Fig. 4.

Multimodality imaging of metastasis of A375M cells stably expressing the hrl-mrfp-ttk fusion reporter gene in living mice. A, bioluminescence imaging of a SCID mouse injected with A375M cells expressing the hrl-mrfp-ttk vector at day 0. 7 × 10⁵ A375M cells stably expressing the triple fusion were injected via tail-vein in a SCID mouse and two hours later imaged for bioluminescence signal following tail-vein injection of coelenterazine. Prominent bioluminescence signal was found from the region of both the lungs [1.3–1.5 × 10⁵ max (p/sec/cm²/sr)]. B, bioluminescence imaging of the same SCID mouse at day 40. At day 40, the same mouse was imaged and relatively high bioluminescence signal [2 × 10⁵ max (p/sec/cm²/sr)] was found from the left lung region and moderate signal from the right lung region. A faint bioluminescence signal (5 × 10³ p/sec/cm²/sr) was also present from the right pelvic region. C, microPET imaging of the same SCID mouse at day 40. Following a bioluminescence scan, the mouse was imaged in microPET using FHBG. Shown is a thin coronal slice of ~1-mm thickness. A strong signal (~0.78% ID/g) was present from the chest region (Ch) with lower signal (0.35% ID/g) from the lung region. The stronger PET signal was found to be from a metastatic tumor present deep inside the body, as evident from the fluorescence photograph (4.E). Note the gallbladder (GB) retains FHBG so background signal from the GB is also seen in the microPET images. D, light photograph of the same SCID mouse after sacrifice and organ exposure (image has been modified by using Adobe Photoshop version 6). E, whole body fluorescence imaging of the same SCID mouse. Fluorescing metastatic tumors were found in lung and chest regions that correspond with the bioluminescence and PET images.