Figure 5. Video intensity from SFRP2 -targeted microbubble contrast agent correlated significantly with SVR angiosarcoma tumor volume.

The baseline-subtracted average pixel intensity for each tumor was plotted against tumor volumes determined using our three-dimensional B-mode scans. Only 1 of 13 animals was observed to have higher signal for the streptavidin control than for the SFRP2 -targeted microbubbles (indicated by arrow). Correlation analysis showed a significant positive relationship between SFRP2 video signal and tumor volume as both increased together whether analyzed with (p = 0.048, Pearson r = 0.56) or without (p = 0.003, Pearson r = 0.78) the single “outlier” animal. Linear regression was used to determine the best-fit line through all data points to represent this relationship.