Categorization of two-photon microscopy images of human cartilage into states of osteoarthritis

Abstract

The method is promising for early OA detection and categorization. In order to achieve a higher benefit for the physician the method must be transferred to an endoscopic setup for an application in surgery.

Collagen Organization Within the Cartilage of Trpv4−/− Mice Studied with Two‐Photon Microscopy and Polarized Second Harmonic Generation

“…In order to determine whether cartilage is malformed when TRPV4 is absent during development, our study was conducted using a label‐free imaging technique based on the measurement of the SHG signal under two‐photon excitation. The structure of the osteoarthritic cartilage has been investigated before using SHG, but data were obtained on cartilage samples subjected to mechanical load, either after surgical induction of OA in mice or from patients undergoing knee surgery for OA . Our present contribution aims to correlate the structural modifications of the cartilage matrix with molecular mechanisms affecting the chondrocytes (i.e., reduction of Ca 2+ transients due to the absence of the TRPV4 channels) at a time point post‐cartilage development but before the tissue has been subjected to ongoing mechanical loads, that is, in pups at P4–5.…”

“…We propose that significant differences with the WT mice could not be observed in the orientation of collagen fibers because at this stage of development, the mechanical load on the articular cartilage is minimal and compensatory mechanisms take place. Indeed, substantial modifications of the structure of the osteoarthritic cartilage have been observed 8 weeks after the surgical induction of OA in mice or in human samples where the advanced stage of OA progression required surgical replacement of the joint .…”

Assessment of Articular Cartilage by Second Harmonic Microscopy: Challenges and Opportunities

“…The discrimination ability of type-I and type-II collagen by p-SHM further adds to the characterization of articular cartilage, which might be advantageous for the postoperative evaluation of regenerated cartilage in the synovial-joint [26,33]. An image-processing algorithm that can automatically categorize two-photon autofluorescence images of human articular cartilage into states of OA has previously been demonstrated [34]. In this article, an algorithm based on artificial neuronal network (ANN) in combination with discrete wavelet transformation to determine image features for the classification of OA stage was presented.…”

“…Depending on the biomarker or morphological feature, it is expected that a rapid and accurate decision can be made via the direct visualization of SHM images. The inclusion of an automated image analysis algorithm to categorize the structural pattern and biomarker, as well as its relation to cartilage degeneration stage, can be more helpful [15,34]. Automated detection and categorizations of those features which couldn't be detected by arthroscope are highly desirable.…”