Delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) in early knee osteoarthritis

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Abstract
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‐DTPA2− at 0.3 mmol/kg body weight. T1 measurements were made in regions of interest in medial and lateral femoral cartilage using sets of five turbo inversion recovery images. Precontrast, R1 (R1 = 1/T1, 1/s) was slightly lower in diseased compared to reference compartment, indicating increased hydration (P = 0.01). Postcontrast, R1 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 R1 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.