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

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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 ( ) 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 (ΔT 1 % < 5%, ΔT 2 % < 7%, ΔADC% < 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.