Table 3.

Correlation between pressure-derived and angiography-derived indices based on collateral circulation.

	Poor collateral (ASITN/SIR 0–2)				Good collateral (ASITN/SIR 3–4)
	Resting Pd/Pa		Pa–Pd (mmHg)		Resting Pd/Pa		Pa–Pd (mmHg)
	r	p	r	p	r	p	r	p
Minimal lumen diameter (mm)	0.318	0.213	−0.591	0.012	0.462	0.018	−0.492	0.011
Diameter stenosis (%)	−0.129	0.622	0.327	0.200	−0.469	0.016	0.538	0.005
Lesion length (mm)	0.105	0.687	−0.115	0.659	−0.069	0.736	0.083	0.687

ASITN/SIR, the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology collateral flow grading system.