Characterization of infarcted myocardium by T1-mapping and its association with left ventricular remodeling

Recent Progress of Cardiac MRI for Nuclear Medicine Professionals

Recent technical innovation enables faster and more reliable cardiac magnetic resonance (CMR) imaging than before. Artificial intelligence is used in improving image resolution, fast scanning, and automated analysis of CMR. Fast CMR techniques such as compressed sensing technique enable fast cine, perfusion, and late gadolinium-enhanced imaging and improve patient throughput and widening CMR indications. CMR feature-tracking technique gives insight on diastolic function parameters of ventricles and atria with prognostic implications. Myocardial parametric mapping became to be included in the routine CMR protocol. CMR fingerprinting enables simultaneous quantification of myocardial T1 and T2. These parameters may give information on myocardial alteration in the preclinical stages in various myocardial diseases. Four-dimensional flow imaging shows hemodynamic characteristics in or through the cardiovascular structures visually and gives quantitative values of vortex, kinetic energy, and wall-shear stress. In conclusion, CMR is an essential modality in the diagnosis of various cardiovascular diseases, especially myocardial diseases. Recent progress in CMR techniques promotes more widespread use of CMR in clinical practice. This review summarizes recent updates in CMR technologies and clinical research.

NT-pro-BNP Level is Related to Left Ventricular Remodeling in Patients With Primary Aldosteronism

AIMS

To assess the relationship between the left ventricular remodeling parameters of cardiac magnetic resonance and NT-pro-BNP in patients with primary aldosteronism (PA).

METHODS

Seventy-four PA and 39 essential hypertension patients were prospectively recruited and underwent cardiac magnetic resonance. Plasma NT-pro-BNP was measured before patients underwent cardiac magnetic resonance. Left ventricular remodeling parameters were defined as left ventricular function parameters, T1 mapping parameters, and strain parameters. Differences in continuous variables between two groups were analyzed using Student's t-test or Mann-Whitney U test. Differences in categorical variables between two groups were analyzed by chi-squared test. Spearman's correlation and linear regression were used to analyze the relationships between left ventricular remodeling parameters and plasma NT-Pro-BNP level. P<0.05 was considered as statistically significant.

RESULTS

Patients with PA demonstrated higher NT-pro-BNP [86.0 (49.5, 145.5) vs. 45.0 (28.5, 73.5) pg/mL, P=0.001] and Native T1 (1227±41 vs. 1206±43 ms, P=0.015) level than essential hypertension patients. Compared to patients with normal NT-pro-BNP levels, those with abnormal levels demonstrated different left ventricular remodeling parameters. NT-pro-BNP level was independently related to native T1 (β=0.316, P=0.006), extracellular volume (β=0.419, P<0.001), short-axis global circumferential strain (β=0.429, P<0.001), four-chamber global longitudinal strain (β=0.332, P=0.002), and four-chamber global radial strain (β=-0.334, P=0.004) in patients after adjusting for baseline characteristics.

CONCLUSIONS

NT-pro-BNP level was related to left ventricular remodeling parameters derived from cardiac magnetic resonance in patients with PA. This result implies that clinicians should pay attention to NT-pro-BNP assessment in patients with PA in routine clinical assessment.

Recent Advances in Cardiac Magnetic Resonance for Imaging of Acute Myocardial Infarction

Acute myocardial infarction (AMI) is one of the primary causes of death worldwide, with a high incidence and mortality rate. Assessment of the infarcted and surviving myocardium, along with microvascular obstruction, is crucial for risk stratification, treatment, and prognosis in patients with AMI. Nonionizing radiation, excellent soft tissue contrast resolution, a large field of view, and multiplane imaging make cardiac magnetic resonance (CMR) a "one-stop" method for assessing cardiac structure, function, perfusion, and metabolism. Hence, this imaging technology is considered the "gold standard" for evaluating myocardial function and viability in AMI. This review critically compares the advantages and disadvantages of CMR with other cardiac imaging technologies, and relates the imaging findings to the underlying pathophysiological processes in AMI. A more thorough understanding of CMR technology will clarify their advanced clinical diagnosis and prognostic assessment applications, and assess the future approaches and challenges of CMR in the setting of AMI.

Predictive value of total ischaemic time and T1 mapping after emergency percutaneous coronary intervention in acute ST-segment elevation myocardial infarction

AIM

To investigate the predictive value of ischaemic time and cardiac magnetic resonance imaging (CMRI) T1 mapping in acute ST-segment elevation myocardial infarction (STEMI) patients undergoing primary percutaneous coronary intervention (PCI).

MATERIALS AND METHODS

A total of 127 patients with STEMI treated by primary PCI were studied. All patients underwent CMRI with native T1 and extracellular volume (ECV) measurement, 61 of whom also had 4-month follow-up data. The total ischaemic (symptom onset to balloon, S2B) time expressed in minutes was recorded. CMRI cine, T1 mapping, and late gadolinium enhancement (LGE) images were analysed to evaluate left ventricular (LV) function, T1 value, ECV, and myocardial infract (MI) scar characteristics, respectively. The correlation between S2B time and T1 mapping was evaluated. The predictive values of S2B time and T1 mapping for large final infarct size were estimated.

RESULTS

The incidence of microvascular obstruction (MVO) increased with the prolongation of ischaemia time. Regardless of MVO or not, ECV in myocardial infarction (ECVMI) was significantly correlated with S2B time (r=0.61, p<0.001), while native T1 in MI (T1MI) was not (r=-0.19, p=0.029). In the 4-month follow-up, native T1MI was improved (1385.1 ± 90.4 versus 1288.6 ± 74 ms, p<0.001). Furthermore, ECVMI was independently associated with final larger infarct size (AUC = 0.89, 95% confidence interval [CI] = 0.81-0.98, p<0.001) in multivariable regression analysis.

CONCLUSION

ECVMI was correlated with total ischaemic time and was an independent predictor of final larger infarct size.