Abstract
ObjectivesTo compare dynamic-contrast-enhanced MRI (DCE) and diffusion-weighted imaging (DWI) in quantifying synovial inflammation in juvenile idiopathic arthritis (JIA).MethodsRegions of interest (ROI) were drawn in the synovium of JIA patients on T1 DCE and T2 DWI, followed by extraction of the maximum enhancement (ME), maximum initial slope (MIS), time to peak (TTP), % of different time intensity curve shapes (TIC) and apparent diffusion coefficient (ADC) of the ROIs. Mann-Whitney-U test was used for comparing parameters between MRI-active and -inactive patients (defined by the juvenile arthritis MRI scoring system). Spearman’s rank was used to analyse the correlation between DCE and DWI.ResultsThirty-five JIA patients (18 MRI active and 17 MRI inactive) were included. Median age was 13.1 years and 71% were female. ME, MIS, TTP, % TIC 5 and ADC were significantly different in MRI-active versus MRI-inactive JIA with median ADC 1.49 × 10-3mm2/s in MRI-active and 1.25 × 10-3mm2/s in MRI-inactive JIA, p = 0.001, 95% confidence interval of difference in medians =0.11-0.53 × 10-3mm2/s. ADC correlated to ME, MIS and TIC 5 shapes (r = 0.62, r = 0.45, r = -0.51, respectively, all p < 0.05).ConclusionsSimilar to DCE parameters, DWI-derived ADC is significantly different in MRI-active JIA as compared to MRI-inactive JIA. The non-invasiveness of DWI combined with its possibility to detect synovial inflammation shows the potential of DWI.Key Points• MRI can quantify: dynamic contrast-enhanced and diffusion-weighted MRI can quantify synovitis• Both DWI and DCE can differentiate active from inactive JIA• The DWI-derived apparent diffusion coefficient (ADC) is higher in active JIA• DWI is non-invasive and thus safer and more patient-friendly• DWI is a potentially powerful and non-invasive imaging biomarker for JIA
Highlights
Interest in the role of magnetic resonance imaging (MRI) in juvenile idiopathic arthritis (JIA) is increasing, especially in detecting active disease and recognising early changes in JIA [1,2,3]
Five patients were excluded: four patients from the MRI-inactive JIA group were excluded because the synovium was too thin to draw Regions of interest (ROI); one patient was excluded because of an incomplete dynamic contrast-enhanced MRI (DCE) sequence resulting from discomfort and subsequent movement during contrast administration
Detection of synovial inflammation by the functional, noninvasive MRI sequence diffusionweighted imaging (DWI) as demonstrated in this study shows the potential of DWI as an imaging biomarker in the assessment of disease activity of the joints in rheumatologic diseases
Summary
Interest in the role of magnetic resonance imaging (MRI) in juvenile idiopathic arthritis (JIA) is increasing, especially in detecting active disease and recognising early changes in JIA [1,2,3]. Semi-quantitative and heuristic DCE parameters such as maximal enhancement of contrast (ME), time to peak (TTP), maximal initial slope of enhancement (MIS) and time intensity curves (TIC) have shown their value in determining disease activity in several studies in JIA [10, 11] and rheumatoid arthritis (RA) patients [12,13,14,15]. Measuring diffusion in the synovial membrane is novel, with only two studies reporting ADCs of the synovium in patients with JIA [17, 18]. Both studies did not include control patients or patients with inactive JIA. The lack of need for gadolinium-based contrast agent (GBCA) administration in DWI is of particular relevance, especially in the light of the recent findings of gadolinium deposition in the brain of patients who repeatedly underwent contrast-enhanced MRI [19,20,21,22,23]
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