This paper proposes a texture analysis technique that can effectively
classify different types of human breast tissue imaged by Optical Coherence
Microscopy (OCM). OCM is an emerging imaging modality for rapid tissue screening
and has the potential to provide high resolution microscopic images that
approach those of histology. OCM images, acquired without tissue staining,
however, pose unique challenges to image analysis and pattern classification. We
examined multiple types of texture features and found Local Binary Pattern (LBP)
features to perform better in classifying tissues imaged by OCM. In order to
improve classification accuracy, we propose novel variants of LBP features,
namely average LBP (ALBP) and block based LBP (BLBP). Compared with the classic
LBP feature, ALBP and BLBP features provide an enhanced encoding of the texture
structure in a local neighborhood by looking at intensity differences among
neighboring pixels and among certain blocks of pixels in the neighborhood.
Fourty-six freshly excised human breast tissue samples, including 27 benign
(e.g. fibroadenoma, fibrocystic disease and usual ductal hyperplasia) and 19
breast carcinoma (e.g. invasive ductal carcinoma, ductal carcinoma in situ and
lobular carcinoma in situ) were imaged with large field OCM with an imaging area
of 10×10mm2
(10, 000 × 10,
000 pixels) for each sample. Corresponding H&E histology was obtained for
each sample and used to provide ground truth diagnosis. 4310 small OCM image
blocks (500 × 500 pixels) each paired with
corresponding H&E histology was extracted from large-field OCM images and
labeled with one of the five different classes: adipose tissue (n =
347), fibrous stroma (n = 2,065), breast lobules (n = 199),
carcinomas (pooled from all sub-types, n = 1,127), and background
(regions outside of the specimens, n = 572). Our experiments show that
by integrating a selected set of LBP and the two new variant (ALBP and BLBP)
features at multiple scales, the classification accuracy increased from
81.7% (using LBP features alone) to 93.8% using a neural network
classifier. The integrated feature was also used to classify large-field OCM
images for tumor detection. A receiver operating characteristic (ROC) curve was
obtained with an area under the curve value of 0.959. A sensitivity level of
100% and specificity level of 85.2% was achieved to
differentiate benign from malignant samples. Several other experiments also
demonstrate the complementary nature of LBP and the two variants (ALBP and BLBP
features) and the significance of integrating these texture features for
classification. Using features from multiple scales and performing feature
selection are also effective mechanisms to improve accuracy while maintaining
computational efficiency.