核子醫學造影配合使用放射性藥劑能以獨特的非侵犯性技術檢視人類活體的局部生化與生理功能，所以核醫在診斷醫學上扮演重要角色。在日本，約1200單位執行這類的體內造影診斷，造影人數快速成長，直到1990年代中期之後成長幅度趨於穩定。SPECT造彬部份主要使用99mTc、123TI及123I。使用99mTc-IIMDP及99mTc-MDP的骨造影在核子醫學居於顯著項目之一。其他造影器官包括心臟、腫瘤及腦。心血管造影主要使用201T1；其次為123I-BMIPP、99mTc-tetrofosmin及99mTc-MIBI。123I-IMP、99mTc-ECD及99mTC-HMPAO的出現促進腦血流造影的發展。腫瘤造影方面，雖然201TI曾被使用於肺、腦與甲狀腺腫瘤的診斷，67Ga-citrate仍為主要的核醫造影藥物。肝造影目前則較少進行。在SPECT檢查成長的同時，有27座迴旋加速器-PET中心在日本運轉，4座設施正在興建。PET檢查己用於腦、心及腫瘤診斷。18F標幟藥物(18F-FDG、18F-DOPA)是最常使用的PET造影劑；其次為15O標幟藥物(15O、C15O、C15O2、H215O)、13N標幟藥物(13NI3)及11C藥物(11C-mcthionine、11C-acetate、11C-N-methyl-spiperone等)。此外，PET技術也正開啟在藥理、毒理、基因治療、藥物學等方面的新研究領域。這類技術可提供藥物在體內行為、有效性及毒理方面的動態與即時資訊，例如：抗組織胺藥物在輸運入腦及藥性間的關係評估、作用在神經傳導物質轉運體系統的精神治療劑的有效性與安全性資訊的提供等，利用PET造影快速提供體內資訊變為可行。為了對精神治療藥之有效性與安全性有更進一步的了解，一些放射性造影劑被用來研究精神治療藥物對多巴胺受體及轉運體的結合。這種侵越的造影技術能夠揭現原本隱匿未知的生物現象，並顯示在藥物作用下的腦內改變。

　　　　　Nuclear medicine imaging methodology provides a unique capability to non-invasively visualize a regional biochemical and physiological function in living humans by administration of radioactive agents. Therefore, nuclear medicine plays an important role in the diagnostic medicine. In Japan, in vivo nuclear medicine studies are currently carried out in about 1,200 institutions and the number of such studies has increased rapidly until the middle of 1990% but thereafter a more steady change has been observed. Most of such studies include the SPECT procedures, using 99mTC, 201TI and 123I. The bone studies constitute one of the preeminent places in nuclear medical diagnosis performed with 99mTc-HMDP and 99mTc-MDP. Other organs being studied are the heart, tumor and brain. Cardiovascular studies are mainly performed using 201TI, followed by 123I-BMIPP, 99mTc-tetrofosmin and 99mTc-MIBI. The advent of 123I-IMP, 99mTc-ECD and 99mTc-HMPAO have promoted brain perfusion studies. For tumor imaging, 67Ga-citrate is the primary radiopharmaceutical, although 201TI is used for lung, brain and thyroid tumor. Presently, liver imagin9 is being performed less frequently. Along with the growth of SPECT studies, 27 cyclotron-PET centers are presently in operation in Japan and four more facili- ties are under constructions. These PET procedures have also been used for the studies of the brain, heart and tumors. The 18F-labeled agents (18F-FDG, 18F-DOPA) are the most frequently utilized, followed by 15O-labeled agents (15O2, C15O, C15O2, H215O), 13N-labeled agents (13NH3), and 11C-labeled agents (11C-methionine, -acetate, -N-methyl-spiperone, etc). Furthermore, these imaging techniques are opening up new areas of research in the field of pharmacology, toxicology, gene targeting, pharmaceuticals, etc. They can offer dynamic and real-time information on the in vivo behavior, effectiveness, as well as toxicological aspect of drugs. The relationship between transport into the brain, for example, and its antihistaminic capacity has been evaluated and visualized. Aisc, the efficiency and safety of psychotropic drugs acting on the neurotransmitter transport system can be provided, should a rapid in-vivo information system become available. To gain a better under- standing of the efficiency and safety of drugs, the effect of treatment of psychotropic agents on dopamine receptor and transporter binding has also been investigated using some radioligands and nuclear imaging systems. The powerful imaging approaches can reveal biological phenomena previously hidden and can show the changes occurring in the brain under the effect of drugs.