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Proceedings Paper

Separation of calcium transients and motion artifact using frequency filtering of fluorescent signals arising from the perfused mouse heart
Author(s): Congwu Du; Yingtian Pan; Guy A. MacGowan; Alan P. Koretsky
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Paper Abstract

To eliminate the influence of motion artifacts on measurements of intracellular calcium, a technique was developed using frequency domain analysis which filters motion artifact from the calcium transient signal arising from the perfused mouse heart using the calcium sensitive, fluorescent dye Rhod-2. The perfused mouse heart was stimulated at 8 Hz and placed in a water-jacketed chamber at 37 degree(s)C. After a washout period following Rhod-2 loading, ~6-fold increase in fluorescence above background was detected spectrofluorimetrically at 589nm when excited at 524 nm. Calcium dependent fluorescence transients mixed with motion artifacts and system noise were measured. Simultaneously, heart motion was monitored by recording the reflected excitation light from the heart. A Fourier transform was utilized to separate signals arising from the fluorescence transients and those resulting from motion in the frequency domain. Several major steps were adopted to implement the algorithm for elimination of motion as well as system instability from the transient signals. These included 1) extracting the fluorescence calcium transient signal from the raw data in the frequency domain by subtracting the motion recorded using the reflectance of excitation light, 2) digitally filtering out the random noise using multiple bandpass filters centralized at harmonic frequencies of the 8 Hz signal, and 3) extracting high frequency noise with the Kernel method. Comparing the processed signal of transients acquired with excessive motion artifact to transients acquired with minimal motion obtained by immobilizing the heart against the detection window demonstrated that the filtering techniques helped minimize the effects of motion.

Paper Details

Date Published: 5 June 2002
PDF: 6 pages
Proc. SPIE 4623, Functional Monitoring and Drug-Tissue Interaction, (5 June 2002); doi: 10.1117/12.469472
Show Author Affiliations
Congwu Du, Carnegie Mellon Univ. and National Institutes of Health (United States)
Yingtian Pan, Univ. of Pittsburgh (United States)
Guy A. MacGowan, Univ. of Pittsburgh (United States)
Alan P. Koretsky, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 4623:
Functional Monitoring and Drug-Tissue Interaction
Manfred D. Kessler; Gerhard J. Mueller, Editor(s)

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