Table 3

 Values of PET variables in patients with and without collaterals other than the circle of Willis

VariableOphthalmic or leptomeningeal collaterals
Yes (n = 27)No (n = 15)
Values are mean (SD). CBF, cerebral blood flow; CMRO2, cerebral metabolic rate of oxygen; OEF, oxygen extraction fraction; CBV, cerebral blood volume. *p<0.05 versus corresponding value in the “No” group (Student’s t test). Comparative values for CBF, CMRO2, OEF, CBV and CBF/CBV in normal volunteers were 44.6 (4.5), 3.43 (0.33), 44.5 (3.8), 3.98 (0.48), and 11.4 (1.8), respectively.
CBF (ml/100g/min)29.7 (7.36)34.0 (9.29)
CMRO2 (ml/100g/min)2.68 (0.55)2.71 (0.58)
OEF (%)53.2 (7.61)*47.3 (5.09)
CBV (ml/100g)4.05 (0.86)3.73 (0.85)
CBF/CBV (/min)7.60 (2.30)*9.30 (2.96)