Room: AAPM ePoster Library
Motion-free high-spatial resolution library is a key component for real-time 3D dynamic keyhole in MRgRT. The aim of this study is to develop a procedure for a motion-free high-spatial resolution library using a compressed-sensing approach in image reconstruction and processing for real-time 3D MRgRT.
In 0.35T MRgRT systems, 3D MR images were acquired using 3D TrueFISP (FOV: 350 x 350 mm, matrix: 150 x 150 x 8, voxel: 2 x 2 x 2 mm3, acquisition time: 5 s) from a motion phantom and a human subject. To reduce motion during imaging, the phantom was posed at the designated position and the human subject was in breath-hold using respiratory visual guidance system. The keyhole library is reconstructed using compressed sensing with parallel imaging. Specifically, coil sensitivity is estimated by the ESPIRiT calibration method, followed by compressed-sensing reconstruction from the input k-space and coil sensitivity with total variation constraint to achieve reduced noise, high contrast images. In the study, under-sampled data were used to improve the temporal resolution of the library. The performance of the method was compared with the Fourier-transformed images
The proposed method can generate a high spatial, high resolution 3D reconstruction from a low spatial, high temporal resolution 3D MRI dataset in the phantom. SNR, CNR of the reconstructed images were =8.1 dB and =16.2 dB, compared to FFT reconstructed images. SSMI was 96% for the 70% data with the reference to 100% of the acquired data. In the human dataset, the templates in 3 different planes reconstructed by the presented method show much less noise and more contrast then the zero filled FFT method.
3D dynamic keyhole with compressed sensing total variation reconstruction could obtain better image quality in less acquisition time.