Decreasing motion artifacts in calcium-dependent fluorescence transients from the perfused mouse heart using...

Area of Science:

• Cardiovascular Physiology
• Biomedical Optics
• Signal Processing

Background:

• Calcium transients are crucial for understanding heart function.
• Motion artifacts and noise significantly impede accurate analysis of fluorescence signals.
• Existing methods for artifact removal are often insufficient.

Purpose of the Study:

• To develop and validate a novel frequency filtering strategy for removing motion artifacts and noise from calcium-dependent fluorescence transients in the perfused mouse heart.
• To improve the accuracy and reliability of fluorescence-based measurements of cardiac function.

Main Methods:

• Utilized frequency filtering based on Fourier analysis and the shift theorem to separate motion artifacts from fluorescence signals.
• Employed power spectrum density (PSD) to extract the calcium transient signal by subtracting motion data obtained via reflectance.
• Applied digital bandpass filters at harmonic frequencies and a Gaussian Kernel filter to eliminate random and high-frequency noise.

Main Results:

• The developed analytical model demonstrated that spectral removal of motion artifacts is independent of motion waveform phase shifts.
• Processed fluorescence transients acquired with significant motion artifact were comparable to those obtained from immobilized hearts.
• The technique successfully eliminated motion artifacts and detection noise from Rhod-2 fluorescence signals.

Conclusions:

• The frequency filtering strategy provides an effective method for removing motion artifacts and noise in cardiac calcium transient analysis.
• This technique enhances the quality of fluorescence signals, facilitating more accurate assessment of cardiac dynamics.
• The method offers a valuable tool for researchers studying heart function using fluorescence imaging.