Program Information
Feasibility of Fast K-Space Reconstruction of Time-Resolved 4DMRI with Adequate Spatiotemporal Resolution Using Post-Acquisition Volumetric Dynamic Keyhole Method
Y Liu1*, K Zakian2 , M Kadbi3 , J Deasy4 , G Li5 , (1) Memorial Sloan Kettering Cancer Center, New York, NY, (2) Memorial Sloan Kettering Cancer Center, New York, NY, (3) Philips Healthcare, Clevelan, OH, (4) Memorial Sloan Kettering Cancer Center, New York, NY, (5) Memorial Sloan Kettering Cancer Center, New York, NY
Presentations
TU-FG-FS2-7 (Tuesday, August 1, 2017) 1:45 PM - 3:45 PM Room: Four Seasons 2
Purpose: In MR-guided radiotherapy using MR-integrated treatment units, only 2D cine (~4Hz) imaging is possible. This study aims to achieve fast k-space reconstruction of time-resolved (TR) volumetric 4DMRI image with adequate spatiotemporal resolution using a post-acquisition volumetric dynamic keyhole (DKH) method.
Methods: A fast 3D MRI scanning protocol with parallel imaging acceleration was applied to acquire both 3D cine images in free breathing (FB) and 3D static images in breath hold (BH). A super-resolution concept is applied to reconstruct TR-4DMRI with a high spatiotemporal resolution by combining high-temporal-resolution (2Hz) but low-spatial-resolution (5x5x5mm³) 3D cine FB images and high-spatial-resolution (2x2x2mm³) BH image via k-space. As a proof-of-concept, k-space raw data of a mobile phantom were acquired at FB and BH conditions for TR-4DMRI reconstruction. Furthermore, a volunteer study (N=3) was conducted under an IRB-approved protocol and the super-resolution approach was examined using simulated FB images with ground truth and acquired FB images. The intensity normalization of the central (FB, low-frequency) and peripheral (BH, high-frequency) k-space from the two image sets were investigated. Volunteer k-space data were retrospectively generated using Fourier transform, combined using DKH, and normalized using intensity match for reconstruction. The image quality of TR-4DMRI was compared with the original 3D BH image based on mean voxel intensity difference (VID) and voxel intensity correlation (VIC).
Results: TR-4DMRI images of the phantom and human subjects demonstrated adequate motion information (2Hz) and image quality with fine structure details. Comparing the image quality of reconstructed TR-4DMRI and BH images, VID=3% and VIC=0.98 for the phantom; and VID=4% and VIC=0.96 for volunteers.
Conclusion: This study demonstrates the feasibility of fast k-space TR-4DMRI reconstruction with a clinically adequate spatiotemporal resolution by combining high-temporal-resolution 3D cine FB images and high-spatial-resolution 3D static BH image using DKH. This technique has great potential to achieve real-time TR-4DMRI reconstruction.
Funding Support, Disclosures, and Conflict of Interest: MSKCC and Philips Healthcare has a research agreement.
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