Deep Learning for Discrimination of Hypertrophic Cardiomyopathy and Hypertensive Heart Disease on MRI Native T1 Maps.

BACKGROUND: Native T1 and radiomics were used for hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD) differentiation previously. The current problem is that global native T1 remains modest discrimination performance and radiomics requires feature extraction beforehand. Deep learning (DL) is a promising technique in differential diagnosis. However, its feasibility for discriminating HCM and HHD has not been investigated. PURPOSE: To examine the feasibility of DL in differentiating HCM and HHD based on T1 images and compare its diagnostic performance with other methods. STUDY TYPE: Retrospective. POPULATION: 128 HCM patients (men, 75; age, 50 years ± 16) and 59 HHD patients (men, 40; age, 45 years ± 17). FIELD STRENGTH/SEQUENCE: 3.0T; Balanced steady-state free precession, phase-sensitive inversion recovery (PSIR) and multislice native T1 mapping. ASSESSMENT: Compare HCM and HHD patients baseline data. Myocardial T1 values were extracted from native T1 images. Radiomics was implemented through feature extraction and Extra Trees Classifier. The DL network is ResNet32. Different input including myocardial ring (DL-myo), myocardial ring bounding box (DL-box) and the surrounding tissue without myocardial ring (DL-nomyo) were tested. We evaluate diagnostic performance through AUC of ROC curve. STATISTICAL TESTS: Accuracy, sensitivity, specificity, ROC, and AUC were calculated. Independent t test, Mann-Whitney U-test and Chi-square test were adopted for HCM and HHD comparison. P < 0.05 was considered statistically significant. RESULTS: DL-myo, DL-box, and DL-nomyo models showed an AUC (95% confidential interval) of 0.830 (0.702-0.959), 0.766 (0.617-0.915), 0.795 (0.654-0.936) in the testing set. AUC of native T1 and radiomics were 0.545 (0.352-0.738) and 0.800 (0.655-0.944) in the testing set. DATA CONCLUSION: The DL method based on T1 mapping seems capable of discriminating HCM and HHD. Considering diagnostic performance, the DL network outperformed the native T1 method. Compared with radiomics, DL won an advantage for its high specificity and automated working mode. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 2.

3D Fractal Dimension Analysis: Prognostic Value of Right Ventricular Trabecular Complexity in Participants with Arrhythmogenic Cardiomyopathy.

BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is characterized by progressive myocardial fibro-fatty infiltration accompanied by trabecular disarray. Traditionally, two-dimensional (2D) instead of 3D fractal dimension (FD) analysis has been used to evaluate trabecular disarray. However, the prognostic value of trabecular disorder assessed by 3D FD measurement remains unclear. PURPOSE: To investigate the prognostic value of right ventricular trabecular complexity in ACM patients using 3D FD analysis based on cardiac MR cine images. STUDY TYPE: Retrospective. POPULATION: 85 ACM patients (mean age: 45 ± 17 years, 52 male). FIELD STRENGTH/SEQUENCE: 3.0T/cine imaging, T2-short tau inversion recovery (T2-STIR), and late gadolinium enhancement (LGE). ASSESSMENT: Using cine images, RV (right ventricular) volumetric and functional parameters were obtained. RV trabecular complexity was measured with 3D fractal analysis by box-counting method to calculate 3D-FD. Cox and logistic regression models were established to evaluate the prognostic value of 3D-FD for major adverse cardiac events (MACE). STATISTICAL TESTS: Cox regression and logistic regression to explore the prognostic value of 3D-FD. C-index, time-dependent receiver operating characteristic (ROC) curves and area under the ROC curve (AUC) to evaluate the incremental value of 3D-FD. Intraclass correlation coefficient for interobserver variability. P < 0.05 indicated statistical significance. RESULTS: 26 MACE were recorded during the 60 month follow-up (interquartile range: 48-67 months). RV 3D-FD significantly differed between ACM patients with MACE (2.67, interquartile range: 2.51 ~ 2.81) and without (2.52, interquartile range: 2.40 ~ 2.67) and was a significant independent risk factor for MACE (hazard ratio, 1.02; 95% confidence interval: 1.01, 1.04). In addition, prognostic model fitness was significantly improved after adding 3D-FD to RV global longitudinal strain, LV involvement, and 5-year risk score separately. DATA CONCLUSION: The myocardial trabecular complexity assessed through 3D FD analysis was found associated with MACE and provided incremental prognostic value beyond conventional ACM risk factors. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 1.

MR Uniformity Ratio Estimates to Evaluate Ventricular Mechanical Dyssynchrony and Prognosis After ST-Segment Elevation Myocardial Infarction.

