Pericarditis MRI

Overview
On MRI, normal pericardium appears as a thin dark band that is bordered by a bright band on both sides on T1 weighted spin imaging. These surrounding bright bands are associated with the surrounding epicardial and pericardial fat. Following the administration of gadolinium, pericardium may appear thick and inflamed in the setting of pericarditis. Lower intensity signal is observed in constrictive pericarditis than in acute pericarditis.

The Appearance of the Normal Pericardium on Cardiac MRI
The low water content pericardium appears as a thin dark band that is bordered by a bright band on both sides on T1 weighted spin imaging. These surrounding bright bands are associated with the surrounding epicardial and pericardial fat. The thickness of the normal pericardium is 2 to 4 mm.

The Appearance of the Inflamed Pericardium on Cardiac MRI
Following the administration of gadolinium the pericardium is enhanced due to inflammation.

The Appearance of the Pericardium in Constrictive Pericarditis
Pericardial thickening on cardiac MRI has become the diagnostic modality of choice in the assessment of constrictive pericarditis with a sensitivity of 88%, specificity of 100%, and diagnostic accuracy of 93%. The pericardium is of a lower intensity signal in constrictive pericarditis than in acute pericarditis.

Other signs of pericardial constriction on cardiac MRI include the following:
 * Dilatation of the inferior vena cava, hepatic veins, and right atrium
 * A compressed and or elongated right ventricle

Cardiac MRI in Pericardial Effusion
A pericardial effusion is black on spin echo images and in contrast is bright on gradient echo images. Small to moderate sized pericardial effusion occupy the space anterior to the right ventricle and are usually 5 mm or greater. A large pericardial effusion is often circumferential.

Insight into the composition of the pericardial effusion can be gleaned based upon the following characteristics:
 * Transudates: low signal on T1-weighted images but high signal on T2-weighted and gradient echo images.
 * Exudates: Intermediate signal on both types of sequences.
 * Hemorrhagic effusions: Wide range of signal intensity on spin-echo sequences that is dependent upon the age of the effusion.

Cardiac MRI in Cardiac Tamponade
Cardiac tamponade is characterized by the diastolic collapse the right-sided chambers and sometimes the left-sided chambers on cine images.

Cardiac MRI in the Detection and Assessment of other Pericardial Pathologies
Cardiac MRI is useful in the detection and assessment of the following pathologic processes:


 * Pericardial cysts
 * Metastasis to the pericardium
 * Primary tumors of the pericardium
 * Intracardiac tumors such as myxomas, lipomas, and teratomas.
 * Pericardial calcification: Calcification is not well distinguished from pericardial thickening on CMR. Calcium appears black on CMR and may be difficult to distinguish from pericardial thickening. Cardiac CT is the preferred imaging modality to assess for pericardial calcification.