The Application Of 3D Free-breathing T2 Mapping In Patients With Acute Coronary Syndrome

Part Ⅰ: T2 mapping: quantification of myocardial edema in acute myocardial infarction and relationship with serum creatine kinasePurpose: Myocardial edema was shown to influence prognosis in acute myocardial infarction(AMI).T2-mapping has been proposed,as a quantitative method of edema.The aim of our study was to find the feasibility of T2 mapping quantificating myocardial edema,and to explore the relationship with serum creatine kinase(CK).Materials and methods:In 30 AMI patients after reperfusion therapy,we performed T2-mapping using a saturation-prepared,T2-prepared radiofrequency-spoiled gradient echo(SPGR)and late gadolinium enhancement(LGE)sequence at 3.0 T MRI.The feasibility of quantitative T2 mapping to detect myocardial edema and the correlation between the result obtained from T2 mapping and serum creatine kinase were then assessed.Result:T2 value on the T2 maps was significantly higher in the infarcted myocardium(59.18 ± 4.23 ms)than in the remote myocardium(43.35 ± 2.11 ms)(p<0.05).Furthermore,T2 value in the area with microvascular obstruction(MVO)(38.68±2.53 ms)was significantly lower in the infarct tissue outside the area of MVO(59.09±3.95 ms)(P<0.001).Overall,there was excellent correlation between myocardial edema size and serum CK(r = 0.82,P < 0.001),but there was no correlation between T2 value for edematous myocardium with serum CK(r=0.475,P=0.054).Conlusion: Quantitative T2 mapping can be used for assessment of myocardial edema in AMI.Maybe it’s more useful to assess edema size after acute myocardial infarction.Part Ⅱ:Quantitative Free-breathing High Resolution T2 Mapping in The Distinction of Salvaged and Infarcted Myocardium within the Ischemic Area-at-risk: Validation and Comparison with T2 STIR images.Objective: To determine the diagnostic performance of free-breathing high resolution T2-mapping in the distinction of salvaged and infarcted myocardium within the ischemic area-at-risk compared with T2 STIR images.Materials and Methods: Thirty-two patients with established reperfused acute myocardial infarction and 10 healthy volunteers were performed CMR at 3.0T,Late gadolinium enhancement images were used to define the infarcted myocardium.T2 STIR images signal intensities(T2 STIR-SI)and T2 values were measured in the corresponding areas.Results: The T2 STIR-SI and T2 value of the salvaged myocardium was higher than that of remote(67.42±12.73 vs.62.09±12.42;55.35±11.80 vs.46.02±9.07 P<0.01).The T2 STIR-SI and T2 value of the infarcted myocardium was also higher than that of remote(68.66±14.69 vs.62.09±12.42;64.39±13.87 vs.46.02±9.07 P<0.01).There were no significant differences between mean T2 STIR-SI in infarcted myocardium and salvaged myocardium.The T2 value of the salvaged myocardium was lower than of infarcted myocardium(55.35±11.80 vs.64.39±13.87 ms,P<0.01).The T2 mapping had higher AUC than T2 STIR-SI.Adopting a threshold value of 59.68 ms,T2 mapping resulted in 89.2% sensitivity,76.3% specificity in the identification of salvaged and infarcted myocardium within the ischemic area-at-risk.Within the infarct zone,areas of microvascular obstruction were characterized by a lower T2 value(39.4±3ms)compared with areas with no microvascular obstruction(59.45±3.5ms,p<0.01).Conclusion: Free-breathing high resolution T2 mapping can be a reliable sequence in quantifying salvaged and infarcted myocardium within the ischemic area-at-risk compared with T2 STIR images.