Mihai Georgeta, Ding Yu, Xue Hui, Chung Yiu-Cho, Rajagopalan Sanjay, Guehring Jens, Simonetti Orlando P
Department of Internal Medicine, Cardiovascular Division, Dorothy M. Davis Heart and Lung Research Institute, Columbus, USA.
J Biomed Sci Eng. 2012 Dec;5(12A):871-877. doi: 10.4236/jbise.2012.512A110.
The purpose of the study was to evaluate the effect of motion compensation by non-rigid registration combined with the Karhunen-Loeve Transform (KLT) filter on the signal to noise (SNR) and contrast-to-noise ratio (CNR) of hybrid gradient-echo echoplanar (GRE-EPI) first-pass myocardial perfusion imaging. Twenty one consecutive first-pass adenosine stress perfusion MR data sets interpreted positive for ischemia or infarction were processed by non-rigid Registration followed by KLT filtering. SNR and CNR were measured in abnormal and normal myocardium in unfiltered and KLT filtered images following non-rigid registration to compensate for respiratory and other motions. Image artifacts introduced by filtering in registered and nonregistered images were evaluated by two observers. There was a statistically significant increase in both SNR and CNR between normal and abnormal myocardium with KLT filtering (mean SNR increased by 62.18% ± 21.05% and mean CNR increased by 58.84% ± 18.06%; p = 0.01). Motion correction prior to KLT filtering reduced significantly the occurrence of filter induced artifacts (KLT only-artifacts in 42 out of 55 image series vs. registered plus KLT-artifacts in 3 out of 55 image series). In conclusion the combination of non- rigid registration and KLT filtering was shown to increase the SNR and CNR of GRE-EPI perfusion images. Subjective evaluation of image artifacts revealed that prior motion compensation significantly reduced the artifacts introduced by the KLT filtering process.
本研究的目的是评估非刚性配准结合卡尔胡宁-洛伊夫变换（KLT）滤波器进行运动补偿对混合梯度回波平面回波（GRE-EPI）首过心肌灌注成像的信噪比（SNR）和对比噪声比（CNR）的影响。对21例连续的首过腺苷负荷灌注MR数据集进行处理，这些数据集经解读为缺血或梗死阳性，先进行非刚性配准，然后进行KLT滤波。在未滤波和经KLT滤波的图像中，对非刚性配准后正常和异常心肌的SNR和CNR进行测量，以补偿呼吸和其他运动。由两名观察者对配准图像和未配准图像中滤波引入的图像伪影进行评估。经KLT滤波后，正常和异常心肌之间的SNR和CNR均有统计学显著增加（平均SNR增加62.18%±21.05%，平均CNR增加58.84%±18.06%；p = 0.01）。在KLT滤波之前进行运动校正可显著减少滤波诱导伪影的发生（55个图像序列中42个仅KLT伪影，而55个图像序列中3个为配准加KLT伪影）。总之，非刚性配准和KLT滤波的组合可提高GRE-EPI灌注图像的SNR和CNR。对图像伪影的主观评估显示，预先进行运动补偿可显著减少KLT滤波过程引入的伪影。
