Suitability of T1Gd as the "dGEMRIC index" at 1.5T and 3.0T

Abstract

Delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) is based on the theory that Gd-DTPA2- will distribute in inverse relation to cartilage glycosaminoglycan (GAG). T1Gd (T1 after penetration of a 0.2 mmol/kg dose of Gd-DTPA2-) has been used as the dGEMRIC index, although (1/T1Gd-1/T1o) should be more representative of Gd-DTPA2- concentration (where T1o = T1 before contrast). T1o and T1Gd were measured in 20 volunteers at both 1.5T and 3T and the correlation between the metrics of T1Gd and (1/T1Gd-1/T1o) was calculated. There was a high correlation coefficient between the two metrics at both field strengths, with R = 0.94, 0.93, and 0.90 for central medial femur, posterior medial femur, and medial tibia, respectively, at 1.5T and 0.87, 0.94, 0.96 at 3T. In all cases P < 0.0001. Therefore, these data suggest that, for native cartilage, the current practice of measuring T1Gd (but not also T1o) is adequate at both 1.5T and 3T. © 2007 Wiley-Liss, Inc.