Discrimination of healthy and osteoarthritic articular cartilage by Fourier transform infrared imaging and Fisher’s discriminant analysis

Zhi-Hua Mao,Jian-Hua Yin,Xiao Wang,Xue-Xi Zhang,Yang Xia

doi:10.1364/boe.7.000448

Abstract

Fourier transform infrared spectroscopic imaging (FTIRI) technique can be used to obtain the quantitative information of content and spatial distribution of principal components in cartilage by combining with chemometrics methods. In this study, FTIRI combining with principal component analysis (PCA) and Fisher's discriminant analysis (FDA) was applied to identify the healthy and osteoarthritic (OA) articular cartilage samples. Ten 10-μm thick sections of canine cartilages were imaged at 6.25μm/pixel in FTIRI. The infrared spectra extracted from the FTIR images were imported into SPSS software for PCA and FDA. Based on the PCA result of 2 principal components, the healthy and OA cartilage samples were effectively discriminated by the FDA with high accuracy of 94% for the initial samples (training set) and cross validation, as well as 86.67% for the prediction group. The study showed that cartilage degeneration became gradually weak with the increase of the depth. FTIRI combined with chemometrics may become an effective method for distinguishing healthy and OA cartilages in future.

Highlights

Articular cartilage (AC) is a type of connective tissue that covers the end of bone to reduce friction, distribute pressure and buffer vibration [1]
As the total accuracy was 86.67% for the prediction group, 94% for initial sample and cross validation, Fourier transform infrared spectroscopic imaging (FTIRI) combined with principal component analysis (PCA)-Fisher’s discriminant analysis (FDA) was effective and reliable to identify the healthy and OA cartilages
FTIRI was combined with PCA and FDA to identify the spectra from the healthy and OA sections at different depth

Summary

Introduction

Articular cartilage (AC) is a type of connective tissue that covers the end of bone to reduce friction, distribute pressure and buffer vibration [1]. It has a critical role during joint motion and loading. The uncalcified cartilage can be subdivided into three histological zones (superficial zone (SZ), transitional zone (TZ) and radial zone (RZ)) from the articular surface to subchondral bone [2]. The primary molecular components of the extracellular matrix in AC are type II collagen and proteoglycan (PG) [3]. Collagen forms the essential structural framework of fibro network that enmeshes PG molecules [4]. PG keeps the resiliency and compressive strength of AC [5]

Methods

Findings

Discussion

Conclusion