Effects of supplemental oxygen on cardiovascular magnetic resonance water proton relaxation time constant measurements (T1, T2 and T2*)

Abstract Objective To study, the effects of supplemental oxygen on the measurement of native cardiovascular water proton relaxation time constants using commercially available protocols. Methods T 1 , T 2 and T 2 * relaxation time constant mapping were performed in twelve volunteers at 1.5 T breathing room air and supplemental oxygen supplied by nasal cannula and a non-rebreather mask. Regions-of-interest were drawn for quantitative measurements in the bloodpool of each ventricle and atria as well as septal myocardium. The effects of supplemental oxygen were investigated statistically using a mixed model analysis of variance. Intra- and inter-observer reproducibility were assessed using the Intraclass Correlation Coefficient and Coefficient of Variation. Results Blood T 1 relaxation time constants in the left ventricle (T 1 change = −241.0 ms) and left atrium (T 1 change = −247.0 ms) decreased significantly in every subject after oxygen inhalation with a non-rebreather mask ( p 1 in the right side of the heart were detected after oxygen inhalation with the non-rebreather mask ( p  = 0.345). Oxygen inhalation with nasal cannula did not significantly change blood T 1 in the study ( p  = 0.497). No significant changes in myocardial T 1 ( p  = 0.390), T 2 ( p  = 0.960) or T 2 * ( p  = 0.438) were observed with supplemental oxygen supplied by nasal cannula or the non-rebreather mask. Results were similar in mid-short-axis and horizontal long-axis acquisitions. Conclusion Supplemental oxygen does not affect myocardial relaxation time constant measurements with current protocols. On the other hand, blood T 1 measurements with the inhalation of supplemental oxygen supplied by a non-rebreather mask change significantly and could affect myocardial tissue characterization if used for the calculation of extracellular volume. Additionally, current relaxation time constant mapping protocols do not reproducibly detect myocardial T 1 changes with supplemental oxygen inhalation.