BACKGROUND: The impact of left ventricular mechanical dyssynchrony (LVMD) on the long-term prognosis of ST-segment elevation myocardial infarction (STEMI) is unclear. HYPOTHESIS: MR uniformity ratio estimates (URE) can detect LVMD and assess STEMI prognosis. STUDY TYPE: Retrospective analysis of a prospective multicenter registry (EARLY-MYO trial, NCT03768453). POPULATION: Overall, 450 patients (50 females) with first-time STEMI were analyzed, as well as 40 participants without cardiovascular disease as controls. FIELD STRENGTH/SEQUENCE: 3.0-T, balanced steady-state free precession cine and late gadolinium enhancement imaging. ASSESSMENT: MRI data were acquired within 1 week of symptom onset. Major adverse cardiovascular events (MACEs), including cardiovascular death, nonfatal re-infarction, hospitalization for heart failure, and stroke, were the primary clinical outcomes. LVMD was represented by circumferential URE (CURE) and radial URE (RURE) calculated using strain measurements. The patients were grouped according to clinical outcomes or URE values. Patients' clinical characteristics and MR indicators were compared. STATISTICAL TESTS: The Student's t-test, Mann-Whitney U test, chi-square test, Fisher's exact test, receiver operating characteristic curve analysis with area under the curve, Kaplan-Meier analysis, Cox regression, logistic regression, intraclass correlation coefficient, c-index, and integrated discrimination improvement were used. P < 0.05 was considered statistically significant. RESULTS: CURE and RURE were significantly lower in patients with STEMI than in controls. The median follow-up was 60.5 months. Patients with both lower CURE and RURE values experienced a significantly higher incidence of MACEs by 3.525-fold. Both CURE and RURE were independent risk factors for MACEs. The addition of UREs improved diagnostic efficacy and risk stratification based on infarct size and left ventricular ejection fraction (LVEF). The indicators associated with LVMD included male sex, serum biomarkers (peak creatine phosphokinase and cardiac troponin I), infarct size, and LVEF. DATA CONCLUSION: CURE and RURE may be useful to evaluate long-term prognosis after STEMI. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 2.

Prognostic value of right ventricular trabecular complexity in patients with arrhythmogenic cardiomyopathy.

OBJECTIVES: The present study aimed to investigate the incremental prognostic value of the right ventricular fractal dimension (FD), a novel marker of myocardial trabecular complexity by cardiac magnetic resonance (CMR) in patients with arrhythmogenic cardiomyopathy (ACM). METHODS: Consecutive patients with ACM undergoing CMR were followed up for major cardiac events, including sudden cardiac death, aborted cardiac arrest, and appropriate implantable cardioverter defibrillator intervention. Prognosis prediction was compared by Cox regression analysis. We established a multivariable model supplemented with RV FD and evaluated its discrimination by Harrell's C-statistic. We compared the category-free, continuous net reclassification improvement (cNRI) and integrated discrimination index (IDI) before and after the addition of FD. RESULTS: A total of 105 patients were prospectively included from three centers and followed up for a median of 60 (48, 66) months; experienced 36 major cardiac events were recorded. Trabecular FD displayed a strong unadjusted association with major cardiac events (p < 0.05). In the multivariable Cox regression analysis, RV maximal apical FD maintained an independent association with major cardiac events (hazard ratio, 1.31 (1.11-1.55), p < 0.002). The Hosmer-Lemeshow goodness of fit test displayed good fit (X2 = 0.68, p = 0.99). Diagnostic performance was significantly improved after the addition of RV maximal apical FD to the multivariable baseline model, and the continuous net reclassification improvement increased 21% (p = 0.001), and the integrated discrimination index improved 16% (p = 0.045). CONCLUSIONS: In patients with ACM, CMR-assessed myocardial trabecular complexity was independently correlated with adverse cardiovascular events and provided incremental prognostic value. CLINICAL RELEVANCE STATEMENT: The application of FD values for assessing RV myocardial trabeculae may become an accessible and promising parameter in monitoring and early diagnosis of risk factors for adverse cardiovascular events in patients with ACM. KEY POINTS: • Ventricular trabecular morphology, a novel quantitative marker by CMR, has been explored for the first time to determine the severity of ACM. • Patients with higher maximal apical fractal dimension of RV displayed significantly higher cumulative incidence of major cardiac events. • RV maximal apical FD was independently associated with major cardiac events and provided incremental prognostic value in patients with ACM.

Prognostic value of left ventricular trabeculae fractal analysis in patients with dilated cardiomyopathy.

BACKGROUND: The prognostic value of left ventricular (LV) myocardial trabecular complexity on cardiovascular magnetic resonance (CMR) in dilated cardiomyopathy (DCM) remains unknown. This study aimed to evaluate the prognostic value of LV myocardial trabecular complexity using fractal analysis in patients with DCM. METHODS: Consecutive patients with DCM who underwent CMR between March 2017 and November 2021 at two hospitals were prospectively enrolled. The primary endpoints were defined as the combination of all-cause death and heart failure hospitalization. The events of cardiac death alone were defined as the secondary endpoints.LV trabeculae complexity was quantified by measuring the fractal dimension (FD) of the endocardial border based on fractal geometry on CMR. Cox proportional hazards regression and Kaplan-Meier survival analysis were used to examine the association between variables and outcomes. The incremental prognostic value of FD was assessed in nested models. RESULTS: A total of 403 patients with DCM (49.31 ± 14.68 years, 69% male) were recruited. After a median follow-up of 43 months (interquartile range, 28-55 months), 87 and 24 patients reached the primary and secondary endpoints, respectively. Age, heart rate, New York Heart Association functional class >II, N-terminal pro-B-type natriuretic peptide, LV ejection fraction, LV end-diastolic volume index, LV end-systolic volume index, LV mass index, presence of late gadolinium enhancement, global FD, LV mean apical FD, and LV maximal apical FD were univariably associated with the outcomes (all P < 0.05). After multivariate adjustment, LV maximal apical FD remained a significant independent predictor of outcome [hazard ratio = 1.179 (1.116, 1.246), P < 0.001]. The addition of LV maximal apical FD in the nested models added incremental prognostic value to other common clinical and imaging risk factors (all <0.001; C-statistic: 0.84-0.88, P < 0.001). CONCLUSION: LV maximal apical FD was an independent predictor of the adverse clinical outcomes in patients with DCM and provided incremental prognostic value over conventional clinical and imaging risk factors.

