Which cardiac pathologies can lead to increased native T1 and ECV values?
A whole lot, among them, myocardial infarction, myocarditis, amyloidosis, Tako-tsubo cardiomyopathy and every clinical entity which can lead to fibrosis.
Which cardiac pathologies can lead to increased T2 values?
Increased T2 reflects myocardial oedema and is typically seen in acute myocardial injury including inflammatory changes as in myocarditis, Tako-tsubo cardiomyopathy or transplant rejection, but also in acute myocardial infarction or reperfusion injury.
What criteria need to be fulfilled for the diagnosis of myocarditis?
According to the updated version of the Lake Louise criteria (2018), a cardiac MRI scan provides strong evidence for myocardial inflammation if at least one T2-based criterion for myocardial oedema and one T1-based criterion for associated non-ischaemic myocardial injury is positive. There are also two supportive criteria, being pericarditis and systolic left-ventricular dysfunction.
Focal myocardial oedema can be seen in the lateral and inferior segments from basal to apical (blue arrowheads).
Myocardial oedema can be also assessed by calculating the T2 signal intensity ratio between myocardium and skeletal muscle within the same image.
Increased native T1 in the basal, midventricular and apical lateral and inferior segments is measured and displayed on a colour-map T1 >1150 ms, z-score of >5 (based on local data).
The T1 values in the septum are within normal limits of the local reference range.
Increased T2 values are measured in the basal, midventricular and apical lateral and inferior wall as another proof of myocardial oedema in those segments.
The T2 values in the septum are within normal limits of the local reference range.
Patchy intramyocardial and focal subepicardial late gadolinium enhancement can be seen on IR-GE images (red arrowheads) which is a characteristic pattern in myocarditis and reflects myocardial injury or myocardial necrosis but is neither very sensitive nor specific if used exclusively 2.