Influences of prolonged apnea and oxygen inhalation on pulmonary hemodynamics during breath holding: Quantitative assessment by velocity-encoded MR imaging with SENSE technique

Purpose: The purpose of our study was to assess the influence of prolonged apnea and administration of oxygen on pulmonary hemodynamics during breath holding (BH) by using velocity-encoded MR imaging combined with the SENSE technique (velocity MRI). Materials and methods: Ten healthy male volunteers underwent velocity MRI during BH with and without O₂ inhalation. All velocity MRI data sets were obtained continuously with the 2D cine phase-contrast method during a single BH period. The data were then divided into three BH time phases as follows: first, second and third. To evaluate the influence of prolonged apnea on hemodynamics, stroke volume (SV) and maximal change in flow rate during ejection (MCFR) of second and third phases were statistically compared with those of first phase by using the ANOVA followed by Turkey's HSD multiple comparison test. To assess the influence of O₂ on hemodynamics, SV and MCFR with or without O₂ were compared by the paired t-test. To assess the measuring agreement of hemodynamic indices during prolonged breath holding, Bland-Altman's analysis was performed. Results: Prolonged apnea had no significant influence on SV and MCFR regardless of administration of O₂ (p > 0.05). Mean MCFR for all phases was significantly lower with administration of O₂ than without (p < 0.05). The limits of agreement for MCFR with O₂ were smaller than without. Conclusion: O₂ inhalation modulated maximal change in flow rate during ejection, and did not influence stroke volume during breath holding. Influence of O₂ inhalation should be considered for MR measurements of pulmonary hemodynamics during breath holding.