Myocardial extracellular volume quantified by cardiac magnetic resonance predicts left ventricular aneurysm following acute myocardial infarction.

OBJECTIVE: This study aimed to investigate the correlation between increased extracellular matrix estimated by cardiac magnetic resonance (CMR) and left ventricular aneurysm after acute myocardial infarction. METHODS: A total of 175 patients from 3 centers with an isolated left anterior descending culprit vessel underwent CMR examinations within 1 week and at a 6-month follow-up. Of these, 92 were identified to have left ventricular aneurysms (LVAs): 74 with functional aneurysm and 18 with anatomical aneurysm. The predictive significance of acute extracellular volume (ECV), left gadolinium enhancement (LGE), and other characteristics were analyzed using binary logistic regression analysis. RESULTS: Patients with LVA were more likely to present with left ventricular adverse remodeling (LVAR) than those without (p = 0.009). With optimal cutoff values of 30.90% for LGE and 33% for ECV to discriminate LVA from non-LVA, the area under the curve (AUC) by receiver operator characteristic curve (ROC) analysis was 0.92 (95% CI: 0.87-0.96; p < 0.001) and 0.93 (95% CI: 0.88-0.96; p < 0.001), respectively. ECV was significantly better than LGE at discriminating between functional and anatomical LVA (p < 0.001). Both acute LGE and ECV were predictors of LVA, with an odds ratio of 1.35 (95% CI: 1.21-1.52, p < 0.001) and 1.23 (95% CI: 1.13-1.33, p < 0.001), respectively, by multivariable logistic regression analysis. CONCLUSIONS: Acute LGE and ECV of the myocardium provided predictive significance for LVA. The discriminative significance of ECV for functional versus anatomical LVA was better than the discriminative significance of LGE. KEY POINTS: • Patients with LVA were more likely to present with LVAR. • Acute LGE and ECV of the myocardium provided the strongest predictive significance for LVA. • The discriminative significance of ECV for functional versus anatomical LVA was better than that of LGE.

A deep learning method for the automated assessment of paradoxical pulsation after myocardial infarction using multicenter cardiac MRI data.

OBJECTIVE: The current study aimed to explore a deep convolutional neural network (DCNN) model that integrates multidimensional CMR data to accurately identify LV paradoxical pulsation after reperfusion by primary percutaneous coronary intervention with isolated anterior infarction. METHODS: A total of 401 participants (311 patients and 90 age-matched volunteers) were recruited for this prospective study. The two-dimensional UNet segmentation model of the LV and classification model for identifying paradoxical pulsation were established using the DCNN model. Features of 2- and 3-chamber images were extracted with 2-dimensional (2D) and 3D ResNets with masks generated by a segmentation model. Next, the accuracy of the segmentation model was evaluated using the Dice score and classification model by receiver operating characteristic (ROC) curve and confusion matrix. The areas under the ROC curve (AUCs) of the physicians in training and DCNN models were compared using the DeLong method. RESULTS: The DCNN model showed that the AUCs for the detection of paradoxical pulsation were 0.97, 0.91, and 0.83 in the training, internal, and external testing cohorts, respectively (p < 0.001). The 2.5-dimensional model established using the end-systolic and end-diastolic images combined with 2-chamber and 3-chamber images was more efficient than the 3D model. The discrimination performance of the DCNN model was better than that of physicians in training (p < 0.05). CONCLUSIONS: Compared to the model trained by 2-chamber or 3-chamber images alone or 3D multiview, our 2.5D multiview model can combine the information of 2-chamber and 3-chamber more efficiently and obtain the highest diagnostic sensitivity. CLINICAL RELEVANCE STATEMENT: A deep convolutional neural network model that integrates 2-chamber and 3-chamber CMR images can identify LV paradoxical pulsation which correlates with LV thrombosis, heart failure, ventricular tachycardia after reperfusion by primary percutaneous coronary intervention with isolated anterior infarction. KEY POINTS: • The epicardial segmentation model was established using the 2D UNet based on end-diastole 2- and 3-chamber cine images. • The DCNN model proposed in this study had better performance for discriminating LV paradoxical pulsation accurately and objectively using CMR cine images after anterior AMI compared to the diagnosis of physicians in training. • The 2.5-dimensional multiview model combined the information of 2- and 3-chamber efficiently and obtained the highest diagnostic sensitivity.

Diagnostic Utility of the Simplified Perfusion Fraction for Identifying Myocardial Injury in Patients With Reperfused ST-segment Elevation Myocardial Infarction.

