Quantification Of Left Ventricular Myocardial Fibrosis And Deformation Using Cardiovascular Magnetic Resonance T1 Mapping And Feature Tracking Technique

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Assessment of left ventricular myocardial using cardiovascular magnetic resonance T1 mapping and feature tracking technique in healthy volunteersObjective: The aim of this study was to establish the normal reference value of left ventricular myocardial T1 time,extracellular volume(ECV)and strain using cardiovascular magnetic resonance(CMR)T1 mapping and feature tracking technique in healthy volunteers,and explore its influencing factors.Methods: A total of 60 healthy volunteers undergoing CMR were included in the present study.CMR T1 mapping was performed with the Modified Look-Locker Inversion recovery(MOLLI)sequence in three short-axis slices(apex,mid,and basic ventricular levels).ECV was calculated from pre-and post-contrast T1 times and hematocrit.Myocardial T1 times and ECV were measured by drawing region-of-interest(ROI)in each segment of left ventricular three short-axis slices according to the American Heart Association(AHA)16-segment model.Myocardial systolic strain,including left ventricular global longitudinal(GLS),circumferential(GCS)and radial strain(GRS),were quantified using CMR cine images by feature tracking analysis software.Results: The mean left ventricular global native T1 time,post-contrast T1 time and ECV of healthy volunteers were 1014.2 ± 26.4 ms,465.2 ± 27.3 ms and 24.9 ± 2.2 %,respectively.The mean global native T1 time and ECV in females were significantly higher than that in males(1027.1 ± 23.6 ms vs.1005.0 ± 24.6 ms,p = 0.001;26.5 ± 1.7% vs.23.7 ± 1.7%,p < 0.001,respectively),and the post-contrast T1 time in females was significantly lower than that in males(452.4 ± 27.3 ms vs.474.3 ± 23.6 ms,p = 0.002).The ECV value of left ventricular apical segment was significantly higher than that of basal and mid segments(26.1 ± 2.7% vs.24.4 ± 2.2% vs.24.5 ± 2.4%,p < 0.001,respectively).The native T1 time in septal segment was higher than that in lateral segment(1022.3±26.3 ms vs.1005.3±28.4 ms,p = 0.014).The native T1 time and ECV showed no significant associations with age(p > 0.05).The ECV was associated with left atrium volume index(LAVI)in females(r = 0.505,p = 0.010).The mean left ventricular GLS,GCS and GRS were-16.8 ± 2.2%,-19.0 ± 2.5% and 42.5 ± 9.9%,respectively.The mean GLS and GCS were significantly higher in females than that in males(-17.8 ± 2.4% vs.-16.0 ± 1.7%,p = 0.003;-20.2 ± 2.5% vs.-18.2 ± 2.2%,p = 0.002,respectively).There was no significant difference in GRS between males and females(40.6 ± 8.9% vs.45.1 ± 10.8%,p = 0.084).The GLS and GCS from mid to apical to basal segments decreased gradually,while the GRS from mid to basal to apical segments increased gradually(p < 0.05 for all).The GLS,GCS and GRS were significantly related to left ventricular ejection fraction(EF)(GLS: r = 0.346,p = 0.007;GCS: r = 0.344,p = 0.007;GRS: r = 0.474,p < 0.001,respectively).Conclusions: This study showed the normal reference value of left ventricular myocardial native T1 time,post-contrast T1 time,ECV and GLS,GCS and GRS in healthy volunteers.Gender and segmental differences of left ventricular myocardial T1 time,ECV and strain were observed.The myocardial ECV in females was related to LAVI.The left ventricular myocardial GLS,GCS and GRS correlated with EF in healthy volunteers.The left ventricular myocardial T1 time,ECV and strain were not associated with age in healthy volunteers.Part ? Association between myocardial extracellular volume and strain analysis through cardiovascular magnetic resonance with histological myocardial fibrosis in patients awaiting heart transplantationObjective: Cardiovascular magnetic resonance(CMR)-derived extracellular volume(ECV)and feature tracking strain analyses are proposed as non-invasive methods for quantifying myocardial fibrosis and deformation.This study has two aims:(1)to histologically validate myocardial ECV against the collagen volume fraction(CVF)measured from tissue samples of patients undergoing heart transplantation and(2)to detect the correlations between myocardial systolic strain and the myocardial ECV and histological CVF in patients undergoing heart transplantation.Methods: A total of 12 dilated cardiomyopathy(DCM)and 10 ischaemic cardiomyopathy(ICM)patients undergoing CMR T1 and T2 mapping and heart transplantation were included in the present study.T1 mapping was performed with the Modified Look Locker Inversion recovery(MOLLI)sequence including basal,mid and apical ventricular short-axis slices.ECV was calculated based on the pre-and post-contrast T1 