participants, preclinical HCM, and overt HCM was 14% ± 4, 17% ± 4, and 22% ± 7, respectively (P < .01 for all comparisons). In multivariable models (controlling for septal thickness and log-transformed N-terminal brain-type natriuretic peptide), cTSD was predictive of preclinical and overt HCM disease status (P < .01). Conclusion Cardiac MRI feature tracking identifies myocardial dysfunction not only in participants with overt hypertrophic cardiomyopathy, but also in carriers of sarcomere mutation without left ventricular hypertrophy, suggesting that contractile abnormalities are present even when left ventricular wall thickness is normal. © RSNA, 2018 Online supplemental material is available for this article.

Decreased biventricular longitudinal strain in patients with systemic sclerosis is mainly caused by pulmonary hypertension and not by systemic sclerosis per se

Purpose

Patients with pulmonary arterial hypertension (PAH) due to systemic sclerosis (SSc) have high mortality. Left ventricular (LV) peak global longitudinal strain (GLS) is decreased in SSc. It is unknown whether low GLS is due to SSc or PAH. Therefore, our primary aim was to evaluate both LV and right ventricular free wall GLS (RVFW GLS) in SSc, with and without PAH, using cardiac magnetic resonance with feature tracking. Secondary aim was to relate GLS to invasive mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR).

Methods

Thirty‐eight patients with SSc, 19 patients with SSc‐PAH and 19 healthy controls for comparison, were included. Endocardial and epicardial borders were delineated in cine images (short‐axis stack and three long‐axis views) for volumetric and strain calculations.

Results

Systemic sclerosis‐PAH had lower LV and RVFW GLS than SSc (LV: P = 0·01, RV: P<0·001) and controls (LV: P = 0·02; RV: P<0·001), with no difference between SSc and controls. LV strain correlated with mPAP (R = 0·42, P = 0·03) and PVR (R = 0·52, P = 0·006). RVFW GLS correlated with mPAP (R = 0·68, P<0·001) and PVR (R = 0·59, P = 0·001). ROC curves for predicting PAH had AUC 0·73 for LV strain (P = 0·003) and 0·86 for RVFW GLS (P<0·001).

Conclusions

Lower GLS is mainly determined by increased pulmonary pressure and not by SSc per se. Low LV and RVFW GLS are indicative of increased mPAP and PVR, which opens for improved non‐invasive methods to select patients eligible for right heart catheterization and to monitor the effects of PAH therapy.

Predictors of segmental myocardial functional recovery in patients after an acute ST-Elevation myocardial infarction

Objective

We hypothesized that Displacement Encoding with Stimulated Echoes (DENSE) and feature-tracking derived circumferential strain would provide incremental prognostic value over the extent of infarction for recovery of segmental myocardial function.

Methods

Two hundred and sixty-one patients (mean age 59 years, 73% male) underwent MRI 2 days post-ST elevation myocardial infarction (STEMI) and 241 (92%) underwent repeat imaging 6 months later.

The MRI protocol included cine, 2D-cine DENSE, T2 mapping and late enhancement.

Wall motion scoring was assessed by 2-blinded observers and adjudicated by a third. (WMS: 1=normal, 2=hypokinetic, 3=akinetic, 4=dyskinetic). WMS improvement was defined as a decrease in WMS ≥ 1, and normalization where WMS = 1 on follow-up. Segmental circumferential strain was derived utilizing DENSE and feature-tracking.

A generalized linear mixed model with random effect of subject was constructed and used to account for repeated sampling when investigating predictors of segmental myocardial improvement or normalization

Results

At baseline and follow-up, 1416 segments had evaluable data for all parameters. Circumferential strain by DENSE (p < 0.001) and feature-tracking (p < 0.001), extent of oedema (p < 0.001), infarct size (p < 0.001), and microvascular obstruction (p < 0.001) were associates of both improvement and normalization of WMS. Circumferential strain provided incremental predictive value even after accounting for infarct size, extent of oedema and microvascular obstruction, for segmental improvement (DENSE: odds ratio, 95% confidence intervals: 1.08 per −1% peak strain, 1.05–1.12, p < 0.001, feature-tracking: odds ratio, 95% confidence intervals: 1.05 per −1% peak strain, 1.03–1.07, p < 0.001) and segmental normalization (DENSE: 1.08 per −1% peak strain, 1.04–1.12, p < 0.001, feature-tracking: 1.06 per −1% peak strain, 1.04–1.08, p < 0.001).

