Method for a detailed evaluation of respiratory cardiac contributions to blood flow in Fontan circulation

Background A recent MRI pilot study [1] indicated that hemodynamics in the Fontan circulation are mainly dependent on respiration according to flow amplitudes and suggested using a respiratory-triggered 4D PC MRI instead of a ECG-triggered 4D PC MRI. The detailed validation of this conclusion with double-triggered PC on acquisition level requires an extensive development of the pulse sequence. In this study, we outline techniques to justify and derive the recent findings in detail on the stage of post-processing using Realtime PC measurements. The regular respiratory-triggered cine measurement is not decoupled but involves the average cardiac effect as offset. The proposed method allows a complete separation of flow into its components stemming from respiration and ventricular function and it allows to study correlation effects.