Feasibility of Dual Flip Angle-Based Fast 3-Dimensional T1 Mapping for Delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage of the Knee: A Histologically Controlled Study.

Abstract

The aim of the study was to validate dual-flip angle-based fast 3-dimensional (3D) T1 mapping for delayed gadolinium-enhanced magnetic resonance imaging (MRI) of cartilage (dGEMRIC) by means of histological analyses in the assessment of the cartilage of the knee in a porcine model. A total of 15 mini pigs were included in this study. The left knee anterior cruciate ligaments of all mini pigs were transected. The mini pigs were divided into 3 groups postoperatively, with 5 pigs randomly assigned to 1 group. Dual-flip angle-based fast T1 mapping for dGEMRIC was obtained in the sagittal planes at 0 week (group 1), 3 weeks (group 2), and 6 weeks (group 3) after operation, using an 8-channel knee coil. Magnetic resonance imaging was performed at 3T with dual-flip angle-based fast 3D T1 mapping sequence for morphological cartilage assessment of dGEMRIC T1 values. After MRI analysis, histological and biochemical composition (water, collagen, and glycosaminoglycan [GAG]) of the knee cartilage in the medial femoral condyle was quantified ex vivo. The T1 values obtained by the dual-flip angle-based fast 3D T1 mapping were positively correlated with the glycosaminoglycan content (r = 0.85; P < 0.05). The values had no significant correlation with the collagen content. The dGEMRIC-T1 values obtained by this method showed the medial femoral condyle cartilage in the anterior cruciate ligament-transected knee after transection decreased with time (P < 0.05). Histological sections of cartilage damage were correlated with MRI data. This study demonstrated the reliability of using dual-flip angle-based fast T1 mapping for dGEMRIC for the biochemical assessment of early cartilage degeneration. This technique is a powerful tool for researchers and clinicians to acquire sufficient resolution data within a reasonable scan time.