• The Korean Journal of Nuclear Medicine
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• v.30 no.3
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• pp.299-314
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• 1996

The purpose of the present study was to validate the use of tissue radioactivity ratios instead of regional metabolic rates for the assessment of regional metabolic changes in Alzheimer's disease(AD) with [$^{18}F$]FDG PET and to examine the correlation of ratio indices with the severity of cognitive impairment in AD. Thirty-seven AD Patients(age $68{\pm}9 yrs$, $mean{\pm}s.d.$; 36 probable and 1 definite AD), 28 patients with dementia of non-Alzheimer type(age $66{\pm}7 yrs$), and 17 healthy controls(age $66{\pm}4 yrs$) underwent [$^{18}F$]FDG PET imaging. Two simplified radioactivity ratio indices were calculated from 37-66 min image: region-to-cerebellar radioactivity ratio(RCR) and a composite radioactivity ratio(a ratio of radioactivity in the most typically affected regions over the least typically affected regions: CRR). Local cerebral metabolic rate for glucose(LCMRglu) was also measured using a three-compartment, five-parameter tracer kinetic model. The ratio indices were significantly lower in AD patients than in controls(RCR in temporoparietal cortex, $0.949{\pm}0.136$ vs. $1.238{\pm}0.129$, p=0.0004; RCR in frontal cortex, $1.027{\pm}0.128$ vs. $1.361{\pm}0.151$, p<0.0001; CRR, $0.886{\pm}0.096$ vs. $1.032{\pm}0.042$. p=0.0024). On the RCR analysis, 86% of AD patients showed a pattern of bilateral temporoparietal hypometabolism with or without frontal involvement; hypometabolism was unilateral in 11% of the patients. When bilateral temporoparietal hypometabolism was considered to be suggestive of AD, the sensitivity and specificity of the RCR analysis for the differential diagnosis of AD were 86% and 73%, respectively. The RCR was correlated significantly with the macroparameter K [$K_1k_3/(k_2+k_3)$] (r=0.775, p<0.0001) and LCMRglu(r=0.633, p=0.0002) measured using the kinetic model. In patients with AD, both average RCR of cortical association areas and CRR were correlated with Mini-Mental Status Examination(r=0.565, p=0.0145; r=0.642, p=0.0031, respectively), Clinical Dementia Rating(r=-0.576, p=0.0124; r=-0.591, p=0.0077), and total score of Mattis Dementia Rating Scale (r=0.574, p=0.0648; r=0.737, p=0.0096). There were also significant correlations between memory and language impairments and corresponding regional RCRs. The results suggest that the [$^{18}F$]FDG PET ratio indices, RCR and CRR, reflect global and regional metabolic rates and correlate with the severity of cognitive impairment in AD. The simplified ratio analysis may be clinically useful for the differential diagnosis and serial monitoring of the disease.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6279-6284
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• 2015

Opisthorchis viverrini (OV)-induced cholangiocarcinoma (CCA) is an important cancer in the Great Mekong region, particularly in Thailand. Limitations of treatment options and the lack of an effective diagnostic tool for early detection of CCA are major concerns for the control of this type of cancer. The aim of the study was to investigate anti-CCA activity of the ethanolic extract of Atractylodes lancea (Thunb.) DC., and the applicability of positron emission tomography-computed tomography (PET-CT) as a tool for detection and monitoring the progression of CCA in Opisthorchis viverrini (OV)/dimethylnitrosamine (DMN)-induced CCA hamsters. Male Syrian hamsters were used for toxicity tests and anti-CCA activity evaluation. Development of CCA was induced by initial feeding of 50 metacercariae of OV, followed by drinking water containing 12.5 ppm of DMN in hamsters. The ethanolic extract of A. lancea (Thunb.) DC. was administered orally for 30 days. PET-CT was performed every 4 weeks after initiation of CCA using 18F-fluorodeoxyglucose ($^{18}F-FDG$). Results from the present study suggest that the ethanolic extract of A. lancea (Thunb.) DC. rhizome exhibited promising anti-CCA activity and safety profile in the OV/DMN-induced hamster model. To successfully apply PET-CT as a tool for early detection of tumor development and progression, modification of radiolabeling approach is required to improve its specificity for CCA cells.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.74-77
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• 2008

