Improved T1 mapping by motion correction and template based B1 correction in 3T MRI brain studies

Marcelo A. Castro; Jianhua Yao; Christabel Lee; Yuxi Pang; Eva Baker; John Butman; David Thomasson

doi:10.1117/12.811180

27 February 2009 Improved T₁ mapping by motion correction and template based B₁ correction in 3T MRI brain studies

Marcelo A. Castro, Jianhua Yao, Christabel Lee, Yuxi Pang, Eva Baker, John Butman, David Thomasson

Proceedings Volume 7262, Medical Imaging 2009: Biomedical Applications in Molecular, Structural, and Functional Imaging; 726202 (2009) https://doi.org/10.1117/12.811180
Event: SPIE Medical Imaging, 2009, Lake Buena Vista (Orlando Area), Florida, United States

Abstract

Accurate estimation of relaxation time T₁ from MRI images is increasingly important for some clinical applications. Low noise, high resolution, fast and accurate T₁ maps from MRI images of the brain can be performed using a dual flip angle method. However, accuracy is limited by the scanners ability to deliver the prescribed flip angle due to the B₁ inhomogeneity, particularly at high field strengths (e.g. 3T). One of the most accurate methods to correct that inhomogeneity is to acquire a subject-specific B₁ map. However, since B₁ map acquisition takes up precious scanning time and most retrospective studies do not have B₁ map, it would be desirable to perform that correction from a template. For this work a dual repetition time method was used for B₁ map acquisition in five normal subjects. Inaccuracies due to misregistration of acquired T₁-weighted images were corrected by rigid registration, and the effects of misalignment were compared to those of B1 inhomogeneity. T₁-intensity histograms were produced and three-Gaussian curves were fitted for every fully-, partially- and non-corrected histogram in order to estimate and compare the white and gray matter peaks. In addition, in order to reduce the scanning time we designed a template based correction strategy. Images from different subjects were aligned using a twelve-parameter affine registration, and B₁ maps were aligned according to that transformation. Recomputed T₁ maps showed a significant improvement with respect to non-corrected ones. These results are very promising and have the potential for clinical application.

Citation Download Citation

Marcelo A. Castro, Jianhua Yao, Christabel Lee, Yuxi Pang, Eva Baker, John Butman, and David Thomasson "Improved T₁ mapping by motion correction and template based B₁ correction in 3T MRI brain studies", Proc. SPIE 7262, Medical Imaging 2009: Biomedical Applications in Molecular, Structural, and Functional Imaging, 726202 (27 February 2009); https://doi.org/10.1117/12.811180

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