| Part Ⅰ Image Quality Evaluation of Myocardium T1 Mapping by MOLLI Sequences under 3.0 TeslaObject:To evaluate image qualities of myocardium T1 mapping generated by MOLLI sequences in both normal controls and patients with cardiomyopathy under 3.0 Tesla MR Scanner.Methods and Materials:9 patients with dilated cardiomyopathy,6 patients with hypertrophic cardiomyopathy and 12 normal controls were enrolled in Beijing Hospital from Jan 2015 to Dec 2016,and all subjects were divided into 3 groups accordingly.All Subjects were underwent cardiac MR scan under Philips Achieva 3.0 T TX scanner.Scanning protocols included cine sequences,late Gd contrast enhancement,and MOLLI T1 mapping sequences with both pre and post contrast enhanced.According to the AHA criteria,4-chambers images were divided into 6 segments with short axial images divided into 16 segments(without segment 17,the apex).Using SPIN Lite software,qualities of T1 mapping images were evaluated,with quality grades from I to IV according to the severities of artifacts and the influences of accuracy in measuring T1 values.Image qualities among three groups were compared.Each segments in 4-chambers and short axial T1 mapping images were evaluated both pre and post Gd contrast enhanced.Images quality grades were counted and compared using Chi square tests.Gd contrast was also analyzed as an influence to image qualities.Results:(1)All 27 subjects,19 males and 8 females,were with averaged age of 45.1 ±14.3 years.Accordingly,216 T1 mapping images were generated with 108 images of native and post T1 each.4-chambers segments were 324,and short axial segments were 864.Therefore,1188 segments of images were evaluated.Among them,0 segment(0%)was assigned Grade Ⅰ;10 segments(0.8%)were assigned Grade Ⅱ;61 segments(5.1%)were assigned Grade Ⅲ;and 1117 segments(94.0%)were assigned Grade Ⅳ.Images with Grade Ⅳ took the highest proportion.(2)Images with Grade Ⅳ took the highest proportion among DCM,HCM and NC groups;the images qualities among three groups were not showing significant differences with all p values ≥0.287.(3)Qualities among segments in 4-chamber images were not showing significant differences(x2=15.809,p=0.797);Qualities among segments in short axial images were not showing significant differences(χ2=83.929,p=0.739).(4)Images in basal inferior lateral segment(Seg5)(χ2=3.977,p=0.046)and mid inferior segment(Seg10)(χ2=9.070,p=0.028)of left ventricle of short axial T1 mapping were found qualities improved after Gd contrast enhanced.Image grade propotions of middle anterior septal(Seg8),inferior septal(Seg9)and apical anterior(Seg13)segments did not change.Images qualities in other segments were found no significant difference before or after Gd contrast enhanced with all p values ≥0.365.Conclusion:Using MOLLI sequences under 3.0 Tesla could generate T1 mapping images with good and stable qualities.Image qualities were not influenced by cardiomyopathy to a certain extent.Image qualities of inferior and inferior lateral segments might get improved after Gd contrast enhanced.Part Ⅱ Preliminary Application of T1 Mapping Techniques in Measuring T1 Value and Calculating ECV in Healthy Volunteers under 3.0 TeslaObject:To explore the average values of left ventricular longitudinal relaxation time(T1)and extracellular volume fraction(ECV)of healthy volunteers under 3.0 Tesla MR.Method and Materials:12 healthy volunteers were enrolled for cardiac T1 mapping imaging from Jan 2015 to Dec 2016.All Subjects were underwent cardiac MR scan under Philips Achieva 3.0T TX scanner.Scanning protocols included cine sequences,late Gadolinium contrast enhancement,and T1 mapping sequences with both pre and post contrast enhanced.T1 mapping images were auto-generated with MOLLI sequences after scanning.ROI methods were utilized to analyze T1 mapping parameters.ROIs were divided into whole slice ROIs and segmental ROIs.According to the AHA criteria,4-chambers images were divided into 6 Segments with short axial images divided into 16 Segments(without segment 17,the apex).Defining ROIs and measuring T1 mapping parameters were all using SPIN Lite