容积采集三维CT血管造影及四维动态增强磁共振血管造影活体动态监测肿瘤血管生成

目的 探讨容积采集三维CT血管造影(3D-CTA)与四维动态增强磁共振血管造影(4D-CE-MRA)活体动态监测兔YX2肌肉肿瘤血管生成的可行性,分析肿瘤血管的生成与肿瘤生长的关系,比较两种血管成像方法的优缺点.方法 新西兰白兔右后腿肌肉内接种VX2肿瘤细胞1 ×107,接种后第4、7、10、13、16天(每个时间点n=6)进行容积采集CT、MRI成像和3D-CTA、4D-CEMRA扫描,然后处死动物取出肿瘤标本.测量肿瘤不同生长时间点的长、短径及体积,并与大体标本比较;比较3D-CTA及4D-CE-MRA所显示肿瘤血管的最小直径;计数并统计不同时间点3D-CTA、4DCE-MRA所显示肿瘤血管的分支数目;动态观察并描述肿瘤血管生成的形态变化规律及特点.结果 (1)CT、MRI及大体标本所测算肿瘤体积的差异无统计学意义(P＞0.05).(2)3D-CTA及4D-CEMRA所显示肿瘤血管的最小直径分别为(0.68±0.07)mm、(0.85±0.12)mm,两者的差异具有统计学意义(t=-6.5075,P=0.005).(3)肿瘤接种后第4、7、10天3D-CTA及4D-CE-MRA所显示新生血管分支数目的 差异无统计学意义,接种第13、16天3D-CTA所显示肿瘤血管分支数目多于4D-CEMRA,差异有统计学意义(P＜0.01).(4)肿瘤血管生成具有从单一细小的胚芽到增多、增粗环绕肿瘤,直到形成扭曲、紊乱的肿瘤血管团的规律.结论 容积采集CT、高场强MRI可实现对肿瘤生长的活体监测,3D-CTA和4D-CE-MRA的方法能动态观察肿瘤血管生成的形态学变化.3D-CTA的空间分辨率优于4D-CE-MRA,但时间分辨率不及后者.

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

Objective To study possibility of dynamic monitoring tumor angiogenesis in vivo by 3DCTA 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. Methods This study had been approved by the institutional animal care and use committee. Thirty New Zealand white rabbits with implanted VX2 tumors in the fight 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 3DCTA and 4D-CE-MRA were also compared. The morphologic process of tumor angiogenesis was monitored and described. Results ( 1 ) The volume of tumors measured by CT imaging, MR imaging and pathological data had no significant difference ( P ＞ 0. 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 P ＜0. 01 ). (4) The morphoiogic 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. Conclusions 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.