Interventional Radiological Anatomy

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Interventional Radiological Anatomy - Puncture Points & Pathways

  • Arterial Access:
    • Common Femoral Artery (CFA): Gold standard. Puncture: Over femoral head, inferior to inguinal ligament.
      • 📌 NAVEL (Lateral to Medial): Nerve, Artery, Vein, Empty space, Lymphatics.
    • Radial Artery: ↑Safety, ↓complications. Allen's test pre-procedure.
  • Venous Access:
    • Internal Jugular Vein (IJV): Preferred central access. Right IJV for direct Superior Vena Cava (SVC) path.
      • Landmark: Sedillot's triangle (SCM heads, clavicle).
    • Femoral Vein: Medial to CFA.
  • Non-Vascular Punctures:
    • Percutaneous Nephrostomy (PCN): Posterolateral, subcostal (below 12th rib).
    • Percutaneous Transhepatic Cholangiography (PTC): Mid-axillary, intercostal.
  • Access Pathway (Seldinger Technique):

Seldinger technique steps

⭐ The Common Femoral Artery (CFA) is the most frequent arterial access site, typically punctured 1-2 cm inferior to the midpoint of the inguinal ligament, overlying the femoral head to avoid retroperitoneal hematoma if puncture is too high, or pseudoaneurysm/AV fistula if too low (into SFA/PFA).

Interventional Radiological Anatomy - Mapping & Blocking Vessels

Vessel Mapping (Angiography):

  • Purpose: Diagnostic visualization of vessel lumen, abnormalities (stenosis, aneurysm, AVM), pre-procedural planning.
  • Technique: Seldinger technique for access. Contrast injection via catheters (e.g., Pigtail, Cobra, Simmons).
  • Imaging: Digital Subtraction Angiography (DSA) for optimal vessel imaging.
  • Common Access Sites:
    • Arterial: Femoral (most common), Radial (safer).
    • Venous: Femoral, Internal Jugular (IJ).

Vessel Blocking (Embolization):

  • Purpose: Therapeutic occlusion of blood flow.
    • Control hemorrhage (trauma, GI bleed).
    • Treat AVMs, aneurysms.
    • Devascularize tumors (e.g., Transarterial Chemoembolization - TACE for HCC).
  • Embolic Agents:
    • Temporary: Gelfoam.
    • Permanent: Coils, Polyvinyl Alcohol (PVA) particles, microspheres, liquid agents (NBCA glue, Onyx).
  • Key Complication: Non-target embolization.

Angiogram showing catheter in femoral artery

Seldinger technique is the cornerstone for percutaneous vascular access in most interventional radiology procedures, enabling both diagnostic angiography and therapeutic embolization.

Interventional Radiological Anatomy - Draining & Zapping Targets

Non-vascular interventions: percutaneous drainage (abscesses, biliary, urinary) & tumor ablation. Anatomical precision is paramount.

  • Drainage Targets & Routes:

    • Abscesses (liver, renal, pelvic): Transhepatic/intercostal access; avoid critical structures.
    • Biliary (PTBD): Right mid-axillary, intercostal to right hepatic duct.
    • Urinary (PCN): Posterolateral, below 12th rib to calyx; Brodel's avascular zone.
      • Avoid: Colon, spleen, liver, pleura.
  • Ablation Targets & Considerations:

    • Tumors: Liver, kidney, lung, bone.
    • Factors: Size/location, proximity to vital structures (vessels, nerves, bowel), heat/cold sink.

⭐ PCN access via Brodel's avascular plane (posteriorly) minimizes bleeding; preferred for safety.

Interventional Radiological Anatomy - Danger Zones & Safe Zones

  • Core Principle: Real-time imaging guidance (US, CT, Fluoro) is paramount for safety.
  • Vascular Access Danger Zones:
    • Femoral: Femoral nerve (lateral to artery). Puncture above inguinal ligament risks retroperitoneal bleed. 📌 NAVEL (Lateral to Medial: Nerve, Artery, Vein, Empty Space, Lymphatics).
    • Neck (IJV/Subclavian): Carotid artery, phrenic nerve, vagus nerve, brachial plexus, pleura (pneumothorax risk), thoracic duct (left side).
  • Organ Intervention Danger Zones:
    • Chest: Intercostal neurovascular bundle (runs inferior to each rib).
    • Liver Biopsy: Gallbladder, right pleura/lung, major hilar vessels, adjacent colon.
    • Kidney Biopsy: Bowel, colon, spleen (left), liver (right), pleura (risk if approach is superior to 12th rib).
  • Key Safe Zones & Techniques:
    • Femoral Artery Access: Puncture site over the femoral head for effective compression.
    • Chest Tube Insertion: "Triangle of Safety" (anterior border of latissimus dorsi, lateral border of pectoralis major, apex inferior to axilla, base at ~5th intercostal space).
    • Kidney Biopsy: Posterolateral approach, targeting lower pole, typically below the 12th rib.

⭐ For femoral artery access, the ideal puncture site is over the mid-femoral head, usually 1-2 cm below the inguinal ligament, to allow effective post-procedure compression and minimize risk of retroperitoneal hematoma.

High‑Yield Points - ⚡ Biggest Takeaways

  • Seldinger technique is fundamental for arterial and venous access.
  • Femoral artery access: preferred site is common femoral artery (CFA), inferior to the inguinal ligament.
  • Radial artery access: increasingly used for coronary interventions, note Allen’s test for collateral circulation.
  • Internal Jugular Vein (IJV) access: ideal for central venous catheterization, often ultrasound-guided between sternal and clavicular heads of SCM.
  • TIPS procedure: creates a shunt between an intrahepatic portal vein branch and a hepatic vein.
  • IVC filter placement: typically infrarenal to trap emboli from lower extremities.
  • PTBD (Percutaneous Transhepatic Biliary Drainage) targets dilated intrahepatic bile ducts for decompression, usually via right mid-axillary line approach.

Practice Questions: Interventional Radiological Anatomy

Test your understanding with these related questions

In which of the following locations should the incision be made for the saphenous cutdown procedure in an obese patient with no visible or palpable superficial veins, requiring intravenous fluids in shock?

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Flashcards: Interventional Radiological Anatomy

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In the mid-clavicular line, the inferior border of lung is at the _____ rib and for pleura is at the level of 8th rib

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In the mid-clavicular line, the inferior border of lung is at the _____ rib and for pleura is at the level of 8th rib

6th

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