Quantitative measurement of cartilage morphology in osteoarthritis: current knowledge and future directions

Abstract

Quantitative measures of cartilage morphology (“cartilage morphometry”) extracted from high resolution 3D magnetic resonance imaging (MRI) sequences have been shown to be sensitive to osteoarthritis (OA)-related change and also to treatment interventions. Cartilage morphometry is therefore nowadays widely used as outcome measure for observational studies and randomized interventional clinical trials. The objective of this narrative review is to summarize the current status of cartilage morphometry in OA research, to provide insights into aspects relevant for the design of future studies and clinical trials, and to give an outlook on future developments. It covers the aspects related to the acquisition of MRIs suitable for cartilage morphometry, the analysis techniques needed for deriving quantitative measures from the MRIs, the quality assurance required for providing reliable cartilage measures, and the appropriate participant recruitment criteria for the enrichment of study cohorts with knees likely to show structural progression. Finally, it provides an overview over recent clinical trials that relied on cartilage morphometry as a structural outcome measure for evaluating the efficacy of disease-modifying OA drugs (DMOAD).

Updates on Compositional MRI Mapping of the Cartilage: Emerging Techniques and Applications

“…It usually requires high‐resolution 3D sequences with sufficient contrast between cartilage and surrounding tissues, assessing morphological features such as cartilage area, volume, and thickness. Cartilage morphometry has shown great repeatability 46 . Also, morphometry with DL is an interesting approach to evaluating the loss of cartilage in longitudinal studies 47 .…”

“…Morphological changes in cartilage in OA can also be quantitatively assessed by segmenting and measuring the segmented cartilage, in a process known as cartilage morphometry. 46 It usually requires high-resolution 3D sequences with sufficient contrast between cartilage and surrounding tissues, assessing morphological features such as cartilage area, volume, and thickness. Cartilage morphometry has shown great repeatability.…”

“…Cartilage morphometry has shown great repeatability. 46 Also, morphometry with DL is an interesting approach to evaluating the loss of cartilage in longitudinal studies. 47 Despite these advantages, morphometry cannot assess premorphological changes in the cartilage ECM compared to most quantitative compositional MRI methods.…”

“…48 Currently, DL approaches have been among the most commonly used and efficient methods for segmenting cartilage. Cartilage segmentation and quantification are important for understanding disease-related structural changes in subjects with or at risk for OA 46 and serve as a pre-requisite to extracting relevant cartilage compositional MRI biomarkers such as T 2 relaxation time. 94 Manual segmentation, though usually used as a gold standard, is labor-intensive and subjective to operator bias and error.…”

Osteoarthritis, part of life or a curable disease? A bird's‐eye view

“…For research purposes, a number of new MRI sequences and processing techniques have been developed to determine the changes of joint structures, including cartilage morphometry [61] and changes to bone shape [62]. In addition, compositional in vivo imaging techniques with MRI-such as T2 and T1rho relaxation time mapping-will provide new insights, in particular into the early development of OA, whereas joint structures are relatively macroscopically intact [63,64].…”