The radiopharmaceuticals are routinely injected to blood vessel for acquiring PET image. For this reason, It is imperative that they undergo strict quality control measures. Especially, Sterility test is more important than any other quality control procedures. According to the FDA guideline, It requires filter integrity test used in the processing of sterile solutions. Among several methods, we can decide to use bubble point test. We usually use vented GS-filters (Millipore co., USA) which are sterilizinggrade (0.22 um pore size) and are placed upper site on product vial. After the synthesis of $^{18}F$-FDG, solutions wet the membrane in filter and then go into the product vial. By all synthesis steps have finished, we can observe the presence of the bubbles in the product vial. Since we have started this study, we have never found any bubbles in the product vial. Because the maximum pressure intensity of the filter which has set by manufacturer is up to 5 bars, but helium gas pressure is up to 1 bar in our module system. So, we can make 5 bars pressure using helium gas bombe and increase pressure up to 5 bars step by step. However, it does not happen to anything in vial.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.1
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• pp.15-22
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• 2018

Purpose Respiratory motion during PET/MRI acquisition may result in image blurring and error in measurement for volume and quantification of lesion. The aim of this study was to evaluate changes of quantitative accuracy, tumor size and image quality by applying MR based respiratory motion correction technique (MBRMCT) using integrated PET/MR scanner. Materials and Methods Data of 30 patients (aged $62.5{\pm}10.2y$) underwent $^{18}F-FDG$ liver PET/MR (Biograph mMR 3.0T, Siemens) study were collected. PET listmode data for 7 minutes was simultaneously acquired with maximum average gate (MAG), minimum time gate (MTG) and non gate (NG) T1 weighted MR images. Gated PET reconstruction was performed using mu-maps generated from MAG and MTG by setting 35% of efficiency window. Maximum SUV ($SUV_{max}$), peak SUV ($SUV_{peak}$), tumor size and full width at half maximum (FWHM) in the z-axis direction of MAG, MTG and NG PET images were evaluated. Results Compared to NG, mean $SUV_{max}$ and $SUV_{peak}$ were increased in MAG 13.15%(p<0.0001), 8.66%(p<0.0001), MTG 13.27%(p<0.0001), 8.80%(p<0.0001) and mean tumor size and FWHM were decreased in MAG 14.47%(p<0.0001), 15.49%(p=0.0004), MTG 14.89%(p<0.0001), 15.79%(p=0.0003) respectively. Mean $SUV_{max}$ and $SUV_{peak}$ of MTG were increased by 0.07%(p=0.8802), 0.13%(p=0.7766). Mean tumor size and FWHM of MTG were decreased by 0.49%(p=0.2786), 0.36%(p=0.2488) compared to MAG. There was no statistically significant difference between MAG and MTG which increase total scan time for about 7 and 2 minutes. Conclusion SUV, accuracy of tumor size and spatial resolution were improved in both of MAG and MTG by applying MBRMCT without installing additional hardware in liver PET/MR study. More accurate information can be provided with the increase of 2 minutes scan time if applying MTG of MBRMCT to various abdominal PET/MR studies affected by respiratory motion.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.5
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• pp.263-270
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• 2006

