Coefficient of variation as an image-intensity metric for cytoskeleton bundling

• Published in: Scientific reports Vol. 10; no. 1; p. 22187
• Main Authors: Higaki, Takumi, Akita, Kae, Katoh, Kaoru
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.12.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 631/114; 631/80; Actin Cytoskeleton - chemistry; Actin Cytoskeleton - ultrastructure; Analysis of Variance; Arabidopsis - chemistry; Arabidopsis - ultrastructure; Cell Line; Confocal microscopy; Cytoskeleton; Cytoskeleton - chemistry; Cytoskeleton - ultrastructure; Humanities and Social Sciences; Image Processing, Computer-Assisted; Laser Scanning Cytometry; Microscopy; Microscopy, Confocal; Microscopy, Fluorescence; multidisciplinary; Nicotiana - chemistry; Nicotiana - ultrastructure; Noise; Plants, Genetically Modified; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-79136-x

The evaluation of cytoskeletal bundling is a fundamental experimental method in the field of cell biology. Although the skewness of the pixel intensity distribution derived from fluorescently-labeled cytoskeletons has been widely used as a metric to evaluate the degree of bundling in digital microscopy images, its versatility has not been fully validated. Here, we applied the coefficient of variation (CV) of intensity values as an alternative metric, and compared its performance with skewness. In synthetic images representing extremely bundled conditions, the CV successfully detected degrees of bundling that could not be distinguished by skewness. On actual microscopy images, CV was better than skewness, especially on variable-angle epifluorescence microscopic images or stimulated emission depletion and confocal microscopy images of very small areas of around 1 μm 2 . When blur or noise was added to synthetic images, CV was found to be robust to blur but deleteriously affected by noise, whereas skewness was robust to noise but deleteriously affected by blur. For confocal images, CV and skewness showed similar sensitivity to noise, possibly because optical blurring is often present in microscopy images. Therefore, in practical use with actual microscopy images, CV may be more appropriate than skewness, unless the image is extremely noisy.