Cardiovascular Magnetic Resonance: Characterization of Myocardial Involvement

One of the primary diagnostic tools for cardiac amyloidosis (CA) is cardiac magnetic resonance (CMR). Increased wall thickness in all heart chambers, thickening of the interatrial septum and cardiac valves, and occasionally pleural and pericardial effusion are the characteristic morphological anomalies. The typical pattern after contrast injection is represented by diffuse areas of late gadolinium enhancement (LGE), which can be focal and patchy in very early stages, circumferential and subendocardial in intermediate stages or even diffuse transmural in more advanced stages (subendocardial-to-transmural gradient). Moreover, LGE typically spreads from the basal to the apical segments (base-apex gradient). More recently, quantification of extracellular volume by T1 mapping, which tracks the severity of amyloid accumulation in extracellular spaces, has acquired an important role for diagnosis, risk stratification, and therapeutic monitoring of CA. Similarly, T2 mapping has been shown to track myocardial oedema and disease activity. On the other hand, CMR needs to be complemented with other clinical and imaging parameters, particularly for the diagnosis of very early stages and for the differential diagnosis between AL and ATTR forms.