To implement and validate a three-dimensional (3D) T1 measurement technique that is suitable for delayed gadolinium (Gd)-enhanced MRI of cartilage (dGEMRIC) and can be easily implemented with clinically available pulse sequences at 1.5T and 3.0T.
A 3D inversion-recovery prepared spoiled gradient-echo (IR-SPGR) imaging pulse sequence with variable TR was used to implement a 3D T1 measurement protocol. The 3D T1 measurements were validated against a gold-standard single-slice 2D IR T1 measurement protocol in both phantoms and in vivo, in both asymptomatic volunteers and volunteers with osteoarthritis (OA).
T1 measurements in phantoms showed a statistically significant correlation between the 2D and 3D measurements at 1.5T (R2=0.993, P<0.001) and 3.0T (R2=0.996, P<0.001). In vivo application demonstrated the feasibility of using this 3D IR-SPGR sequence to evaluate the molecular status of articular cartilage throughout the knee joint with 0.63x0.63x3.0 mm spatial resolution within a 20-minute acquisition, even with the measurement parameters set for the higher T1(Gd) of cartilage at 3T (range=400-900 msec mean T1 within a region of interest (ROI) in cartilage, compared to 200-600 msec mean T1 at 1.5T).
This 3D T1 measurement protocol may prove useful for the evaluation and follow-up of cartilage dGEMRIC indices in clinical studies of OA.