What cardiac MRI protocol should be used to evaluate a thickened pericardium with associated effusion and assess for constrictive physiology?

Cardiac MRI Protocol for Thickened Pericardium with Effusion and Suspected Constriction

A comprehensive cardiac MRI protocol should include dark-blood T1-weighted fast spin-echo imaging, bright-blood cine steady-state free-precession (SSFP) sequences, T2-weighted STIR imaging for edema detection, and late gadolinium enhancement (LGE) imaging with intravenous gadolinium to assess for pericardial inflammation, thickening, and constrictive physiology. 1

Core Imaging Sequences

Morphologic Assessment

• Dark-blood T1-weighted fast spin-echo imaging to visualize pericardial anatomy and measure thickness (normal 1.2-1.7 mm; >4 mm considered abnormal) 1
• Bright-blood cine SSFP imaging serves as the reference sequence for cardiac volumes, ventricular function, and myocardial mass quantification 1
• The pericardium appears as a thin hypointense ("dark") curvilinear structure surrounded by hyperintense ("bright") mediastinal and epicardial fat on T1-weighted imaging 1

Tissue Characterization

• T2-weighted short-tau inversion-recovery (STIR) imaging to detect pericardial edema and active inflammation, which has 84% diagnostic accuracy for recurrent pericarditis 1, 2
• Late gadolinium enhancement (LGE) imaging following intravenous paramagnetic gadolinium chelates to identify pericardial inflammation, fibrosis, or fusion of pericardial layers 1
• LGE shows strong pericardial enhancement in acute inflammation and can distinguish between active inflammation and chronic fibrosis 1

Functional and Hemodynamic Assessment

• Real-time cine SSFP imaging to assess ventricular coupling by evaluating ventricular septal shape and motion changes over the respiratory cycle, which is critical for diagnosing constrictive physiology 1
• Phase contrast imaging to evaluate ventricular inflow and venous flow patterns 1
• Real-time sequences provide dynamic hemodynamic information indicative of constriction 3

Key Diagnostic Features for Constrictive Pericarditis

Morphologic Findings

• Thickened pericardial layers (though thickening may be mild to moderate) 1
• Abnormalities usually most pronounced at the base of the ventricles (RV>LV), atrioventricular grooves, and atria 1
• Compression of cardiac contents by rigid, deformed pericardium 1

Tissue Characterization Patterns

• Pericardial LGE enhancement suggests potentially reversible or transient forms of constrictive pericarditis with active inflammation 1, 4
• Absence of LGE may indicate chronic fibrotic constriction 4
• CMR can demonstrate fibrotic fusion of pericardial layers, an advantage over CT 1

Hemodynamic Consequences

• Inspiratory motion abnormalities on real-time cine CMR due to decreased pericardial compliance 1
• Ventricular septal bounce and abnormal ventricular coupling 1
• CMR provides superior information regarding hemodynamic consequences of the non-compliant pericardium on cardiac filling compared to CT 1

Clinical Advantages and Diagnostic Accuracy

CMR is probably the preferred imaging modality to optimally assess pericardial disease because it has shifted from purely morphologic imaging to comprehensive evaluation with tissue characterization capabilities 1

• CMR has 94% to 100% sensitivity in detecting pericardial inflammation 1
• Particularly important for diagnosing atypical presentations including minimally thickened pericardium or effusive-constrictive pericarditis 1
• A multiparametric CMR approach allows distinction between active inflammation, chronic pericarditis with constriction, and effusion without inflammation 4

Prognostic Value

• Presence of myocardial LGE is associated with adverse events in constrictive pericarditis 4
• Pericardial thickening on CMR predicts adverse events including recurrences, tamponade, and progression to constrictive pericarditis 2
• Pericardial LGE presence is associated with lower risk of complications, suggesting active inflammation that may respond to treatment 2

Common Pitfalls

• Pericardial enhancement or thickening can be seen in both acute inflammation and chronic pericardial fibrosis, requiring correlation with T2-weighted sequences to distinguish edema from fibrosis 1
• Normal pericardial thickness does not exclude constrictive pericarditis; CMR is particularly valuable for these atypical presentations 1
• Effusive-constrictive pericarditis can rapidly evolve to pure constrictive pericarditis, requiring follow-up imaging 5