Imaging and quantifying transverse flow velocity with the Doppler bandwidth in a phase-resolved functional optical coherence tomography.

The Doppler bandwidth extracted from the standard deviation of the frequency shift in phase-resolved functional optical coherence tomography (F-OCT) was used to image the velocity component that is transverse to the optical probing beam. It was found that above a certain threshold level the Doppler bandwidth is a linear function of flow velocity and that the effective numerical aperture of the optical objective in the sample arm determines the slope of this dependence. The Doppler bandwidth permits accurate measurement of flow velocity without the need for precise determination of flow direction when the Doppler flow angle is within +/-15 degrees perpendicular to the probing beam.

Blood flow velocity profiles in the aortic annulus: a 3-dimensional freehand color flow Doppler imaging study.

Background: The use of a single sample volume in Doppler measurements of the velocity time integral (VTI) in the aortic annulus may introduce errors in calculations of stroke volumes, shunts, regurgitant fractions, and aortic valve area. To study the blood flow velocity distribution and assess this potential error, we used a dynamic 3-dimensional color flow Doppler imaging method.

Methods And Results: Seventeen healthy volunteers were studied.

Velocity profiles in mitral blood flow based on three-dimensional freehand colour flow imaging acquired at high frame rate.

Aims: To describe the mitral blood flow velocity distribution, we applied a freehand dynamic three-dimensional (3D) colour flow method using a moving sample surface that followed the mitral apparatus during diastole.

Methods: Nineteen healthy volunteers were studied. The ultrasound data were captured from 10-20 heartbeats at high frame rate (mean 46 frames/s) while freely tilting the transducer in an apical position.

Measurement of volumetric mitral and aortic blood flow based on a new freehand three-dimensional colour flow imaging method. An in vivo validation.

Aims: To validate a new three-dimensional (3D) colour flow method used to calculate cardiac output (CO) in aortic and mitral blood flow.

Methods: The transducer was freely tilted transthoracically using a magnetic locating device recording its spatial position. Raw digital ultrasound data were recorded in healthy subjects during 10-20 heartbeats at a high frame rate ranging from 41 to 66 frames/s and analysed off-line with no loss in temporal resolution.