Movement artefact suppression in blood perfusion measurements using a multifrequency technique

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Signal Processing

Background:

• Conventional high-pass filters for Doppler measurements suppress movement artifacts but also eliminate low-velocity blood flow.
• Movement artifacts in Doppler signals are typically high in amplitude and low in frequency.

Purpose of the Study:

• To propose and evaluate a new method for reducing movement artifacts in blood perfusion measurements using a continuous-wave Doppler system.
• To overcome the limitations of traditional filtering techniques in preserving low-velocity blood flow information.

Main Methods:

• Simultaneous transmission and reception of multiple frequencies in a continuous-wave Doppler system.
• Utilizing the uncorrelated nature of blood Doppler signals and correlated nature of tissue movements for frequency separation.
• Employing a subtraction algorithm on time-domain processed perfusion estimates to suppress correlated signals.

Main Results:

• The proposed subtraction algorithm effectively reduces movement artifacts in both in vitro and in vivo models.
• The algorithm yields a linear perfusion estimate, though with increased standard deviation compared to channel averaging.
• Channel imbalance can lead to incomplete artifact reduction, which may be mitigated by pre-subtraction filtering, albeit introducing non-linearity.

Conclusions:

• The multi-frequency continuous-wave Doppler method offers a promising approach to mitigate movement artifacts in blood perfusion measurements.
• Careful implementation and potential pre-filtering are necessary to optimize artifact suppression and maintain estimate linearity.
• This technique has the potential to improve the accuracy of Doppler-based blood flow assessments.