Spiral cardiac quantitative susceptibility mapping for differential cardiac chamber oxygenation-Initial validation in relation to invasive blood sampling.

Purpose: To develop a breath-hold cardiac quantitative susceptibility mapping (QSM) sequence for noninvasive measurement of differential cardiac chamber blood oxygen saturation (ΔSO₂).

Methods: A non-gated three-dimensional stack-of-spirals QSM sequence was implemented to continuously sample the data throughout the cardiac cycle. Measurements of ΔSO₂ between the right and left heart chamber obtained by the proposed sequence and a previously validated navigator Cartesian QSM sequence were compared in three cohorts consisting of healthy volunteers, coronavirus disease 2019 survivors, and patients with pulmonary hypertension. In the pulmonary-hypertension cohort, Bland-Altman plots were used to assess the agreement of ΔSO₂ values obtained by QSM and those obtained by invasive right heart catheterization (RHC).

Results: Compared with navigator QSM (average acquisition time 419 ± 158 s), spiral QSM reduced the scan time on average by over 20-fold to a 20-s breath-hold. In all three cohorts, spiral QSM and navigator QSM yielded similar ΔSO₂. Among healthy volunteers and coronavirus disease 2019 survivors, ΔSO₂ was 17.41 ± 4.35% versus 17.67 ± 4.09% for spiral and navigator QSM, respectively. In pulmonary-hypertension patients, spiral QSM showed a slightly smaller ΔSO₂ bias and narrower 95% limits of agreement than that obtained by navigator QSM (1.09% ± 6.47% vs. 2.79% ± 6.99%) when compared with right heart catheterization.

Conclusion: Breath-hold three-dimensional spiral cardiac QSM for measuring differential cardiac chamber blood oxygenation is feasible and provides values in good agreement with navigator cardiac QSM and with reference right heart catheterization.