High Resolution Multispectral qMRI Protocol: PD, T1, T2, T2*, ADC, MT

We implemented a dual sequence version of the mixed-TSE sequence, termed here as tandem-mixed-TSE with the following parameters: pulse sequence 1, dual-echo RARE: TE1=14ms, TE2=27ms, TR=4000; pulse sequence 2, dual-echo RARE with inversion recovery pulse: TE1=14ms, TE2=27ms, TI=400ms, TR=4400ms (Figure 1) (1). Images acquired with these two sequences were used to calculate parametric PD, T1, and T2 maps. A tri-echo gradient echo (FLASH) with the following parameters was implemented: TE1=4.5ms, TE2=6.8ms, TE3=9.0ms, TR=140ms, flip angle=30° (Figure 2). Directly acquired images were used to construct parametric T2* maps (Figure 2). For diffusion weighted MRI (DWI), a multi-slice spin echo image pulsed field gradient (PFG) acquisition (TE=10ms, TR=2000ms) was utilized with b-values of 21, 301, and 601 s/mm2 for constructing parametric ADC maps (Figure 3). For the quantitative magnetization transfer (qMT) experiments, we used a single 15ms Gaussian pulse with 13 frequency offsets ranging from ranging from 435Hz to 50kHz (logarithmic spacing). A single magnetization transfer pulse power was used (16uT). A twodimensional spoiled gradient echo sequence (FLASH) was used with the magnetization transfer pre-pulse for image acquisition with the following parameters: TE= 4ms, TR=260ms, flip angle=30 (Figure 4). An additional reference dataset with the identical parameters was also acquired without a magnetization transfer pulse.