BACKGROUND: Acute myocardial infarction (AMI) is a disease with high morbidity and mortality worldwide and the evaluation of myocardial injury and perfusion status following myocardial ischemia and reperfusion is of clinical value. PURPOSE: To assess the diagnostic utility of simplified perfusion fraction (SPF) in differentiating salvage and infarcted myocardium and its predictive value for left ventricular remodeling in patients with reperfusion ST-segment elevation myocardial infarction (STEMI). STUDY TYPE: Prospective. POPULATION: Forty-one reperfused STEMI patients and 20 healthy volunteers. FIELD STRENGTH/SEQUENCE: 3.0T MRI. The MR examination included cine, T2 -short tau inversion recovery (T2 -STIR), first pass perfusiong (FPP)，phase sensitive inversion recovery (PSIR), and diffusion-weighted imaging (DWI). ASSESSMENT: SPF values among different myocardium regions (infarcted, salvaged, remote, and MVO) and stages of reperfused STEMI patients as well as normal controls were measured. The diagnostic utility of SPF values in differentiating salvaged and infarcted myocardium was assessed. STATISTICAL ANALYSIS: Independent t-test and the Mann-Whitney U-test. Logistic regression. RESULTS: SPF values in healthy controls were not significantly different than SPF values in the remote myocardium of patients (40.09 ± 1.47% vs. 40.28 ± 1.93%, P = 0.698). In reperfusion STEMI patients, SPF values were lower in infarcted myocardium compared to remote and salvaged myocardium (32.15 ± 2.36% vs. 40.28 ± 1.93%, P < 0.001; 32.15 ± 2.36% vs. 36.68 ± 2.71%, P < 0.001). SPF values of infarcted myocardium showed a rebound increase from acute to convalescent stages (32.15 ± 2.36% vs. 34.69 ± 3.69%, P < 0.001). When differentiating infarcted and salvaged myocardium, SPF values demonstrated an area under the curve (AUC) of 0.89 (sensitivity 85.4%, specificity 80.5%, cutoff 34.42%). Lower SPF values were associated with lower odds ratio (OR = 0.304) of left ventricular remodeling after adjusting for potential confounders with a confidence interval (CI) of 0.129-0.717, P = 0.007. DATA CONCLUSION: SPF might be able to differentiate salvaged and infarcted myocardium and is a strong predictor of left ventricular remodeling in reperfused STEMI patients. Level of Evidence 2 Technical Efficacy Stage 2.

Myocardial extracellular volume fraction radiomics analysis for differentiation of reversible versus irreversible myocardial damage and prediction of left ventricular adverse remodeling after ST-elevation myocardial infarction.

OBJECTIVES: Our study sought to explore the prognostic value of radiomic TA (texture analysis) on quantitative ECV (extracellular volume) fraction mapping to differentiate between reversible and irreversible myocardial damage and to predict left ventricular adverse remodeling in patients with reperfused STEMI (ST-elevation myocardial infarction). METHODS: This observational prospective cohort study identified 70 patients (62 ± 9 years, 62 men [85.70%]) with STEMI for TA who consecutively performed native and contrast T1 mapping. Texture features were extracted from each stack of ECV mapping based on ROI (region of interest) analysis. RESULTS: After texture feature selection and dimension reduction, five selected texture features were found to be statistically significant for differentiating the extent of myocardial injury. ROC (receiver operating characteristic) curve analysis for the differentiation of unsalvageable infarction and salvageable myocardium demonstrated a significantly higher AUC (area under the curve) (0.91 [95% CI, 0.86-0.96], p < 0.0001) for horizontal fraction than other texture features (p < 0.05). LVAR (left ventricular adverse remodeling) was predicted by those selected features. The differences in qualitative and quantitative baseline parameters and horizontal fractions were significant between the patients with and without LVAR. LGE (late gadolinium enhancement) and horizontal fraction features of infarcted myocardium in acute STEMI were the only two parameters selected in forming the optimal overall multivariable model for LVAR at 6 months. CONCLUSIONS: Radiomic analysis of ECV could discriminate reversible from irreversible myocardial injury after STEMI. LGE as well as radiomics TA (texture analysis) of ECV may provide an alternative to predict LVAR and functional recovery. KEY POINTS: • ECV quantification was able to differentiate between infarcted myocardium and non-infarcted myocardium. • Radiomics analysis of ECV could discriminate reversible from irreversible myocardial injury. • Radiomics TA analysis shows a promising similarity with LGE findings which could aid the prognosis of myocardial infarction patients.

RAD sequencing resolves the phylogeny, taxonomy and biogeography of Trichophoreae despite a recent rapid radiation (Cyperaceae).

Trichophoreae is a nearly cosmopolitan Cyperaceae tribe that contains ~17 species displaying striking variation in size, inflorescence complexity, and perianth morphology. Although morphologically distinct, the status of its three genera (Cypringlea, Oreobolopsis and Trichophorum) is controversial because recent phylogenetic studies have suggested they might not be reciprocally monophyletic. However, previous analyses have shown conflicting topologies and consistently poor support due to an initial rapid diversification of the tribe. We analysed restriction-site associated DNA sequencing (RADseq) data from nearly all species of the clade, combined with five Sanger-based markers (matK, ndhF, rps16, ETS-1f, ITS) sampled extensively within species. This approach allowed us to resolve deep and shallow relationships within Trichophoreae for the first time, despite an anomaly zone spanning several successive short branches that produced considerable gene tree incongruence. Analyses reveal a primary phylogenetic split of the tribe into two clades roughly corresponding to an East Asian-North American disjunction that dates back to the mid-Miocene, with both clades comprised of a mixture of reduced unispicate and larger taxa with highly compound inflorescences. Morphological characters traditionally used in the circumscription of Trichophoreae genera are shown to be homoplasious. Several of these characters correlate best with climatic conditions, with the most reduced species occurring in open habitats at high latitudes and altitudes. Close relatives with highly compound inflorescences are found in temperate or subtropical forest understories. Cypringlea and Oreobolopsis are deeply nested within Trichophorum, and we merge all three genera into a more broadly circumscribed Trichophorum. We also show that Scirpus filipes is another previously unrecognized East Asian species of Trichophorum with highly compound inflorescences.

