Delayed contrast-enhanced MRI of cartilage (dGEMRIC) is a noninvasive technique to study cartilage glycosaminoglycan (GAG) content in vivo. This study evaluates dGEMRIC in patients with preradiographic degenerative cartilage changes. Seventeen knees in 15 patients (age 35-70) with arthroscopically verified cartilage changes (softening and fibrillations) in the medial or lateral femoral compartment, knee pain, and normal weight-bearing radiography were included. MRI (1.5 T) was performed precontrast and at 1.5 and 3 hr after an intravenous injection of Gd-DTPA 2؊ at 0.3 mmol/kg body weight. T 1 measurements were made in regions of interest in medial and lateral femoral cartilage using sets of five turbo inversion recovery images. Precontrast, R 1 (R 1 ‫؍‬ 1/T 1 , 1/s) was slightly lower in diseased compared to reference compartment, indicating increased hydration (P ‫؍‬ 0.01). Postcontrast, R 1 was higher in diseased than in reference compartment at 1.5 hr, 3.45 ؎ 0.90 and 2.64 ؎ 0.58 (mean ؎ SD), respectively (P < 0.01), as well as at 3 hr, 2.94 ؎ 0.60 and 2.50 ؎ 0.37, respectively (P ‫؍‬ 0.01). The washout of the contrast medium was faster in diseased cartilage as shown by a higher R 1 at 1.5 than at 3 hr in the diseased but not in the reference compartment. In conclusion, dGEMRIC can identify GAG loss in early stage cartilage disease with a higher sensitivity at 1.5 than 3 hr. Magn Reson Med 49: 488 -492, 2003.

The negatively charged contrast agent Gd-DTPA 2-distributes inversely to the cartilage fixed charged density. This enables structural cartilage examinations by contrast-enhanced MRI. In line with the development of a clinically applicable protocol for such examinations, this study describes the temporal pattern of Gd-DTPA 2-distribution in femoral knee cartilage at three different doses in healthy volunteers. Nineteen volunteers (ages 21-28 years) were examined with a 1.5T MRI system. Quantitative relaxation rate measurements were made in weight-bearing central parts of femoral cartilage using sets of five turbo inversion recovery images with different inversion times.

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is a new imaging technique to estimate joint cartilage glycosaminoglycan content by T 1 -relaxation time measurements after penetration of the hydrophilic contrast agent Gd-DTPA 2-. This study compares dGEMRIC in age-matched healthy volunteers with different levels of physical activity: Group 1 (n ‫؍‬ 12): nonexercising individuals; Group 2 (n ‫؍‬ 16): individuals with physical exercise averaging twice weekly; Group 3 (n ‫؍‬ 9): male elite runners. dGEMRIC was performed 2 hr after an intravenous injection of Gd-DTPA 2-at 0.3 mmol/kg body weight.

Objective. To examine the glycosaminoglycan (GAG) content in cartilage and that in synovial fluid and determine whether they are associated, in patients with an acute anterior cruciate ligament (ACL) injury.Methods. Twenty-four patients (14 of whom were male) with a mean age of 27 years (range 17-40 years) were assessed with delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage an average of 3 weeks after an ACL rupture and compared with 24 healthy volunteers. Two hours after an intravenous injection of Gd-DTPA 2؊ (0.3 mmoles/kg body weight), quantitative measurements of the T1 relaxation time (T1 Gd [T1 relaxation time in the presence of Gd-DTPA]) were made in lateral and medial femoral weight-bearing cartilage. In the patients, synovial fluid was aspirated immediately before the MRI, and GAG was analyzed using dye precipitation with Alcian blue.Results. Fifteen of the 24 patients had an isolated bone bruise in the lateral femoral condyle, where the cartilage T1 Gd was shorter than that in the controls (mean ؎ SD 385 ؎ 83 msec and 445 ؎ 41 msec, respectively; P ‫؍‬ 0.004), consistent with decreased GAG content. However, the T1 Gd was also decreased in the medial femoral cartilage, where bone bruises were rare (376 ؎ 76 msec in patients versus 428 ؎ 38 msec in controls; P ‫؍‬ 0.006). The mean ؎ SD synovial fluid GAG concentration in patients was 157 ؎ 86 g/ml and showed a positive correlation with the T1 Gd (r ‫؍‬ 0.49, P ‫؍‬ 0.02).Conclusion. This study indicates that an ACL injury causes posttraumatic edema of the lateral femoral cartilage but initializes a generalized biochemical change within the knee that leads to GAG loss from both lateral and medial femoral cartilage. In cartilage with a high GAG content (long T1 Gd ), more GAG is released into the synovial fluid, suggesting that cartilage quality is a factor to consider when interpreting cartilage biomarkers of metabolism.

Eight asymptomatic volunteers and 10 patients with early hip osteoarthritis (OA) were investigated with hip delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) at 30, 65, 100, and 135 min after IV injection with Gd-DTPA 2-. In asymptomatic volunteers there was a decrease in the dGEMRIC index (T 1 (Gd)) between 30 and 100 min. In patients the wash-in of Gd-DTPA 2-was faster, with a low T 1 (Gd) at 30 min that did not change significantly over time. Therefore, earlier time points showed a larger separation in T 1 (Gd) between asymptomatic and OA hips, with more convenient timing logistics. However, T 1 (Gd) at 30 min had a larger standard deviation (SD) in the OA group, possibly due to variability of the steep slope of wash-in. This sensitivity to the imaging window may be less desirable for longitudinal studies in which reproducibility is a concern. At all time points, T 1 (Gd) was 20 -30% lower in patients than in asymptomatic volunteers (P < 0.003), which demonstrates the sensitivity of dGEMRIC to early hip OA. Magn Reson Med 57: 803-805, 2007.