Compositional MRI techniques for evaluation of cartilage degeneration in osteoarthritis

Abstract

Osteoarthritis (OA), a leading cause of disability, affects 27 million people in the United States and its prevalence is rising along with the rise in obesity. So far, biomechanical or behavioral interventions as well as attempts to develop disease-modifying OA drugs have been unsuccessful. This may be partly due to antiquated imaging outcome measures such as radiography, which are still endorsed by regulatory agencies such as the United States Food and Drug Administration (FDA) for use in clinical trials. Morphological magnetic resonance imaging (MRI) allows unparalleled multi-feature assessment of the OA joint. Furthermore, advanced MRI techniques also enable evaluation of the biochemical or ultrastructural composition of articular cartilage relevant to OA research. These compositional MRI techniques have the potential to supplement clinical MRI sequences in identifying cartilage degeneration at an earlier stage than is possible today using morphologic sequences only. The purpose of this narrative review is to describe compositional MRI techniques for cartilage evaluation, which include T2 mapping, T2* Mapping, T1 rho, dGEMRIC, gagCEST, sodium imaging and diffusion weighted imaging (DWI). We also reviewed relevant clinical studies that have utilized these techniques for the study of OA. The different techniques are complementary. Some focus on isotropy or the collagen network (e.g., T2 mapping) and others are more specific in regard to tissue composition, e.g., gagCEST or dGEMRIC that convey information on the GAG concentration. The application and feasibility of these techniques is also discussed, as they will play an important role in implementation in larger clinical trials and eventually clinical practice.

Does Periacetabular Osteotomy Have Depth-related Effects on the Articular Cartilage of the Hip?

“…Compositional MRI techniques such as delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), T2, T1rho, T2*, gagCEST, and sodium imaging all attempt to measure the biochemical composition of cartilage [12]. T2, T1rho, and dGEMRIC have been studied extensively in the knee, whereas most studies in the hip, to date, used dGEMRIC.…”

New Techniques in MR Imaging of the Ankle and Foot

“…T1 rho probes slow motion interactions between motion-restricted water molecules and their local macromolecular environment. In vitro studies demonstrated that depletion of proteoglycan resulted in increased T1 rho values, suggesting T1 rho estimates proteoglycan content 86,87 . There is some evidence that other factors, including collagen fiber orientation and concentration of other macromolecules, may contribute to T1 rho values 88 .…”

Magnetic resonance imaging of the knee: An overview and update of conventional and state of the art imaging

“…Resolution requirements to detect fissuring and fraying of cartilage are quoted at ∼0.3 mm, in‐plane . In contrast, compositional assessment of cartilage aims to evaluate molecular status of the fluid‐filled collagen and proteoglycan network comprising hyaline articular cartilage . Compositional cartilage imaging includes techniques such as T 2 mapping, delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC), sodium ion imaging, T 1 ρ ( T 1 rho) mapping, and diffusion‐weighted imaging …”

“…3D FSE techniques have demonstrated diagnostic accuracy similar to that of 2D FSE techniques . The 3D SPGR sequence, sometimes referred to as FLASH, is available for clinical use on many MRI systems . The main limitation of SPGR is the decreased contrast (compared to T 2 or proton density) between joint fluid and articular cartilage, which somewhat limits its sensitivity for surface defects .…”