Three-dimensional simultaneous brain T1, T2, and ADC mapping with MR Multitasking

Purpose To develop a simultaneous T-1, T-2, and ADC mapping method that provides co-registered, distortion-free images and enables multiparametric quantification of 3D brain coverage in a clinically feasible scan time with the MR Multitasking framework. Methods The T-1/T-2/diffusion weighting was generated by a series of T-2 preparations and diffusion preparations. The underlying multidimensional image containing 3 spatial dimensions, 1 T-1 weighting dimension, 1 T-2-preparation duration dimension, 1 b-value dimension, and 1 diffusion direction dimension was modeled as a 5-way low-rank tensor. A separate real-time low-rank model incorporating time-resolved phase correction was also used to compensate for both inter-shot and intra-shot phase inconsistency induced by physiological motion. The proposed method was validated on both phantom and 16 healthy subjects. The quantification of T-1/T-2/ADC was evaluated for each case. Three post-surgery brain tumor patients were scanned for demonstration of clinical feasibility. Results Multitasking T-1/T-2/ADC maps were perfectly co-registered and free from image distortion. Phantom studies showed substantial quantitative agreement (R2=0.999) with reference protocols for T-1/T-2/ADC. In vivo studies showed nonsignificant T-1 (P = .248), T-2 (P = .97), ADC (P = .328) differences among the frontal, parietal, and occipital regions. Although Multitasking showed significant differences of T-1 (P = .03), T-2 (P < .001), and ADC (P = .001) biases against the references, the mean bias estimates were small (Delta T-1% < 5%, Delta T-2% < 7%, Delta ADC% < 5%), with all intraclass correlation coefficients greater than 0.82 indicating excellent agreement. Patient studies showed that Multitasking T-1/T-2/ADC maps were consistent with the clinical qualitative images. Conclusion The Multitasking approach simultaneously quantifies T-1/T-2/ADC with substantial agreement with the references and is promising for clinical applications.