• Toxicological Research
• /
• 제29권1호
• /
• pp.1-6
• /
• 2013

The process of drug discovery and development requires substantial resources and time. The drug industry has tried to reduce costs by conducting appropriate animal studies together with molecular biological and genetic analyses. Basic science research has been limited to in vitro studies of cellular processes and ex vivo tissue examination using suitable animal models of disease. However, in the past two decades new technologies have been developed that permit the imaging of live animals using radiotracer emission, X-rays, magnetic resonance signals, fluorescence, and bioluminescence. The main objective of this review is to provide an overview of small animal molecular imaging, with a focus on nuclear imaging (single photon emission computed tomography and positron emission tomography). These technologies permit visualization of toxicodynamics as well as toxicity to specific organs by directly monitoring drug accumulation and assessing physiological and/or molecular alterations. Nuclear imaging technology has great potential for improving the efficiency of the drug development process.

• 대한핵의학회:학술대회논문집
• /
• 대한핵의학회 2003년도 제25차 연수교육
• /
• pp.37-45
• /
• 2003

• 핵의학기술
• /
• 제27권2호
• /
• pp.111-127
• /
• 2023

Purpose: Gallium-68 (⁶⁸Ga) is increasingly used in nuclear medicine imaging for various conditions such as lymphoma and neuroendocrine tumors by labeling tracers like Prostate Specific Membrane Antigen (PSMA) and DOTA-TOC. However, compared to Fluorine-18 (¹⁸F) used in conventional nuclear medicine imaging, ⁶⁸Ga has lower spatial resolution and relatively higher Signal to Background Ratio (SBR). Therefore, this study aimed to investigate the optimized parameters and reconstruction methods for PET/CT imaging using the ⁶⁸Ga radiotracer through model-based image evaluation. Materials and Methods: Based on clinical images of ⁶⁸Ga-PSMA PET/CT, a NEMA/IEC 2008 PET phantom model was prepared with a Hot vs Background (H/B) ratio of 10:1. Images were acquired for 9 minutes in list mode using DMIDR (GE, Milwaukee WI, USA). Subsequently, reconstructions were performed for 1 to 8 minutes using OS-EM (Ordered Subset Expectation Maximization) + TOF (Time of Flight) + Sharp IR (VPFX-S), and BSREM (Block Sequential Regularized Expectation Maximization) + TOF + Sharp IR (QCFX-S-400), followed by comparative evaluation. Based on the previous experimental results, images were reconstructed for BSREM + TOF + Sharp IR / 2 minutes (QCFX-S-2min) with varying β-strength values from 100 to 700. The image quality was evaluated using AMIDE (freeware, Ver.1.0.1) and Advanced Workstation (GE, USA). Results: Images reconstructed with QCFX-S-400 showed relatively higher values for SNR (Signal to Noise Ratio), CNR (Contrast to Noise Ratio), count, RC (Recovery Coefficient), and SUV (Standardized Uptake Value) compared to VPFX-S. SNR, CNR, and SUV exhibited the highest values at 2 minutes/bed acquisition time. RC showed the highest values for a 10 mm sphere at 2 minutes/bed acquisition time. For small spheres of 10 mm and 13 mm, an inverse relationship between β-strength increase and count was observed. SNR and CNR peaked at β-strength 400 and then decreased, while SUV and RC exhibited a normal distribution based on sphere size for β-strength values of 400 and above. Conclusion: Based on the experiments, PET/CT imaging using the ⁶⁸Ga radiotracer yielded the most favorable quantitative and qualitative results with a 2 minutes/bed acquisition time and BSREM reconstruction, particularly when applying β-strength 400. The application of BSREM can enhance accurate quantification and image quality in ⁶⁸Ga PET/CT imaging, and an optimization process tailored to each institution's imaging objectives appears necessary.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권16호
• /
• pp.6843-6848
• /
• 2014

