Ren, LeiCai, JingYang, Zi2018-05-312020-05-152018https://hdl.handle.net/10161/17066<p>Purpose: Motion artifacts induced by breathing variations are common in 4D-MRI</p><p>images. This study aims to reduce the motion artifacts by developing a novel, robust 4DMRI</p><p>sorting method based on anatomic feature matching, which is applicable in both</p><p>cine and sequential acquisition.</p><p>Method: The proposed method uses the diaphragm as the anatomic feature to guide the</p><p>sorting of 4D-MRI images. Initially, both abdominal 2D sagittal cine MRI images and</p><p>axial MRI images (in both axial cine and sequential scanning modes) were acquired. The</p><p>sagittal cine MRI images were divided into 10 phases as ground truth. Next, the phase of</p><p>each axial MRI image is determined by matching the diaphragm position in the</p><p>intersection plane between the axial MRI and the ground truth cine MRI. Then, those</p><p>matched phases axial MRI images were sorted into 10-phase bins identical to the ground</p><p>truth cine images. Finally, 10-phase 4D-MRI were reconstructed from these sorted axial</p><p>MRI images. The accuracy of reconstructed 4D-MRI data was evaluated in a simulation</p><p>study using the 4D eXtended Cardiac Torso (XCAT) digital phantom with a sphere</p><p>tumor in the liver. The effects of breathing signal, including both regular (cosine</p><p>function) and irregular (patient data), on reconstruction accuracy were investigated by</p><p>calculating total relative error (TRE) of the 4D volumes, Volume-Percent-Difference</p><p>(VPD) and Center-of-Mass-Shift(COMS) of the simulated tumor between the</p><p>reconstructed and the ground truth images.</p><p>Results: In both scanning modes, reconstructed 4D-MRI images matched well with the</p><p>ground truth except minimal motion artifacts. The averaged TRE of the 4D volume, VPD</p><p>and COMS of the EOE phase in both scanning modes were 0.32%/1.20%/±0.05𝑚𝑚 for</p><p>regular breathing, and 1.13%/4.26%/±0.21𝑚𝑚 for patient irregular breathing,</p><p>respectively.</p><p>Conclusion: The preliminary results illustrated the robustness of the new 4D-MRI</p><p>sorting method based on anatomic feature matching. This method improved image</p><p>quality with reduced motion artifacts in the resulting reconstructed 4D MRI is applicable</p><p>for axial MR images acquired using both cine and sequential scanning modes.</p>Medical imaging4D-MRIMotion artifactsSortingMaster's thesis