3 research outputs found
Implementation and Application of PSF-Based EPI Distortion Correction to High Field Animal Imaging
The purpose of this work is to demonstrate the functionality and performance of a PSF-based geometric distortion correction for high-field functional animal EPI. The EPI method was extended to measure the PSF and a postprocessing chain was implemented in Matlab for offline distortion correction. The correction procedure was applied to phantom and in vivo imaging of mice and rats at 9.4T using different SE-EPI and DWI-EPI protocols. Results show the significant improvement in image quality for single- and multishot EPI. Using a reduced FOV in the PSF encoding direction clearly reduced the acquisition time for PSF data by an acceleration factor of 2 or 4, without affecting the correction quality
Time-efficient, High Resolution 3T Whole Brain Quantitative Relaxometry using 3D-QALAS with Wave-CAIPI Readouts
Purpose: Volumetric, high resolution, quantitative mapping of brain tissues
relaxation properties is hindered by long acquisition times and SNR challenges.
This study, for the first time, combines the time efficient wave-CAIPI readouts
into the 3D-QALAS acquisition scheme, enabling full brain quantitative T1, T2
and PD maps at 1.15 isotropic voxels in only 3 minutes. Methods: Wave-CAIPI
readouts were embedded in the standard 3d-QALAS encoding scheme, enabling full
brain quantitative parameter maps (T1, T2 and PD) at acceleration factors of
R=3x2 with minimum SNR loss due to g-factor penalties. The quantitative maps
using the accelerated protocol were quantitatively compared against those
obtained from conventional 3D-QALAS sequence using GRAPPA acceleration of R=2
in the ISMRM NIST phantom, and ten healthy volunteers. To show the feasibility
of the proposed methods in clinical settings, the accelerated wave-CAIPI
3D-QALAS sequence was also employed in pediatric patients undergoing clinical
MRI examinations. Results: When tested in both the ISMRM/NIST phantom and 7
healthy volunteers, the quantitative maps using the accelerated protocol showed
excellent agreement against those obtained from conventional 3D-QALAS at R=2.
Conclusion: 3D-QALAS enhanced with wave-CAIPI readouts enables time-efficient,
full brain quantitative T1, T2 and PD mapping at 1.15 in 3 minutes at R=3x2
acceleration. When tested on the NIST phantom and 7 healthy volunteers, the
quantitative maps obtained from the accelerated wave-CAIPI 3D-QALAS protocol
showed very similar values to those obtained from the standard 3D-QALAS (R=2)
protocol, alluding to the robustness and reliability of the proposed methods.
This study also shows that the accelerated protocol can be effectively employed
in pediatric patient populations, making high-quality high-resolution full
brain quantitative imaging feasible in clinical settings