The liver is a common site for metastases for multiple cancer types – with adenocarcinoma being the most common subtype. Standard pathology assessments fail to identify a site of origin for three to five percent of these patients, who are then treated in an empirical manner.1 Computational pathology is an ideal technology to improve diagnostic accuracy for metastatic cancers with a significant reduction in costs and increase in tissue preservation for future testing. Recently, Deep Learning (DL)-based algorithms have been developed to automatically identify the origination of metastases using only H&E-stained whole slide images as inputs.2 However, immunohistochemical based analysis is time- and resource-intensive and tissue destructive, while the “black box” nature of the DL-based approach makes it difficult if not impossible to explain the biology behind the classifier’s decision. This pilot study demonstrates that an analysis of computer extracted quantitative cellular features from tumor epithelial nuclei, including a tumor nuclei morphological feature and graph feature as well as cytoplasm texture from H&E stained histology slides, can be used to identify the origination of liver metastasis. Since the primary source of liver metastasis is typically the colon, breast, pancreas, or esophagus,3 a data set consisting of 120 patients with primary adenocarcinoma and matched liver metastases from the breast, colon, esophagus, and pancreas was constructed. A combination of supervised classification and unsupervised clustering was applied in order to identify the tumors’ origination using the above mentioned histomorphometric features from the data set. We evaluated the utility of histomorphometric features to identify the origination of the metastatic tumors in the liver using both supervised machine classifiers and unsupervised clustering. A Random Forest classifier achieved AUCs of 0.83, 0.63, 0.82, and 0.64 in classifying the primary or metastatic tumor from colon, esophagus, breast, and pancreas. The top performing features included local cellular diversity as well as cytoplasmic texture feature families. We further verified selected features using unsupervised methods such as UMAP, hierarchical clustering, and content-based image retrieving. Based off similarity measures calculated between image tiles in the primary and metastatic tissue, a heatmap corresponding to the WSIs for the primary tumor was constructed to highlight the sites representing potential points of origination of the metastases. Our preliminary results suggest that the site of origination for metastases in the context of primary breast tumors appears to be within the stroma.
Glandular features play an important role in the evaluation of prostate cancer. There has been significant interest in the use of 2D pathomics (feature extraction) approaches for detection, diagnosis, and characterization of prostate cancer on digitized tissue slide images. With the development of 3D microscopy techniques, such as open-top light-sheet (OTLS), there is an opportunity for rapid 3D imaging of large tissue specimens such as whole biopsies. In this study, we sought to investigate whether 3D features of gland morphology, namely volume and surface curvature, from OTLS images offer superior discrimination between malignant and benign glands compared to the traditional 2D gland features, namely area and curvature, alone. In this study, a cohort of 8 de-identified fresh prostate biopsies comprehensively imaged in 3D via the OTLS platform. A total of 367 glands were segmented from these images, of which 79 were identified as benign and 288 were identified as malignant. Glands were segmented using a 3D watershed algorithm followed by post-processing steps to filter out falsepositive regions. The 2D and 3D features were compared quantitatively and qualitatively. Our experiments demonstrated that a model using 3D features outperformed one using 2D features in differentiating benign and malignant glands. In 3D, both features, gland volume (p = 1.45 × 10−3) and surface curvature (p = 3.2 × 10−3), were found to be informative whereas in 2D, only gland area (p = 9 × 10−18) was found to be discriminating (p = 0.79 for 2D curvature). Notable visual and quantitative differences between 3D benign/malignant glands encourage the development of additional more sophisticated features in the future.
Lung adenocarcinoma (LUAD), the most common type of lung cancer, has an average 5-year survival rate of 15%. In LUAD, interaction between tumor and immune cells has been shown to be highly associated with the likelihood of disease progression and metastases. We have previously demonstrated the association between spatial architecture and arrangement of tumor-infiltrating lymphocytes (TILs) with likelihood of recurrence in early stage NSCLC. Recently, gene set enrichment analysis-derived immune scores have been found to be prognostic of outcome. However, this requires transcriptomics techniques as a precursor, which involves mechanical disruption of cells and tissues. In this work (N = 170), we extracted graph-based histomorphometric features on segmented nuclei from digitized H and E biopsy images and then performed principal component analysis (PCA) to select the most representative tiles from each patient. We then identified TILs and quantitative histomorphometric attributes of different nuclei groups (all-nuclei, TILs, non-TILs) prognostic of overall patient survival (OS) and further investigated their associations with immune scores and biological pathways implicated immune response using gene-set enrichment analysis (GSEA). We found TIL-compactness (a set of TIL density features) derived risk scores were prognostic of OS (Hazard Ratio (HR) = 3.26, p = 0.012, C-index = 0.634). The median immune score (IS) in the cohort was used as a threshold to divide the cases into low and high IS expression groups. The TIL compactness measures prognostic of OS were also statistically significantly correlated with the IS and biological pathways related to immune response (Immune System Process, Immune Response, Adaptive Immune Response, and Humoral Immune Response Mediated by Circulating Immunoglobulin).
