Department of Computer Science and Engineering, Lehigh University, Bethlehem, PA 18015, USA.
Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, MIT, Cambridge, MA 02139, USA.
Med Image Anal. 2017 May;38:104-116. doi: 10.1016/j.media.2017.03.002. Epub 2017 Mar 8.
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 × 10 mm (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.
本文提出了一种纹理分析技术,可有效分类光学相干显微镜(OCM)成像的不同类型的人类乳腺组织。OCM 是一种新兴的快速组织筛选成像方式,具有提供接近组织学的高分辨率微观图像的潜力。然而,未经组织染色的 OCM 图像对图像分析和模式分类提出了独特的挑战。我们研究了多种类型的纹理特征,发现局部二值模式(LBP)特征在分类 OCM 成像的组织方面表现更好。为了提高分类准确性,我们提出了 LBP 特征的新变体,即平均 LBP(ALBP)和基于块的 LBP(BLBP)。与经典 LBP 特征相比,ALBP 和 BLBP 特征通过观察局部邻域中相邻像素和邻域中某些像素块之间的强度差异,提供了对纹理结构的增强编码。46 个新鲜切除的人类乳腺组织样本,包括 27 个良性(例如纤维腺瘤、纤维囊性疾病和普通导管增生)和 19 个乳腺癌(例如浸润性导管癌、导管原位癌和小叶原位癌)用大视场 OCM 成像,每个样本的成像面积为 10×10mm(每个样本 10000×10000 像素)。为每个样本获得相应的 H&E 组织学,并用于提供地面实况诊断。从大视场 OCM 图像中提取了 4310 个小 OCM 图像块(500×500 像素),每个图像块都与相应的 H&E 组织学配对,并标记为五个不同类别之一:脂肪组织(n=347)、纤维基质(n=2065)、乳腺小叶(n=199)、癌(所有亚型的合并,n=1127)和背景(标本外区域,n=572)。我们的实验表明,通过整合一组选定的 LBP 和两个新变体(ALBP 和 BLBP)特征,分类准确性从使用 LBP 特征的 81.7%提高到使用神经网络分类器的 93.8%。集成特征还用于分类大视场 OCM 图像以进行肿瘤检测。获得了曲线下面积为 0.959 的接收器工作特征(ROC)曲线。实现了 100%的灵敏度和 85.2%的特异性来区分良性和恶性样本。其他几个实验还证明了 LBP 及其两个变体(ALBP 和 BLBP 特征)的互补性,以及集成这些纹理特征进行分类的重要性。使用多尺度特征和执行特征选择也是提高准确性同时保持计算效率的有效机制。