A 2D graphical approach to assess the reconstruction algorithms for the dynamic MRI

• Main Authors: Tzu-Cheng Chao, 趙梓程
• Other Authors: 鍾孝文
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/76720037080803571268

博士 === 國立臺灣大學 === 電機工程學研究所 === 97 === As the number and complexity of partially sampled dynamic imaging methods continue to increase, reliable strategies to evaluate performance may prove most useful. In the present work, an analytical framework to evaluate given reconstruction methods is presented. A perturbation algorithm allows the proposed evaluation scheme to perform robustly without requiring knowledge about the inner workings of the method being evaluated. A main output of the evaluation process consists of a 2D modulation transfer function (MTF), an easy-to-interpret visual rendering of a method’s ability to capture all combinations of spatial and temporal frequencies. Approaches to evaluate noise properties and artifact content at all spatial and temporal frequencies are also proposed. One fully sampled phantom and three fully sampled cardiac cine datasets were subsampled (R=4 and 8), and reconstructed with the different methods tested here. A hybrid method, which combines the main advantageous features observed in our assessments, was proposed and tested in a cardiac cine application, with acceleration factors of 3.5 and 6.3 (skip factor of 4 and 8, respectively). This approach combines features from methods such as k-t sensitivity-encoding (k-t SENSE), unaliasing by Fourier encoding the overlaps in the temporal dimension-SENSE (UNFOLD-SENSE), generalized autocalibrating partially parallel acquisition (GRAPPA), sensitivity profiles from an array of coils for encoding and reconstruction in parallel (SPACE-RIP), self, hybrid referencing with UNFOLD and GRAPPA (SHRUG) and GRAPPA-enhanced sensitivity maps for SENSE reconstructions (GEYSER).