Tjuvajev J, Muraki A, Ginos J, Berk J, Koutcher J, Ballon D, Beattie B, Finn R, Dahighian F, Blasberg R
Cotzias Neuro-Oncology Laboratory, Memorial Sloan Kettering Cancer Center, New York, NY 10021.
J Nucl Med. 1993 Jul;34(7):1152-62.
Iodine-131-iododeoxyuridine (IUdR) uptake and retention was measured in two C6 glioma cell lines (C6m and C6a) with different growth characteristics. Animals with intracerebral (i.c.) C6a tumors had a mean survival of 16 days, whereas only 1 of 20 animals with i.c. C6m tumors died during an 8-wk period of observation. The growth of i.c. C6m tumors could be described by the Gompertz equation; tumor doubling time increased from 1.9 to 5.2 days between Days 8 and 16 after tumor inoculation. Corresponding measurements of 131I-IUdR uptake and retention (24 hr after IUdR administration) by i.c. C6m tumors were also time-dependent and decreased from 0.075 to 0.027 to 0.011 %dose/g in 8-, 10- and 16-day-old tumors, respectively. Iodine-131-IUdR uptake in "rapidly growing" i.c. C6a tumors was substantially higher (0.30 %dose/g at 24 hr) than that in "slowly growing" i.c. C6m tumors and corresponded with differences in the survival data. Subcutaneous C6a tumors had comparable high uptake values (0.49 %dose/g at 24 hr), and 93% of total tumor radioactivity was recovered in DNA 24 hr after IUdR administration. Clearance of radioactivity was rapid in nonproliferative tissues; more than 80% of plasma radioactivity was cleared in 24 hr. Tumor-to-cortex radioactivity ratios ranged from 100/1 to 120/1 and 150/1 between 24, 48 and 96 hr after IUdR injection respectively. A "washout strategy," which reduces tissue background activity and increases specificity for PET and SPECT imaging of IUdR-DNA incorporation, is possible with longer-lived radioisotopes of iodine.
在具有不同生长特性的两种C6胶质瘤细胞系（C6m和C6a）中测量了碘-131-碘脱氧尿苷（IUdR）的摄取和滞留情况。患有脑内（i.c.）C6a肿瘤的动物平均存活16天，而在为期8周的观察期内，20只患有脑内C6m肿瘤的动物中只有1只死亡。脑内C6m肿瘤的生长可用Gompertz方程描述；肿瘤接种后第8天至第16天，肿瘤倍增时间从1.9天增加到5.2天。脑内C6m肿瘤对131I-IUdR的摄取和滞留（IUdR给药后24小时）的相应测量结果也随时间变化，在8日龄、10日龄和16日龄肿瘤中分别从0.075%剂量/克降至0.027%剂量/克再降至0.011%剂量/克。“快速生长”的脑内C6a肿瘤中碘-131-IUdR的摄取量（24小时时为0.30%剂量/克）显著高于“缓慢生长”的脑内C6m肿瘤，且与生存数据的差异相符。皮下C6a肿瘤具有相当高的摄取值（24小时时为0.49%剂量/克），IUdR给药后24小时，93%的肿瘤总放射性在DNA中被回收。非增殖组织中放射性清除迅速；24小时内超过80%的血浆放射性被清除。IUdR注射后24小时、48小时和96小时，肿瘤与皮质的放射性比值分别为100/1至120/1和150/1。使用寿命更长的碘放射性同位素，有可能采用“洗脱策略”，该策略可降低组织本底活性并提高IUdR-DNA掺入的PET和SPECT成像的特异性。