Prognostic Value of Late Gadolinium Enhancement in Predicting Life-Threatening Arrhythmias in Heart Failure Patients With Implantable Cardioverter-Defibrillators: A Systematic Review and Meta-Analysis.

BACKGROUND: The presence of late gadolinium enhanced (LGE), which may enable better evaluation of myocardial impairment, would help predict the occurrence of life-threatening arrhythmias and major adverse cardiovascular events (MACE) in patients suffering from ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM) patients and who underwent a process of implantable cardioverter-defibrillator (ICD). PURPOSE: To evaluate the prognostic value of cardiac MR-LGE for ICM and NICM patients with ICD. STUDY TYPE: Systematic review and meta-analysis. POPULATION: A total of 33 studies of 3457 patients were included. FIELD STRENGTH: 1. 5T and 3.0T, LGE. ASSESSMENT: PubMed, Cochrane Library, EMBASE, and Web of Science were systematically searched for studies reporting LGE in ICM or NICM patients with ICD implantation with several kinds of endpoints: MACE, life-threatening arrhythmia, cardiovascular mortality, and all-cause mortality. STATISTICAL TESTS: A meta-analysis was performed using a random-effects model to calculate odds ratios or standard mean differences (SMDs) for binary and continuous data. RESULTS: MR-LGE was positive in 1923 (55.6%) of ICM and NICM patients. LGE-present patients were more likely to have life-threatening arrhythmia (odds ratio [OR]: 5.1; 95% confidence interval [CI]: 3.8-6.8), MACE (OR: 5.2; 95% CI: 3.8-6.9), cardiovascular mortality (OR: 2.4; 95% CI: 1.2-4.6), and all-cause mortality (OR: 2.1; 95% CI: 1.3-3.4) compared with those without LGE. Moreover, ICM and NICM patients with LGE both had increased life-threatening arrhythmia (OR: 4.6; 95% CI: 2.7-8.0; OR: 5.2; 95% CI: 3.6-7.8, respectively) and MACE (OR: 4.7; 95% CI: 2.8-7.9; OR: 4.7; 95% CI: 2.7-8.1, respectively). DATA CONCLUSION: The presence of MR-LGE may worsen the prognosis for adverse cardiovascular events in both ICM and NIMC patients who benefit more from ICDs. LEVEL OF EVIDENCE: 3 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2020;51:1422-1439.

Myocardial Extracellular Volume Fraction Allows Differentiation of Reversible Versus Irreversible Myocardial Damage and Prediction of Adverse Left Ventricular Remodeling of ST-Elevation Myocardial Infarction.

BACKGROUND: The relationship between dynamic changes of myocardial injury in ST-elevation myocardial infarction (STEMI) patients and long-term prognosis is still unclear. PURPOSE: To evaluate the extracellular volume fraction (ECV) in the differentiation of reversible from irreversible myocardial injury and the prediction value of left ventricular adverse remodeling in patients with STEMI after reperfusion. STUDY TYPE: Prospective. POPULATION: Twenty-four STEMI patients after reperfusion were included FIELD STRENGTH/SEQUENCE: 3.0 T, T1 mapping, ECV, T2 -STIR, and late gadolinium enhancement (LGE). ASSESSMENT: All the patients underwent cardiac MRI at four timepoints (days 1, 3, and 7, and at 6 months). The regions of interest (ROIs) were selected at the infarcted myocardium (with/without intramyocardial hemorrhage [IMH] and microvascular obstruction [MVO]). STATISTICAL TESTS: One-way analysis of variance and the Kruskal-Wallis test were used for the statistical analysis. RESULTS: Native T1 of MI (without MVO/IMH) gradually decreased after reperfusion (P < 0.05). The ECV of MI increased during the first 3 days and then slowly declined. Native T1 of MI with MVO/IMH was the lowest (1184 msec; 1108.5-1266), while ECV (78%; 65.5-87%) was the highest, P < 0.001. Native T1 and ECV of salvageable myocardium were higher than those of the remote myocardium but lower than those of the MI without MVO or IMH (P < 0.001). ROC analysis revealed an area under the curve (AUC) of ECV (0.85, P < 0.001) for differentiating infarcted and salvageable myocardium was higher than that of native T1 mapping (AUC: 0.63, P < 0.001) in the first week after STEMI (P < 0.0001). T1 and ECV differed significantly between patients with and without left ventricle adverse remodeling (P < 0.05). DATA CONCLUSION: Dynamic temporal changes in reversibly and irreversibly damaged myocardia were differentiated via native T1 and ECV mapping after primary percutaneous coronary intervention in STEMI patients. ECV may better reflect microvascular injury severity and myocardial viability. MI with higher native T1 and ECV or with severe microvascular injury (MVO and IMH) was correlated with adverse LV remodeling. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2020. J. Magn. Reson. Imaging 2020;52:476-487.

