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. 2025 Dec 30.
doi: 10.1002/mrm.70234. Online ahead of print.

In Vivo Meso-Scale Whole-Brain Quantitative Imaging With Tailored MRF on the NexGen 7T Scanner

Xiaozhi Cao  1   2 , Alexander Beckett  3   4 , Congyu Liao  5 , Erica Walker  3   4 , Zheren Zhu  5 , Yurui Qian  5 , Mengze Gao  1   2 , Nan Wang  1   2 , Yimeng Lin  1   2 , Lisong Gong  1   6 , Matthew A McCready  2 , Zhixing Wang  7 , Zhitao Li  8 , An Vu  5   9 , Samantha Ma  10 , Gabriel Ramos-Llordén  11 , Qiyuan Tian  12 , Adam Kerr  2 , Yang Yang  5 , David A Feinberg  3   4 , Kawin Setsompop  1   2
Affiliations

In Vivo Meso-Scale Whole-Brain Quantitative Imaging With Tailored MRF on the NexGen 7T Scanner

Xiaozhi Cao et al. Magn Reson Med. .

Abstract

Purpose: To push the speed and resolution limit of in vivo quantitative imaging and enable estimation of quantitative tissue parameters of subtle brain structures that were previously difficult to assess.

Methods: This study implemented an efficient quantitative imaging approach, 3D-SPI MRF, on the NexGen 7T scanner equipped with a high-performance head-only gradient and 96-channel receiver array. To address challenges associated with performing rapid mesoscale MRF on this system, acquisition and reconstruction mitigation methods were developed and incorporated into the MRF framework, including: (i) flip-angle-aware dictionary fitting to account for both B1 + inhomogeneity and voxel-specific RF frequency response, (ii) gradient imperfection corrections via Skope measurements that incorporates a new per-TR trajectory rewinder compensation, (iii) incorporation of rapid B1 + and B0 mappings into the MRF sequence, and (iv) high-temporal motion navigation.

Results: Whole-brain T1 and T2 maps were obtained at 560-μm isotropic resolution within 4 min, where ablation studies demonstrated the necessity of the various mitigation methods implemented in removing bias and artifacts. For comparison, MRF data were acquired using current state-of-the-art method but limited to typical whole-body gradient specifications to demonstrate that the proposed developments resulted in ∼3× shorter scan time while producing more accurate parameter maps. Data were also acquired at ∼3.8× smaller voxel size, 360-μm isotropic, using the developed technique, to achieve mesoscale multi-parameter quantitative mapping in vivo.

Conclusion: Tailored 3D MRF acquisition and reconstruction were developed to enable fast and accurate T1 and T2 mapping across the whole-brain at mesoscale resolution on the NexGen 7T scanner.

Keywords: MRF; high field; mesoscale; quantitative mapping.

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