Cardiac MRI can be useful for evaluation of constrictive pericarditis, through a combination of anatomic and functional information. The functional component is critical because even though the classic threshold for thickened pericardium is >4 mm on CT and MRI, as many as 28% of cases with surgically proven constrictive pericarditis have a normal pericardial thickness (18% were normal on histologic examination).1
One of the main problems in constrictive pericarditis is the inability of the ventricles to expand in diastole (they are "constricted"). This can lead to the "septal bounce" seen on echocardiography and MRI. The grid sequence above can highlight the lack of a normal sliding movement of the pericardium, strongly suggesting constrictive pericarditis.2 Abnormal thickening of the pericardium, pericardial enhancement, and regions of confluence of the pericardium and myocardium (as seen on the above images) further suggest constrictive pericarditis.