Conclusions

Circumferential strain provides incremental prognostic value over segmental infarct size in patients post STEMI for predicting segmental improvement or normalization by wall-motion scoring.

Normal Values of Myocardial Deformation Assessed by Cardiovascular Magnetic Resonance Feature Tracking in a Healthy Chinese Population: A Multicenter Study

Reference values on atrial and ventricular strain from cardiovascular magnetic resonance (CMR) are essential in identifying patients with impaired atrial and ventricular function. However, reference values have not been established for Chinese subjects. One hundred and fifty healthy volunteers (75 Males/75 Females; 18–82 years) were recruited. All underwent CMR scans with images acceptable for further strain analysis. Subjects were stratified by age: Group 1, 18–44 years; Group 2, 45–59 years; Group 3, ≥60 years. Feature tracking of CMR cine imaging was used to obtain left atrial global longitudinal (LA E_ll) and circumferential strains (LA E_cc) and respective systolic strain rates, left ventricular longitudinal (LV E_ll), circumferential (LV E_cc) and radial strains (LV E_rr) and their respective strain rates, and right ventricular longitudinal strain (RV E_ll) and strain rate. LA E_ll and LA E_cc were 32.8 ± 9.2% and 40.3 ± 13.4%, respectively, and RV E_ll was −29.3 ± 6.0%. LV E_ll, LV E_cc and LV E_rr were −22.4 ± 2.9%, −24.3 ± 3.1%, and 79.0 ± 19.4%, respectively. LV E_ll and LV E_cc were higher in females than males (P < 0.05). LA E_ll, LA E_cc, and LV E_cc decreased, while LV E_rr increased with age (P < 0.05). LV E_ll and RV E_ll were not shown to be associated with age. Normal ranges for atrial and ventricular strain and strain rates are provided using CMR feature tracking in Chinese subjects.

Longitudinal Deformation of the Right Ventricle in Hypoplastic Left Heart Syndrome: A Comparative Study of 2D-Feature Tracking Magnetic Resonance Imaging and 2D-Speckle Tracking Echocardiography

In hypoplastic left heart syndrome (HLHS), long-term outcome is closely related to right ventricular function. Echocardiography and magnetic resonance imaging (MRI) are routinely used for functional assessment. MRI 2D-tissue feature tracking (2D-FT) allows quantification of myocardial deformation but has not yet been applied to HLHS patients. We sought to investigate the feasibility of this technique and to compare the results to 2D-speckle tracking echocardiography (2D-STE). In routine MRI 2D anatomical four chamber view, cine images were recorded in 55 HLHS patients (median age 4.9 years [1.6, 17.0]). Regional and global peak systolic longitudinal strain (LS) and strain rate (LSR) were determined using 2D-FT software. Echocardiographic four chamber view was analyzed with 2D-STE. Visualization of all myocardial segments with MRI was excellent, regional, and global LS and LSR could be assessed in all data sets. In 2D-STE, 28% of apical segments could not be analyzed due to poor image quality. Agreement of 2D-FT MRI and 2D-STE was acceptable for global LS, but poor for global LSR. In MRI, regional LS was lower in the septal segments, while LSR was not different between the segments. GLS and GLSR correlated with ejection fraction (GLS: r = - 0.45 and r < 0.001, GLSR: r = - 0.34 and p = 0.01). With new post-processing options, the assessment of regional and global LS and LSR is feasible in routine MRI of HLHS patients. For LS, results were comparable with 2D-STE. The agreement was poor for LSR, which might relate to differences in temporal resolution between the two imaging modalities.

One-Year Follow-up Study Detects Myocardial Changes with Cardiovascular Magnetic Resonance Tagging in Active Rheumatoid Arthritis

RATIONALE AND OBJECTIVES

To evaluate the effects of 1 year of medical treatment on myocardial function in active rheumatoid arthritis (RA).

MATERIALS AND METHODS

Thirty-nine female patients with RA without any known cardiovascular disease underwent a cardiovascular magnetic resonance (CMR) examination before and after 1 year of antirheumatic treatment. The population comprised untreated active early RA (ERA) and chronic RA patients, who were grouped accordingly. The CMR protocol included volumetric determinations, late gadolinium enhancement imaging, myocardial tagging, and native T1 mapping. DAS28-CRP disease activity scores were calculated before and after the treatment.

