A Preliminary Study Of Myocardial Quantitative Evaluation Using A Cardiac Magnetic Resonance T1 And T2 Mapping Techniques

ObjectionTo quantitatively evaluate the myocardium in the patients of myocardial infarction and healthy volunteers using a T1 mapping technique by modified Look-Locker FIESTA imaging with saturation recovery(MLLSR) and a T2 mapping technique by multi-echo fast spin-echo(MEFSE) :(1) to investigate the clinical feasibility and repeatability of these two techniques;(2) to investigate the diagnostic values of the T1 native, post-contrast T1, extracellular volume(ECV) and T2 values in the patients of myocardial infarction;(3) to evaluate the left ventricular myocardial T1 native and T2 values in different segments in healthy volunteers.Materials and Methods(1)With a 3.0T magnetic resonance imaging system, cardiovascular magnetic imaging(CMR) was performed in 8 patients of myocardial infarction to calculate the T1 native,post-contrast T1, ECV and T2 values in myocardial infarction and normal myocardium using T2 mapping, pre-contrast T1 mapping, post-contrast T1 mapping, combined with Cine, T2 WI, first-pass perfusion and late-gadolinium enhancement(LGE). Student’s t test,One-way ANOVA and ROC curve were used for statistical analysis.(2)Altogether 30 healthy volunteers were selected and scanned by CMR on the sequence of Cine imaging, T2 WI, T1 mapping and T2 mapping so as to perform quantitative measurement of ROI(Region of Interest) T1 native and T2 values. Then, the Student’s t test and ANOVA were deployed to analyze the difference of the T1 native and T2 values in 17 segments of myocardium, different coronary arterial blood supply areas, age and gender.Results(1)There were significant differences of the T1 native, post-contrast T1, ECV and T2 values between the myocardial infarction and the normal myocardium(t = 3.752、-2.910、5.029 and 4.137,P<0), the values were as follows: 754.8±273.8ms vs 561.4±152.8ms;438.8±73.6 ms vs 506.1±120.0ms;0.334±0.179 ms vs 0.158±0.116ms;81.9±15.7ms vs 65.1±10.0ms. The T1 native, ECV and T2 values in recent myocardial infarction were higher than those in subacute and chronic myocardial infarction(F=14.210,10.367 and12.342,P<0.001).(2)There were significant differences of the T1 native and T2 values between some different myocardial segments.(P < 0.01). Besides, mean myocardial T1native/T1 native of blood pool/mean myocardial T2 were :717.6 ± 100.6/1208.9 ± 224.2/71.6 ±7.1ms(base),773.9±101.2/1281.2±251.7/77.3±9.2ms(middle), 955.4±191.1/1829.6±584.8/83.0 ± 8.5ms(apex). Apical T1 native values of myocardium and blood pool were higher than the basal and the middle(P<0.01), and myocardial T2 values raised gradually from the basal to the apical(F= 14.245,P<0.01). Also, in different blood supply areas,myocardial T1 native values were different(F = 47.862,P <0.01) while myocardial T2 values were similar(F = 1.656,P = 0.192).The measurement of T1 native and T2 values had a good inter-observer agreement.ConclusionQuantitative MLLSR T1 mapping and MEFSE T2 mapping techniques are feasible and repeatable. They can be used to diagnose the myocardial infarction quantitatively and have good clinical application prospects. Myocardial T1 native and T2 reference values for the specific CMR setting are provided and they have regional variation.