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Topic

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Transverse pericardial sinus

The transverse pericardial sinus is a short, tunnel-like passage within the pericardial cavity, formed by reflections of the serous pericardium. It lies posterior to the ascending aorta and pulmonary trunk and anterior to the superior vena cava (SVC) and left atrium.

Embryologically, it develops as a result of folding of the primitive heart tube and pericardial reflections around the arterial and venous ends. It communicates with the main pericardial cavity and has important surgical relevance.

Clinically, the transverse sinus is used as a surgical landmark in cardiac surgery: during procedures such as coronary artery bypass grafting (CABG) or valve replacement, a surgeon can pass a finger or clamp through the sinus behind the great arteries to control inflow or identify anatomical relationships.

Synonyms

  • Pericardial transverse sinus

  • Sinus transversus pericardii

Function

  • Forms part of the pericardial cavity, allowing free motion of great vessels during cardiac cycle

  • Provides a surgical plane for clamping or identifying great arteries during open-heart procedures

  • Serves as an imaging landmark for differentiating arterial and venous structures in the pericardial space

MRI Appearance

T1-weighted images:

  • Appears as a low-signal space filled with pericardial fluid, located between arterial (aorta, pulmonary trunk) and venous (SVC, left atrium) structures

T2-weighted images:

  • Fluid within the sinus appears bright (hyperintense), clearly contrasting with the hypointense walls of great vessels and atrium

T2 TRUFISP (cardiac-gated):

  • Demonstrates the transverse sinus as a bright fluid-filled space with dynamic visualization of surrounding great vessels during the cardiac cycle

  • Useful for evaluating pericardial effusion extension into the sinus

STIR (Short Tau Inversion Recovery):

  • Suppresses fat, highlighting the sinus as a bright hyperintense space against darkened mediastinal fat

  • Helpful in detecting inflammatory exudates or pericardial thickening

T1 Post-Contrast (Gadolinium-enhanced MRI):

  • Pericardial fluid in the sinus does not enhance

  • Enhancing pericardium indicates inflammation or neoplastic involvement

MRI Non-Contrast 3D Cardiac-Gated Imaging (Whole-heart):

  • Provides a 3D reconstruction of the pericardial space and great vessel relationships

  • Clearly delineates the tunnel-like sinus between ascending aorta/pulmonary trunk (anterior) and SVC/left atrium (posterior)

  • Particularly useful for surgical planning or congenital anomaly assessment when contrast is contraindicated

CT Appearance

CT Coronary Angiography (CCTA):

  • Transverse sinus visualized as a contrast-free pericardial recess situated between enhancing ascending aorta/pulmonary trunk and posterior venous structures (SVC, left atrium)

  • Clearly depicted on axial, sagittal, and coronal reconstructions

  • Useful for distinguishing pericardial recesses from mediastinal masses or lymphadenopathy

  • Identifies pericardial effusion distribution and extension into the transverse sinus

CT image

Transverse pericardial sinus anatomy CT axial image -img-00000-00000

MRI image

Transverse pericardial sinus mri image