Fig. 5.

Tumor contrast-to-noise ratio (CNR) comparison is shown between targeted fluorescence uptake and dual-reporter images. A box-plot of the tumor CNR determined from targeted fluorescence uptake images at 1 and 24 h after reporter injection in mice with blocked (FL B) and unblocked (FL) U251 tumors are presented in (a). Each data point represents an individual average tumor CNR from one mouse. Blue data points represent measurements taken in unblocked U251 tumors and red data points represent measurements taken in blocked U251 tumors. A similar box plot is presented in (b), with the tumor CNR determined from the dual-reporter (DR) images at 1 and 24 h after reporter injection. Examples of the targeted fluorescence uptake images at 1 and 24 h are presented in (c) and (e), respectively, and examples of the dual-reporter images at 1 and 24 h are presented in (d) and (f). The maximum value in each image was chosen as the maximum threshold of the color scale, and the lower threshold was chosen independently in each image by a receiver operating characteristic analysis to optimize the tumor CNR in each case.