Xucheng Zhu1, Fei Tan2, Kevin Johnson3, Peder Larson4. 1. UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, United States; Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States; GE Healthcare, Menlo Park, CA, United States. 2. UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, United States; Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States. 3. Medical Physics, University of Wisconsin, Madison, WI, United States; Radiology, University of Wisconsin, Madison, WI, United States. 4. UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, San Francisco and University of California, Berkeley, CA, United States; Radiology and Biomedical Imaging, University of California, San Francisco, CA, United States. Electronic address: peder.larson@ucsf.edu.
Abstract
PURPOSE: Additional spoiler gradients are required in 3D UTE sequences with random view ordering to suppress magnetization refocusing. By leveraging the encoding gradient induced spoiling effect, the spoiler gradients could potentially be reduced or removed to shorten the TR and increase encoding efficiency. An analysis framework is built that models the gradient spoiling effects and a new ordering scheme is proposed for fast 3D UTE acquisition. THEORY AND METHODS: UTE signal evolution and spatial encoding gradient induced spoiling effect are derived from the Bloch equations. And the concept is validated in 2D radial UTE simulation. Then an optimized ordering scheme, named reordered 2D golden angle (r2DGA) scheme, for 3D UTE acquisition is proposed. The r2DGA scheme is compared to the sequential and 3D golden angle schemes in both phantom and volunteer studies. RESULTS: The proposed r2DGA ordering scheme was applied to two applications, single breath-holding and free breathing 3D lung MRI. With r2DGA ordering scheme, breath-holding lung MRI scan increased 60% scan efficiency by removing the spoiler gradients and the free breathing scan reduced 20% scan time compared to the 3D golden angle scheme by reducing the spoiler gradients. CONCLUSIONS: The proposed r2DGA ordering scheme UTE acquisition reduces the need of spoiler gradients and increases the encoding efficiency, and shows improvements in both breath-holding and free breathing lung MRI applications.
PURPOSE: Additional spoiler gradients are required in 3D UTE sequences with random view ordering to suppress magnetization refocusing. By leveraging the encoding gradient induced spoiling effect, the spoiler gradients could potentially be reduced or removed to shorten the TR and increase encoding efficiency. An analysis framework is built that models the gradient spoiling effects and a new ordering scheme is proposed for fast 3D UTE acquisition. THEORY AND METHODS: UTE signal evolution and spatial encoding gradient induced spoiling effect are derived from the Bloch equations. And the concept is validated in 2D radial UTE simulation. Then an optimized ordering scheme, named reordered 2D golden angle (r2DGA) scheme, for 3D UTE acquisition is proposed. The r2DGA scheme is compared to the sequential and 3D golden angle schemes in both phantom and volunteer studies. RESULTS: The proposed r2DGA ordering scheme was applied to two applications, single breath-holding and free breathing 3D lung MRI. With r2DGA ordering scheme, breath-holding lung MRI scan increased 60% scan efficiency by removing the spoiler gradients and the free breathing scan reduced 20% scan time compared to the 3D golden angle scheme by reducing the spoiler gradients. CONCLUSIONS: The proposed r2DGA ordering scheme UTE acquisition reduces the need of spoiler gradients and increases the encoding efficiency, and shows improvements in both breath-holding and free breathing lung MRI applications.
Authors: Jiang Du; Michael Carl; Mark Bydder; Atsushi Takahashi; Christine B Chung; Graeme M Bydder Journal: J Magn Reson Date: 2010-09-25 Impact factor: 2.229
Authors: Joseph Y Cheng; Tao Zhang; Nichanan Ruangwattanapaisarn; Marcus T Alley; Martin Uecker; John M Pauly; Michael Lustig; Shreyas S Vasanawala Journal: J Magn Reson Imaging Date: 2014-10-20 Impact factor: 4.813