MR imaging of the arthritic rabbit knee joint using albumin (Gd-DTPA)(30) with correlation to histopathology

The purpose of this study was to demonstrate a technique, in a pilot study, for measuring abnormal capillary permeability in synovial tissue of rabbit arthritic knees using dynamic MRI with a gadolinium-based blood pool agent . Arthritis, simulating rheumatoid arthritis, was induced in knees of 8 rab bits by intra-articular injection of carrageenan (n = 4) or ovalbumin (n = 4), Sequential fat presaturated T-1-weighted Spoiled Grass images were obta ined before and up to 30 min after intravenous administration of albumin-(G d-DTPA)(30). Estimates of synovial tissue plasma-volume (PV), fractional-le ak-rate (FLR), and permeability-surface-area-product (PS) were computed. Hi stologic correlation was obtained in the corresponding regions. Dynamic MRI showed extravasation of albumin-(Gd-DTPA)(30) into hypertrophic synovium i n six of the eight arthritic knees. Histologic examination of these six kne es showed markedly inflamed synovium, The two knees that did not show abnor mal vascular permeability contained non-hypertrophic synovium, None of the rabbits showed abnormal permeability in muscle. MRI derived microvascular c haracteristics (PV, FLR and PS) correlated positively (r(2) = 0.51, 0.97 an d 0.86) with the histology, Factors involving the structural and functional microvascular characteristics of synovial tissue can be estimated non-inva sively using albumin-(Gd-DTPA)(30). This technique may be useful for monito ring disease progression and treatment response in rheumatoid arthritis. (C ) 1999 Elsevier Science Inc.