Background: Diffusion-weighted magnetic resonance imaging (DWI) is reported to be useful for detecting malignant lesions. The purpose of this study is to clarify characteristics of imaging, detection rate and sensitivity of DWI for recurrence or metastasis of lung cancer. Methods: A total of 36 lung cancer patients with recurrence or metastasis were enrolled in this study. While 16 patients underwent magnetic resonance imaging (MRI), computed tomography (CT) and positron emission tomography-computed tomography (PET-CT), 17 underwent MRI and CT, and 3 underwent MRI and PET-CT. Results: Each recurrence or metastasis showed decreased diffusion, which was easily recognized in DWI. The detection rate for recurrence or metastasis was 100% (36/36) in DWI, 89% (17/19) in PET-CT and 82% (27/33) in CT. Detection rate of DWI was significantly higher than that of CT (p=0.0244) but not significantly higher than that of PET-CT (p=0.22). When the optimal cutoff value of the apparent diffusion coefficient value was set as $1.70{\times}10^{-3}mm^2/sec$, the sensitivity of DWI for diagnosing recurrence or metastasis of lung cancer was 95.6%. Conclusions: DWI is useful for detection of recurrence and metastasis of lung cancer.

• Nuclear Medicine and Molecular Imaging
• /
• 제42권sup1호
• /
• pp.52-59
• /
• 2008

In the management of colo-retal and anal cancer, accurate staging, treatment evaluation, early detection of recurrence are main clinical problems. F-18 FDG PET (PET/CT) has been reported as useful in the management of colo-rectal and anal cancer because that PET has high diagnostic performance comparing to conventional studies. In case of liver metastases, for confirmation of no extrahepatic metastases, in case of high risk of metastasis, for avoiding unnecessary operation, PET (PET/CT) is expected more useful. In anal cancer, PET is expected useful in lymph node staging. For the early prediction of chemotherapy or radiation therapy effect PET has been reported as useful, also. In early detection of recurrence by PET, cost-benefit advantages has been suggested, also. PET/CT is expected to have higher diagnostic performance than PET alone.

• Nuclear Medicine and Molecular Imaging
• /
• 제43권3호
• /
• pp.240-244
• /
• 2009

F-18 FDG PET is a metabolic imaging modality that is efficacious in staging and assessment of treatment response for variety of lymphomas. We report usefulness of F-18 FOG PET/Cl in evaluating severity of the disease and response to therapy in a patient with subcutaneous panniculitis- like T-cell lymphoma (SPTCL). Here we describe a case of SPTCL in 24-year-old man who had wide spread firm and tender nodular lesions with increased F-18 FOG uptake. After chemotherapy follow up F-18 FDG PET/CT image shows disseminated malignancy and then the patient died with hemophagocytic syndrome. This report suggests that F-18 FDG PET/CT may be useful in determining disease activity at the time of initial diagnosis, after treatment, and evaluating a suspected outcome of SPTCL.

• Nuclear Medicine and Molecular Imaging
• /
• 제43권4호
• /
• pp.357-360
• /
• 2009

Malignant mesothelioma of the peritoneum is a rare neoplasm with a rapidly fatal course. The tumour arises from the mesothelial cells lining the pleura and peritoneum or, rarely, in the pericardium or tunica vaginalis. This neoplasm is characterized by being difficult to diagnose, having a rapid evolution and a poor response to therapy. Mesothelioma is very glucose avid, and malignant pleural mesothelioma has been reported concerning the utility of F-18 FDG PET or PET/CT. But little has been known about the imaging finding of malignant peritoneal mesothelioma on F-18 FDG PET/CT. We report a case of malignant peritoneal mesothelioma mimicking peritoneal carcinomatosis of F-18 FDG PET/CT.

• 핵의학기술
• /
• 제27권2호
• /
• pp.83-93
• /
• 2023

Hypoxia indicates the condition of low oxygen levels in tissues. In oncology, hypoxia can induce cancer progression and metastasis, as well as cause resistance to cancer therapies. The detection of hypoxia by using molecular imaging, particularly, positron emission tomography (PET) has been extensively studied due to many advantages. Nitroimidazoles, the moieties that can be trapped in hypoxic tissues due to selective reduction, have been used to design and synthesize of hypoxia-targeting radiopharmaceuticals. This review provides a summary of synthetic routes towards ¹⁸F-labeled-nitroimidazole radiotracers for PET imaging of hypoxia.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2010년도 추계학술대회
• /
• pp.103-112
• /
• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system ($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• 대한안전경영과학회지
• /
• 제12권4호
• /
• pp.67-72
• /
• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic(USG) system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic(R/F) system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.