Diagnostic and prognostic role of late gadolinium enhancement in cardiomyopathies

Abstract

Late gadolinium enhancement (LGE) is the most relevant tool of cardiac magnetic resonance for tissue characterization, and it plays a pivotal role for diagnostic and prognostic assessment of cardiomyopathies. The pattern of presentation of LGE allows differential diagnosis between ischaemic and non-ischaemic heart disease with high diagnostic accuracy, and among different cardiomyopathies, specific presentation of LGE may help to make a diagnosis. Late gadolinium enhancement may be caused by conditions that significantly increase the interstitial space or, less frequently, that slow down Gd exit, like myocardial fibrosis. In chronic myocardial infarction, hypertrophic cardiomyopathies (HCM), dilated cardiomyopathy, Fabry disease, and other conditions, LGE is a marker of myocardial fibrosis, but also in patients with acute myocarditis where LGE may be also explained by the increase of interstitial space caused by interstitial oedema or by tissue infiltration of inflammatory cells. In cardiac amyloidosis, LGE represents myocardial fibrosis but the interstitial overload of amyloid proteins should also be considered as a potential cause of LGE. The identification of the pattern of presentation of LGE is also very important. In the ischaemic pattern, LGE always involves the subendocardial layer with more or less transmural extent, it is confluent, and every single scar should be located in the territory of one coronary artery. In the non-ischaemic pattern, LGE does not fulfil the previous criteria, being midwall, subepicardial, or mixed, not necessarily confluent or confined to a territory of one coronary artery. For cardiomyopathies, the exact pattern of non-ischaemic LGE is important. Quantitative analysis of LGE is required in some specific conditions as in HCM. Magnetic resonance imaging with LGE technique should be performed in every patient with suspect of cardiomyopathy. The lack of standardization of pulse sequence and mostly of quantification methods is the main limitation of LGE technique.

Keywords: Cardiac magnetic resonance; Cardiomyopathy; Late gadolinium enhancement; Prognosis.

Figure 1

Mechanism of late gadolinium enhancement (LGE). A small concentration of Gadolinium-based (Gd) contrast agent in normal interstitium and the exit kinetic is effective producing a fast wash out. In case di LGE, interstitial space may be moderately or severely increased and exit kinetic preserved or impaired, producing a slower wash out of Gd.

Figure 2

Examples of pattern of LGE in hypertrophic cardiomyopathy (HCM): the pattern of LGE follows the distribution of hypertrophy: in the left panel, hypertrophy is asymmetrical septal and LGE is in the septal midwall; in the middle panel a concentric hypertrophy and diffuse midwall LGE is found; in the right panel, an example of apical HCM with LGE is shown.

Figure 3

LGE in a patient with dilated cardiomyopathy. LGE is seen in midwall of anterior and inferior basal septum.