Table 1.

Information provided by various CMR techniques applied in the evaluation of acute myocarditis, with main imaging features

CMR technique	Information provided	Imaging features
Cine-SSFP	Regional and global biventricular function, ventricular mass, and parietal wall thickness	- Normal or mildly dilated left or biventricular cavities
		- Ejection fraction depending on clinical presentation, usually mildly depressed (45–50 %)
		- Parietal wall thickness normal or slightly increased (>10 mm)
		- Pericardial effusion in 30–50 % of cases
T2w-STIR	Increased myocardial free water content	- Subepicardial or patchy areas of high signal intensity following LGE distribution
		- Global hyperintensity compared to skeletal muscle (T2 ratio > 1.9 according to LLc)
Pre- and post-Gd T1w FSE	Myocardial hyperemia and expansion of extracellular compartment	- Sequences frequently affected by severe artefacts
		- Myocardial hyper-enhancement compared to skeletal muscle (EGEr > 4 according to LLc)
Delayed enhancement	Myocardial necrosis, scars	- No enhancement
		- Focal subepicardial enhancement typically involving inferolateral LV wall
		- Patchy or longitudinal striae of mid-wall enhancement
Native T1 mapping	Pixel-by-pixel assessment of T1-rt revealing myocardial changes, first of all oedema	- T1-rt prolongation: proposed cut-off > 990 ms (59)
Pre- and post-Gd T1 mapping	ECV expansion due to enhanced diffusion of free water and cardiomyocyte apoptosis	- ECV increase: proposed cut-off ≥ 27 %; still few published data (34)
T2 mapping	Pixel-by-pixel assessment of T2-rt revealing myocardial oedema	- T2-rt prolongation; still few published data (64)

CMR cardiovascular magnetic resonance, SSFP steady-state free precession, T2w-STIR T2-weighted short-tau inversion recovery, FSE fast spin echo, Gd gadolinium, T1-rt T1 relaxation time, ECV extracellular volume, T2-rt T2 relaxation time, LGE late gadolinium enhancement, LLc Lake Louise criteria, EGEr early gadolinium enhancement ratio, LV left ventricle