Contrast‐enhanced computed tomography (CECT) attenuation is associated with stiffness of intact knee cartilage

Abstract

Contrast-enhanced computed tomography (CECT) using charged contrast-agents enables quantification of cartilage glycosaminoglycan content. Since glycosaminoglycan content is a key determinant of cartilage compressive stiffness, CECT measurements have the potential to non-invasively assess cartilage stiffness. The objective of this study was to determine whether CECT attenuation, using a cationic contrast-agent (CA4+), correlates with the stiffness of intact cartilage. Six fresh femoral and six fresh tibial compartments with intact cartilage were obtained from patients undergoing total knee replacement surgery. The instantaneous stiffness was determined for 25-50 points on the surface of each compartment using an established indentation technique. The samples were then immersed in CA4+ solution for 48 h, scanned in a micro-CT scanner, and the average CECT attenuation at each indentation site was found for the superficial cartilage. A significant (p < 0.01) and positive correlation was observed between stiffness and CECT attenuation for sites from each individual cartilage surface, with correlation coefficients ranging from r = 0.37-0.57 and r = 0.48-0.69 (p < 0.01) for the tibia and femur, respectively. When data for each type of cartilage surface were pooled together, the correlation coefficients were r = 0.73 for femoral condyle data points and r = 0.49 for tibial plateau data points. CECT provided a map of cartilage stiffness across each surface, which allows regions of low stiffness to be identified. These findings support continued evaluation and development of quantitative imaging techniques to assess the functional properties of cartilage. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2641-2647, 2018.

Contrast‐enhanced micro‐computed tomography of articular cartilage morphology with ioversol and iomeprol

“…The light blue-shaded curve shows the 95% confidence intervals for individual points, and the dark blue-shaded curve shows the 95% confidence interval curve for the mean bone CT attenuation in Figure 4. Our results supported our hypothesis, showing that unlike Hexabrix and CA4+ (Palmer et al, 2006;Cockman et al, 2006;Kallioniemi et al, 2007;Bansal et al, 2010;Xie et al, 2010;Yoo et al, 2011;Nickmanesh et al, 2018), there are no correlations between Optiray and Iomeron CECT attenuation and GAG content of cartilage ( Figure 7). This indicates that although Optiray and Iomeron are promising agents for morphological assessment of cartilage, they cannot be used as indicators of GAG loss related to OA.…”

“…The concentration and immersion time for both CAs were chosen based on the morphological assessment study, with adjustments in immersion time to offset the absence of subchondral bone, and solution concentration to target an attenuation value of approximately 4000 HU—slightly lower than the midpoint of no‐contrast cartilage and bone CT attenuation in Figure 4. Our results supported our hypothesis, showing that unlike Hexabrix and CA4+ (Palmer et al ., 2006; Cockman et al ., 2006; Kallioniemi et al ., 2007; Bansal et al ., 2010; Xie et al ., 2010; Yoo et al ., 2011; Nickmanesh et al ., 2018), there are no correlations between Optiray and Iomeron CECT attenuation and GAG content of cartilage (Figure 7). This indicates that although Optiray and Iomeron are promising agents for morphological assessment of cartilage, they cannot be used as indicators of GAG loss related to OA.…”

Tibial cartilage, subchondral bone plate and trabecular bone microarchitecture in varus‐ and valgus‐osteoarthritis versus controls

“…17 Micro-computed tomography (micro-CT) enables the nondestructive 3D assessment of entire excised human tibial plateaus at high resolutions. 10,[19][20][21] While historically used for the characterization of bone microarchitecture, [22][23][24][25] there is growing interest in using micro-CT for the examination of human tibial articular cartilage with contrast agents 20,21,[26][27][28] and without. 19,29,30 While studies have separately examined cartilage thickness, bone microarchitecture or joint alignment, to the best of our knowledge, these examinations have never been performed altogether in the same cohort.…”

Application of an indentation sensor for the arthroscopic measurement of articular cartilage stiffness

“…In addition, estimating the degeneration of cartilage is important in proposing treatment options for osteoarthritis patients. Recently, methods for non-invasive measurement of cartilage thickness have been reported, such as sodium MRI, contrast-enhanced computed tomography, and shear wave elastography 16–19 but it is a good opportunity to measure the stiffness of cartilage directly during endoscopic surgery. During endoscopic meniscus reconstruction or anterior cruciate ligament reconstruction, cartilage stiffness can be measured, and accumulating stiffness data for each age will provide a beneficial dataset.…”