New Technology in Imaging Cartilage of the Ankle

Abstract

The incidence of osteochondral lesions, as well as osteoarthritis of the ankle joint following osteochondritis dissecans and trauma, has been reappraised in recent years. Consequently, an increasing number of surgical interventions using different cartilage repair techniques is performed in the ankle joint, which has resulted in a growing demand for repetitive and objective assessment of cartilage tissue and its repair. While morphological imaging does enable monitoring of macroscopic changes with increasing precision, it fails to provide information about the ultrastructural composition of cartilage. The significance of molecular changes in cartilage matrix composition, however, is increasingly recognized, as it is assumed that macroscopic cartilage degeneration is preceded by a loss in glycosaminoglycans and a disorganization of the collagen network. Recent advances in biochemical magnetic resonance imaging (MRI) have yielded sequences sensitive to these changes, thus providing invaluable insight into both early cartilage degeneration and maturation of repair tissue, on a molecular level. The aim of this review was to provide a comprehensive overview of these techniques, including water and collagen-sensitive T2/T2* mapping, as well as glycosaminoglycan-sensitive sequences such as delayed gadolinium-enhanced MRI of cartilage dGEMRIC, and sodium imaging, and describe their applications for the ankle joint.

A 24-Month Follow-Up Study of the Effect of Intra-Articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis

“…We used the pairwise t-test for paired and subsequent measurements of the same patient or a knee. Within-individual variation was defined on the basis of the dGEMRIC error rates, which were based on previously published papers, and this indicated that the mean difference per region of interest between the two T1Gd measurements ranged from 3.7% to 6.8% [14,16,18]. Based on this, we defined the arbitrary change of 15% in subsequent measurements as clinically relevant, and considered this as the liminal value (on the basis of two standard deviations from the estimated error rate).…”

“…We estimated a percentage change of the dGEMRIC results and estimated the number of clinically relevant improvements vs. deteriorations in each patient ( Figures S1-S10), where a 15% change was considered a relevant change (based on the error rates acquired from the available literature and our studies) [14].…”

“…Therefore, healthy cartilage that contains an abundance of GAGs will have low concentrations of Gd-DTPA2, whereas degraded cartilage will have high concentrations of the contrast agent in the areas where GAGs have been lost. T1-relaxation times are inversely proportional to the concentration of Gd-DTPA2, and thus provide a quantitative metric of cartilage integrity [12][13][14]. In this study, we hypothesized that there are changes in the composition of the articular cartilage extracellular matrix after administration of autologous and microfragmented fat tissue in patients with knee osteoarthritis that are detectable by the means of pre-structural cartilage assessment using MRI [7].…”

The Effect of Intra-articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis

“…In this study, we used delayed gadolinium (Gd)-enhanced magnetic resonance imaging of cartilage (dGEMRIC) in order to assess proteoglycan synthesis. dGEMRIC is a molecular imaging technique that has been used to study glycosaminoglycan (GAG) loss in the articular cartilage of patients with primary OA [ 25 , 26 ], and it can be readily used on patients with cruciate ligament injury [ 27 , 28 ]. With dGEMRIC, T1-maps of hyaline cartilage are created following the intravenous (IV) administration of an anionic gadolinium-based contrast agent gadopentetate dimeglumine (Gd-DTPA 2− ).…”

Post-traumatic ankle osteoarthritis: quality of life, frequency and associated factors

“…This is the principal difference for increased cartilage degeneration and the high rate of primary OA in the knee. Moreover the cartilage of the ankle is thinner with respect to knee or hip, but owns a higher compressive stiffness, proteoglycan density, lower matrix degradation, and less response to catabolic stimulations (25)(26)(27). (18).…”