RESUMO
OBJECTIVE: Our aim was to test the feasibility of blood oxygen level dependent magnetic resonance imaging (BOLD MRI) and dynamic contrast-enhanced (DCE) MRI to monitor periarticular hypoxic/inflammatory changes over time in a juvenile rabbit model of arthritis. METHODS: We examined arthritic and contralateral nonarthritic knees of 21 juvenile rabbits at baseline and days 1,14, and 28 after induction of arthritis by unilateral intra-articular injection of carrageenin with BOLD and DCE MRI at 1.5 Tesla (T). Nine noninjected rabbits served as controls. Associations between BOLD and DCE-MRI and corresponding intra-articular oxygen pressure (PO2) and blood flow [blood perfusion units (BPU)] (polarographic probes, reference standards) or clinical-histological data were measured by correlation coefficients. RESULTS: Percentage BOLD MRI change obtained in contralateral knees correlated moderately with BPU on day 0 (r = -0.51, p = 0.02) and excellently on day 28 (r = -0.84, p = 0.03). A moderate correlation was observed between peak enhancement DCE MRI (day 1) and BPU measurements in arthritic knees (r = 0.49, p = 0.04). In acute arthritis, BOLD and DCE MRI highly correlated (r = 0.89, p = 0.04; r = 1.0, p < 0.0001) with histological scores in arthritic knees. CONCLUSION: The proposed techniques are feasible to perform at 1.5 T, and they hold potential as surrogate measures to monitor hypoxic and inflammatory changes over time in arthritis at higher-strength MRI fields. KEY POINTS: ⢠BOLD and DCE MRI detect interval perisynovial changes in a rabbit knee ⢠BOLD and DCE MRI act as surrogate markers of physiologic changes in arthritis ⢠BOLD MRI signal represents oxygen extraction compared with intra-articular PO 2 ⢠DCE MRI measurements estimate physiologic periarticular vascular properties ⢠In rabbit knees with acute arthritis, BOLD/DCE MRI highly correlated with histological scores.