QUANTIFICATION OF SYNOVITIS BY MRI - CORRELATION BETWEEN DYNAMIC AND STATIC GADOLINIUM-ENHANCED MAGNETIC-RESONANCE-IMAGING AND MICROSCOPIC AND MACROSCOPIC SIGNS OF SYNOVIAL INFLAMMATION

Dynamic and static gadolinium-diethylenetriaminepentaacetic acid(Gd-DT PA)-enhanced magnetic resonance imaging (MRI) were evaluated as measur es of joint inflammation in arthritis, by a comparison with macroscopi c and microscopic signs of synovitis, Furthermore, the importance of t he size of the evaluated synovial areas was investigated, as was the o ptimal time for enhancement measurements. Seventeen rheumatoid arthrit is knees and 25 osteoarthritis knees, scheduled for arthroscopy or art hrotomy, were included. Macroscopic end microscopic synovial inflammat ion as well as nine histologic tissue characteristics were graded at f our preselected biopsy sites. Preoperative T-1-weighted dynamic fast l ow angle shot and static spin-echo Gd-enhanced MRT were performed. The dynamic enhancement rate and the static enhancement were measured in the entire synovial membrane of a preselected slice as well as at the four biopsy sites, and compared to synovial pathology. The rate of ear ly enhancement of the total synovial membrane of the preselected slice , determined by dynamic MRI, was highly correlated with microscopic ev idence of active inflammation (Spearman rho = 0.73; p < 10(-7) Dynamic MRI could distinguish knees with and without synovial inflammation wi th a high predictive value (0.81-0.90). Moderate and severe inflammati on could not be differentiated. The early enhancement rate was correla ted with histologic features of active inflammation, particularly vess el proliferation and mononuclear leucocyte infiltration. Dynamic evalu ation of small synovial sections at the biopsy sites and static spin-e cho MRI resulted in considerably weaker correlations to histologic inf lammation than dynamic evaluation of the total synovium, The optimal t ime for enhancement measurements was one-half to one minute after Gd i njection, as the highest correlation coefficients to histologic inflam mation were observed in this interval. Dynamic MRI can be used to dete rmine synovial inflammation. Evaluation of large synovial areas one-ha lf to one minute after Gd injection best reflects joint inflammation. (C) 1998 Elsevier Science Inc.