3D-CTA and 4D-CE-MRA for dynamic monitoring tumor angiogenesis in a rabbit VX2 tumor

To study possibility of dynamic monitoring tumor angiogenesis in vivo by 3D-CTA on a 64-row multidetector CT and 4D-CE-MRA on a 3T MR scanner; compare the advantages and faults of these two methods; and analyze the relationship between tumor angiogenesis and tumor growth.This study had been approved by the institutional animal care and use committee. Thirty New Zealand white rabbits with implanted VX2 tumors in the right thigh muscle were randomly divided into five groups according to survive time (n = 6). The rabbits were scanned by a 64-row multidetector CT and a 3T MR at 4, 7, 10, 13, 16 days after tumor implantation respectively, and then sacrificed to extract the tumor. The tumors' long diameters, short diameters and volume measurements derived from CT and MR imaging were compared with pathological data. The minimum tumor diameter and the number of new tumor blood vessels detectable by 3D-CTA and 4D-CE-MRA were also compared. The morphologic process of tumor angiogenesis was monitored and described.(1) The volume of tumors measured by CT imaging, MR imaging and pathological data had no significant difference (P0.05). (2) The minimum diameter of tumor vessels displayed on 3D-CTA and 4D-CE-MRA images was 0.68 mm +/- 0.07 mm and 0.85 mm +/- 0.12 mm respectively. The minimum diameter of tumor vessels displayed on 3D-CTA imaging was significantly smaller than 4D-CE-MRA imaging (t = -6.5075, P = 0.005). (3) The number of tumor vessels on 3D-CTA imaging and 4D-CE-MRA imaging had no significant difference at 4, 7, 10 days after tumor implantation. The number of tumor vessels on 3D-CTA images were significantly more than that on 4D-CE-MRA images at 13, 16 days after tumor implantation (all P0.01). (4) The morphologic process of tumor angiogenesis was demonstrated as sprouting from pre-existing blood vessel, forming lots of new vessels around tumor, and forming the immature vessels web with lots of tortuous, dilated, irregular vessels penetrating into the tumor at last.Volume CT and high magnet field MR can monitor tumor growth in vivo. 3D-CTA and 4D-CE-MRA can dynamicly monitor morphological changes of tumor angiogenesis in vivo. Of the two methods, 3D-CTA has better spatial resolution, but 4D-CE-MRA allows better temporal resolution of tumor angiogenesis monitoring.