[The diagnostic value of quantitative imaging for acute myocardial infarction].

Objective: To explore the diagnostic performance of cardiac magnetic resonance imaging (CMR) with T1 mapping and T2 mapping for detection of acute phase of ischemic cardiomyopathy.

Methods: Twenty-four patients with acute myocardial infarction (AMI) detected by coronary angiography from May 2020 to April 2021 in Tianjin First Center Hospital were selected. All patients underwent CMR (Philips Ingenia 3.0-T) at (9±4) days after definite diagnosis, which was defined as the first diagnosis. After 3 months and 6 months of chronic myocardial infarction (CMI) phase, one CMR was performed. On the same period with age and sex matching, a total of 26 cases of healthy volunteers and outpatient with non-specific chest pain and CMR examination without abnormality as control group. Plain scan included Cine, T2-weighted (STIR), and native T1/T2 mapping. The enhanced scan included perfusion, late gadolinium enhancement, post-T1 mapping. The changes of myocardial quantitative parameters before and after myocardial infarction were compared. Receiver operator characteristic curves (ROC curve) were developed to evaluate, compare, and distinguish the changes in the AMI group and the CMI group after 6 months.

Results: Pre-enhanced T1 value, T2 value and extracellular volume (ECV) of AMI group were significantly higher than those of control group [pre-enhanced T1 value (ms): 1 438.7±173.4 vs. 1 269.2±42.3, pre-enhanced T2 value (ms): 49.8±9.3 vs. 21.7±4.0 , ECV (%): 33.2±10.2 vs. 27.2±2.1, all P < 0.05]. ECV was significantly higher in AMI (%: 33.2±10.2 vs. 27.2±2.1), but stabilized after 3 months (%: 33.2±10.2 vs. 32.4±5.1), and after 6 months later (%: 27.7±4.9 vs. 32.4±5.1), there were no significant difference (all P > 0.05). Pre-enhanced T1 and T2 values were significantly higher in AMI, lower after 3 months, but significantly decreased after 6 months [pre-enhanced T1 values (ms): 1 438.7±173.4 vs. 1 272.1±25.2, pre-enhanced T2 values (ms): 49.8±9.3 vs. 29.0±4.0, all P < 0.05]. The ROC curve showed that the specificity of pre-enhanced T1 and T2 values between AMI and CMI were 100%, and the sensitivity were 72.7%, 100%, respectively, pre-enhanced T1 and T2 value could be better distinguish between AMI and CMI diagnosis method.

Conclusions: T1 mapping and T2 mapping with ECV can clearly diagnosis ischemic cardiomyopathy, especially pre-enhanced myocardial T1 and T2 values which is non-invasive diagnosis method of AMI, and can distinguish AMI or CMI, has a great significance to the patient's clinical treatment and follow-up.