T2-prepared velocity selective labelling: A novel idea for full-brain mapping of oxygen saturation

Disturbances in cerebral oxygenation saturation (SO2) have been linked to adverse outcome in adults, children, and neonates. In intensive care, the cerebral SO2 is increasingly being monitored by Near-InfraRed Spectroscopy (NIRS). Unfortunately NIRS has a limited penetration depth. The “modified T2-prepared Blood Imaging of Oxygen Saturation” (T2-BIOS) MR sequence provides a step towards full brain SO2 measurement. Tissue SO2, and venous SO2 (SvO2) were obtained simultaneously by T2-BIOS during a respiratory challenge in ten healthy volunteers. These two measures were compared to SO2 that was obtained by a single probe MR-compatible NIRS setup, and to cerebral blood flow and venous SO2 that were obtained by arterial spin labelling and T2-TRIR, respectively. SO2-T2-BIOS and SO2-NIRS had a mean bias of −4.0% (95% CI −21.3% to 13.3%). SvO2-T2-BIOS correlated with SO2-NIRS (R2=0.41, p=0.002) and SvO2-T2-TRIR (R2=0.87, p=0.002). In addition, SO2-NIRS correlated with SvO2-T2-TRIR (R2=0.85, p=0.003) Frontal cerebral blood flow correlated with SO2-T2-BIOS (R2=0.21, p=0.04), but was not significant in relation to SO2-NIRS. Full brain SO2 assessment by any technique may help validating NIRS and may prove useful in guiding the clinical management of patient populations with cerebral injury following hypoxic-ischaemic events. The agreement between NIRS and T2-BIOS provides confidence in measuring cerebral SO2 by either technique. As it stands now, the T2-BIOS represents a novel idea and future work will focus on improvements to make it a reliable tool for SO2 assessment. •A MRI sequence is presented for voxel wise estimation of cerebral oxygen saturation.•Cerebral oxygen saturation was measured simultaneously by MRI and NIRS.•Healthy adults were subjected to three episodes of hypercapnia breathing.•Frontal oxygen saturation determined by MRI and NIRS had minimal bias.•Between two MRI techniques, venous oxygen saturation was comparable.