Simple computational technique to quantify nuclear shape asymmetry

Abstract

The nucleus of an eukaryotic cell is a membrane-bound organelle containing a major part of the cellular genome. Nuclear shape is controlled by forces generated in the cytoskeleton, nuclear envelope and matrix of the nucleus and may change when the balance of these forces is disturbed. In certain cases, such changes may be indicative of cell pathology. Nuclear shape feature is being commonly addressed in both experimental research and diagnostics; nevertheless its symmetry-related aspects receive little attention. This article introduces a technique allowing to estimate nuclear shape asymmetry in digital images captured from cyto-or histological preparations. Implemented in a software package, this technique quantifies the asymmetry using two scenarios. The first one presumes the identification of nuclear pixels laying outside the largest inscribed circle. According to the second scenario, the algorithm searches for nuclear pixels lacking pixelpartners symmetric with respect to the nuclear area's centroid. In both cases, the proportion of "asymmetric" pixels is used to estimate the feature of interest. The technique was validated on images of cell nuclei having distinctive shape phenotypes. A conclusion was made that shape asymmetry feature may be useful accessory to the toolbox of nuclear morphometry. V C 2014 International Society for Advancement of Cytometry

Evaluating Nuclear Membrane Irregularity for the Classification of Cervical Squamous Epithelial Cells

“…The nuclei of cervical squamous epithelial cells are nearly spherical, which change to oblate spheroidal due to cells flattening during smear preparation. Under microscope, nuclei appear to have near circular profile (that is, round or oval) [ 18 ]. Alteration in nuclear shape is either due to changes in the nuclear lamina or by forces from the cytoplasm [ 28 , 29 ].…”

“…Statistical analysis was performed to seek any significant differences among the three diagnostic classes. Studies have reported various methods of nuclear shape evaluation [ 18 – 22 ]. Performance of the proposed techniques was compared with three techniques of nuclear shape evaluation in the literature, namely, radial asymmetric (RA) [ 18 ], shape factor (SF) [ 18 ], and rim difference (RD) [ 23 ].…”

“…Studies have reported various methods of nuclear shape evaluation [ 18 – 22 ]. Performance of the proposed techniques was compared with three techniques of nuclear shape evaluation in the literature, namely, radial asymmetric (RA) [ 18 ], shape factor (SF) [ 18 ], and rim difference (RD) [ 23 ]. Briefly, a technique employing RA initially computes the centroid of the nuclear area to be used as the center to inscribe the largest circle in a nuclear area.…”

“…Briefly, a technique employing RA initially computes the centroid of the nuclear area to be used as the center to inscribe the largest circle in a nuclear area. RA is the proportion of the nuclear pixels lying outside the inscribed circle [ 18 ]. SF, which is mathematically expressed as Eq ( 1 ), is another nuclear shape metric in [ 18 ].…”

“…RA is the proportion of the nuclear pixels lying outside the inscribed circle [ 18 ]. SF, which is mathematically expressed as Eq ( 1 ), is another nuclear shape metric in [ 18 ]. SF of a perfect circle is one.…”