Ultrasonic high frequency blood flow imaging of small animal tumor models

In this paper, a 45 MHz ultrasonic small animal imaging system and its applications in blood flow measurements on mouse tumors are presented. Specifically, the system was used to perform in vivo mouse imaging with a tumor cell line named WF-3. The WF-3 tumor cells were injected into the C57BL/6 mice subcutaneously and it was used as an ovarian cancer model. Vascularity of the tumor was successfully imaged when the diameter of the tumor was around 2 mm with flow velocities on the order of a few mm/s. The blood flow images were also correlated with histology after the mice were sacrificed. Good correlation between the blood flow images and the histology was demonstrated in that the lack of blood flow signals in the image for a tumor at a late development stage corresponded to necrosis at the center of the tumor shown in histology.