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

Area of Science:

• Radiology
• Medical Imaging
• Orthopedics

Background:

• Magnetic Resonance (MR) arthrography requires optimal contrast agents for visualizing intra-articular structures.
• Current agents like saline have limitations in image contrast and sequence requirements.

Purpose of the Study:

• To identify the ideal contrast agent for MR arthrography by evaluating signal behavior and relaxation times (T1 and T2) of joint tissues.
• To compare the efficacy of various substances, including Gd-DTPA, albumin solutions, saline, Renografin, and air, as MR arthrography contrast agents.

Main Methods:

• Knee joints from cadavers and healthy volunteers were analyzed.
• Signal characteristics and T1/T2 values were measured for articular cartilage, menisci, and ligaments.
• Imaging was performed after intra-articular administration of Gd-DTPA, albumin-saline solutions, saline, Renografin, air, and blood.

Main Results:

• A 500-microM concentration of Gd-DTPA demonstrated excellent contrast differences with articular structures on T1-weighted images.
• A 12% albumin concentration, simulating severe inflammatory arthritis, provided adequate contrast for articular cartilage on T1-weighted images.
• Renografin and saline showed inadequate contrast on T1-weighted images; saline required T2-weighted sequences. Intra-articular blood offered insufficient contrast during the acute phase.

Conclusions:

• Gd-DTPA is a highly effective contrast agent for MR arthrography, offering significant advantages over current agents.
• Synovial fluid in severe arthritis may serve as a better biological contrast agent than fresh intra-articular blood.
• While saline is standard, Gd-DTPA warrants further safety testing for clinical application in MR arthrography.