Histogram Analysis of Native T1 Mapping and Its Relationship to Left Ventricular Late Gadolinium Enhancement, Hypertrophy, and Segmental Myocardial Mechanics in Patients With Hypertrophic Cardiomyopathy.

BACKGROUND: The use of native T1 mapping for evaluation of hypertrophic cardiomyopathy (HCM) is being explored, and its combination with histogram analysis may benefit the accuracy of such assessments. PURPOSE: To investigate the relationship of segmental left ventricular wall thickness (LVWT), myocardial fibrosis, and strain parameters with segmental histogram parameters of native T1 mapping in HCM patients. STUDY TYPE: Retrospective. SUBJECTS: Ninety-three HCM patients without previous cardiovascular diseases were included. FIELD STRENGTH/SEQUENCE: 3.0T cardiac MR. Steady-state free precession cine imaging, modified Look-Locker inversion recovery, phase-sensitive inversion recovery. ASSESSMENT: Images were assessed by three experienced radiologists. STATISTICAL TESTS: Mann-Whitney U-tests, area under the curve (AUC), Spearman's rank correlation, intraclass correlation coefficient, and Bland-Altman test were used for statistical analysis. RESULTS: A higher LVWT value correlated with higher means, minimums, 10th /25th /50th /75th /90th percentiles, maximums, kurtosis, entropy, and lower SD and energy of T1 mapping (P < 0.05 for all), with the correlation being stronger for entropy and energy (Spearman's rho = 0.439 and -0.413, respectively) than other parameters. Late gadolinium enhancement positive (LGE+) segments exhibited higher mean, minimum, 10th /25th /50th /75th /90th percentiles, maximum, entropy, and lower energy of T1 times than late gadolinium enhancement negative (LGE-) segments (P < 0.001 for all). Impaired strain function parameters (peak thickening and thickening rate in radial, circumferential, and longitudinal directions) demonstrated a weak correlation with higher entropy (P < 0.001 for all) and lower energy (P < 0.001 for all). DATA CONCLUSION: Histogram parameters of native T1 mapping provide more information than mean T1 times alone. Among these parameters, entropy and energy may correlate better with LVWT, myocardial late gadolinium enhancement, and strain parameters than mean T1 times in HCM patients. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:668-677.

BOLD cardiac MRI for differentiating reversible and irreversible myocardial damage in ST segment elevation myocardial infarction.

OBJECTIVES: BOLD imaging is a quantitative MRI technique allowing the evaluation of the balance between supply/demand in myocardial oxygenation and myocardial haemorrhage. We sought to investigate the ability of BOLD imaging to differentiate reversible from irreversible myocardial injury as well as the chronological progression of myocardial oxygenation after reperfusion in patients with ST segment elevation myocardial infarction (STEMI). METHODS: Twenty-two patients (age, 60 ± 11 years; 77.3% male) with STEMI underwent cardiac MRIs on four occasions: on days 1, 3, 7 and 30 after reperfusion. BOLD MRI was obtained with a multi-echo turbo field echo (TFE) sequence on a 3-T scanner to assess myocardial oxygenation in MI. RESULTS: T2* value in MI with intramyocardial haemorrhage (IMH) was the lowest (9.77 ± 3.29 ms), while that of the salvaged zone was the highest (33.97 ± 3.42 ms). T2* values in salvaged myocardium demonstrated a unimodal temporal pattern from days 1 (37.91 ± 2.23 ms) to 30 (30.68 ± 1.59 ms). T2* values in the MI regions were significantly lower than those in remote myocardium, although the trends in both were constant overall. There was a slightly positive correlation between T2* in MI regions and EF (Rho = 0.27, p < 0.05) or SV (Rho = 0.22, p = 0.04) and a slightly negative correlation between T2* in salvaged myocardium and LVEDV (Rho = - 0.23, p < 0.05). CONCLUSIONS: BOLD MRI performed in post-STEMI patients allows accurate evaluation of myocardial damage severity and could differentiate reversible from irreversible myocardial injury. The increased T2* values may imply the pathophysiological mechanism of salvaged myocardium. BOLD MRI could represent a more accurate alternative to the other currently available options. KEY POINTS: • Myocardial oxygenation and haemorrhage after myocardial infarction affect BOLD MRI values • BOLD MRI could be used to differentiate irreversible from reversible myocardial damage • Changed oxygenation implies the pathophysiological mechanism of salvaged myocardium.

Diagnostic performance of intravoxel incoherent motion diffusion-weighted imaging in the assessment of the dynamic status of myocardial perfusion.

