Fig. 5.

Color near-infrared (NIR) composite images recorded with a beam-splitter NIRF system while the instrument is at an operating temperature of (a) 15°C and (b) 32°C. The tumor-targeted probe LS301 is used to highlight the location of the tumor, which is under the sciatic nerve. The instrument is calibrated at 15°C, so the NIR and color images in (a) are correctly co-registered, and the location of the sciatic nerve is visible due to absence of fluorescence signal (arrow). In contrast, at 32°C (b), the NIR fluorescence image is spatially shifted and superimposed on the incorrect anatomic features (arrow) due to the thermal shift of individual optical elements comprising the instrument. Thus, the location of the sciatic nerve is incorrectly highlighted as cancerous tissue.