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Pericardium

The pericardium is a double-walled fibroserous sac enclosing the heart and the roots of the great vessels. It consists of two main components: the fibrous pericardium, a tough outer connective tissue layer that anchors the heart to the diaphragm and sternum, and the serous pericardium, which has two layers — the parietal layer (lining the inner fibrous sac) and the visceral layer (epicardium), which adheres directly to the heart surface. Between these serous layers lies the pericardial cavity, containing a thin film of lubricating fluid that reduces friction during cardiac contraction.

Synonyms

  • Heart sac

  • Fibroserous pericardial sac

  • Epicardium (visceral pericardium layer)

Function

  • Provides a protective covering for the heart

  • Maintains the heart’s position in the mediastinum

  • Prevents overdistension of the cardiac chambers during increased venous return

  • Reduces friction between the heart and surrounding structures via pericardial fluid

  • Acts as a barrier to infection spread from adjacent thoracic structures

Arterial Supply

  • Pericardiacophrenic arteries (branches of the internal thoracic arteries)

  • Musculophrenic arteries

  • Bronchial, esophageal, and superior phrenic arteries

  • Small contributions from coronary arteries to the visceral pericardium

Venous Drainage

  • Pericardiacophrenic veins → internal thoracic vein

  • Azygos venous system

  • Small tributaries into coronary sinus for visceral pericardium

Nerve Supply

  • Phrenic nerves (C3–C5): sensory innervation to fibrous and parietal serous pericardium (pain often referred to shoulder)

  • Vagus nerves (CN X): parasympathetic contributions

  • Sympathetic trunks: vasomotor innervation

MRI Appearance

T1-weighted images:

  • Pericardium appears as a thin, hypointense line encasing the heart

  • Normal pericardium measures ≤2 mm; thickening (>4 mm) suggests pathology (e.g., constrictive pericarditis)

  • Pericardial fluid shows low signal intensity

T2-weighted images:

  • Pericardium remains hypointense

  • Pericardial fluid appears hyperintense, allowing detection of effusion

  • Thickened or inflamed pericardium may show intermediate-to-high signal

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, improving visualization of pericardial edema, inflammation, or effusion

  • Inflamed pericardium appears bright hyperintense

  • Distinguishes acute pericarditis from chronic fibrotic thickening

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal pericardium may enhance faintly

  • Inflamed or neoplastic pericardium shows intense, heterogeneous enhancement

  • Useful for diagnosing pericarditis, pericardial tumors, and post-surgical changes

CT Appearance

Non-contrast CT:

  • Pericardium appears as a thin hyperdense line surrounding the heart

  • Calcification (in chronic pericarditis) appears as dense, bright deposits

  • Pericardial effusion appears as a hypodense fluid collection around the heart

Contrast-enhanced CT (CECT):

  • Enhances visualization of pericardial thickening, masses, and effusion

  • Differentiates serous vs hemorrhagic effusions based on attenuation

  • Demonstrates pericardial calcification, constrictive pericarditis, or tumor invasion

MRI images

Pericardium mri axial image

MRI images

Pericardium MRI coronal image -img-00000-00000

CT image

Pericardium CT AXIAL image -img-00000-00000