Cardiac Magnetic Resonance Tissue Characterization in Ischemic Cardiomyopathy

Abstract

Ischemic cardiomyopathy (ICM) is one of the most common causes of congestive heart failure. In patients with ICM, tissue characterization with cardiac magnetic resonance imaging (CMR) allows for evaluation of myocardial abnormalities in acute and chronic settings. Myocardial edema, microvascular obstruction (MVO), intracardiac thrombus, intramyocardial hemorrhage, and late gadolinium enhancement of the myocardium are easily depicted using standard CMR sequences. In the acute setting, tissue characterization is mainly focused on assessment of ventricular thrombus and MVO, which are associated with poor prognosis. Conversely, in chronic ICM, it is important to depict late gadolinium enhancement and myocardial ischemia using stress perfusion sequences. Overall, with CMR's ability to accurately characterize myocardial tissue in acute and chronic ICM, it represents a valuable diagnostic and prognostic imaging method for treatment planning. In particular, tissue characterization abnormalities in the acute setting can provide information regarding the patients that may develop major adverse cardiac event and show the presence of ventricular thrombus; in the chronic setting, evaluation of viable myocardium can be fundamental for planning myocardial revascularization. In this review, the main findings on tissue characterization are illustrated in acute and chronic settings using qualitative and quantitative tissue characterization.

Revascularization of chronic total occlusion coronary artery and cardiac regeneration

“…Even if excellent collateral circulation develops, symptomatic patients with a CTO usually have a persistent ischemic zone, evidenced by lower fractional flow reserve of the myocardium supplied by a CTO ( 24 ). Cardiac magnetic resonance (CMR) can be used to identify inducible myocardial ischemia and viability in the perfusion territory of the artery with CTO; thus, it is believed that CMR is helpful for selecting patients likely to benefit from revascularization ( 25 ). In a prospective study of 50 consecutive CTO patients undergoing CMR, Bucciarelli-Ducci et al reported that CTO recanalization reduces ischemic burden, favors reverse remodeling, and improves quality of life for patients, showing CMR evidence of significant myocardial inducible perfusion defects and viability ( 26 ).…”

Multimodality imaging in acute myocarditis

“…60,61 In order to overcome these limitations, mapping sequences have been developed allowing a more quantitative approach. 51…”

“…In particular, there is less influence on image of surface coil, slow intracardiac flow and presence of inflammatory systemic disease. 51 F I G U R E 1 A case of 85-year-old female patient showing acute myocarditis (AM). Trans-thoracic echocardiographic imaging revealed a moderate left ventricular systolic disfunction due to global hypokinesis, more marked in the middle part of anterior and anterolateral wall (arrow A and B), and a mild pericardial effusion in parasternal short axis view (asterisks, A) and apical four chamber view (asterisks, B).…”

“…64 Changes of ECV can be an expression of different pathologies such as amyloid deposits, fibrosis, edema, or iron overload. 64,65 Native T1 mapping can be acquired without administration of contrast agent and can provide information regarding myocyte and ECV. 64 The acquisition of native T1 mapping requires the sampling of T1 relaxations of fat and water protons followed by an inversion preparation pulse, saturation pulse, or combining them.…”

“…73 Presence of hyperintense myocardium on LGE sequences does not reflect myocardial fibrosis while it could be attributable to decreased wash out of gadolinium in the damaged myocardium. 51,74,75 LGE sequences are acquired around 10-15 min after the administration of contrast agent using T1-weighted gradient echo acquisition with application of inversion recovery. 76 In the presence of damaged myocardium the nulled, normal myocardium will be dark, the blood pool will be slightly bright while the damaged myocardium will be bright.…”