Figure 5.

Comparison of filtered and non-filtered images obtained with targeted and control microbubbles in a mouse tumor model. A, D: Interframe filtered broadband (T1R5.5) images of cRGD microbubbles highlight the tumor region due to the retention of cRGD microbubbles (normalized intensity of 0.69±0.16) and suppression of flowing microbubble echoes. B, E: The injection of non-targeted microbubbles does not generate significant contrast intensity in the broadband (T1R5.5) image after interframe filtering (normalized intensity in the tumor region of 0.04±0.01). C, F: Interframe filtering applied to the data acquired 7 minutes after microbubble injection does not significantly alter the contrast intensity of bound microbubbles. A, F: Both images show the presence of bound cRGD microbubbles, but through different approaches. Image (A), bound microbubble echoes were acquired 2 minutes after the cRGD microbubble injection and were differentiated from circulating microbubble echoes by the 7^th order IIR filter; while on image (F), image data were acquired 7 minutes after the microbubble injection when most circulating microbubbles were cleared from the blood stream. The scale bar represents 5 mm. The solid arrow indicates tumor region and dashed arrow indicates normal tissue region. G: Normalized intensity in the tumor region with varied scenarios (n=5, significance was achieved when p<0.05). The normalized intensity of bound cRGD microbubbles in the tumor region was visualized by multi-pulse (CPS) imaging at the 7 minute time point and compared to that with wideband imaging with interframe filtering.