Comparison of optical coherence tomography and histopathology in quantitative assessment of goat talus articular cartilage

Abstract

Background and purpose Optical coherence tomography (OCT) is a light-based imaging technique suitable for depiction of thin tissue layers such as articular cartilage. Quantification of results and direct comparison with a reference standard is needed to confirm the role of OCT in cartilage evaluation.Materials and methods Goat talus articular cartilage repair was assessed quantitatively with OCT and compared with histopathology using semi-automated analysis software. Osteochondral defects were created centrally in goat tali with subsequent healing over 24 weeks. After sacrifice, the tali were analyzed using OCT and processed into histopathology slides. Cartilage thickness, repair tissue area, and surface roughness were measured. Also, light attenuation coefficient measurements were performed to assess differences in the properties of healthy tissue and repair tissue.Results Intra-class correlation coefficients for resemblance between the 2 techniques were 0.95 (p < 0.001) for thickness, 0.73 (p = 0.002) for repair tissue area, and 0.63 (p = 0.015) for surface roughness. Light attenuation differed significantly between healthy cartilage (8.2 (SD 3.9) mm-1) and repair tissue (2.8 (SD 1.5) mm-1) (p < 0.001).Interpretation Compared to histopathology as the standard reference method, OCT is a reproducible technique in quantitative analysis of goat talus articular cartilage, especially when assessing cartilage thickness and to a lesser extent when measuring repair tissue area and surface roughness. Moreover, differences in local light attenuation suggest measurable variation in tissue structure, enhancing the clinical applicability of quantitative measurements from cartilage OCT images.

Semi‐automated International Cartilage Repair Society scoring of equine articular cartilage lesions in optical coherence tomography images

“…This may be attributable to lower resolutions of the OCT images, effectively limiting the minimal discernible roughness of the cartilage surface, and the possible expansion of lesions during the preparation of histological samples. Additionally, the difficulty of matching the planes of histology and OCT images exactly should be acknowledged because only a small discrepancy in the orientation of a slide may result in different scoring outcomes [12,19]. Furthermore, in the present study, the osteochondral samples were subjected to one freeze-thaw cycle prior to OCT analysis and one prior to histological processing.…”

“…Therefore, the calculation of quantitative parameters such as the ORI and relative lesion depth as a percentage of cartilage thickness is essential. Other quantitative OCT parameters of articular cartilage determined by (semi-)automated software analysis that have been reported recently include cartilage thickness, repair tissue area, various surface roughness parameters, and homogeneity, attenuation and backscattering indices [12,14,[27][28][29][30]. A combination of these quantitative parameters is of particular relevance in the detection of early degenerative changes in areas surrounding articular cartilage lesions.…”

“…Earlier studies reported the additional value of optical coherence tomography (OCT) during conventional arthroscopy, which results in the more accurate determination of morphological characteristics of cartilage lesions and better quantification of parameters such as cartilage thickness, surface roughness and repair tissue area [11,12]. Levels of intra-and interobserver agreement in International Cartilage Repair Society (ICRS) scoring of focal lesions based on OCT images were shown to be significantly better than in arthroscopic images [13].…”

Contrast enhanced μCT imaging of early articular changes in a pre-clinical model of osteoarthritis

“…While many of the histological hallmarks of OA progression have been measured using EPIC-mCT analysis, cartilage surface roughness changes associated with fibrillation 15 has not yet been quantified using this technique. Quantitative local measurements of cartilage surface roughness have been performed with other imaging modalities, including optical coherence tomography 16 , scanning electron microscopy 17 , and atomic force microscopy 17 , but these local measures are useful only in small areas in relation to the entire surface of a rat tibia and are usually destructive techniques. Ultrasound has shown some utility in detecting changes in cartilage surface roughness in cartilage plugs 18e22 , intact rabbit joints 23 , and ex vivo rat joints 24 .…”

Nondestructive Techniques to Evaluate the Characteristics and Development of Engineered Cartilage

“…46, 99, 100, 113, 134, 162 In addition, OCT is sensitive to collagen orientation and fibrillation, which makes it well suited for evaluating osteoarthritic and repaired tissue. 29, 34, 60, 92, 162 Using OCT areas of fibro-cartilage that are indicative of attempted but inadequate repair have been identified, although these might not be observed on visual arthroscopic examination of a joint. 34, 60 Using OCT, differences in the ultrastructural features of regenerated cartilage, and the integration of host and regenerated tissue have been evaluated.…”