Table 3.
Hemodynamic parameters.
| Abbreviation | Parameter | Formula | Unit | |
|---|---|---|---|---|
| Doppler ultrasound | ||||
| PSV | Peak-systolic velocity | cm/s | ||
| EDV | End-diastolic velocity | cm/s | ||
| MV | Mean velocity | cm/s | ||
| RI | Resistance index | (PSV-EDV)/PSV | ||
| PI | Pulsatility index | (PSV-EDV)/MV | ||
| VTI | Velocity time integral | cm | ||
| Magnetic resonance imaging | Sequence used in studies | |||
| CBF | Cerebral blood flow | ml/min | PC | |
| iCBF | Indexed cerebral blood flow or cerebral perfusion | ml/min/100 g or ml/min/100 mla | ASL or PC | |
| CDO2 | Cerebral oxygen delivery | CDO2 = SaO2 × Hb × 1.36b × CBF21,23 | ml O2/min | PC |
| iCDO2 | Indexed cerebral oxygen delivery | iCDO2 = SaO2 × Hb × 1.36b × iCBF | ml O2/min/100 g | PC |
| O2D | Cerebral oxygen delivery | O2D = CBF × ((0.003 × PO2) + (1.34 × O2Sat × Hb))42 | Not given | PC |
| iCMRO2 | Cerebral metabolic rate of oxygen consumption | iCMRO2 = Ca × CBF × OEF22 (OEF: (SaO2−SvO2)/SaO2)22 | ml O2/min/100 g | PC |
ASL arterial spin labeling, Ca arterial oxygen concentration, Hb hemoglobin concentration, MRI magnetic resonance imaging, OEF oxygen extraction fraction, O2Sat oxygen saturation, PC phase contrast, PO2 partial pressure of oxygen, SaO2 arterial oxygen saturation, SvO2 venous oxygen saturation.
aConvertible to ml/min/100 g by multiplying with brain tissue density.
bThe value 1.36 is the amount of oxygen bound per gram of Hb at 1 atmosphere (Hüfner’s constant).21