Implementation of spectral width Doppler in pulsatile flow measurements.

Area of Science:

• Medical Imaging
• Ultrasound Technology
• Biomedical Engineering

Background:

• Current clinical Doppler ultrasound requires manual vessel axis setting for accurate flow velocity measurement.
• Manual alignment introduces potential errors in estimating beam-vector angle and corrected flow velocity.

Purpose of the Study:

• To develop and implement an automatic method for measuring beam-vector (Doppler) angle and flow velocity.
• To validate the method in pulsatile flow measurements using a clinical Doppler ultrasound system.

Main Methods:

• Utilized an annular array transducer to generate a conical, focused ultrasound beam.
• Measured flow velocity vectors parallel and perpendicular to the ultrasound beam axis.
• Calculated beam-vector angle and flow velocity from Doppler spectrum mode (f(d)) and maximum frequency (f(max)).
• Developed a spectrum normalization algorithm for Doppler spectrum averaging within a cardiac cycle.
• Applied spectrum averaging to reduce noise and enable pulsatile flow analysis.

Main Results:

• Successfully implemented an automatic method for Doppler angle and flow velocity measurement.
• In vivo validation demonstrated low standard deviations: < 2.2 degrees for beam-vector angles and < 12 cm/s (13.3%) for flow velocities.
• Measurements were verified across a wide range of angles (52 to 80 degrees) in the carotid artery.

Conclusions:

• The developed automatic method accurately measures beam-vector angle and flow velocity in pulsatile Doppler ultrasound.
• This automated approach enhances precision and reduces operator dependency compared to manual methods.
• The technique shows significant potential for improved clinical flow velocity assessments.