Synovitis is an important feature in arthritis and is commonly visualised using contrast enhanced magnetic resonance imaging (MRI). Currently, the reference standard for assessing synovitis is gadolinium enhanced MRI which requires an intravenous injection and carries significant potential risks such as nephrogenic systemic fibrosis. Removing the necessity for using gadolinium will reduce these risks and result in greater patient acceptance of MRI investigation of synovitis.
The aims of the research were to investigate the use of MRI imaging sequences and include them in a novel non-contrast MRI protocol, The COSMOS protocol (Contrast-obviated MRI scanning of synovitis) to identify synovitis in the knees of patients with osteoarthritis.
Potential sequences, both qualitative and quantitative, that could be included in the COSMOS protocol were identified initially through (i) a comprehensive review of the literature and (ii) review of historic images within a large research centre. The sequences were then trialled, optimised and then assessed on a large cohort of patients (n=101) with knee osteoarthritis in order to determine the protocol’s suitability to identify synovitis without contrast.
The results of the new COSMOS protocol show that it is feasible and practical to delineate synovitis in the knee using MRI without the use of intravenous gadolinium contrast. The characteristics of the tissues within the knee can be measured using magnetisation transfer ratio and T1 values to provide empirical differentiation of structures. The identification of a distinct range in T1 values for synovitis provided data that was exploited to produce a further inversion recovery sequence that was optimised to supress synovitis in patients with knee osteoarthritis (OA).
While further work is required to validate the COSMOS protocol, this study has demonstrated that it is possible to image synovitis without intravenous gadolinium contrast agents in a cohort of patients with a clinical diagnosis of OA knee.
Read the lay summary of this research here COSMOS (345 downloads)