Roelcke U
PET-Program, Paul Scherrer Institute, Villigen, Switzerland.
J Neurooncol. 1994;22(3):275-9. doi: 10.1007/BF01052933.
Most mechanisms of drugs which are used in brain tumor chemotherapy are well characterized: alkylation of DNA components (nitrosoureas), binding with tubulin protein resulting in metaphase arrest (vincristine), chromatid breaks and chromosome translocations (procarbazine), or inhibition of ribonucleotide reductase (hydroxyurea) [1]. These drugs exert their effects mainly during certain cell cycle phases of proliferating cells, particularly when DNA is synthesized. From this it can be assumed that the efficacy of these drugs depends on the fraction of proliferating cells. Thus it would be of great importance to estimate the proliferation rate of brain tumors which could guide chemotherapy in individual patients. Positron emission tomography (PET) measures quantitatively the in vivo tissue uptake of tracer substances. In tumors, the uptake appears to be altered in a characteristic way determined by biochemical properties of tumor tissue. Some aspects of brain tumor metabolism which are theoretically related to proliferation have been investigated with PET. In the following, the literature is reviewed with regard to: 1) tracer substances whose uptake has been thought to reflect tumor malignancy (11C-methionine, 18F-fluoro-deoxyglucose), and 2) tracers which theoretically could reflect mechanisms specifically related to DNA synthesis (11C-putrescine, ligands for peripheral benzodiazepine receptors).
DNA成分的烷基化（亚硝基脲类）、与微管蛋白结合导致中期阻滞（长春新碱）、染色单体断裂和染色体易位（丙卡巴肼），或抑制核糖核苷酸还原酶（羟基脲）[1]。这些药物主要在增殖细胞的特定细胞周期阶段发挥作用，特别是在DNA合成时。由此可以推测，这些药物的疗效取决于增殖细胞的比例。因此，估计脑肿瘤的增殖率对于指导个体患者的化疗具有重要意义。正电子发射断层扫描（PET）可定量测量示踪物质在体内组织中的摄取情况。在肿瘤中，摄取情况似乎会以由肿瘤组织生化特性决定的特征性方式发生改变。已利用PET对一些理论上与增殖相关的脑肿瘤代谢方面进行了研究。以下将针对以下方面对文献进行综述：1）摄取被认为反映肿瘤恶性程度的示踪物质（11C-蛋氨酸、18F-氟脱氧葡萄糖），以及2）理论上可反映与DNA合成具体相关机制的示踪剂（11C-腐胺、外周苯二氮䓬受体配体）。
