Whole Slide Imaging and Its Applications to Histopathological Studies of Liver Disorders

Abstract

Histological analysis of hepatic tissue specimens is essential for evaluating the pathology of several liver disorders such as chronic liver diseases, hepatocellular carcinomas, liver steatosis, and infectious liver diseases. Manual examination of histological slides on the microscope is a classically used method to study these disorders. However, it is considered time-consuming, limited, and associated with intra- and inter-observer variability. Emerging technologies such as whole slide imaging (WSI), also termed virtual microscopy, have increasingly been used to improve the assessment of histological features with applications in both clinical and research laboratories. WSI enables the acquisition of the tissue morphology/pathology from glass slides and translates it into a digital form comparable to a conventional microscope, but with several advantages such as easy image accessibility and storage, portability, sharing, annotation, qualitative and quantitative image analysis, and use for educational purposes. WSI-generated images simultaneously provide high resolution and a wide field of observation that can cover the entire section, extending any single field of view. In this review, we summarize current knowledge on the application of WSI to histopathological analyses of liver disorders as well as to understand liver biology. We address how WSI may improve the assessment and quantification of multiple histological parameters in the liver, and help diagnose several hepatic conditions with important clinical implications. The WSI technical limitations are also discussed.

Keywords: digital pathology; digital slide; hepatic tissue; histology; histopathology; liver disorders; virtual microscopy; whole slide imaging.

Figure 1

A representative whole-slide image of a human liver biopsy showing hepatocellular carcinoma. Sample was stained with hematoxylin and eosin and viewed with a digital scanner.

Figure 2

Examples of whole-slide images of human liver biopsies showing fibrosis. Samples were stained with hematoxylin and eosin (A) or Gomori trichrome (B) and viewed with a digital scanner.

Figure 3

Whole slide imaging of a liver section showing granulomas elicited by Schistosoma mansoni infection in mice. After loading the slides (A) in the scanner (B), a built-in digital camera captures the entire tissue section and viewer software generates a high-resolution digital slide (C), which can be assessed by the operator by selecting and marking the area (s) of interest for qualitative and quantitative analyses. In (D), a representative digital slide in which granulomas and non-granulomatous inflammatory regions were manually outlined for subsequent morphometric evaluations using associated software. In (E,F), granulomas are seen at high magnification. The equipment and software illustrated in this figure are 3D Histech Pannoramic scanner and Pannoramic Viewer 1.15.2 SP2 RTM software, respectively.

Figure 4

Hepatic steatosis evaluation using whole slide imaging. (A) A representative view of an entire liver section stained with Oil Red O (ORO) and counterstained with hematoxylin-eosin (HE). Observe at high magnification in (B) a tissue area with numerous lipid droplets (LDs) seen as round structures stained in red within hepatocytes. In (Bi), hepatocyte nuclei were marked in orange whereas cytoplasmic LDs were outlined in green within individual hepatocytes. Quantification of the marked elements (Bii) with associated software enables steatosis evaluation in large areas of the liver. ORO and HE staining were performed on cryosections from rat liver fragments fixed in buffered paraformaldehyde. After staining, glass slides were digitized using an automated scanner.