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Inferior phrenic vein

The inferior phrenic veins are paired vessels that provide the major venous drainage of the diaphragm. They accompany the inferior phrenic arteries, coursing along the diaphragmatic surface, and show significant variation in their drainage pattern.

The right inferior phrenic vein usually drains directly into the inferior vena cava (IVC), sometimes joining with the right hepatic vein. The left inferior phrenic vein most commonly drains into the left renal vein but may also empty into the IVC, left adrenal vein, or rarely the hepatic vein. They collect tributaries from the diaphragm, pericardium, and suprarenal glands.

Clinically, the inferior phrenic veins are significant in portal hypertension, where they can form porto-systemic collaterals with esophageal veins, contributing to varices. They are also important in imaging and interventions involving the diaphragm, adrenal glands, and hepatic tumors.

Synonyms

  • Venae phrenicae inferiores

  • Inferior diaphragmatic veins

Function

  • Drain venous blood from the inferior diaphragm

  • Receive tributaries from the adrenal glands and pericardium

  • Provide collateral venous channels in portal hypertension and IVC obstruction

  • Serve as anatomical landmarks in retroperitoneal surgery and venous interventions

Drainage Patterns

  • Right inferior phrenic vein: usually to IVC, occasionally joins right hepatic vein

  • Left inferior phrenic vein: usually to left renal vein, also to IVC or left adrenal vein

  • Tributaries: diaphragmatic, esophageal, pericardial, and superior suprarenal venules

MRI Appearance

T1-weighted images:

  • Veins appear as flow voids (black lumen); best appreciated when surrounded by retroperitoneal fat

  • Small tributaries difficult to visualize without contrast

T2-weighted images:

  • Veins show signal voids; thrombus appears as intermediate to high signal depending on clot stage

STIR:

  • Fat suppression increases conspicuity of venous channels against the retroperitoneal background

  • Helps in identifying perivascular edema or inflammatory extension

T1 Post-Gadolinium (Gd-enhanced MRI):

  • Veins enhance brightly and homogeneously with contrast

  • Filling defects indicate thrombosis or extrinsic compression

  • Useful in venous mapping before adrenal or hepatic interventions

MR Venography (Contrast-enhanced):

  • Provides 3D delineation of the inferior phrenic venous course and drainage into IVC, renal, or hepatic veins

  • Identifies collateral venous channels in portal hypertension

CT Appearance

CT Post-Contrast (CT Venography):

  • Inferior phrenic veins enhance clearly, coursing with their arteries along the diaphragm

  • Right vein visualized joining the IVC or hepatic vein; left vein draining to renal or adrenal vein

  • Multiplanar reconstructions depict drainage patterns, collateral channels, and variations

  • Useful for portal hypertension mapping, retroperitoneal pathology, and surgical planning

CT image

Inferior phrenic vein CT AXIAL IMAGE