Trajectory of cartilage loss within 4 years of knee replacement--a nested case-control study from the osteoarthritis initiative.
OBJECTIVE In 1994, the first article on quantitative magnetic resonance imaging (qMRI) of articular cartilage was published, and tremendous progress in image acquisition, image analysis, and applications has since been made. The objective of this personal perspective is to highlight milestones in the field of qMRI of cartilage and other articular tissues over these past 20 years. METHODS Based on a Pubmed search of original articles, the authors selected 30 articles which they deemed to be among the first to provide an important technological step forward in qMRI of cartilage, provided a first application in a particular context, or provided mechanistic insight into articular cartilage physiology, pathology, or treatment. RESULTS This personal perspective summarizes results from these 30 articles. Further, the authors provide examples of how qMRI of cartilage has translated to quantitative analysis approaches of other articular tissues, including bone, meniscus, and synovium/edema. Eventually, the report provides a summary of how the lessons learned might be applied to future clinical trials and clinical practice. CONCLUSIONS Over the past 20 years, quantitative imaging of articular tissues has emerged from a method to a dynamic field of research by its own. Continuing the qMRI biomarker qualification process will be crucial in convincing regulatory agencies to accept these as primary outcomes in phase 3 intervention trials. Once successful structural intervention will actually become available in OA, qMRI biomarkers may play an essential role in monitoring response to therapy in the clinic, and in stratifying disease phenotypes that respond differently to treatment.