BACKGROUND: Acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide and places a significant financial burden on our society. PURPOSE: To determine the feasibility of cardiac intravoxel incoherent motion (IVIM) in the consecutive evaluation of myocardial perfusion in myocardial infarction patients postpercutaneous coronary intervention (PCI) and to investigate the dynamic biological phenomena in myocardial perfusion after AMI. STUDY TYPE: Prospective observational study. POPULATION: Twenty ST-segment elevation myocardial infarction (STEMI) patients after reperfusion therapy and 12 healthy volunteers served as controls. FIELD STRENGTH/SEQUENCE: Cardiac MRI at 3T, including steady-state free precession (SSFP) cine imaging, T2 -short time inversion recovery (T2 -STIR), late gadolinium enhancement (LGE), T2 mapping, and IVIM diffusion-weighted imaging (DWI) were performed. ASSESSMENT: Myocardial T2 value and IVIM-DWI-associated parameters (ADCfast , ADCslow , and f value) of the infarcted myocardium at different timepoints, remote myocardium, and normal myocardium were analyzed by two experienced radiologists. STATISTICAL TESTS: Independent sample's t-test, Pearson's, and Spearman's correlation and interobserver variability were applied. P ≤ 0.05 was considered significant. RESULTS: The T2 value in ischemic myocardium measured on day 3 (73.58 ± 4.37 msec) was greater than at any other timepoint (24 hours, day 7, day 30; 66.66 ± 4.71 msec, 68.36 ± 4.18 msec, 64.98 ± 5.39 msec, respectively, P < 0.001). ADCfast and f values were significantly lower in ischemic myocardium than in the remote myocardium as well. The f value in ischemic myocardium at day 3 (0.0989 ± 0.02) was lower than at any other timepoint (24 hours, 7 day, 30 day; 0.1203 ± 0.02, 0.1109 ± 0.02, 0.1213 ± 0.02, respectively, P < 0.001. DATA CONCLUSION: This preliminary study demonstrated that a dynamic process exists in the status of myocardial edema and myocardial perfusion in MI patients after PCI. The findings suggest myocardial perfusion would be best evaluated between day 3 and day 7. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1602-1609.

Myocardial fibrosis evaluated by diffusion-weighted imaging and its relationship to 3D contractile function in patients with hypertrophic cardiomyopathy.

BACKGROUND: Previous studies have shown that diffusion-weighted imaging (DWI) is sensitive to myocardial fibrosis in ischemic and nonischemic cardiomyopathy. PURPOSE: To explore the prognostic value of apparent diffusion coefficient (ADC) for detecting myocardial fibrosis and its relationship to the contractile function in hypertrophic cardiomyopathy (HCM). STUDY TYPE: Prospective. POPULATION: A total of 45 HCM patients and 20 controls. FIELD STRENGTH/SEQUENCE: 3.0T cardiac MRI. The cardiac MR sequences included cine, T1 mapping, and DWI. ASSESSMENT: According to the presence of late gadolinium enhancement (LGE) and the extracellular volume (ECV) values (+2 SD of control subjects), respectively, reader W and reader J assessed the value of ADC of each segment for detecting myocardial fibrosis and its relationship to impaired contractile function in HCM patients. STATISTICAL TESTS: Independent sample t-test, Pearson analysis, and intraclass correlation (ICC). RESULTS: The value of ECV was 23.6 ± 3.0% for control. ECV ≥ 29.6% and ECV < 29.6% groups were classified. ADC values in the ECV ≥ 29.6% group were significantly increased compared to the ECV < 29.6% group, (2.41 ± 0.23 µm2 /ms vs. 2.03 ± 0.16 µm2 /ms, P < 0.005). Compared to the LGE - group, ECV (32.1 ± 2.3% vs. 29.0 ± 2.8%, P < 0.005) and ADC (2.60 ± 0.18 µm2 /ms vs. 2.10 ± 0.07 µm2 /ms, P < 0.005) values were significantly increased in the LGE + group. ADC values were linearly associated with ECV values (R2 = 0.65) in HCM patients. ADC values were linearly associated with circumferential and longitudinal strain (R2 = 0.60, R2 = 0.46), as well as circumferential, longitudinal, and radial strain rate (R2 = 0.13, R2 = 0.25, R2 = 0.17, respectively). DATA CONCLUSION: Contractile dysfunction in HCM is predominantly associated with ADC, which is a feasible alternative to ECV and LGE for detecting myocardial fibrosis. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1139-1146.

Oxygenation-sensitive cardiovascular magnetic resonance in hypertensive heart disease with left ventricular myocardial hypertrophy and non-left ventricular myocardial hypertrophy: Insight from altered mechanics and cardiac BOLD imaging.

BACKGROUND: BOLD (blood oxygen level dependent) MRI can detect regional condition of myocardial oxygen supply and demand by means of paramagnetic properties. PURPOSE: Noninvasive assessment of myocardial oxygenation by BOLD MRI in hypertensive patients with hypertension (HTN) left ventricular myocardial hypertrophy (LVMH) and HTN non-LVMH and its correlation with myocardial mechanics were performed. STUDY TYPE: Prospective. POPULATION: Twenty patients with HTN LVMH, 21 patients with HTN non-LVMH, and 23 normotensive controls were enrolled. FIELD STRENGTH/SEQUENCE: Cine imaging, T2* and T1 mapping sequences were achieved at 3.0T. ASSESSMENT: Dedicated T1 mapping, T2*, and cine imaging analysis were performed by two radiologists using cvi42. STATISTICAL TESTS: One-way analysis of variance, Kruskal-Wallis test, Bland-Altman analysis, Pearson's correlation coefficient, Spearman's rank correlation. RESULTS: T2* values of HTN LVMH group were significantly lower versus the controls (23.78 ± 3.09 versus 30.77 ± 2.71; P < 0.001) and HTN non-LVMH group (23.78 ± 3.09 versus 28.64 ± 4.23; P < 0.001). Left ventricular peak circumferential strain were reduced in HTN LVMH patients compared with other two groups (-11.32 [-15.64, -10.3], -16.78 [-19.35, -15.34], and -19.73 [-20.57, -18.73]; P < 0.05); and longitudinal strain of HTN LVMH patients were lower than other two groups (-11.31 ± 2.91, -15.1 ± 3.06, and -18.85 ± 1.85; P < 0.05); radial strain of HTN LVMH patients were also lower than other two groups (25.03 ± 16, 40.95 ± 17.5 and 47.9 ± 10.23; P < 0.05). Extracellular volume correlated with peak circumferential, longitudinal, and radial strain (spearman rho = 0.6, 0.64, and -0.69; P < 0.05), respectively; T2* negatively correlated with peak circumferential and longitudinal strain (spearman rho = -0.43 and -0.49; P < 0.05), respectively. Patients with lower T2* values had significant decreases in myocardial mechanics (P < 0.05). DATA CONCLUSION: HTN LVMH patients have both impaired myocardial mechanics and decreased T2* values compared with HTN non-LVMH and normotensive groups. BOLD MRI could provide a feasible assessment modality for detecting altered T2* due to the change of de-oxygenated hemoglobin and hence to the change of signal intensity in oxygenation-sensitive images. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1297-1306.

