Title :
A fast ultrasound molecular imaging method and its 3D visualization in vivo
Author :
Hu, Xiaowen ; Mahakian, Lisa ; Caskey, Charles ; Beegle, Julie ; Kruse, Dustin ; Rychak, Joshua ; Sutcliffe, Patrick ; Ferrara, Katherine
Author_Institution :
Univ. of California, Davis, CA, USA
Abstract :
Using targeted microbubbles (MBs), ultrasound molecular imaging can be used to selectively and specifically visualize upregulated vascular receptors. In order to acquire bound MB echoes, a delay of ~7-15 minutes is commonly required for the clearance of freely circulating MBs. Here, we test whether echoes from MBs can be distinguished from the surrounding tissue, based on the transmission of pulses at low (1.5 MHz) and reception at high (5.5 MHz) frequencies (TLRH), without the requirement for destructive pulses. Pulses with a peak negative pressure of 230 kPa were transmitted (10 fps) and a 7th order IIR pulse-to-pulse filter was applied to the TLRH radiofrequency (RF) data to distinguish the signature of bound MBs from that of flowing MBs. 3D images of the accumulation of intravenously-administrated integrin-targeted MBs in a Met-1 mouse tumor model were acquired. An in vitro study demonstrated that the T2R15 contrast imaging technique has a ~2-fold resolution improvement over 2MHz contrast pulse sequencing (CPS) imaging. By applying the 7th order IIR filter to the TLRH RF data acquired at 2 minutes, echoes from flowing MBs in the surrounding tissue region were suppressed by 26±2 dB, while the signal intensity within the tumor was suppressed by 4±1 dB. The targeted images correctly represented the distribution of bound MBs. After the filter, the signal intensity resulting from cyclic RGD bearing MBs was 25±2 dB higher than that after the injection of non-targeted MBs.
Keywords :
IIR filters; biomedical ultrasonics; data visualisation; image resolution; image sequences; medical image processing; molecular biophysics; proteins; tumours; ultrasonic imaging; 3D image; 3D visualization; 7th order IIR pulse-to-pulse filter; CPS imaging; Met-1 mouse tumor model; RF data; T2R15 contrast imaging technique; TLRH radiofrequency data; contrast pulse sequencing imaging; cyclic RGD bearing MB; destructive pulse; fast ultrasound molecular imaging method; frequency 1.5 MHz; frequency 5.5 MHz; in vitro study; pressure 230 kPa; pulse transmission; signal intensity; targeted microbubbles; tumor; upregulated vascular receptors; IIR filters; Image resolution; Molecular imaging; Radio frequency; Tumors; Ultrasonic imaging; TLRH; molecular imaging; slow time filter; targeted microbubble;
Conference_Titel :
Ultrasonics Symposium (IUS), 2011 IEEE International
Conference_Location :
Orlando, FL
Print_ISBN :
978-1-4577-1253-1
DOI :
10.1109/ULTSYM.2011.0402