Zhao S, Kruse D E, Ferrara K W, Dayton P A
Department of Biomedical Engineering, University of California, Davis, USA.
Phys Med Biol. 2007 Apr 21;52(8):2055-72. doi: 10.1088/0031-9155/52/8/002. Epub 2007 Mar 20.
The goal of ultrasonic molecular imaging is the detection of targeted contrast agents bound to receptors on endothelial cells. We propose imaging methods that can distinguish adherent microbubbles from tissue and from freely circulating microbubbles, each of which would otherwise obscure signal from molecularly targeted adherent agents. The methods are based on a harmonic signal model of the returned echoes over a train of pulses. The first method utilizes an 'image-push-image' pulse sequence where adhesion of contrast agents is rapidly promoted by acoustic radiation force and the presence of adherent agents is detected by the signal change due to targeted microbubble adhesion. The second method rejects tissue echoes using a spectral high-pass filter. Free agent signal is suppressed by a pulse-to-pulse low-pass filter in both methods. An overlay of the adherent and/or flowing contrast agents on B-mode images can be readily created for anatomical reference. Contrast-to-tissue ratios from adherent microbubbles exceeding 30 dB and 20 dB were achieved for the two methods proposed, respectively. The performance of these algorithms is compared, emphasizing the significance and potential applications in ultrasonic molecular imaging.
超声分子成像的目标是检测与内皮细胞上受体结合的靶向造影剂。我们提出了一些成像方法，这些方法能够将附着的微泡与组织以及自由循环的微泡区分开来，否则这两者都会掩盖来自分子靶向附着剂的信号。这些方法基于一系列脉冲返回回波的谐波信号模型。第一种方法采用“图像推图像”脉冲序列，其中通过声辐射力快速促进造影剂的附着，并通过靶向微泡附着引起的信号变化来检测附着剂的存在。第二种方法使用频谱高通滤波器抑制组织回波。在两种方法中，自由剂信号都通过逐脉冲低通滤波器来抑制。附着和/或流动的造影剂在B模式图像上的叠加可以很容易地创建，以供解剖学参考。对于所提出的两种方法，附着微泡的对比组织比分别超过30 dB和20 dB。比较了这些算法的性能，强调了其在超声分子成像中的意义和潜在应用。
