Abstract
Cerebral venous oxygenation (Y(v) ) is a valuable biomarker for a variety of brain diseases. T(2) relaxation under spin tagging (TRUST) MRI is a widely used method for Y(v) quantification. In this work, there were two main objectives. The first was to evaluate the reproducibility of TRUST Y(v) measurements across MRI scanners from different vendors. The second was to examine the correlation between Y(v) and end-tidal CO(2) (EtCO(2) ) in a multisite, multivendor setting and determine the usefulness of this correlation to account for variations in Y(v) caused by normal variations and physiological fluctuations. Standardized TRUST pulse sequences were implemented on three scanners from major MRI vendors (GE, Siemens, Philips). These scanners were located at two research institutions. Ten healthy subjects were scanned. On each scanner, the subject underwent two scan sessions, each of which included three TRUST scans, to evaluate the intrasession and intersession reproducibility of Y(v) . Each scanner was also equipped with a capnograph device to record the EtCO(2) of the subject during the MRI scan. We found no significant bias in Y(v) measurements across the three scanners (P = 0.18). The measured Y(v) values on the three scanners were also strongly correlated with each other (intraclass correlation coefficients > 0.85, P < 0.001). The intrasession and intersession coefficients of variation of Y(v) were less than 4% and showed no significant difference among the scanners. In addition, our results revealed that (1) within the same subject, Y(v) increased with EtCO(2) at a rate of 1.24 ± 0.17%/mmHg (P < 0.0001), and (2) across different subjects, individuals with a higher EtCO(2) had a higher Y(v) , at a rate of 0.94 ± 0.36%/mmHg (P = 0.01). These results suggest that (1) the standardized TRUST sequences had similar accuracies and reproducibilities for the quantification of Y(v) across the scanners, and (2) recording of EtCO(2) may be a useful complement to Y(v) measurement to account for CO(2) -related physiological fluctuations in Y(v) in multisite, multivendor studies.