• 대한방사성의약품학회지
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• 제1권1호
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• pp.15-22
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• 2015

$^{18}F$-labeling reaction of bioactive molecule via click chemistry is widely used to produce $^{18}F$-labeled radiotracer in the field of radiopharmaceutical science and molecular imaging. In particular, bioorthogonal strain-promoted alkyne-azide cycloaddition (SPAAC) reaction has received much attention as an alternative ligation method for radiolabeling bioactive molecules such as peptides, DNA, proteins as well as nanoparticles. Moreover, SPAAC based pretargeting method could provide tumor images successfully on positron emission tomography system using nanoparticle such as mesoporous silica nanoparticles.

• 대한핵의학회지
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• 제32권2호
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• pp.168-171
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• 1998

We present a case in which a patient with acute hemorrhagic gastritis demonstrated abnormal gastrointestinal accumulation of radiotracer during $^{99m}Tc$-methylene diphosphonate(MDP) skeletal scintigraphy. A hemorrhagic gastritis was subsequently demonstrated by endoscopy. The mechanism for the intestinal localization of $^{99m}Tc$-MDP in this patient is not clear, but we guess that the extravasated blood containing the radiopharmaceutical cannot recirculate and stays at the bleeding site, so we can see the intestinal activity.

• 한국환경농학회지
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• 제12권3호
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• pp.309-318
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• 1993

A few technical methods including lysimeter, micro-ecosystem and soil column experiments which have been used for elucidation of the behaviour of pesticide residues in soil by means of the $^{14}C-radiotracer$ were introduced. They are essential for the investigation of soil-bound residues of pesticides, and hence the continued development and support in this field are urgently required.

• 대한방사성의약품학회지
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• 제2권1호
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• pp.37-42
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• 2016

The translocator protein (TSPO) has attracted scientist's attention for Positron Emission Tomography (PET) imaging due to correlation with brain cancer, stroke, and neurodegeneration. Recently, GE-180, a novel tricyclic derivative has been developed as a new high affinity agent for the TSPO and evaluated to confirm a possibility for the TSPO ligand. In this highlight review, several studies for the novel TSPO radiotracer are described.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 요약집 춘계학술발표대회
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• pp.380.2-380.2
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• 2004

• 대한핵의학회지
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• 제38권3호
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• pp.268-271
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• 2004

A 43-year-old man was presented with persistent headache for two weeks. 72 weighted MR imaging showed high signal intensity with surrounding edema in the left frontal lobe. These findings were considered with intracranial tumor such as glioma or metastasis. Tc-99m tetrofosmin SPECT showed focal radiotracer accumulation in the left frontal lobe. The operative specimen contained cerebral infarction with organizing leptomeningeal hematoma by pathologist. Another 73-year-old man was hospitalized for chronic headache. Initial CT showed ill-defined hypodensity with mass effect in the right parietal lobe. Tc-99m tetrofosmin SPECT showed focal radiotracer uptake in the right parietal lobe. These findings were considered with low-grade glioma or infarction. Follow-up CT after 5 months showed slightly decreased in size of low density in the right parietal lobe, and cerebral infarction is more likely than others. Tc-99m tetrofosmin has been proposed as a cardiotracer of myocardial perfusion imaging and an oncotropic radiotracer. Tc-99m tetrofosmin SPECT image provides a better attractive alternative agent than T1-201 as a tumor-imaging agent, with characteristics such as high-energy flux, short half-life, favorable biodistribution, dosimetry and lower background radioactivity. We have keep in mind on the analysis of Tc-99m tetrofomin imaging when cerebral infarction is being differentiated from brain tumor.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.79-84
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• 2021

Radiopharmaceuticals are important for tumor diagnosis and therapy. To deliver a radiotracer at the desired target excluding non-targeted tissues is difficult The development of a targeted tracer that has a good clearance profile while maintaining high biostability and biocompatibility is key to optimizing its biodistribution and transport across biological barriers. Improving the hydrophilicity of radiotracers by PEGylation can reduce serum binding, allowing the tracer to circulate without retention and reducing its affinity for non-targeted tissues. In this study, we synthesized a new benzamido tracer (SnBz-PEG₃₆) with the introduction of a low molecular weight polyethylene glycol unit (PEG₃₆, ~2,100 Da). The tumor targeting efficiency and biodistribution of [¹³¹I]-Bz-PEG₃₆ or radiotracer-loaded liposomes were evaluated after their administration to normal mice or mouse tumor models including CT26 (xenograft) and 4T1 (xenograft and orthotopic). Most of the radiotracer was cleared out rapidly (1-24 h post-administration) through the kidney and there was little tumor uptake.

