Single-shot Multi-slice T1 Mapping at High Spatial Resolution – Inversion-Recovery FLASH with Radial Undersampling and Iterative Reconstruction
Xiaoqing Wang*, Volkert Roeloffs, K. Dietmar Merboldt, Dirk Voit, Sebastian Schätz, Jens Frahm
Identifiers and Pagination:Year: 2015
First Page: 1
Last Page: 8
Publisher Id: TOMIJ-9-1
Article History:Received Date: 28/08/2014
Revision Received Date: 17/11/2014
Acceptance Date: 16/12/2014
Electronic publication date: 24/4/2015
Collection year: 2015
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
To develop a method for T1 mapping at high spatial resolution and for multiple slices.
The proposed method emerges as a single-shot inversion-recovery experiment which covers the entire spin-lattice relaxation process by serial acquisitions of highly undersampled radial FLASH images, either in single-slice or multi-slice mode. Serial image reconstructions are performed in time-reversed order and first involve regularized nonlinear inversion (NLINV) to estimate optimum coil sensitivity profiles. Subsequently, the coil profiles are fixed for the calculation of differently T1-weighted frames and the resulting linear inverse problem is solved by a conjugate gradient (CG) technique. T1 values are obtained by pixelwise fitting with a Deichmann correction modified for multi-slice applications.
T1 accuracy was validated for a reference phantom. For human brain, T1 maps were obtained at 0.5 mm resolution for single-slice acquisitions and at 0.75 mm resolution for up to 5 simultaneous slices (5 mm thickness). Corresponding T1 maps of the liver were acquired at 1 mm and 1.5 mm resolution, respectively. All T1 values were in agreement with literature data.
Inversion-recovery sequences with highly undersampled radial FLASH images and NLINV/CG reconstruction allow for fast, robust and accurate T1 mapping at high spatial resolution and for multiple slices.