Advanced MR Imaging for Knee Osteoarthritis: A Review on Local and Brain Effects

Abstract

Knee osteoarthritis is one of the leading causes of chronic disability worldwide and is a significant social and economic burden on healthcare systems; hence it has become essential to develop methods to identify patients at risk for developing knee osteoarthritis at an early stage. Standard morphological MRI sequences are focused mostly on alterations seen in advanced stages of osteoarthritis. However, they possess low sensitivity for early, subtle, and potentially reversible changes of the degenerative process. In this review, we have summarized the state of the art with regard to innovative quantitative MRI techniques that exploit objective and quantifiable biomarkers to identify subtle alterations that occur in early stages of osteoarthritis in knee cartilage before any morphological alteration occurs and to capture potential effects on the brain. These novel MRI imaging tools are believed to have great potential for improving the current standard of care, but further research is needed to address limitations before these compositional techniques can be robustly applied in research and clinical settings.

Keywords: DGEMRIC; MRI; T1ρ mapping; T2-mapping; brain; knee osteoarthritis; quantitative imaging.

Figure 1

Axial T2 (A) and GRE (C), sagittal PD (B), and coronal STIR (D) MRI sequences showing features of severe knee osteoarthritis, including femoropatellar and femorotibial cartilage damage (blue arrows), effusion with synovitis (red arrows), marginal osteophytosis (green arrows), and subchondral bone marrow edema (yellow arrows).

Figure 2

Meniscal segmentation and software graphic interface to estimate quantitative T2 mapping curve.

Figure 3

DGEMRIC technique with inversion recovery (IR) images acquired with variable inversion time (IT) and the relative color-coded map of hyaline cartilage.