Interventional Radiological Anatomy

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):

⭐ 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.

⭐ 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.