Hemodynamics in Alzheimer's disease.

Brain activity depends critically on oxygen consumption. Regional quantification of oxygen saturation, which is possible noninvasively with MSOT, has been used in conjunction with co-registered, MRI-derived, cerebral blood flow (CBF) measurements, to determine oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO2).

Brain oxygenation

In vivo brain oxygen saturation in wild-type mice under oxygen challenge with photoacoustic tomography. Representative coronal SO2 map derived from PAT measurements of Hb and HbO2 of a head of a wild-type mouse under (A) hyperoxic and (B) normoxic conditions, approximately Bregma -1.5+/-0.3 mm; overlaid with T2- weighted magnetic resonance image (C) delta SO2 map to show differences in oxygenation in hyperoxia-normoxia challenge; (D) Cortical StO2 and SvO2 derived from PAT measurements during normoxia (grey region) and hyperoxia in brain of wild-type mice (n = 10); (E) Significant differences between cortical StO2 and SvO2 under normoxia and hyperoxia condition. Mann-Whitney Rank Sum Test, *** p < 0.001; StO2: tissue oxygen saturation; SaO2: arterial oxygen saturation SvO2: venous oxygen saturation.

Brain metabolism and oxygen consumption

In vivo assessment of brain oxygenation with PAT in arcAb mice.

(A, B) SO2 maps of arcAb and wild-type mice at 6- and 24-month (coronal view, approximately Bregma -1.5+/-0.3 mm)
(B) ROIs are drawn over the middle cerebral artery (MCA) and superior sagittal sinus (SSS), scale bar = 1.5 mm images overlaid on T2-weighted anatomical image.
(C) Quantification of OEF and CMRO2 (mmol/g/min) in the brain of arcAb and wild-type at 6-months and 24-months. CMRO2 is lower in the 24-month arcAb mouse compared to wild-type and 6-months arcAb mice. OEF does not significantly differ in the brain of wild-type and arcAb mice of both ages (n = 6-8 per group).

Results are Mean SD, *,# p < 0.05, one way ANOVA with post hoc correction for multiple comparison.
CMRO2, cerebral oxygen metabolic rate; OEF, oxygenation extraction fraction; SO2, oxygen saturation

Ni R et al., Cortical hypoperfusion and reduced cerebral metabolic rate of oxygen in the arcAβ mouse model of Alzheimer's disease, Photoacoustics. 2018 Jun; 10: 38-47. DOI: 10.1016/j.pacs.2018.04.001.

  • Ni R et al.,
    Cortical hypoperfusion and reduced cerebral metabolic rate of oxygen in the arcAβ mouse model of Alzheimer’s disease,
    Photoacoustics. 2018 Jun; 10: 38–47. DOI: 10.1016/j.pacs.2018.04.001.
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