Advancing Imaging of the Hip: Cartilage

Developmental dysplasia of the hip is a common risk factor of early osteoarthritis (OA). Current classical non-invasive magnetic resonance imaging (MRI) methods can be used to identify qualitative, macroscopic alterations of cartilage related to gross thickness and integrity. However, these structural changes in the cartilage often manifest late in the OA progression. In the early stage of OA, changes of the biochemical composition occur in the extracellular matrix of the cartilage. This chapter discusses quantitative MRI techniques that are sensitive to these early biochemical changes in the cartilage tissue that can be used to evaluate the hip cartilage. The concepts of the most common methods for biochemical assessment of the hip cartilage (dGEMRIC, T2, T2∗ and T1ρ mapping) are introduced and their application in the context of hip dysplasia is discussed. The necessary infrastructure for setup, conduction, and evaluation of biochemical sensitive hip cartilage MR imaging is outlined. The data post-processing steps are presented, showing the necessary steps involved to generate, analyze, and interpret the quantitative cartilage maps. The quantitative MRI cartilage mapping methods discussed are promising tools for clinical researchers to examine structural and biochemical changes in the cartilage that occur in hip dysplasia.