Peripheral Vascular Imaging

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Modalities - Pixel Power

  • Doppler Ultrasound (DUS):
    • First-line, non-invasive, real-time haemodynamics.
    • B-mode (morphology), Color & Spectral Doppler (flow).
    • Limitations: operator skill, obesity, vessel calcification.
  • CT Angiography (CTA):
    • Rapid, high-resolution 3D anatomy. Iodinated contrast.
    • Radiation. Bolus tracking.
    • For stenosis, aneurysms, dissection, trauma. CTA lower limb arteries 3D reconstruction
  • MR Angiography (MRA):
    • No ionizing radiation. Techniques: Time-of-Flight (TOF), Contrast-Enhanced (CE-MRA).
    • Gadolinium (CE-MRA) - Nephrogenic Systemic Fibrosis (NSF) risk.
    • For stenosis, occlusion, run-off.
  • Digital Subtraction Angiography (DSA):
    • Invasive gold standard; diagnostic & therapeutic.
    • Catheter-based, iodinated contrast, radiation.
    • Enables angioplasty, stenting. Risks: access site.

⭐ DSA remains the gold standard for peripheral vascular imaging, especially when intervention is planned.

Arterial Disease - Clog Combat

  • Patho: Atherosclerosis is the main cause. Endothelial injury → lipid deposition → plaque → stenosis/occlusion.
  • Risks: Key risks: Smoking, DM, HTN, HLD, Age, Male.
  • Clinical:
    • Claudication: Exercise-induced pain, relieved by rest.
    • CLI: Chronic rest pain, ulcers, or gangrene. ABI < 0.4.
    • ALI: 📌 6 P's: Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia.
  • Imaging:
    • Doppler USG: First-line. ABI (Normal > 0.9; Claudication 0.5-0.9; CLI < 0.4). Waveform analysis: Triphasic (normal) → Biphasic → Monophasic (severe).
    • CTA: Shows anatomy, calcification, stenosis. Requires IV contrast. CTA peripheral arteries with atherosclerotic stenosis
    • MRA: No radiation. Gadolinium contrast (NSF risk if eGFR < 30). Non-contrast TOF MRA.
    • DSA: Gold standard, invasive. Allows therapeutic intervention.
  • Findings: Common findings: Stenosis, occlusion, aneurysm (>50% normal diameter), dissection.

⭐ Leriche Syndrome: Aortoiliac occlusion. Triad: buttock/thigh claudication, absent femoral pulses, impotence.

Venous Disease - Deep Dive

  • Deep Vein Thrombosis (DVT)
    • Pathophysiology: Virchow's triad (stasis, hypercoagulability, endothelial injury).
    • Imaging:
      • Doppler US (1st line): Non-compressible vein, echogenic thrombus, absent/reduced flow, loss of phasicity/augmentation.
      • CTV/MRV: For suspected iliac vein DVT or equivocal US; shows filling defects.
    • Complications: Pulmonary Embolism (PE), Post-Thrombotic Syndrome (PTS).
  • Chronic Venous Insufficiency (CVI)
    • Pathophysiology: Valvular incompetence → venous hypertension.
    • Doppler US: Reflux > 0.5s (superficial veins), > 1s (deep veins).
    • Clinical: Edema, skin changes (lipodermatosclerosis, pigmentation), medial malleolar ulceration.
  • Varicose Veins
    • Dilated, tortuous superficial veins.
    • Doppler US: Identifies reflux source (e.g., sapheno-femoral junction incompetence).
  • May-Thurner Syndrome
    • Compression of left common iliac vein by right common iliac artery.
    • Imaging: CTV/MRV, venography.
  • Superior Vena Cava (SVC) Obstruction
    • Causes: Malignancy (e.g., lung cancer, lymphoma), thrombosis.
    • Imaging: CECT shows obstruction & development of collaterals.

Phlegmasia Cerulea Dolens is a severe form of DVT characterized by sudden massive swelling, cyanosis, and pain in an extremity, potentially leading to gangrene. It involves iliofemoral DVT with near-total venous occlusion.

Normal vs. Thrombosed Common Femoral Vein Ultrasound

Other Syndromes - Pattern Pursuit

  • Klippel-Trenaunay Syndrome (KTS)
    • Triad: Capillary malformation (port-wine stain), venous varicosities, limb hypertrophy.
    • Imaging: MRI, Venography. No significant AV shunting.
  • Parkes Weber Syndrome (PWS)
    • KTS-like with high-flow arteriovenous (AV) fistulas; risk of cardiac failure.
    • Imaging: Doppler US, MRA, Angiography (shows AV shunts).
  • May-Thurner Syndrome (MTS)
    • Left common iliac vein (LCIV) compressed by right common iliac artery (RCIA) against vertebrae.
    • Imaging: CTV, MRV, IVUS (gold standard).

    ⭐ MTS: LCIV compression by RCIA; ↑ left leg DVT risk, esp. young women.

  • Nutcracker Syndrome
    • Left renal vein (LRV) compression:
      • Anterior: Between SMA & Aorta (most common).
      • Posterior: Between Aorta & Vertebral column.
    • Hematuria, flank pain. Imaging: Doppler US (↑ LRV velocity, beak sign), CTA, MRA.
  • Popliteal Artery Entrapment (PAES)
    • Popliteal artery compression by gastrocnemius/band; claudication in young.
    • Imaging: Doppler US (with provocative maneuvers), MRA, CTA.

May-Thurner Syndrome CT and venogram

High‑Yield Points - ⚡ Biggest Takeaways

  • Doppler USG is the first-line investigation for most PVDs, including DVT and PAD.
  • CTA is gold standard for PAD assessment and pre-operative planning.
  • MRA is valuable in contrast allergy or renal impairment as an alternative to CTA.
  • DSA is the gold standard for intervention and complex diagnostic dilemmas.
  • ABI <0.9 is diagnostic for PAD; a key non-imaging test.
  • Non-compressibility of veins on USG confirms DVT.
  • Doppler USG maps reflux in varicose veins.

Practice Questions: Peripheral Vascular Imaging

Test your understanding with these related questions

Deep vein thrombosis post-operatively is diagnosed by:

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Flashcards: Peripheral Vascular Imaging

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The X-ray shows _____ sign which is suggestive of _____ anomalous pulmonary venous return.

TAP TO REVEAL ANSWER

The X-ray shows _____ sign which is suggestive of _____ anomalous pulmonary venous return.

Scimitar; partial

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