Comparison of oxygen-15 PET and transcranial Doppler CO2-reactivity measurements in identifying haemodynamic compromise in patients with symptomatic occlusion of the internal carotid artery

EJNMMI Research

Table 2 Comparison of absolute ipsilateral PET values and hemispheric ratios with TCD CO ₂ -reactivity

	All patients	Impaired CVR (≤20%)	Normal CVR (>20%)	p value	Absent CVR or steal (≤0%)	No absent CVR or steal (>0%)	p value	Test
	n = 24	n = 17	n = 7	p value	n = 6	n = 18	p value	Test
CO₂-reactivity (%), mean ± SD	15.5 ± 15.9	7.0 ± 8.7	36.0 ± 9.0		−2.7 ± 4.8	21.6 ± 13.5
CBF (mL/min/100 mL), mean ± SD	31.9 ± 5.6	32.3 ± 6.0	30.9 ± 4.8	0.572	30.8 ± 5.0	32.3 ± 5.9	0.598	t
CBF ratio, mean ± SD	0.88 ± 0.09	0.87 ± 0.08	0.90 ± 0.12	0.461	0.84 ± 0.09	0.89 ± 0.09	0.178	t
OEF (%), median (IQR)	45.1 (42.2 to 50.9)	45.0 (42.5 to 50.1)	47.8 (40.2 to 55.2)	0.634	47.6 (42.1 to 58.4)	45.0 (41.5 to 50.8)	0.424	U
OEF ratio, median (IQR)	1.06 (1.00 to 1.11)	1.06 (1.01 to 1.11)	1.08 (0.97 to 1.12)	0.949	1.09 (1.04 to 1.26)	1.05 (0.99 to 1.10)	0.116	U
CBV/CBF, mean ± SD	0.10 ± 0.03	0.10 ± 0.03	0.11 ± 0.03	0.563	0.09 ± 0.04	0.10 ± 0.02	0.266	t
CBV/CBF ratio, mean ± SD	1.27 ± 0.18	1.32 ± 0.15	1.15 ± 0.21	0.035	1.36 ± 0.15	1.24 ± 0.18	0.174	t

CBF, cerebral blood flow; CBV, cerebral blood volume; CVR, cerebrovascular reactivity; IQR, interquartile range; OEF, oxygen extraction fraction; t, Student’s t test; U, Mann–Whitney test.