磁共振成像（MRI）无创无害、对比度多、可以任意剖面成像的特点特别适合用于心脏成像，却因扫描时间长限制了其在临床上的应用.为了解决心脏磁共振电影成像屏气扫描时间过长的问题，该文提出了一种基于同时多层激发的多倍加速心脏磁共振电影成像及其影像重建的方法，该方法将相位调制多层激发（CAIPIRINHA）技术与并行加速（PPA）技术相结合，运用到分段采集心脏电影成像序列中，实现了在相位编码方向和选层方向的四倍加速，并使用改进的SENSE/GRAPPA算法对图像进行重建.分别在水模以及人体上进行了实验，将加速序列图像与不加速序列图像进行对比，结果验证了重建算法的有效性，表明该方法可以在保障图像质量以及准确测量心脏功能的前提下成倍节省扫描时间.
赵乐乐
,
陈利勇
,
黄小倩
,
徐健
,
陈群
. 基于同时多层激发和并行成像的心脏磁共振电影成像[J]. 波谱学杂志, 2017
, 34(3)
: 283
-293
.
DOI: 10.11938/cjmr20172555
Cardiac magnetic resonance imaging (CMRI) is a non-invasive technique that features multi-contrast and allows imaging at arbitrary orientations. However, the clinical applications of cardiac MRI are limited, mainly due to its long scan time. To speed up cardiac CINE imaging, a multi-fold accelerated cardiac CINE imaging method based on simultaneous multi-slice imaging and reconstruction technique was proposed. By combining the controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique and a partial parallel acquisition (PPA) scheme, a four-fold acceleration (i.e., 2-fold along the phase encoding direction and 2-fold along the slice encoding direction) was achieved. The proposed technique was tested and verified on phantoms and human subjects using an improved image reconstruction method SENSE/GRAPPA. Results demonstrated that the proposed method is effective in reducing cardiac CINE scan time, while preserving image quality and accuracy of cardiac function assessment.
[1] PENNELL D J, SECHTEM U P, HIGGINS C B, et al. Clinical indications for cardiovascular magnetic resonance (CMR):Consensus Panel report[J]. Eur Heart J, 2004, 25(21):1940-1965.
[2] PETITJEAN C, DACHER J N. A review of segmentation methods in short axis cardiac MR images[J]. Med Image Anal, 2011, 15(2):169-184.
[3] HEIDEMANN R M, ÖZSARLAK Ö, PARIZEL P M, et al. A brief review of parallel magnetic resonance imaging[J]. Eur Radiol, 2003, 13(10):2323-2337.
[4] BREUER F A, BLAIMER M, HEIDEMANN R M, et al. Controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) for multi-slice imaging[J]. Magn Reson Med, 2005, 53(3):684-691.
[5] BARTH M, BREUER F, KOOPMANS P J, et al. Simultaneous multislice (SMS) imaging techniques[J]. Magn Reson Med, 2016, 75(1):63-81.
[6] OPPELT B A, GRAUMANN R, BARFUB H, et al. FISP:A new fast MRI sequence[J]. Electromedica, 1986, 54:15-18.
[7] WEBER O M, SPEIER P, SCHEFFLER K, et al. Assessment of magnetization transfer effects in myocardial tissue using balanced steady-state free precession (bSSFP) cine MRI[J]. Magn Reson Med, 2009, 62(3):699-705.
[8] STÄB D, RITTER C O, BREUER F A, et al. CAIPIRINHA accelerated SSFP imaging[J]. Magn Reson Med, 2011, 65(1):157-164.
[9] BLAIMER M, BREUER F A, SEIBERLICH N, et al. Accelerated volumetric MRI with a SENSE/GRAPPA combination[J]. J Magn Reson Imaging, 2006, 24(2):444-450.
[10] SOBOL W T, GAUNTT D M. On the stationary states in gradient echo imaging[J]. J Magn Reson Imaging, 1996, 6(2):384-398.
[11] PRUESSMANN K P, WEIGER M, SCHEIDEGGER B, et al. SENSE:sensitivity encoding for fast MRI[J]. Magn Reson Med, 1999, 42(5):952-962.
[12] GRISWOLD M A, JAKOB P M, HEIDEMANN R M, et al. Generalized autocalibrating partially parallel acqusitions(GRAPPA)[J]. Magn Reson Med, 2002, 47(6):1202-1210.
[13] SETSOMPOP K, GAGOSKI B A, POLIMENI J R, et al. Blipped-controlled aliasing in parallel imaging for simultaneous multislice echo planar imaging with reduced g-factor penalty[J]. Magn Reson Med, 2012, 67(5):1210-1224.
[14] KELLMAN P, MCVEIGH E R. Image reconstruction in SNR units:A general method for SNR measurement[J]. Magn Reson Med, 2005, 54(6):1439-1447.
[15] NEMA. National Manufacturers Electrical Association standards (MS1-2008):determination of signal-to-noise ratio in diagnostic magnetic resonance imaging[R]. 2008.
[16] DING Y, CHUNG Y C, SIMONETTI O P. A method to assess spatially variant noise in dynamic MR image series[J]. Magn Reson Med, 2010, 63(3):782-789.
[17] OTAZO R, KIM D, AXEL L, et al. Combination of compressed sensing and parallel imaging for highly accelerated first-pass cardiac perfusion MRI[J]. Magn Reson Med, 2010, 64(3):767-776.
[18] YUTZY S R, SEIBERLICH N, DUERK J L, et al. Improvements in multislice parallel imaging using radial CAIPIRINHA[J]. Magn Reson Med, 2011, 65(6):1630-1637.
