Significance of xenon‐133 clearance rate from canine and human joints

Abstract

The clearance curve of 133Xe from canine and human knee joints has two monoexponential components. The rapid half clearance time is designated T1/2F and the slower T1/2S. 133Xe concentration in periarticular tissues was measured; the nuclide was predominately in the intraarticular fat during T1/2S and was distributed between the synovial fluid, synovial membrane and fat during T1/2F. Because of predominant tissue localization of 133Xe during T1/2S and T1/2F, T1/2S is thought to represent clearance from articular fat and T1/2F to represent clearance from synovial fluid and membrane. Use of xenon clearance to calculate the blood flow to synovium or articular fat requires several assumptions that cannot be experimentally verified at this time. Elevation of intraarticular pressure, but not intraarticular volume, decreased 133Xe clearance from both compartments. Crystal‐induced inflammation was usually associated with faster T1/2S, although in one human volunteer T1/2S was slower until a part of the inflammatory exudate was removed. On the other hand, T1/2F was variable. Copyright © 1972 American College of Rheumatology