Fig. 7.

The temporal correlation of DCE MSOT signals can evaluate if fluence is affected by the contrast agent injection.

The 680 nm signal was used for this analysis. A. Each voxel within an ROI of the entire mouse (red) was compared to the average signal in an AIF seed region (white). The temporal Pearson correlation coefficients (r² between the signals of each pixel and AIF seed region were estimated and displayed as a parametric map. Most pixels within the AIF seed region were highly correlated with the average AIF seed region signal (yellow pixels). This analysis also identified other regions that are highly correlated (r² ≥ 0.80) with the average AIF (purple pixels). No pixels with r² < 0.0 were found (scale bar  = 4 mm). B. The temporal changes in the average signal for the AIF seed region and the average signal for voxels with r² ≥ 0.90 demonstrate this correlation. Signals are shown relative to pre-injection signal. C. Using the same analysis method with the tumor as the seed region (blue) yielded regions of positive correlation (yellow) and negative correlation (purple). Pixels with | r² | ≥ 0.90 are shown in color. A negative correlation indicated that the accumulation of Genhance 680 in the tumor region reduced the optoacoustic signal in another region, and thus the fluence was not constant in these purple regions with respect to the tumor (scale bar  = 4 mm). D. The temporal changes in the average signal for the tumor seed region and the average signal for voxels with r² ≤ −0.90 demonstrate this negative correlation.