A new diagnostic method of cancer with Positron Emission Tomography

目的)血吗啡素衍生物(HPD)优先于正常组织在肿瘤组织中蓄积，随后的630 nm激光照射肿瘤可导致肿瘤坏死。PHOTOFRIN II(HPD的一种；PH2)从1996年4月起在日本用于癌症的临床光动力治疗。本研究的目的是标记一种向PH2释放正电子的同位素，检测PH2在大鼠体内的组织分布，并通过正电子发射计算机断层扫描(PET)和平面成像来检测大鼠背部的肿瘤。方法：从68&gt；68&gt；Ge；68&gt；Ga发生器中提取。将~&lt；68&gt；Ga标记为Ph_2，经精制、薄层层析和高压液相层析分析后，经静脉给药。用正电子发射计算机断层扫描6h和闪烁计数器1…观察~(68)Ga-Ph_2的组织分布给药后2小时以上。PET定量测定脏器组织中~(68)Gt；Gt；Ga-Ph_2的含量，并与磁共振成像结果进行对比。用正电子发射计算机断层扫描(PET)和平面成像(HPK)对大鼠背部肿瘤进行成像。结果)~PH2的标记率为46.4%，最低为17.3%，最低为84.7%。静脉注射~(68)Ga-Ph_2后，虽然在肝、脾、肾中有较高的蓄积，但肾中的浓度较肝、脾中的浓度下降较快。在给药后12h，肿瘤组织中~(68)Ga-Ph_2浓度显著升高。在给药后6-12小时，^&lt；68&gt；Ga-Ph_2在以下器官中蓄积，表现出较高的摄取量：liver&gt；spleen&gt；kidney&gt；tumor&gt；blood&gt；lung&gt；small肠、心脏和皮肤。肿瘤的检测准确率为100%，然而，平面成像(Hamamatsu Photonics)显示，^&lt；68&gt；Ga-PH2在肿瘤中的积聚比PET更强。然而，由于^&lt；68&gt；Ga的半衰期很短，使用^&lt；68&gt；Ga-PH2会增加肿瘤检测和将^&lt；68&gt；Ga标记为PH2的困难。较少

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