software.Native and post Tls could be measured on 4-chamber and short axial images according to segments.ECVs were calculated through measured native and post Tls.Comparisons of 4-chamber whole slice,short axial basal whole slice,short axial middle whole slice,short axial apical whole slice and segmental native T1,post T1 and ECV of left ventricles were carried out.T1 mapping parameters were analyzed according to genders with two sample t-tests.Correlations between T1 mapping parameters with ages were tested with Pearson’s analysis.Finally,native T1,post T1 and ECV of left ventricles were compared by coronary arteries supplying areas as LAD,LCX and RCA.Results:(1)12 healthy volunteers,9 males and 3 females,average age 36.5±11.1 years,BSA(1.78±0.20)m2,BMI(23.64±2.54)kg/m2,Hct 44.0%±3.7%;(2)Mean overall of left ventricle Native T1 was(1282.2±46.4)ms,Post T1 was(579.2±62.4)ms,and ECV was 0.24±0.02;Segmental Native T1s,Post T1s and ECVs were not all with similar in figures;Native Tls and ECVs of 4-chamber whole slice,short axial basal whole slice,short axial middle whole slice,short axial apical whole slice ROIs were higher than those of segmental ROIs.Post Tls of short axial basal whole slice,short axial middle whole slice,short axial apical whole slice ROIs were lower than those of segmental ROIs;Native Tls and ECVs of segments in apical slice were slightly higher than those of other segmental ROIs.Native Tls and ECVs compared with those of Segll were significant different.The differences of native T1 and ECV among segments of 4-chamber and short axial images were similar,while Post T1s were showing the opposite tendency.(3)Male left ventricular myocardiaum native Tls(1268.66±35.31)ms were lower than the female(1322.93±59.34)ms;Male left ventricular myocardiaum post T1s(598.36±53.26)ms were higher than the male(521.90±58.86)ms;Male left ventricular myocardiaum ECVs(0.24±0.01)were lower than the female(0.25±0.02).The gender differences were not significant(p>0.05).However,segmental differences existed,especially in short axial anterior segment and segment in middle whole slice.(4)Age was positive correlated with ECV of Segll;Except ECV of Segll,all other segmental parameters were showing no correlations with age.(5)Native Tls in coronary arteries supplying areas of healthy volunteers were found highest in LAD and lowest in LCX;Post Tls were found highest in LCX and lowest in RCA;ECVs in LAD were same with those in RCA,and lowest in LCX;However,parameters among these three blood supplying areas were not showing significant differences(p>0.05).Conclusions:(1)Average T1 mapping parameters of left ventricles in 12 healthy volunteers under 3.0 Tesla MR were as followed:Native T1(1282.2±46.4)ms,Post T1(579.2±62.4)ms,ECV(0.24±0.02);(2)T1s and ECVs were not the same according to different scanning slices,different segments and different methods of ROI defining;(3)T1 mapping parameters were not influenced with genders,ages and different coronary arteries supplying areas.Part III Preliminary Application of T1 Mapping Techniques in Evaluation of Myocardium Fibrosis in Patients with Dilated Cardiomyopathy and Hypertrophic Cardiomyopathy under 3.0 TeslaObject:To evaluate T1 values and extracellular volume fractions(ECV)of left ventricular myocardium in patients with dilated cardiomyopathy and hypertrophic cardiomyopathy through T1 mapping sequences.Method and Materials:12 normal controls,9 patients with dilated cardiomyopathy and 6 patients with hypertrophic cardiomyopathy were enrolled in Beijing Hospital from Jan 2015 to Dec 2016.All Subjects were underwent cardiac MR scan under Philips Achieva 3.0T TX scanner.Scanning protocols included cine sequences,late Gd contrast enhancement,and T1 mapping sequences with both pre and post contrast enhanced.With post-processing of cine short axial images,left ventricular function parameters were generated,including left ventricular ejection fraction(LVEF),left ventricular end diastolic volume(LVEDV),left ventricular end systolic volume(LVESV),stroke volume(SV),and left ventricular mass(LVM);Except LVEF,function parameters mentioned above