$^{188}Re$ (${\beta}^-=2.2$ MeV; ${\gamma}^-$=155 keV; $T_{1/2}$=16.9 hours) is an attractive therapeutic radioisotope which is produced from decay of reactor-produced tungsten-188 parent ($T_{1/2}$=69 days). $^{188}W$ has been produced from the double neutron capture reaction of $^{186}W.\;^{188}Re$ can be easily obtained by elution of saline on alumina based $^{188}W/^{188}Re$ generator, which is commercially available. Complexes labelled with $^{188}Re$ have been developed for the radiotherapy treatment of diseases because of the desirable nuclear properties of the radioisotope and it's chemical properties similar to those of technetium, a well established diagnostic agent.

There is considerable interest in $^{188}Re$ due to its favorable properties as a therapeutic radionuclide $^{188}Re$ and $^{99m}Tc$ act as a matched pair because of their similar chemical properties, and therefore methods of labeling with $^{99m}Tc$ can be applied to the labeling with $^{188}Re$. With appropriately chosen agents as carriers of $^{188}Re$, the labeling can be readily carried out using $^{188}ReO_4^-$ in the presence of a reducing agent. $^{188}Re$ radio-pharmaceuticals based on $^{99m}Tc$ complexes have been synthesized and are currently being studied for clinical use. Some of them are shown to be suitable for therapeutic use and promising for radiotherapy in nuclear medicine.

Radiation synovetomy with various radiopharmaceuticals has been used to alleviate pain and swelling of rheumatoid arthritis and related joint diseases for more than 40 years. It is an attractive alternative to the surgical synovectomy for the management of the various joint diseases. Recently, the development of new radiopharmaceuticals labeled with $^{90}Y,\;^{32}P,\;^{186}Re,\;^{188}Re,\;^{153}Sm,\;^{165}Dy$ and $^{166}Ho$, for the effective management of synovial inflammation and related arthritic problems are gaining attention. In this article the general concepts and the clinical application of radiation synovectomy are reviewed.

Rheumatoid arthritis (RA) is o chronic inflammatory disease of joints with proliferation of synovial epithelial tissue. Therapeutic approach of the RA consists of pharmacological and surgical interventions. Synovectomy is indicated in patients with progressive inflammatory signs and symptoms intractable to medical treatment including local intracavitary steroid injection. Recently, local injection of radionuclides which emit high energy beta rays are labeled with chemical compounds such as $^{90}Y,\;^{165}Dy-ferric$ hydroxide macroaggregate and have been introduced as an alternative therapeutic modality to surgical synovectomy. Holmium-166 is one of beta emitter and Ho-166-chitosan complex was developed for radiation synovectomy. Preclinical trial is on-going at our hospital using Ho-166-chitosan. The procedure and methods of preclinical trial are discussed.

재협착에 관여하는 인자는 매우 다양하다. 평활근 세포의 증식, ECM의 형성, 혈관벽의 초기 혈전형성, 그리고 혈관 재형성 등이 모든 것들이 재협착의 병인에 기여하고 있다. 환자마다 이런 요소들의 기여정도가 다르며 동일 환자에서도 병변에 따른 기여정도가 또한 다르리라 여긴다. 그러나 아직까지 우리는 외막섬유모세포의 역할, 내피세포의 재생, 증식세포의 계획된 죽음 등 재협착의 기전을 불완전하게 이해하고 있고 따라서 보다 완전한 이해를 통해 효과적인 재협착 예방치료가 시행될 수 있을 것이다.

Coronary restenosis is still regarded as Achilles' Hill of interventional cardiology despite relentless efforts of many investigators. Recent experimental and clinical studies have suggested that both gamma and beta radiation can reduce restenosis after angioplasty. Currently, intracoronary brachytherapy for the prevention of restenosis has become a new evolving treatment modality in interventional cardiology. This report discusses a physical aspect of gamma and beta radiation, initial clinical results and delivery systems used in intracoronary brachytherapy. We shall take a brief overview of methods and their advantages in intra-coronary brachytherapy. Future work should provide further insight for the best way of treating restenosis.

Re-188 is suitable for endovascular liquid-balloon brachytherapy for the prevention of restenosis after angioplasty. Re-188 was concentrated to 3700 MBq/ml and labeled with DTPA. According to dosimetric calculation, it took 420 seconds using Re-188 solution with concentration of 3700 MBq/ml to irradiate 17.6 Gy to the target at 1 mm from the balloon surface. Software was made to estimate the irradiation time. MIRD calculation with dynamic bladder model yielded the whole body dose of Re-188-DTPA as 0.005 mGy/MBq in case of balloon rupture and release of the whole amount into the blood.

Percutaneous coronary angioplasty is well established therapeutic modality in the management of coronary artery disease. However, the high restenosis rate of 30 to 50% limits its usefulness. The principal mechanism of restenosis, intimal hyperplasia, is the proliferative response of vessel wall to injury, which consists largely of smooth muscle cells. A large body of animal investigations and a limited number of clinical studies have established the ability of ionizing radiation to reduce neointimal proliferation and restenosis rate significantly. Human studies have been reported that intravascular radiation after first restenosis inhibits a second restenosis. Encouraged by these reports, we are also conducting a double blind, placebo-controlled, randomized trial to evaluate this new therapeutic modality in patients with coronary artery stenosis. The objective of our trial is to determine the safety and efficacy of catheter-based solutional beta emitting radioisotope system in preventing restenosis after angioplasty. This review describes the vascular brachytherapy systems and isotopes that have been utilized in the initial clinical trials performed in this area of post PTCA coronary restenosis. The results of many worldwide ongoing clinical trials will determine whether this new technology will change the future practice of vascular intervention.