Quantitative validation of MRI mapping of cerebral venous oxygenation with direct blood sampling: A graded-O₂ study...

To validate two neonatal cerebral venous oxygenation (Y_v ) MRI techniques, T₂ relaxation under phase contrast (TRUPC) and accelerated TRUPC (aTRUPC) MRI, with oxygenation measured with direct blood sampling.

In vivo experiments were performed on seven healthy newborn piglets. For each piglet, a catheter was placed in the superior sagittal sinus to obtain venous blood samples for blood gas oximetry measurement as a gold standard. During the MRI experiment, three to five venous oxygenation levels were achieved in each piglet by varying inhaled O₂ content and breathing rate. Under each condition, Y_v values of the superior sagittal sinus measured by TRUPC, aTRUPC, and blood gas oximetry were obtained. The Y_v quantification in TRUPC and aTRUPC used a standard bovine blood calibration model. The aTRUPC scan was repeated twice to assess its reproducibility. Agreements among TRUPC Y_v , aTRUPC Y_v , and blood gas oximetry were evaluated by intraclass correlation coefficient (ICC) and paired Student's t-test.

The mean hematocrit was 23.6 ± 6.5% among the piglets. Across all measurements, Y_v values were 51.9 ± 21.3%, 54.1 ± 18.8%, and 53.7 ± 19.2% for blood gas oximetry, TRUPC and aTRUPC, respectively, showing no significant difference between any two methods (P > .3). There were good correlations between TRUPC and blood gas Y_v (ICC = 0.801; P < .0001), between aTRUPC and blood gas Y_v (ICC = 0.809; P < .0001), and between aTRUPC and TRUPC Y_v (ICC = 0.887; P < .0001). The coefficient of variation of aTRUPC Y_v was 8.1 ± 9.9%.

The values of Y_v measured by TRUPC and aTRUPC were in good agreement with blood gas oximetry. These findings suggest that TRUPC and aTRUPC can provide accurate quantifications of Y_v in major cerebral veins.