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Abstract: Ultra-Short Echo Time 31P 3D MRSI at 3T/7T with Novel Rosette k-space Trajectory
Conference: International Society for Magnetic Resonance in Medicine Annua
Conference: International Society for Magnetic Resonance in Medicine Annual Meeting 2022 At London
Abstract #ID: 1783
Our group proposes a 31-P MRSI sequence utilizing Rosette-Petal shaped 3D k-space acquisition to achieve 1 mL isotropic resolution (10x10x10mm^3) over a FOV of 480x480x480mm^3 with a total scanning duration of 6.7 minutes using a Siemens Prisma 3T/7T scanner.
Method
A custom rosette trajectory (Shen et al. 2022) was used with an isotropic FOV = (480mm)^3 and an imaging matrix grid of 48x48x48 voxels. The spectral bandwidth was 2083 Hz, a TE = 50 us, a TR = 350 ms, and a total of 1444 Petals. Total scan duration = 8.4 minutes. Anatomical data was acquired through an Ultrashort Echo Time Magnetization Transfer (UTE-MT) sequence which uses a pair of adiabatic hyperbolic secant (sech) 180-degree pulses with a pulse duration of 24ms, a pulse bandwidth of 1kHz, an offset frequency of ~1300 Hz from water. Image reconstruction and post-processing steps were performed in MATLAB (MathWorks, USA). Nonuniform fast Fourier transform (NUFFT) was used to calculate the forward encoding transform of the acquired k-space data. A compressed sensing approach was used for image reconstruction, using total generalized variation (TGV) as the sparsifying penalty. The complex-valued coil sensitivity maps were first extracted from the center of k-space using ESPIRIT for coil combination. We used LCModel for the quantification of in vivo 31P NMR Brain Spectra.
In order to achieve acceptable acquisition timing in clinical settings (reconstructed images with acceleration factors = 2 and 4 were tested for further acceleration purposes.
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Uzay E Emir uemir@purdue.edu
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