||Combination of Compressed Sensing and Parallel Imaging for Highly Accelerated Cardiac Cine MRI
||Institute of Medical Informatics
Cardiac CINE imaging
心臟動態磁振造影於臨床上已被廣為使用，一般掃描時需配合病人的閉氣與心電圖同步。而閉氣對於病人來說是個負擔，所以如何縮短掃描時間更是一項重要的研究。加速掃描除了可以縮短掃描時病人所需的閉氣時間，或可以在相同的掃描時間下，得到更高的時間解析度，抑或可在有限時間內增加影像矩陣的大小來達到更高的空間解析度。關於掃描加速已有多項技術被提出，如平行成像技術與壓縮感知技術。本研究提出一項新的技術k-t CS-SENSE，其為結合平行成像技術和壓縮感知技術，希望藉由結合二者達到在心臟動態成像上面更進一步的加速，且在達到高加速時保留二者的特性，即在影像上面擁有更好的時間解析度與空間解析度。本研究的重建方法首先對收取的資料先使用壓縮感知技術進行重建，再將初步的重建結果作為後續平行影像重建所需的資訊。本研究在壓縮感知技術的使用為k-t FOCUSS，而後續的平行影像重建，則是藉由修改敏感度編碼來對其做改善。而在模擬實驗的部分，在3.0T機器下收到的資料，本研究提出的k-t CS-SENSE在加速六倍的情況下仍可擁有較少雜訊的影像且其時間解析度亦沒有太多的損失。
Cardiac CINE MRI has been extensively used in clinical exams and it typically requires patient’s breath-hold and ECG gating. Breath-hold could be a burden for patient so it is important to reduce the scan time for cardiac CINE imaging. Accelerated scan can reduce the duration of patient’s breath-hold, achieve the higher temporal resolution with the same scan time, or get the higher spatial resolution by increasing the matrix size. Numerous techniques have been proposed for accelerating the scan, such as parallel imaging and compressed sensing. Our study proposed a new method called k-t CS-SENSE. It sequentially combines the parallel imaging and compressed sensing to reconstruct highly undersampled data with higher temporal resolution and spatial resolution for cardiac CINE imaging. The proposed strategy uses the k-t FOCUSS for the initial compressed sensing reconstruction, and then the result is used in the later parallel imaging reconstruction to serve as reference information for parallel imaging reconstruction. Subsequently we use SENSE-based algorithm to perform parallel imaging reconstruction associated with additional regularization information to improve image reconstruction quality. For the simulation experiment with data acquired on a 3.0T scanner, k-t CS-SENSE could achieve 6-fold acceleration rate and having the reconstruction result with less noise and without too much reduction of temporal resolution.
LIST OF FIGURES vi
LIST OF TABLES viii
Chapter 1 Introduction 1
1.1 Developed acceleration methods 2
1.2 Combination of compressed sensing and parallel imaging 4
1.3 Purpose of this study 5
Chapter 2 Materials and Methods 6
2.1 Design of experiment 7
2.2 k-t FOCUSS 9
2.3 SENSE 11
2.3.1 SENSE with Tikhonov regularization 12
2.4 k-t CS-SENSE 13
2.5 Evaluation of reconstruction 16
2.5.1 Root mean square error (RMSE) and y-f/y-t correlation 17
Chapter 3 Result 19
Chapter 4 Discussion 30
4.1 Comparison of different reconstruction methods 30
4.2 Different regularization factors 34
4.3 Different random sampling patterns 37
Chapter 5 Conclusion 39
 J. A. Utz, R. J. Herfkens, J. A. Heinsimer, T. Bashore, R. Califf, G. Glover, N. Pelc, and A. Shimakawa, "CINE MR determination of left ventricular ejection fraction," AJR Am J Roentgenol, vol. 148, pp. 839-43, May 1987.
 I. A. Simpson, K. J. Chung, R. F. Glass, D. J. Sahn, F. S. Sherman, and J. Hesselink, "CINE magnetic resonance imaging for evaluation of anatomy and flow relations in infants and children with coarctation of the aorta," Circulation, vol. 78, pp. 142-8, Jul 1988.
 P. Chatelain and D. Didier, "Detection of myocardial rupture by CINE-magnetic resonance imaging," Am J Cardiol, vol. 73, pp. 1033-5, May 15 1994.
 S. Okayama, T. Nakano, S. Uemura, S. Fujimoto, S. Somekawa, M. Watanabe, T. Nakajima, and Y. Saito, "Evaluation of left ventricular diastolic function by fractional area change using CINE cardiovascular magnetic resonance: a feasibility study," J Cardiovasc Magn Reson, vol. 15, p. 87, 2013.
 D. J. Atkinson and R. R. Edelman, "CINEangiography of the heart in a single breath hold with a segmented turboFLASH sequence," Radiology, vol. 178, pp. 357-60, Feb 1991.
 S. Miller, O. P. Simonetti, J. Carr, U. Kramer, and J. P. Finn, "MR Imaging of the heart with CINE true fast imaging with steady-state precession: influence of spatial and temporal resolutions on left ventricular functional parameters," Radiology, vol. 223, pp. 263-9, Apr 2002.
 D. K. Sodickson and W. J. Manning, "Simultaneous acquisition of spatial harmonics (SMASH): fast imaging with radiofrequency coil arrays," Magn Reson Med, vol. 38, pp. 591-603, Oct 1997.
 K. P. Pruessmann, M. Weiger, M. B. Scheidegger, and P. Boesiger, "SENSE: sensitivity encoding for fast MRI," Magn Reson Med, vol. 42, pp. 952-62, Nov 1999.
 M. A. Griswold, P. M. Jakob, R. M. Heidemann, M. Nittka, V. Jellus, J. Wang, B. Kiefer, and A. Haase, "Generalized autocalibrating partially parallel acquisitions (GRAPPA)," Magn Reson Med, vol. 47, pp. 1202-10, Jun 2002.
 P. Kellman, F. H. Epstein, and E. R. McVeigh, "Adaptive sensitivity encoding incorporating temporal filtering (TSENSE)," Magn Reson Med, vol. 45, pp. 846-52, May 2001.
 K. P. Pruessmann, M. Weiger, P. Bornert, and P. Boesiger, "Advances in sensitivity encoding with arbitrary k-space trajectories," Magn Reson Med, vol. 46, pp. 638-51, Oct 2001.
 J. Tsao, P. Boesiger, and K. P. Pruessmann, "k-t BLAST and k-t SENSE: dynamic MRI with high frame rate exploiting spatiotemporal correlations," Magn Reson Med, vol. 50, pp. 1031-42, Nov 2003.
 U. Gamper, P. Boesiger, and S. Kozerke, "Compressed sensing in dynamic MRI," Magn Reson Med, vol. 59, pp. 365-73, Feb 2008.
 H. Jung, J. C. Ye, and E. Y. Kim, "Improved k-t BLAST and k-t SENSE using FOCUSS," Phys Med Biol, vol. 52, pp. 3201-26, Jun 7 2007.
 F. Huang, W. Lin, G. R. Duensing, and A. Reykowski, "K-t sparse GROWL: sequential combination of partially parallel imaging and compressed sensing in k-t space using flexible virtual coil," Magn Reson Med, vol. 68, pp. 772-82, Sep 2012.
 R. Otazo, D. Kim, L. Axel, and D. K. Sodickson, "Combination of compressed sensing and parallel imaging for highly accelerated first-pass cardiac perfusion MRI," Magn Reson Med, vol. 64, pp. 767-76, Sep 2010.