Improved MR fingerprinting for relaxation measurement in the presence of semisolid magnetization transfer

Abstract

Purpose: To characterize and minimize the magnetization transfer (MT) effect in MR fingerprinting (MRF) relaxation measurements with a 2-pool (2P) MT model of multiple tissue types. Theory and Methods: Semisolid MT effect in MRF was modeled using 2P Bloch-McConnell equations. The combinations of MT parameters of multiple tissues (white [WM] and gray matter [GM]) were used to build the MRF dictionary. Both 1-pool (1P) and 2P models were simulated to characterize the dependence on MT. Relaxations measured using MRF with spin-echo saturation-recovery (SR) or inversion-recovery preparations were compared with conventional SR-prepared T 1 and multiple spinecho T 2 measurements. The simulations results were validated with phantoms and brain tissue samples. Results: The MRF signal was different from the 1P and 2P models. 1P MRF produced significantly (P < .05) underestimated T 1 in WM (20-30%) and GM (7-10%), while 2P MRF measured consistent T 1 and T 2 in both WM and GM with conventional measurements (pairwise test P > .1; correlated P < .05). Simulations showed that SRprepared MRF measuring T 1 had much less errors against the variation of the macromolecular fraction. Compared with inversion-recovery preparation, SR-prepared MRF produced higher relaxation correlations (R > 0.9) with conventional measurements in both WM and GM across samples, suggesting that SR-prepared MRF was less sensitive to the compositive effect of multiple MT parameters variations. Conclusions: 2P MRF using a combination of MT parameters for multiple tissue types can measure consistent relaxations with conventional methods. With the 2P models, SR-prepared MRF would provide an option for robust relaxation measurement under heterogeneous MT. K E Y W O R D S MRF, MT, saturation-recovery 728 | MENG Et al.

3D MR fingerprinting using Seiffert spirals

“…Additionally, the T 2 values were lower for the MRF techniques in the white and gray matter, which could be due to B 1 inhomogeneity or diffusion effects. However, the MRF T 2 values in this study are similar to T 2 values reported in other MRF studies of the brain 1,7,37–39 …”

“…However, the MRF T 2 values in this study are similar to T 2 values reported in other MRF studies of the brain. 1,7,[37][38][39] The relaxation maps obtained using the multi-axis 2D spiral trajectory are similar to those obtained in other studies. Although they compare well with our proposed trajectory, there are small differences in image quality in which the Seiffert trajectory shows improved performance.…”

Dynamic and rapid deep synthesis of chemical exchange saturation transfer and semisolid magnetization transfer MRI signals

“…This process is expected to be relatively straightforward via the use of the open-source pulseq standard format sequences 31 . Similarly, the same model could be used to generate traditional water pool T and T signal dictionaries for conventional MRF 48 while taking into consideration the magnetization transfer effect on the measured relaxivity 49 , 50 .…”

Magnetic resonance fingerprinting of the pancreas at 1.5 T and 3.0 T

“…The challenges associated with MRF are similar to those for any quantitative MRI technique: motion, spatial resolution, and B 0 and B 1 field non-uniformity. MRF may also be sensitive to magnetization transfer, partial volume, and slice profile effects 21,[28][29][30][31][32] . Spiral sampling use in MRF is advantageous in that it may reduce motion sensitivity by oversampling the centre of k-space 33 and matching a temporal pattern with MRF reconstruction.…”