Epicardial adipose tissue in obesity with heart failure with preserved ejection fraction: Cardiovascular magnetic resonance biomarker study.

BACKGROUND: Obesity has become a serious public health issue, significantly elevating the risk of various complications. It is a well-established contributor to Heart failure with preserved ejection fraction (HFpEF). Evaluating HFpEF in obesity is crucial. Epicardial adipose tissue (EAT) has emerged as a valuable tool for validating prognostic biomarkers and guiding treatment targets. Hence, assessing EAT is of paramount importance. Cardiovascular magnetic resonance (CMR) imaging is acknowledged as the gold standard for analyzing cardiac function and morphology. We hope to use CMR to assess EAT as a bioimaging marker to evaluate HFpEF in obese patients. AIM: To assess the diagnostic utility of CMR for evaluating heart failure with preserved ejection fraction [HFpEF; left ventricular (LV) ejection fraction ≥ 50%] by measuring the epicardial adipose tissue (EAT) volumes and EAT mass in obese patients. METHODS: Sixty-two obese patients were divided into two groups for a case-control study based on whether or not they had heart failure with HFpEF. The two groups were defined as HFpEF+ and HFpEF-. LV geometry, global systolic function, EAT volumes and EAT mass of all subjects were obtained using cine magnetic resonance sequences. RESULTS: Forty-five patients of HFpEF- group and seventeen patients of HFpEF+ group were included. LV mass index (g/m2) of HFpEF+ group was higher than HFpEF- group (P < 0.05). In HFpEF+ group, EAT volumes, EAT volume index, EAT mass, EAT mass index and the ratio of EAT/[left atrial (LA) left-right (LR) diameter] were higher compared to HFpEF- group (P < 0.05). In multivariate analysis, Higher EAT/LA LR diameter ratio was associated with higher odds ratio of HFpEF. CONCLUSION: EAT/LA LR diameter ratio is highly associated with HFpEF in obese patients. It is plausible that there may be utility in CMR for assessing obese patients for HFpEF using EAT/LA LR diameter ratio as a diagnostic biomarker. Further prospective studies, are needed to validate these proof-of-concept findings.

Prognostic value of right atrial strains in arrhythmogenic right ventricular cardiomyopathy.

OBJECTIVES: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy characterized by progressive fibrofatty infiltration of atrial and ventricular myocardium resulting in adverse cardiac events. Atrial function has been increasingly recognized as prognostically important for cardiovascular disease. As the right atrial (RA) strain is a sensitive parameter to describe RA function, we aimed to analyze the prognostic value of the RA strain in ARVC. METHODS: RA strain parameters were derived from cardiac magnetic resonance (CMR) images of 105 participants with definite ARVC. The endpoint was defined as a combination of sudden cardiac death, survival cardiac arrest, and appropriate implantable cardioverter-defibrillator intervention. Cox regression and Kaplan-Meier survival analyses were performed to evaluate the association between RA strain parameters and endpoint. Concordance index (C index), net reclassification index (NRI), and integrated discrimination improvement (IDI) were calculated to assess the incremental value of RA strain in predicting the endpoint. RESULTS: After a median follow-up of 5 years, 36 (34.3%) reaching the endpoint displayed significantly reduced RA strain parameters. At Kaplan-Meier analysis, impaired RA reservoir (RARS) and booster strains (RABS) were associated with an increased risk of the endpoint. After adjusting for conventional risk factors, RARS (hazard ratio [HR], 0.956; p = 0.005) and RABS (HR, 0.906; p = 0.002) resulted as independent predictors for endpoint at Cox regression analyses. In addition, RARS and RABS improved prognostic value to clinical risk factors and CMR morphological and functional predictors (all p < 0.05). CONCLUSION: RARS and RABS were independent predictors for adverse cardiac events, which could provide incremental prognostic value for conventional predictors in ARVC. CRITICAL RELEVANCE STATEMENT: We evaluated the prognostic value of right atrial strain in ARVC patients and suggested cardiologists consider RA strain as a predictive parameter when evaluating the long-term outcome of ARVC patients in order to formulate better clinical therapy. KEY POINTS: • Patients with ARVC had significantly reduced RA strain and strain rates compared with healthy participants. • Participants with lower RA reservoir and booster stains were associated with a significantly higher risk of adverse cardiac events. • RA booster and reservoir strain provide incremental value to conventional parameters.