Noninvasive Imaging of Quantitative Cerebral Blood Flow Changes during 100% Oxygen Inhalation Using Arterial Spin-Labeling MR Imaging

G. Zaharchuk; A.J. Martin; W.P. Dillon

doi:10.3174/ajnr.A0896

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Fig 1.
ASL signal-intensity difference (ΔM, control − label) images in all subjects. Decreased ΔM signals were seen in all subjects in all regions of interest during the 100% oxygen inhalation. However, accounting for the reduced hyperoxygenated blood T1, we found that only small CBF decreases were measured with oxygen.

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Table 1:
Physiologic parameters before, during, and after 100% oxygen inhalation*
Condition Heart Rate (bpm) Systolic BP (mm Hg) Diastolic BP (mm Hg) HgbO₂ Sat (%)
Before 65 ± 11 113 ± 10 74 ± 16 98 ± 1
During 59 ± 10 113 ± 12 71 ± 10 99 ± 0
After 67 ± 13 114 ± 14 71 ± 9 98 ± 1
Note:—bpm indicates beats per minute; BP, blood pressure; HgbO₂ Sat, saturation.
* Noninvasive physiological monitoring of subjects (n = 7). There are no significant changes between the different breathing conditions (P > .05). Ninety-nine percent was the highest number our oxygen saturation monitoring equipment could record.

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Table 2:

ASL difference signal (ΔM, control − label images), CBF, and CBF changes before, after 15 minutes 100% oxygen inhalation, and 15 minutes following resumption of room air breathing in 7 healthy young subjects

		Room Air Baseline (before)	100% Oxygen (during)	Room Air (after)
T_1a	Blood	1230 ms	1050 ms	1230 ms
ΔM change (% from baseline)	Global	–	−23 ± 11^*	1 ± 17
ΔM change (% from baseline)	Gray	–	−21 ± 11^*	2 ± 15
	White	–	−28 ± 19^†	−3 ± 35
CBF (ml/100 g/min)	Global	50 ± 10	47 ± 10	50 ± 9
	Gray	62 ± 11	60 ± 13	63 ± 9
	White	30 ± 9	25 ± 3	29 ± 7
CBF change (% from baseline)	Global	–	−5 ± 14	0 ± 17
CBF change (% from baseline)	Gray	–	−2 ± 14	1 ± 15
	White	–	−12 ± 23	−3 ± 39

Note:— –, indicates data not available.
* P < .01.
† P < .05. All values are mean ± SD. The SDs are across subjects.

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Table 3:
Reproducibility of the CASL perfusion method*
Gray matter White matter Global
Region of interest size (mL) 49 ± 11 27 ± 5 76 ± 13
Quantitative (mL/100 g/min) 8 ± 8 8 ± 9 7 ± 8
% difference (% baseline) 12 ± 7 29 ± 24 14 ± 8
* Root-mean-square variability measured for both quantitative CBF (mL/100 g/min) and % CBF change for 7 healthy subjects breathing room air. Comparison is between measurements acquired before oxygen inhalation and 15 minutes after the inhalation of oxygen ceased; they were separated in time by 45 minutes