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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
89
89-POS
Board 45
Detection and Characterization of Spontaneous Calcium Release Events in Cardiac
Myocytes
Alex Vallmitjana
1
, Carmen Tarifa
2
, Raul Benitez
1
.Leif Hove-Madsen
2
.
2
Institut Català de Ciències Cardiovasculars, Barcelona, Spain.
1
Universitat Politècnica de
Catalunya, Barcelona, Spain,
In cardiac function, calcium handling plays a critical role since it is responsible of the excitation-
contraction coupling at the cellular level. Indeed, the spontaneous release of intracellular calcium
in cardiac cells is a well-established mechanism underlying cardiac arrhythmias among other
heart pathologies. An accurate, robust detection of such spatio-temporal patterns is key to further
understand the cell physiology mechanisms underlying cardiac function and disease.
Most cell level studies in the past have focused in linescan (X-T) images which do not capture
spatial characteristics such as the release area, spatial dynamics or the localization with respect to
nearby subcellular structures.
We have developed an automatic image processing system that allows detecting, localizing and
characterizing calcium release events from a sequence of live cell fluorescence microscopy
images. The system is able to process both linescan and framescan (X-Y-T) image sequences and
detect different event release types such as sparks and calcium waves.
The system uses a multilevel wavelet analysis in order to identify events with a duration within a
given temporal range and a modified watershed segmentation algorithm in to determine the
space-time shape and centroid of the event. The event candidates are further filtered out using
morphological features such as amplitude, full width at half maximum or characteristic decay
time.
The method has been applied to an experimental database previously validated by a human
expert including a total of 621 events from 8 human atrial cardiomyocytes. As a measure of
overall performance, the approach achieves an average area under the ROC curve (AUC) of 0.8
with a standard error of 0.017.