Posterior Interosseous Veins: Anatomy, Course, Function, Imaging

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Posterior interosseous veins

The posterior interosseous veins are paired deep veins that accompany the posterior interosseous artery along the posterior aspect of the forearm. They belong to the deep venous system of the forearm and are part of the venae comitantes that drain the extensor (posterior) compartment muscles. These veins play a key role in returning deoxygenated blood from the deep forearm to the heart, forming an essential connection between the dorsal venous network and the brachial venous system through the ulnar and radial veins.

The veins closely follow the posterior interosseous artery, beginning in the upper third of the forearm and eventually joining the anterior interosseous veins near the proximal border of the pronator quadratus muscle, forming the common interosseous veins, which then drain into the ulnar veins.

Synonyms

Deep posterior interosseous veins
Venae comitantes of the posterior interosseous artery

Origin, Course, and Termination

Origin: Begin as small venous channels in the posterior compartment of the forearm, draining blood from the extensor muscles and interosseous membrane region.
Course:

Ascend proximally along the posterior interosseous artery in the posterior compartment.
Run between the superficial and deep extensor muscles, closely applied to the interosseous membrane.
Passes upward between extensor pollicis longus and extensor indicis muscles.
Termination:
Join the anterior interosseous veins near the proximal forearm to form the common interosseous veins, which subsequently drain into the ulnar veins.

Relations

Anteriorly: Interosseous membrane and anterior interosseous artery (separated by membrane)
Posteriorly: Deep extensor muscles of the forearm (extensor pollicis longus, extensor digitorum, extensor indicis)
Laterally: Radius and its periosteum
Medially: Ulna and adjacent connective tissues
Superiorly: Anastomoses with anterior interosseous veins near the cubital region

Function

Venous drainage: Drains the posterior (extensor) compartment of the forearm.
Accompanying veins: Serve as venae comitantes to the posterior interosseous artery, ensuring efficient countercurrent exchange.
Pressure modulation: Helps regulate venous return during muscle contraction by acting as capacitance vessels.
Collateral pathway: Provides communication between deep venous and superficial venous systems through small perforating branches.

Clinical Significance

Thrombosis: Deep vein thrombosis (DVT) of the forearm may involve the posterior interosseous veins, particularly in immobilized or post-traumatic patients.
Venous congestion: May occur secondary to compression or compartment syndrome, producing swelling and pain in the posterior forearm.
Surgical importance: These veins are encountered in posterior forearm approaches, vascular grafting, and flap surgeries.
Imaging relevance: MRV and CTV essential for assessing thrombosis, flow obstruction, or post-surgical patency.

MRI Appearance

T1-weighted images:

Normal veins: dark flow void due to fast flow.
Slow-flowing blood: may appear intermediate-to-bright signal within lumen.
Thrombosis: intermediate-to-bright signal with loss of flow void and expansion of vein.
Perivenous fat appears bright, outlining vessels clearly.

T2-weighted images:

Normal veins: dark (flow void); smooth tubular structures.
Slow-flowing or stagnant blood: shows intermediate or bright signal depending on velocity and turbulence.
Acute thrombus: bright T2 signal with wall thickening and perivenous edema.

STIR:

Normal vein: intermediate-to-dark flow void.
Slow flow or thrombus: hyperintense or intermediate bright lumen.
Edematous soft tissues or perivascular inflammation appear bright hyperintense.

Proton Density Fat-Saturated (PD FS):

Normal vein: intermediate-to-dark flow void.
Slow flow: intermediate bright signal within lumen.
Thrombosed vein: focal bright signal intensity with wall enhancement on post-contrast.

T1 Fat-Sat Post-Contrast:

Normal veins: uniform enhancement with brisk venous return.
Thrombosed veins: central non-enhancing area with peripheral rim enhancement (inflammatory reaction).
Chronic thrombosis: may show irregular enhancement or collateral formation.

MRV (Magnetic Resonance Venography) Appearance

Normal: Posterior interosseous veins visualized as paired enhancing channels accompanying the posterior interosseous artery.
Best seen in contrast-enhanced MRV or 2D TOF (Time-of-Flight) venography sequences.
Pathology:
- Thrombosis: segmental filling defect or absence of enhancement.
- Collateral flow: serpiginous enhancing vessels.
- Compression: narrowed lumen with perivascular signal change.

CT Appearance

Non-Contrast CT:

Veins not easily visible unless thrombosed or surrounded by inflammation.
Acute thrombosis: hyperdense tubular structure within posterior compartment.
Chronic phase: calcified phleboliths or post-thrombotic changes may be seen.

Post-Contrast CT (standard):

Veins show enhancing tubular channels running with posterior interosseous artery.
Thrombus: non-enhancing intraluminal filling defect.
Perivenous inflammation: fat stranding or soft tissue enhancement.

CTV (CT Venography) Appearance

Normal: Posterior interosseous veins appear as enhancing paired venous channels accompanying the posterior interosseous artery along the posterior forearm.
Timing: Optimal visualization during venous phase (40–60 seconds post-contrast injection).
Pathology:
- Thrombosis: segmental absence or intraluminal filling defect.
- Venous congestion: enlarged, tortuous veins with delayed emptying.
- Collateral circulation: prominent serpiginous enhancing veins around occlusion.
- Post-surgical changes: venous interruption or reconstituted channels.

MRI images

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