Diabetic macular edema (DME) is a leading cause of vision loss in diabetic patients. The underlying cause for the onset of DME is the degradation of the blood-retinal barrier, whose primary function is maintaining the extracellular fluid at an optimal range. Vascular endothelial growth factor (VEGF) has proven to be a catalyst in altering the permeability of the blood-retinal barrier, thereby initiating a cascade of events that ultimately results in a loss of visual acuity.1 The primary imaging techniques to recognize and diagnose DME are fluorescein angiography (FA) and spectral-domain optical coherence tomography (SD-OCT). Taking a multimodal approach of FA in combination with SD-OCT provides images of vasculature and other eye structures to help better identify key features such as level, location, and amount of leakage.2 First-line treatments for DME have now evolved to using anti-VEGF to inhibit the effects VEGF has on increasing the permeability of the blood-retinal barrier.3 Because VEGF also increases the chance of leakage, we can also expect anti-VEGF treatments to decrease the amount of leakage DME patients suffer from. Anti-VEGF treatments also have a peripheral effect of modifying the disease burden and allowing for extended time in between treatments.4 Although current conventional treatment parameters exist to determine the efficacy of such VEGF treatments, many of these markers rely on clinicians to make a judgment call based on a minor qualitative difference of retinal scans or involve clinicians taking a fluid assessment, an option deemed too invasive to demand from all patients. In this work, we seek to find new imaging features that derive from a sub-visual feature analysis, and ideally provide a prognostic metric for clinicians to help streamline the diagnostic process. The rationale for these new biomarkers derives from leakage properties and their activity in the retina once edema develops. A decrease in leakage within certain structures in the eye would also lead to a change in the densities of leakage patterns, correlating with better clinical outcomes. In this work, we use morphological and graph-based attributes to model the global properties and spatial distribution of leakage areas on baseline FA scans of patients subsequently treated with intravitreal anti-VEGF therapy (i.e. aibercept). The features were then used in conjunction with a classifier to distinguish between eyes tolerating extended dosing intervals (N=15) and those eyes requiring more frequent dosing (N=12), based on initial response following treatment interval extension. The cross-validated area under the receiver operating characteristic curve (AUC) was found to be 0.74±0.11% using the computed imaging attributes. Edge length disorder of minimum spanning tree showed a statistically significant difference (p=0.007) between the two groups. Clinical parameters such as central subfield thickness and macular volume were not statistically significantly different. Our results indicate that there may be differences in spatial distribution of leakage areas between eyes that will exhibit favorable response to extended interval aibercept dosing and eyes that require more frequent dosing.
Automated detection and segmentation of nuclei from high-resolution histopathological images is a challenging problem owing to the size and complexity of digitized histopathologic images. In the context of breast cancer, the modified Bloom–Richardson Grading system is highly correlated with the morphological and topological nuclear features are highly correlated with Modified Bloom–Richardson grading. Therefore, to develop a computer-aided prognosis system, automated detection and segmentation of nuclei are critical prerequisite steps. We present a method for automated detection and segmentation of breast cancer nuclei named a convolutional neural network initialized active contour model with adaptive ellipse fitting (CoNNACaeF). The CoNNACaeF model is able to detect and segment nuclei simultaneously, which consist of three different modules: convolutional neural network (CNN) for accurate nuclei detection, (2) region-based active contour (RAC) model for subsequent nuclear segmentation based on the initial CNN-based detection of nuclear patches, and (3) adaptive ellipse fitting for overlapping solution of clumped nuclear regions. The performance of the CoNNACaeF model is evaluated on three different breast histological data sets, comprising a total of 257 H&E-stained images. The model is shown to have improved detection accuracy of F-measure 80.18%, 85.71%, and 80.36% and average area under precision-recall curves (AveP) 77%, 82%, and 74% on a total of 3 million nuclei from 204 whole slide images from three different datasets. Additionally, CoNNACaeF yielded an F-measure at 74.01% and 85.36%, respectively, for two different breast cancer datasets. The CoNNACaeF model also outperformed the three other state-of-the-art nuclear detection and segmentation approaches, which are blue ratio initialized local region active contour, iterative radial voting initialized local region active contour, and maximally stable extremal region initialized local region active contour models.
Automatic detection of lymphocytes could contribute to develop objective measures of the infiltration grade of tumors, which can be used by pathologists for improving the decision making and treatment planning processes. In this article, a simple framework to automatically detect lymphocytes on lung cancer images is presented. This approach starts by automatically segmenting nuclei using a watershed-based approach. Nuclei shape, texture, and color features are then used to classify each candidate nucleus as either lymphocyte or non-lymphocyte by a trained SVM classifier. Validation was carried out using a dataset containing 3420 annotated structures (lymphocytes and non-lymphocytes) from 13 1000 × 1000 fields of view extracted from lung cancer whole slide images. A Deep Learning model was trained as a baseline. Results show an F-score 30% higher with the presented framework than with the Deep Learning approach. The presented strategy is, in addition, more flexible, requires less computational power, and requires much lower training times.
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