were devided by body surface area(BSA)to generate LVEDI、LVESI、SVI、LVMI.BSAs were calculated through the formula of BSA=0.0061 X Height+0.0128 X Weight-0.1529.T1 mapping images were auto-generated with MOLLI sequences after scanning.ROI methods were utilized to analyze T1 mapping parameters.ROIs were divided into whole slice ROIs and segmental ROIs.According to the AHA criteria,4-chambers images were divided into 6 Segments with short axial images divided into 16 segments(without segment 17,the apex).Defining ROIs and measuring T1 mapping parameters were all using SPIN Lite software.Native and post Tls could be measured on 4-chamber and short axial images according to segments.ECVs were calculated through measured native and post Tls.ANOVA and Kruskal-Wallis test were carried out to compare the differences of CMR function parameters,native T1,post T1 and ECV among three subject groups.Parameters of whole slice ROIs and segmental ROIS were compared with paired-t tests.The correlations between CMR cardiac functional parameters and T1 mapping parameters were tested with Pearson’s analysis.AUC comparions of LVEDV/LVEDVI and T1 mapping parameters in predicting severe heart failure were analysed in ROCs.Results:(1)DCM subjects were found dilated left ventricle and decreased ventricular wall motions.Compared to HCM and NC subjects,left ventricular systolic function and stroke volume were found decreased with LVEFDCM(25.5%±9.8%)and SVIDCM(32.3±10.9)ml/m2.The differences of LVEF(F=54.561,p<0.0001)and SVI(F=3.436,p=0.049)were found significant.There was no significant difference in cardiac function between HCM and NC subjects.(2)Native Tls of three groups were as followed:DCM(1394.3±73.4)ms,HCM(1325.3±22.1)ms,and NC(1282.2±46.4)ms;Post T1s were as followed:DCM(549.3±42.4)ms,HCM(632.8±79.3)ms,and NC(579.2±62.4)ms;and ECVs were as followed:DCM(0.34±0.06),HCM(0.26±0.02),and NC(0.24±0.02).Native T1s(P=0.022)and ECVs(P<0.0001)of DCMs were higher than those of HCMs,while Post T1s(P=0.015)were lower.Native T1s(P<0.0001)and ECVs(P<0.0001)of DCMs were higher than those of NCs.Post Tls tended to be lower.However,the difference in Post T1 between DCMs and NCs was insignificant(P=0.274).Native T1s,Post Tls and ECVs were found lower in HCM than in NC.However,the difference between HCM and NC was showing no significance.(3)Native Tls of hypertrophic segments(1360.1 ±42.0)ms in HCM were higher than those of controlled segments(1319.0±53.5)ms,while the difference was not significant(p=0.170).(4)Native Tls measured through whole layer ROIs were higher than average segmental ROIs(P<0.01),and Post T1s were showing the opposite(P<0.05).(5)LVEF were negatively correlated with ECVm in DCM(r=-0.670,p=0.048).CMR cardiac functional parameters were show no significant differences between NativeTl,Post T1 and ECV.(6)AUCs of LVEDVI and ECV were larger among those of other parameters.AUCs of LVEDVI and ECV were larger than AUC of Post T1,and their differences were significant.AUC of combined T1 mapping parameters was larger than that of LVEDVI;however,the difference was not significant(p>0.05).Conclusion:(1)T1 mapping techniques could quantify fibrosis of myocardium.T1 mapping parameters of DCM and HCM in our research center under 3.0 Tesla of Philips Achieva MR scanner were acquireed.DCM:Native T1(1394.3±73.4)ms,Post T1(549.3±42.4)ms,ECV(0.34±0.06);HCM:Native T1(1325.3±22.1)ms,Post T1(632.8±79.3)ms,ECV(0.26±0.02).Elevation of native T1 and ECV in DCM could be used to detect and evaluate diffused fibrosis of myocardium.HCM with mild lesions might show no differences in Native T1 and ECV compared to those of NC.(2)T1 mapping was correlated with some parameters of CMR cardiac function such as LVEF;however,the correlations were not significant.(3)Different methods of defining ROIs would cause differences in T1 and ECV measurement and results.(4)The diagnostic efficiency of LVEDV/LVEDVI,Native T1 and ECV,and combined T1 mapping parameters in predicting severe heart failure were similar.Native T1 and ECV could be used to predict severe heart failure. |
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