Toward vendor-independent measurement of cerebral venous oxygenation: Comparison of TRUST MRI across three major MRI manufacturers and association with end-tidal CO2

Abstract

Cerebral venous oxygenation (Y_v ) is a valuable biomarker for a variety of brain diseases. T₂ 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 CO₂ (EtCO₂ ) 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 EtCO₂ 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 EtCO₂ at a rate of 1.24 ± 0.17%/mmHg (P < 0.0001), and (2) across different subjects, individuals with a higher EtCO₂ 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 EtCO₂ may be a useful complement to Y_v measurement to account for CO₂ -related physiological fluctuations in Y_v in multisite, multivendor studies.

Keywords: TRUST; end-tidal CO2; multisite; multivendor; pulse sequence standardization; venous oxygenation.