times.T2 mapping was acquired in basal,mid and apical ventricular short-axis slices(identical to T1 mapping)before the contrast agent injection using a T2-prepared balanced steady state free precession(b SSFP)sequence.Myocardial systolic strain,including left ventricular global longitudinal(GLS),circumferential(GCS)and radial strain(GRS),were quantified using CMR cine images with feature tracking analysis software.Tissue samples were collected from each of 16 segments of the explanted hearts and were stained with picrosirius red for histological CVF quantification.Results: The mean histological CVF was 14.3 ± 4.6% and 17.0 ± 5.5% in the DCM and ICM patients,respectively.A strong relationship was observed between the global myocardial ECV and histological CVF in the DCM and ICM patients based on a per-patient analysis(r = 0.904,p < 0.001 and r = 0.901,p < 0.001,respectively).In the linear mixed-effects regression analysis,ECV correlated well with the histological CVF in the DCM and ICM patients on a per-segment basis(? = 0.838,p < 0.001 and ? = 0.915,p < 0.001,respectively).In the multivariate linear regression analysis,histological CVF was the strongest independent determinant of ECV in the patients awaiting heart transplantation(standardised ? = 0.860,p < 0.001).However,the T2 time,GLS,GCS and GRS showed no significant associations with ECV and CVF in the patients awaiting heart transplantation.Conclusions: ECV derived from CMR correlated well with histological CVF,indicating its potential as a non-invasive tool for the quantification of myocardial fibrosis.Additionally,impaired myocardial systolic strains were not associated with the ECV and CVF in the patients awaiting heart transplantation.Part ? Quantification of left ventricular myocardial fibrosis and deformation using cardiovascular magnetic resonance T1 mapping and feature tracking technique in hypertrophic cardiomyopathy patientsObjective: The aim of this study was to investigate the diagnostic performance of myocardial native T1 time,extracellular volume(ECV)and strain for differentiating hypertrophic cardiomyopathy(HCM)patients from healthy volunteers and explore the relationships among them.Methods: A total of 25 HCM patients and 28 healthy volunteers who underwent cardiovascular magnetic resonance(CMR)were enrolled in the present study.CMR T1 mapping was performed with the Modified Look-Locker Inversion recovery(MOLLI)sequence in three short-axis slices(apex,mid and basic ventricular levels).ECV was calculated from pre-and post-contrast T1 times and hematocrit.The myocardial T1 time and ECV were measured by drawing region-of-interest(ROI)in each segment of left ventricular three short-axis slices according to the American Heart Association(AHA)16-segment model.Myocardial systolic strain,including left ventricular global longitudinal(GLS),circumferential(GCS)and radial strain(GRS),were quantified using CMR cine images by feature tracking analysis software.The differences of T1 time,ECV value and myocardial systolic strain were compared between HCM patients and healthy volunteers,and their relationships were analyzed.Results: The mean left ventricular global native T1 time and ECV of HCM patients were significantly higher than that of control group(1047.3 ± 43.7 ms vs.1013.8 ± 26.9 ms,p = 0.001 and 28.2 ± 4.7% vs.24.0 ± 1.9%,p < 0.001,respectively).The mean GLS and GCS in HCM patients were significantly lower than that in control group(-13.6 ± 3.7% vs.-16.9 ± 1.9%,p < 0.001 and-16.3 ± 4.8% vs.-19.2 ± 2.7%,p = 0.011,respectively).No significant differences in post-contrast T1 value and GRS were observed between HCM patients and controls(p > 0.05).In the multivariate regression analysis,the sex and GRS were independent determines for ECV in HCM patients(standardized ? = 0.429,p = 0.012 and standardized ? =-0.471,p = 0.007,respectively).Compared with native T1 time and myocardial strain,ROC curve analysis indicated that ECV provided greatest distinction between HCM patients and controls(AUC = 0.846,p < 0.001).At the optimal cutoff value,ECV identified HCM patients with 80.0% sensitivity,85.7% specificity,83.3% positive predictive value(PPV),and 82.8% negative predictive value(NPV),respectively.Conclusions: The increased ECV in HCM patients reflected myocardial fibrosis.FT-CMR can be used as a noninvasive tool for the quantification of myocardial deformation.The decreased GLS and GCS in HCM patients with normal EF suggested that myocardial strain can detect systolic dysfunction earlier than EF.Gender and left ventricular GRS were related to myocardial fibrosis in HCM patients.Myocardial ECV provided good diagnostic performance for identifying HCM patients from healthy volunteers.