title: Two-dimensional intraventricular flow mapping by digital processing conventional color-Doppler echocardiography images.
abstract: Doppler echocardiography remains the most extended clinical modality for the evaluation of left ventricular (LV) function. Current Doppler ultrasound methods, however, are limited to the representation of a single flow velocity component. We thus developed a novel technique to construct 2D time-resolved (2D+t) LV velocity fields from conventional transthoracic clinical acquisitions. Combining color-Doppler velocities with LV wall positions, the cross-beam blood velocities were calculated using the continuity equation under a planar flow assumption. To validate the algorithm, 2D Doppler flow mapping and laser particle image velocimetry (PIV) measurements were carried out in an atrio-ventricular duplicator. Phase-contrast magnetic resonance (MR) acquisitions were used to measure in vivo the error due to the 2D flow assumption and to potential scan-plane misalignment. Finally, the applicability of the Doppler technique was tested in the clinical setting. In vitro experiments demonstrated that the new method yields an accurate quantitative description of the main vortex that forms during the cardiac cycle (mean error for vortex radius, position and circulation). MR image analysis evidenced that the error due to the planar flow assumption is close to 15% and does not preclude the characterization of major vortex properties neither in the normal nor in the dilated LV. These results are yet to be confirmed by a head-to-head clinical validation study. Clinical Doppler studies showed that the method is readily applicable and that a single large anterograde vortex develops in the healthy ventricle while supplementary retrograde swirling structures may appear in the diseased heart. The proposed echocardiographic method based on the continuity equation is fast, clinically-compliant and does not require complex training. This technique will potentially enable investigators to study of additional quantitative aspects of intraventricular flow dynamics in the clinical setting by high-throughput processing conventional color-Doppler images.
authors.affiliation: CRCHUM-Research Centre, University of Montreal Hospital, Montreal, QC H2L2W5, Canada.
authors.forename: Damien
authors.initials: D
authors.lastname: Garcia
authors.forename: Juan C
authors.initials: JC
authors.lastname: Del Alamo
authors.forename: David
authors.initials: D
authors.lastname: Tanne
authors.forename: Raquel
authors.initials: R
authors.lastname: Yotti
authors.forename: Cristina
authors.initials: C
authors.lastname: Cortina
authors.forename: Eric
authors.initials: E
authors.lastname: Bertrand
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Antoranz
authors.forename: Esther
authors.initials: E
authors.lastname: Perez-David
authors.forename: Régis
authors.initials: R
authors.lastname: Rieu
authors.forename: Francisco
authors.initials: F
authors.lastname: Fernandez-Aviles
authors.forename: Javier
authors.initials: J
authors.lastname: Bermejo
mesh_terms: D000465:Algorithms; D003326:Coronary Circulation / Q000502:physiology*; D018618:Echocardiography, Doppler, Color / Q000379:methods*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D016277:Ventricular Function, Left / Q000502:physiology*