Potential contrast agents for MR arthrography: in vitro evaluation and practical observations

Abstract

In an attempt to identify an ideal contrast agent for MR arthrography, signal behavior as well as T1 and T2 values for articular cartilage, menisci, and ligaments were determined in knees from cadavers and normal volunteers. Comparison was made with similar data derived for intraarticular blood, varying concentrations of an albumin-saline solution (simulating synovial fluid) and Gd-DTPA, 0.9% saline, Renografin 60%, and air. Cadaveric specimens were imaged after intraarticular administration of each substance. A 500-microM volume of Gd-DTPA proved to be an ideal contrast agent for MR arthrography, exhibiting excellent contrast differences with articular structures on T1-weighted images. An albumin concentration of 12%, potentially occurring in severe inflammatory arthritis, also manifested adequate contrast to articular cartilage on T1-weighted images. Renografin and saline provided inadequate contrast on T1-weighted images, and saline necessitated the use of T2-weighted sequences. Air was not found to be an optimal contrast agent. Intraarticular blood exhibited insufficient contrast differences with articular cartilage during the acute hemorrhagic phase. Synovial fluid associated with severe arthritis as compared with fresh intraarticular hemorrhage may thus prove to be a better biological contrast agent for MR arthrography. Saline is currently recommended for use in arthrography, but Gd-DTPA offers significant advantages and should be safety-tested for potential clinical use.