Relatively generous contrast bolus (contrast injection transiently increases intraluminal pressure)
Digital subtraction angiography injection rates
| 6 cc/sec for total of 8 cc, common carotid |
| 5 cc/sec for total of 6 cc, internal carotid |
| 5 cc/sec for total of 5 cc, vertebral |
| 3-5 ml hand injection for external carotid |
Linear rise 0.1 to 0.3 sec
Superselective catheterization of each vessel with a potential collateral
Better visualization with increased peripheral resistance or decreased size of peripheral vascular bed (spasm, congenital vessel hypoplasia)
Internal carotid collaterals better visualized with increased intracranial pressure (hydrocephalus)
More commonly identified in infants and children (partial persistence of embryologic circulation vs. hyperventilation vs. inhaled anesthesia agents)