Image classification of human carcinoma cells using complex wavelet-based covariance descriptors

Abstract

Cancer cell lines are widely used for research purposes in laboratories all over the world. Computer-assisted classification of cancer cells can alleviate the burden of manual labeling and help cancer research. In this paper, we present a novel computerized method for cancer cell line image classification. The aim is to automatically classify 14 different classes of cell lines including 7 classes of breast and 7 classes of liver cancer cells. Microscopic images containing irregular carcinoma cell patterns are represented by subwindows which correspond to foreground pixels. For each subwindow, a covariance descriptor utilizing the dual-tree complex wavelet transform (DT-[Formula: see text]WT) coefficients and several morphological attributes are computed. Directionally selective DT-[Formula: see text]WT feature parameters are preferred primarily because of their ability to characterize edges at multiple orientations which is the characteristic feature of carcinoma cell line images. A Support Vector Machine (SVM) classifier with radial basis function (RBF) kernel is employed for final classification. Over a dataset of 840 images, we achieve an accuracy above 98%, which outperforms the classical covariance-based methods. The proposed system can be used as a reliable decision maker for laboratory studies. Our tool provides an automated, time- and cost-efficient analysis of cancer cell morphology to classify different cancer cell lines using image-processing techniques, which can be used as an alternative to the costly short tandem repeat (STR) analysis. The data set used in this manuscript is available as supplementary material through http://signal.ee.bilkent.edu.tr/cancerCellLineClassificationSampleImages.html.

Figure 1. Sample images from different cancer cell line classes.

a) BT-20, b) Focus, c) HepG2, d) MDA-MB-157, e) MV, f) PLC, g) SkHep1, h) T47D.

Figure 2. Examples of misclassified images (20×).

Misclassified images are shown in the first column. Examples from their true cell line are given in the second column. Images in the third column show examples of the cell line that the images got misclassified into.

Figure 3. Filterbanks for the dual-tree complex wavelet transform.

Figure 4. Examples of segmentation into foreground and background.

a) Original image, b) EM Segmentation, c) EM segmentation followed by morphological closing and median filtering.