Three‐dimensional delayed gadolinium‐enhanced MRI of cartilage (dGEMRIC) at 1.5T and 3.0T

Abstract

Purpose: 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. Materials and Methods: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).Results: T1 measurements in phantoms showed a statistically significant correlation between the 2D and 3D measurements at 1.5T (R 2 ϭ 0.993, P Ͻ 0.001) and 3.0T (R 2 ϭ 0.996, P Ͻ 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 0.63 ϫ 0.63 ϫ 3.0 mm spatial resolution within a 20-minute acquisition, even with the measurement parameters set for the higher T1(Gd) of cartilage at 3T (range ϭ 400 -900 msec mean T1 within a region of interest (ROI) in cartilage, compared to 200 -600 msec mean T1 at 1.5T). Conclusion:This 3D T1 measurement protocol may prove useful for the evaluation and follow-up of cartilage dGEM-RIC indices in clinical studies of OA.

Quantitative parametric MRI of articular cartilage: a review of progress and open challenges

“…This would be beneficial for in vitro and in vivo studies alike because quantitative T 1 mapping techniques are typically time consuming. This is increasingly relevant at higher field strengths where T 1 relaxation times increase, resulting in even longer scan times [29]. Accurate 3D T 1 mapping protocols have been implemented on 1.5-and 3.0-T platforms using 3D inversion-recovery spoiled gradient echo [29], 3D Look-Locker [30] and 3D fast two-angle T 1 mapping [31] methods.…”

Rapid 3D‐T1 mapping of cartilage with variable flip angle and parallel imaging at 3.0T

“…Similarly, to validate the 3D-T 1 mapping of the OA subjects after the contrast agent Gd(DTPA) 2-injection, the OA subjects were injected intravenously with 0.2 mmol/kg of gadopentetate dimeglumine (Magnevist). The OA subjects were then asked to walk for at least 10 minutes to facilitate the transport of the contrast agent into the cartilage (12). About 90 minutes after injection, the OA subjects were imaged a second time after the contrast agent injection with the same imaging scheme.…”

Local flip angle correction for improved volume T1‐quantification in three‐dimensional dGEMRIC using the look‐locker technique

“…These levels are easily calculated using the fitted parameters T1*, M A , and M B , as shown in Eqs. [5] and [6].…”

“…[7] and [8]) with the known variables M Tstart and M Tstop (Eqs. [5] and [6]) together with the expression for the inversion quality, Eq. [9] is retrieved, solving the previously unknown M 0 .…”