Objective-The performance characteristics of hyaline articular cartilage measurement on magnetic resonance imaging (MRI) need to be accurately delineated before widespread application of this technology. Our objective was to assess the rate of natural disease progression of cartilage morphometry measures from baseline to 1 year in knees with osteoarthritis (OA) from a subset of participants from the Osteoarthritis Initiative (OAI).Methods-Subjects included for this exploratory analysis are a subset of the approximately 4700 participants in the OAI Study. Bilateral radiographs and 3T MRI (Siemans Trio) of the knees and clinical data were obtained at baseline and annually in all participants. 160 subjects from the OAI Progression subcohort all of whom had both frequent symptoms and, in the same knee, radiographic OA based on a screening reading done at the OAI clinics were eligible for this exploratory analysis. One knee from each subject was selected for analysis. 150 participants were included. Using sagittal 3D DESSwe (double echo, steady-state sequence with water excitation) MR images from the baseline and 12 follow-up month visit, a segmentation algorithm was applied to the cartilage plates of the index knee to compute the cartilage volume, normalised cartilage volume (volume normalised to bone surface interface area), and percentage denuded area (total cartilage bone interface area denuded of cartilage).Results-Summary statistics of the changes (absolute and percentage) from baseline at 1 year and the standardised response mean (SRM), ie, mean change divided by the SD change were calculated. On average the subjects were 60.9 years of age and obese, with a mean body mass index of 30. Despite being extraordinarily prevalent OA remains a condition that is poorly understood, and a condition for which available effective therapeutic options are limited to symptomatic treatment. The development of therapies aimed at joint preservation in OA is constrained by the slow progress of the condition, its heterogeneous clinical manifestations and the need for long-term follow-up to observe changes in structure. NIH Public AccessNew technologies may improve the assessment of early disease development, and progression, and could greatly facilitate measurement of structural outcomes in OA clinical trials. Foremost among these is magnetic resonance imaging (MRI), a sensitive non-invasive method for assessing joint morphology. 5 6 MRI is ideally suited for imaging arthritic joints as: (1) it is free of ionising radiation; (2) it defines both calcified as well as soft tissue joint components; and (3) its tomographic viewing perspective obviates morphological distortion, magnification and superimposition. MRI of the knee can directly visualise hyaline articular cartilage and cover the whole joint in one examination, meaning that the cartilage defects in the joint can be visualised directly regardless of their location. 5Although yet to be formally accepted by regulatory authorities, many experts now agree that MRI may b...

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