Glycosaminoglycan in articular cartilage: In vivo assessment with delayed Gd(DTPA)(2-)-enhanced MR imaging

PURPOSE: To investigate the feasibility of applying magnetic resonance (MR) imaging with use of an anionic compound, Gd(DTPA)(2-) (gadolinium diethylenetriaminepentaacetic acid), for measuring glycosaminoglycan concentration in human cartilage in clinical studies. MATERIALS AND METHODS: Penetration of Gd(DTPA)(2-) into cartilage was monitored through sequential T1-calculated images obtained after intraarticular (n = 2) or intravenous (n = 2) injection. T1-weighted and T1-calculated image series were then obtained in seven volunteers (nine knees) after penetration of Gd(DTPA)(2-) into cartilage. If T1 was heterogeneous on Gd(DTPA)(2-)-enhanced images, images were also obtained after penetration of the cartilage with the nonionic contrast agent, gadoteridol. RESULTS: Gd(DTPA)(2-) penetrated cartilage from the articular surface after intraarticular injection and from both the articular surface and the subchondral bone after intravenous injection. The latter resulted in shorter overall penetration time. T1 values on Gd(DTPA)(2-)-enhanced images were homogeneous in four knees, but in five knees T1 differences of up to 30% were observed. These T1 differences were not seen in the presence of gadoteridol. These variations in T1 reflected about 50% variations in glycosaminoglycan. CONCLUSION: The data suggest that Gd(DTPA)(2-)-enhanced MR imaging has potential for monitoring glycosaminoglycan content of cartilage in vivo.