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. 2019 Jul 3;10:719. doi: 10.3389/fneur.2019.00719

Table 1.

Cerebral hemodynamic parameters commonly used for ischemic stroke evaluation.

Modality Hemodynamic parameter Definition of the hemodynamic parameter Normal value (mean ± SD)
Cerebral perfusion imaging
(PET, SPECT, CTP, PWI, ASL)		 CBF The volume of blood moving through a determinate amount of brain tissue in a given time Gray matter: 50 ± 15 ml/100 g/min
White matter: 22 ± 5 ml/100 g/min*
CBV The volume of flowing blood for a given volume of brain (in units of milliliters of blood per 100 g of brain tissue) Gray matter: 2.5 ± 0.4 ml/100 g
White matter: 1.7 ± 0.4 ml/100 g*
MTT The mean amount of time it takes blood to pass through a given volume of brain (in units of seconds) Gray matter: 4 s
White matter: 4.8 s*
Cerebral blood flow sonography (TCD, TCCS) Mean blood flow velocity (Peak systolic velocity + [end diastolic velocity × 2])/3 MCA: 55 ± 12 cm/s
ACA: 50 ± 11 cm/s
PCA: 40 ± 10 cm/s
BA: 41 ± 10 cm/s
VA: 38 ± 10 cm/s (19)
Cortical oxygenation (PET, fMRI, NIRS) OEF 1-(cerebral venous O2 content/cerebral arterial O2 content) 0.44 ± 0.06 (20)
CMRO2 Cerebral arterial O2 content × OEF × CBF 3.3 ± 0.5 ml/100 ml/min (20)
rSO2 Percentage of oxyhemoglobin of regional brain tissue 69 ± 6.0% (21)
Cerebral autoregulation Mx The Pearson correlation between CPP and MCA flow velocity over a 300 s moving window (22) 0.21 ± 0.16 (23)
Phase shift (in low frequency range) The displacement of a waveform relative to another waveform with the same period (24) 37.1 ± 3.0° (25)
Gain (in low frequency range) The damping effect between the input and output of the transfer function (24) 0.95 ± 0.08 cm/s/mmHg (25)

SD indicates standard deviation; PET, positron emission tomography; SPECT, single-photon emission computed tomography; CTP, CT perfusion; PWI, perfusion weighed imaging; ASL, arterial spin labeling; CBF, cerebral blood flow; CBV, cerebral blood volume; MTT, mean transit time; TCD, transcranial Doppler sonography; TCCS, transcranial color-coded duplex sonography; MCA, middle cerebral artery; ACA, anterior cerebral artery; PCA, posterior cerebral artery; BA, basilar artery; VA, vertebral artery; fMRI, functional magnetic resonance imaging; NIRS, near-infrared spectroscopy; OEF, oxygen extraction fraction; CMRO2, cerebral metabolic rate of oxygen; rSO2, regional saturation of oxygen; Mx, mean flow index.