计算机科学
信噪比(成像)
点扩散函数
混叠
图像分辨率
还原(数学)
信号(编程语言)
核磁共振
算法
物理
材料科学
数学
光学
人工智能
几何学
欠采样
程序设计语言
作者
Suhyung Park,Salvatore Torrisi,Jennifer Townsend,Alexander Beckett,David Feinberg
摘要
To achieve highly accelerated submillimeter resolution T2 -weighted functional MRI at 7T by developing a three-dimensional gradient and spin echo imaging (GRASE) with inner-volume selection and variable flip angles (VFA).GRASE imaging has disadvantages in that (a) k-space modulation causes T2 blurring by limiting the number of slices and (b) a VFA scheme results in partial success with substantial SNR loss. In this work, accelerated GRASE with controlled T2 blurring is developed to improve a point spread function (PSF) and temporal signal-to-noise ratio (tSNR) with a large number of slices. To this end, the VFA scheme is designed by minimizing a trade-off between SNR and blurring for functional sensitivity, and a new GRASE-optimized random encoding, which takes into account the complex signal decays of T2 and T2∗ weightings, is proposed by achieving incoherent aliasing for constrained reconstruction. Numerical and experimental studies were performed to validate the effectiveness of the proposed method over regular and VFA GRASE (R- and V-GRASE).The proposed method, while achieving 0.8 mm isotropic resolution, functional MRI compared to R- and V-GRASE improves the spatial extent of the excited volume up to 36 slices with 52%-68% full width at half maximum (FWHM) reduction in PSF but approximately 2- to 3-fold mean tSNR improvement, thus resulting in higher BOLD activations.We successfully demonstrated the feasibility of the proposed method in T2 -weighted functional MRI. The proposed method is especially promising for cortical layer-specific functional MRI.
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