In-vivo high resolution three-dimensional MRI studies of rat joints at 7 T.

It is important to obtain high resolution images of joints for the study of disease, especially in rodent experimental models. We optimized (1)H magnetic resonance imaging three-dimensional sequences at 7 T, with lipid signal suppression, and T(1) and T(2) measurements for in-vivo experiments on rat joints, in order to assess the effectiveness of high-field MRI. The method was validated by applying it to the early diagnosis of arthritis. We studied the progress of rheumatoid arthritis in an arthritic rat model. We observed the rats' knees for 21 days after inducing arthritis. The images acquired over one hour had a high resolution of 1.75 x 10(-3) mm(3), (105 x 105 x 145 microm(3)) which allowed us to spot the early stages of joint degeneration, such as bone erosion, and to observe an apparent 'MRI' loss of cartilage thickness, attributed to dehydration of the cartilage tissue. The MR images obtained during the early stages of rheumatoid arthritis enabled us to study joint changes accurately before any histological signs of attack were visible. Copyright 2003 John Wiley & Sons, Ltd.