A new diagnostic method of cancer with Positron Emission Tomography

目的）血卟啉衍生物（Hematoporphirin derivatives，HpD）在癌组织中的蓄积较正常组织明显，630 nm激光照射肿瘤可导致肿瘤坏死。Photofrin II（一种HpD ; Ph 2）自1996年4月在日本临床上可用于癌症的光动力治疗。本研究的目的是将释放正电子的同位素标记到Ph 2，以检查Ph 2在大鼠中的组织分布，并通过正电子发射计算机断层扫描（PET）和Planner成像检测大鼠背部的肿瘤。方法从<68>~（18）Ge-~（18）Ga发生器中提取~（18）Ga<68><68>。将<68>~（60）Ga标记为Ph_2，并将~（60）Ga<68>标记的Ph_2（<68>~（60）Ga-Ph_2）提纯，用薄层色谱和高压液相色谱分析，并融合用于药物<68>治疗。用<68>PET观察6 h，用闪烁计数器观察1h， ...更多信息 给药后2小时。通过<68>PET定量测量器官中~（13）Ga-Ph 2的含量，并将PET图像与磁共振成像图像进行对比。通过PET和Planner成像（HPK）对大鼠背部的肿瘤进行成像。结果）1Ga<68>对Ph 2的标记率为46.4（[SY. ±. 21.1%，范围为17.3 - 84.7%。虽然<68>在静脉内给药后立即在肝、脾和肾中密集地积累，但与肝和脾中的浓度相比，其在肾中的浓度迅速下降。给<68>药后12 h，肿瘤中的1Ga-Ph 2浓度显著增加。在给药后6-12小时，6 <68>Ga-Ph 2在以下器官中积累，顺序显示较高的摄取：肝&gt;脾&gt;肾&gt;肿瘤&gt;血液&gt;肺&gt;小肠&gt;心脏&gt;皮肤。肿瘤的检测率为100%，然而，Planner Imaging（Hamamatsu Photonics）显示了<68>比PET更强的肿瘤中15 Ga-Ph 2积累<68>的图像。然而，由于16 Ga的半衰期<68>短，使用16 <68>Ga-Ph 2增加了检测肿瘤和将16 Ga标记<68>为Ph 2的困难。少

Objective) Hematoporphirin derivatives (HpD) accumulate in cancer tissues in preference to normal tissues and subsequent 630 nm-laser light irradiation to tumor results in tumor necrosis. Photofrin II (a kind of HpD ; Ph2) is clinically available for photodynamic therapy of cancer from April, 1996 in Japan. The aims of this study were to label an isotope which releases positron, to Ph2, to examine the tissue distribution of Ph2 in rats, and to detect tumors on the back of rats by imaging with positron emission computed tomography (PET) and Planner Imaging. Methods) ^<68>Ga was extracted from ^<68>Ge-^<68>Ga generator. ^<68>Ga was labelled to Ph2 and ^<68>Ga-labelled Ph2 (^<68>Ga-Ph2) was refined, analyzed with thin layr chromatography and high pressure liquid chromato-graphy, and fused for medication The ^<68>Ga-Ph2 was intravenously administered to rats with or without tumors. Tissue distribution of the ^<68>Ga-Ph2 was observed with PET for 6 hours and with scintillation counter for 1 … More 2 hours after administration. Amount of the ^<68>Ga-Ph2 in organs was measured quantitatively by PET.Images by PET were contrasted with those by magnetic resonance imaging. Tumors on the back of rats were imaged by PET and Planner Imaging (HPK). Results) Labelling rates of ^<68>Ga to Ph2 were 46.4(]SY.+-.])21.1%, ranging from 17.3 to 84.7%. Although the ^<68>Ga-Ph2 accumulated densely in the liver, spleen and kidney immediately after intravenous administration, its concentration in the kidney decreased rapidly, compared to those in the liver and spleen. The ^<68>Ga-Ph2 concentration in tumors increased significantly until 12 h after the administration. At 6-12 hours after administration, ^<68>Ga-Ph2 accumulated in the following organs in the order showing higher uptake : liver>spleen>kidney>tumor>blood>lung>small intestine>heart>skin. Detection rate of tumors was 100%, however, Planner Imaging (Hamamatsu Photonics) revealed images of stronger accumulation of ^<68>Ga-Ph2 in tumors than PET.In conclusion, we succeeded in labelling ^<68>Ga to Ph2. However, because half-life of ^<68>Ga is short, using the ^<68>Ga-Ph2 raised difficulties in detection of tumor and labelling ^<68>Ga to Ph2. Less