Cerebral angiographic projections

Case Discussion

Intracranial selective cerebral angiographic projections

Baseline patient positioning

• Patient supine, head supported in radiolucent head holder or curved sponge
• Strap across patient's head to minimize movement
• Head positioned without rotation
• Head tilt (radiographic baseline) determined by patient comfort
  • Patient should not be forced into an uncomfortable head tilt
  • Adjustments made for head tilt by cranio-caudal C-arm angulation

Internal carotid artery - posteroanterior (PA) projection

• Petrous ridge superimposed on supraorbital margin
  • Projects middle cerebral artery away from bony landmarks, minimizing beam hardening
• Include entire skull vault

Internal carotid artery - lateral projection

• Right lateral where possible
  • Minimize dose to operator (if standing in room during acquisitions)
• Include entire skull

Internal carotid artery - transorbital oblique projection

• Petrous ridge positioned on infra-orbital margin
• Ipsilateral obliquity 30 degrees
• Collimation - generally include entire skull vault; however, magnification can be employed if indication is specifically for intracranial aneurysm
• Center on lateral edge of orbit

Internal carotid artery - reverse trans-orbital oblique projection

• Petrous ridge positioned on infraorbital margin
• Contralateral obliquity of 30 degrees
• Collimation - generally include entire skull vault; however, magnification can be employed if indication is for aneurysm
• Center to include lateral edge (side of interest) of skull

Internal carotid artery - cross compression projection

• Petrous ridge positioned on infra-orbital margin
• No obliquity
• Collimate image on top and bottom
• Image must be annotated with cross compression (or x-compression)

Vertebral artery - posteroanterior (PA) projection

• Petrous ridge positioned on supra-orbital margin
• Collimation to include lambdoid suture at top and approximately 5 cm below the infraorbital margin (for inclusion of possible extracranial PICA)
• Technique variations -
  • Increase cranial angle (Townes) to demonstrate Posterior cerebral arteries
  • Decrease angle (Waters) to best demonstrate basilar artery)

Vertebral artery - lateral projection

• Compared to lateral ICA projection
  • Increase magnification
  • Posterior border of collimation to include skull vault
  • Inferior border of collimation to include posterior arch of C1 (inclusion of possible extracranial PICA)