Image Registration: The Navigation System for Digital Pathology Diagnostics and Biomedical Research
DOI: https://doi.org/10.47184/tp.2025.01.02 Image registration is the automatic alignment of similar images such as consecutive tissue sections in pathology diagnostics and biomedical research. In a digital workflow, image registration allows pathologists to seamlessly switch between various stains, minimizing repetitive navigation tasks and thereby streamlining the diagnostic procedure. In research, it integrates direct and third-party information from differently stained slides, combining otherwise separate information in pharmacological studies and biomarker discovery. For this integration to work in practice, image registration must be robust against variations found in routine pathology images, such as differences in stain intensity and artifacts, to ensure widespread applicability. Diverse approaches are possible for registration: feature-based, intensity-based, deep learning, and combinations thereof. As computational pathology continues to advance, leveraging image registration technologies significantly improves diagnostic efficiency and accuracy, paving the way for enhanced patient outcomes and groundbreaking research discoveries.
rigid transformation, deformable transformation, image viewer, image management system
Pathology routine diagnostics involves multiple repetitive steps such as examining Whole Slide Images (WSIs), procuring additional samples, analyzing patient non-image data, maintaining diagnostic principles, drafting reports, and participating in video conferences on short notice. Rapid execution is sometimes necessary, particularly during histopathological rapid incision examination.
One task when examining differently stained consecutive slides is the repeated identification of corresponding regions of interest across multiple slides. This is especially relevant in examinations such as breast and prostate cancer diagnostics, which typically require a series of consecutive slides, stained with various immunohistochemical (IHC) reagents. To streamline the workflow, it is crucial to minimize time-consuming navigation tasks. In road transport, navigation assistance is omnipresent; why should it be any different for pathology?
Image registration provides a solution: By automatically aligning all consecutive tissue sections from a block, pathologists can navigate between stains without losing focus on the key areas.
Biomedical Research
Beyond guiding users to their desired destination, image registration in histology integrates the information from distinct immunohistochemical or immunofluorescent slides. It also combines the results from third party analysis tools, enhancing the overall synthesis of information. Merging data from multiple stained slides is beneficial for pharmacological research, where often only a combination of markers in a specific area is relevant for prognosis.
What is Image Registration?
Originating in applied mathematics, image registration describes the process of finding a reasonable image transformation to achieve optimal similarity between images. Transformations can be either rigid or deformable. Rigid transformations are represented by a global transformation rule composed of rotation and translation, affecting the whole image. On the contrary, deformable transformations deform individual points “elastically” within a grid overlayed on the image. Typically, images are first preliminarily aligned using a global, rigid transformation, followed by a detailed local deformation for each grid point (Fig. 1).