• 환경생물
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• 제39권4호
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• pp.550-558
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• 2021

본 연구에서는 방사성동위원소 추적자 실험을 통해서 산화아연 또는 두 종류의 은나노물질로 오염시킨 토양에서 지렁이(Eisenia fetida)의 금속축적과 제거율을 비교하였고, 이들을 이온상의 Ag와 Zn으로 처리한 대조구와 비교하였다. 추가적으로 토양의 금속을 다단계추출법(sequential extraction method)을 이용하여 금속의 결합 형태로부터 생물이용도(bioavailability)를 예측하고 실제 생물축적(BAF, bioaccumulation factor)과 비교하였다. ZnO 처리구의 BAF (0.06)는 아연이온 처리구 BAF (1.86)보다 31배 낮았는데, 이는 토양에서 ZnO의 생물전이가 매우 낮음을 제시해 준다. 한편, 은의 BAF는 금속의 오염 형태에에 무관하게 0.11~0.17의 범위를 보였다. 다단계추출법을 통해서 아연이온 처리구의 아연은 토양에 비교적 약한 결합을 하는 형태(mobile fraction)에 35% 분포하여 아연이온처리구 값(<20%)보다 높았고, 이는 전자의 더 높은 BAF와 일치한다. 하지만, ZnO 처리구의 다단계추출은 생물이용도나 BAF를 잘 예측하지 못했으며 이는 ZnO가 토양에서 아연이온과 지화학적으로 다른 거동을 하기 때문으로 추정된다. 지렁이 체내에 축적된 은의 제거율(3.2~3.8% d^-1)은 아연의 제거율(1.2~1.7% d^-1)보다 2~3배 더 높았다.

• 대한방사성의약품학회지
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• 제3권2호
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• pp.91-97
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• 2017

$^{18}F-THK-5351$ is a PET radiotracer to image the hyperphosphorylated tau fibrillar aggregates in human brain. This protocol describes the optimized radiosynthesis of $^{18}F-THK-5351$ using a commercial GE $TRACERlab^{TM}$ $FX_{FN}$ radiosynthesis module. $^{18}F-THK-5351$ was prepared by nucleophilic [$^{18}F$]fluorination from its protected tosylate precursors, (S)-(2-(2-methylaminopyrid-5-yl)-6-[[2-(tetrahydro-2H-pyran-2-yloxy)-3-tosyloxy]propoxy] quinolone(THK-5352), at $110^{\circ}C$ for 10 min in dimethyl sulfoxide, followed by deprotection with 1 N HCl. The average radiochemical yield of $^{18}F-THK-5351$ was $31.9{\pm}6.7%$(decay-corrected, n = 10), with molar activity of $198.1{\pm}33.9GBq/{\mu}mol$($5.4{\pm}0.9Ci/{\mu}mol$, n = 10). The radiochemical purity was determined to be above 98%. The overall production time including HPLC purification is approximately 70 min. This fully-automated protocol is validated for clinical use.

• Nuclear Medicine and Molecular Imaging
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• 제42권3호
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• pp.185-191
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• 2008

While indirect targeting strategies using reporter-genes are taking center stage in current molecular imaging research, another vital strategy has long involved direct imaging of specific receptors using radiolabeled ligands. Recently, there is renewal of immense interest in this area with particular attention to the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein critically involved in the regulation of many cellular functions and malignancies. Recently, two novel classes of EGFR-targeting anticancer drugs have entered clinical trials with great expectations. These are monoclonal antibodies such as cetuximab that target the extracellular domain, and small molecule tyrosine kinase inhibitors such as gefitinib (lressa) and erlotinib (Tarceva) that target the catalytic domain of the receptor. However, early results have showed disappointing survival benefits, disclosing a major challenge for this therapeutic strategy; namely, the need to identify tumors that are most likely to respond to the agents. To address this important clinical issue, several noninvasive imaging techniques are under investigation including radiolabeled probes based on small molecule tyrosine kinase inhibitors, anti-EGFR antibodies, and EGF peptides. This review describes the current status, limitations, and future prospects in the development of radiotracer methods for EGFR imaging.