VX2 tumors were implanted into the right thigh muscle of 30 New Zealand white rabbits. The animals were randomly assigned to 5 groups, which, respectively, were scanned by 3D-CTA and 4D-CE-MRA on day 4, 7, 10, 13, or 16 after tumor implantation. After scanning, tumors were resected and processed for conventional histology and CD-31 immunohistochemistry. Tumor volume measurements derived from CT and MR imaging were compared with histopathological data. The minimum tumor diameter and the number of new tumor blood vessels detectable by 3D-CTA and 4D-CE-MRA were also compared.
There were no significant differences in the tumor volume measurements derived from CT, MR, and histological analysis. The minimum diameter of tumor vessels detectable by 3D-CTA (0.68 ¡À 0.07 mm) was significantly less than that by 4D-CE-MRA (0.85 ¡À 0.12 mm) (P = 0.005). The number of tumor vessels detected by each imaging method was not significantly different until day 13 after implantation, when 3D-CTA detected a greater number (P < 0.001). The morphologic process of tumor angiogenesis was demonstrated dynamically by 3D-CTA and 4D-CE-MRA in vivo.
Tumor angiogenesis can be dynamically monitored in vivo by 3D-CTA and 4D-CE-MRA. Of the two methods, 3D-CTA has better spatial resolution, but 4D-CE-MRA allows temporal resolution of tumor angiogenesis.