RESULTS

Results are reported as median (quartile 1-quartile 3). Time to peak diastolic filling rate improved in ERA (495 [443-561] ms vs 441 [340-518] ms, P = .018). Peak diastolic mean mid short-axis circumferential strain rate of all six segments was improved (82 [74-91] %/s vs 91 [77-100] %/s, P = .05), particularly in the anterior segment (82 [63-98] %/s vs 86 [77-109] %/s, P = .013). DAS28-CRP decreased in ERA (3.8 [3.2-4.1] vs 1.6 [1.4-2.2], P < .001). In chronic RA, no statistically significant improvement was detected.

CONCLUSIONS

Early treatment of active RA is important, as myocardial function detected with CMR tagging improved in ERA in parallel with decreasing inflammatory activity.

MRI-Derived Myocardial Strain Measures in Normal Subjects

OBJECTIVES

The aim of this study was to perform a systematic review and meta-analysis to estimate the normal ranges of magnetic resonance imaging (MRI)-based feature tracking (FT) and to identify sources of variations. Similar analyses were also performed for strain encoding, displacement encoding with stimulated echoes, and myocardial tagging.

BACKGROUND

MRI-FT is a novel technique for quantification of myocardial deformation using MRI cine images. However, the reported 95% confidence intervals (CIs) from the 2 largest studies have no overlaps.

METHODS

Four databases (EMBASE, SCOPUS, PUBMED, and Web of Science) were systematically searched for MRI strains of the left (LV) and right (RV) ventricles. The key terms for MRI-FT were "tissue tracking," "feature tracking," "cardiac magnetic resonance," "cardiac MRI," "CMR," and "strain." A random effects model was used to pool LV global longitudinal strain (GLS), global circumferential strain (GCS), global radial strain (GRS), and RVGLS. Meta-regressions were used to identify the sources of variations.

RESULTS

659 healthy subjects were included from 18 papers for MRI-FT. Pooled mean of LVGLS was -20.1% (95% CI: -20.9% to -19.3%), LVGCS -23% (95% CI: -24.3% to -21.7%), LVGRS 34.1% (95% CI: 28.5% to 39.7%), and RVGLS -21.8% (95% CI: -23.3% to -20.2%). Although there were no publication biases except for LVGCS, significant heterogeneities were found. Meta-regression showed that variation of LVGCS was associated with field strength (β = 3.2; p = 0.041). Variations of LVGLS, LVGRS, and RVGLS were not associated with any of age, sex, software, field strength, sequence, LV ejection fraction, or LV size. LVGCS seems the most robust in MRI-FT. Among the MRI-derived strain techniques, the normal ranges were mostly concordant in LVGLS and LVGCS but varied substantially in LVGRS and RVGLS.

CONCLUSIONS

The pooled means of 4 MRI-derived myocardial strain methods in normal subjects are demonstrated. Differences in field strength were attributed to variations of LVGCS.

A Novel Method for Estimating Myocardial Strain: Assessment of Deformation Tracking Against Reference Magnetic Resonance Methods in Healthy Volunteers

We developed a novel method for tracking myocardial deformation using cardiac magnetic resonance (CMR) cine imaging. We hypothesised that circumferential strain using deformation-tracking has comparable diagnostic performance to a validated method (Displacement Encoding with Stimulated Echoes- DENSE) and potentially diagnostically superior to an established cine-strain method (feature-tracking). 81 healthy adults (44.6 ± 17.7 years old, 47% male), without any history of cardiovascular disease, underwent CMR at 1.5 T including cine, DENSE, and late gadolinium enhancement in subjects >45 years. Acquisitions were divided into 6 segments, and global and segmental peak circumferential strain were derived and analysed by age and sex. Peak circumferential strain differed between the 3 groups (DENSE: −19.4 ± 4.8%; deformation-tracking: −16.8 ± 2.4%; feature-tracking: −28.7 ± 4.8%) (ANOVA with Tukey post-hoc, F-value 279.93, p < 0.01). DENSE and deformation-tracking had better reproducibility than feature-tracking. Intra-class correlation co-efficient was >0.90. Larger magnitudes of strain were detected in women using deformation-tracking and DENSE, but not feature-tracking. Compared with a reference method (DENSE), deformation-tracking using cine imaging has similar diagnostic performance for circumferential strain assessment in healthy individuals. Deformation-tracking could potentially obviate the need for bespoke strain sequences, reducing scanning time and is more reproducible than feature-tracking.