3D histopathological grading of osteochondral tissue using contrast-enhanced micro-computed tomography

• Published in: Osteoarthritis and cartilage Vol. 25; no. 10; pp. 1680 - 1689
• Main Authors: Nieminen, H.J, Gahunia, H.K, Pritzker, K.P.H, Ylitalo, T, Rieppo, L, Karhula, S.S, Lehenkari, P, Hæggström, E, Saarakkala, S
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-10-2017; W.B. Saunders For The Osteoarthritis Research Society
• Subjects: Aged; Aged, 80 and over; Arthroplasty, Replacement, Knee; Calcinosis - diagnostic imaging; Cartilage, Articular - diagnostic imaging; Cartilage, Articular - pathology; Contrast Media; Extracellular Matrix - pathology; Feasibility Studies; Histology; Humans; Imaging; Micro-computed tomography; Middle Aged; Observer Variation; Osteoarthritis; Osteoarthritis, Knee - diagnostic imaging; Osteoarthritis, Knee - pathology; Osteoarthritis, Knee - surgery; Pathology; Rheumatology; Severity of Illness Index; X-Ray Microtomography - methods; Pathology; Histology; Micro-computed tomography; Osteoarthritis; Imaging
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2017.05.021

Summary Objective Histopathological grading of osteochondral (OC) tissue is widely used in osteoarthritis (OA) research, and it is relatively common in post-surgery in vitro diagnostics. However, relying on thin tissue section, this approach includes a number of limitations, such as: (1) destructiveness, (2) sample processing artefacts, (3) 2D section does not represent spatial 3D structure and composition of the tissue, and (4) the final outcome is subjective. To overcome these limitations, we recently developed a contrast-enhanced μCT (CEμCT) imaging technique to visualize the collagenous extracellular matrix (ECM) of articular cartilage (AC). In the present study, we demonstrate that histopathological scoring of OC tissue from CEμCT is feasible. Moreover, we establish a new, semi-quantitative OA μCT grading system for OC tissue. Results Pathological features were clearly visualized in AC and subchondral bone (SB) with μCT and verified with histology, as demonstrated with image atlases. Comparison of histopathological grades (OARSI or severity (0–3)) across the characterization approaches, CEμCT and histology, excellent (0.92, 95% CI = [0.84, 0.96], n  = 30) or fair (0.50, 95% CI = [0.16, 0.74], n  = 27) intra-class correlations (ICC), respectively. A new μCT grading system was successfully established which achieved an excellent cross-method (μCT vs histology) reader-to-reader intra-class correlation (0.78, 95% CI = [0.58, 0.89], n  = 27). Conclusions We demonstrated that histopathological information relevant to OA can reliably be obtained from CEμCT images. This new grading system could be used as a reference for 3D imaging and analysis techniques intended for volumetric evaluation of OA pathology in research and clinical applications.