MP2RAGE, a self bias-field corrected sequence for improved segmentation and T1-mapping at high field

José P. Marques, Tobias Kober, Gunnar Krueger, Wietske van der Zwaag, Pierre François Van de Moortele, Rolf Gruetter

Research output: Contribution to journalArticle

477 Scopus citations

Abstract

The large spatial inhomogeneity in transmit B1 field (B1+) observable in human MR images at high static magnetic fields (B0) severely impairs image quality. To overcome this effect in brain T1-weighted images, the MPRAGE sequence was modified to generate two different images at different inversion times, MP2RAGE. By combining the two images in a novel fashion, it was possible to create T1-weigthed images where the result image was free of proton density contrast, T2* contrast, reception bias field, and, to first order, transmit field inhomogeneity. MP2RAGE sequence parameters were optimized using Bloch equations to maximize contrast-to-noise ratio per unit of time between brain tissues and minimize the effect of B1+ variations through space. Images of high anatomical quality and excellent brain tissue differentiation suitable for applications such as segmentation and voxel-based morphometry were obtained at 3 and 7 T. From such T1-weighted images, acquired within 12 min, high-resolution 3D T1 maps were routinely calculated at 7 T with sub-millimeter voxel resolution (0.65-0.85 mm isotropic). T1 maps were validated in phantom experiments. In humans, the T1 values obtained at 7 T were 1.15 ± 0.06 s for white matter (WM) and 1.92 ± 0.16 s for grey matter (GM), in good agreement with literature values obtained at lower spatial resolution. At 3 T, where whole-brain acquisitions with 1 mm isotropic voxels were acquired in 8 min, the T1 values obtained (0.81 ± 0.03 s for WM and 1.35 ± 0.05 for GM) were once again found to be in very good agreement with values in the literature.

Original languageEnglish (US)
Pages (from-to)1271-1281
Number of pages11
JournalNeuroImage
Volume49
Issue number2
DOIs
StatePublished - Jan 15 2010

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