Figure 5:

Optical imaging and MGd-enhanced T1-weighted imaging of rat glioma tumors collected at different time points after MGd administration. Optical images (top row) and overlay optical images (second row) show that tumors have highest signal intensity at 15–30 minutes after administration of MGd, and signal intensity becomes weak during observation times of 4 hours. Axial T1-weighted MR images (third row) show strongest enhancement of tumors at 15 minutes, with signal intensity of MGd-enhanced tumors decreasing during observation times. Cross-sectional view of hematoxylin and eosin–stained sections (fourth row) confirms presence of tumors in brains. Graphs show time-to-photon intensity (left) and time-to-signal-to-noise ratio (SNR) curves (right). Steep increase in signal intensity was seen at 15 minutes, followed by gradual signal intensity decline on both optical and MR images. T1WI = T1-weighted imaging.