Purpose: Several radioisotope-labeled thymidine derivatives such as $[^{11}C]$thymidine was developed to demonstrate cell proliferation in tumor. But it is difficult to track metabolism with $[^{11}C]$thymidine due to rapid in vivo degradation and its short physical half-life. 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) was reported to have the longer half life of fluorine-18 and the lack of metabolic degradation in vivo. Here, we described the synthesis of the 3'-$[^{18}F]$fluoro-3'-deoxythymidine ($[^{18}F]$FLT) and compared with $([^{18}F]FET)\;and\;([^{18}F]FDG)$ in cultured 9L cell and obtained the biodistribution and PET image in 9L tumor hearing rats. Material and Methods: For the synthesis of $[^{18}F]$FLT, 3-N-tert-butoxycarbonyl-(5'-O-(4,4'-dimet hoxytriphenylmethyl)-2'-deoxy-3'-O-(4-nitrobenzenesulfonyl)-${\beta}$-D-threopentofuranosyl)thymine was used as a FLT precursor, on which the tert-butyloxycarbonyl group was introduced to protect N3-position and nitrobenzenesulfonyl group. Radiolabeling of nosyl substitued precursor with $^{18}F$ was performed in acetonitrile at $120^{\circ}C$ and deproteced with 0.5 N HCI. The cell uptake was measured in cultured 9L glioma cell. The biodistribution was evaluated in 9L tumor bearing rats after intravenous injection at 10 min, 30 min, 60 min and 120 min and obtained PET image 60 minutes after injection. Results: The radiochemical yield was about 20-30% and radiochemical purity was more than 95% after HPLC purification. Cellular uptake of $[^{18}F]$FLT was increased as time elapsed. At 120 min post-injection, the ratios of tumor/blood, tumor/muscle and tumor/brain were $1.61{\pm}0.34,\;1.70{\pm}0.30\;and\;9.33{\pm}2.22$, respectively. The 9L tumor was well visualized at 60 min post injection in PET image. Conclusion: The uptake of $[^{18}F]$FLT in tumor was higher than in normal brain and PET image of $[^{18}F]$FLT was acceptable. These results suggest the possibility of $[^{18}F]$FLT at an imaging agent for brain tumor.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.935-942
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• 2021

Involuntary movement of internal organs by respiration is a factor that greatly affects the results of radiotherapy and diagnosis. In this study, a moving phantom was fabricated to simulate the movement of an organ or a tumor according to respiration, and ¹⁸F-FDG PET/CT scan images were acquired under various respiratory simulating conditions to analyze the movement range of the tumor movement by respiration, the level of artifacts according to the size of the tumor and the maximum standardized uptake value (SUVmax). Based on Windows CE 6.0 as the operating system, using electric actuator, electric actuator positioning driver, and programmable logic controller (PLC), the position and speed control module was operated normally at a moving distance of 0-5 cm and 10, 15, and 20 reciprocations. For sphere diameters of 10, 13, 17, 22, 28, and 37 mm at a delay time of 100 minutes, 80.4%, 99.5%, 107.9%, 113.1%, 128.0%, and 124.8%, respectively were measured. When the moving distance was the same, the difference according to the respiratory rate was insignificant. When the number of breaths is 20 and the moving distance is 1 cm, 2 cm, 3 cm, and 5 cm, as the moving distance increased at the sphere diameters of 10, 13, 17, 22, 28, and 37 mm, the ability to distinguish images from smaller spheres deteriorated. When the moving distance is 5 cm compared to the still image, the maximum values of the standard intake coefficient were 18.0%, 23.7%, 29.3%, 38.4%, 49.0%, and 67.4% for sphere diameters of 10, 13, 17, 22, 28, and 37 mm, respectively.

• The Korean Journal of Nuclear Medicine Technology
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• v.22 no.2
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• pp.79-83
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• 2018

Purpose $^{18}F-FDG$, which is commonly used in PET-CT examinations, is low in capacity and it is difficult to keep the amount of radioactivity busy when the specific activity is high, increasing the amount of space dose and radioactive contamination in the distribution room. Therefore, while evaluating the actual dose administered to patients during the manual dispense process, the medical institution intends to assess the usefulness of the auto dispenser by comparing the differences from the actual dose administered to the patient using the new automatic dispense. Materials and Methods From July 2016 to December 2016, 846 patients were manually administered by workers using $^{18}F-FDG$ and $^{18}F-FDG$ 906 patients were using auto dispenser from July 2017 to December 2017. Results Capacity administered to patients during the manual dispense averaged $35.41{\pm}27.79%$ compared to the recommended dose, and the auto dispenser process showed a small difference of $-2.15{\pm}3.99%$ compared to the recommended dose(p<0.05). Conclusion Working people did not have to touch radioactive medicines directly while they were busy in the auto dispenser, and because of the availability of other tasks far away, the time and distance to receive the exposure were also advantageous. It is believed that future use by many medical institutions will not only reduce the dose to patients but also help reduce the exposure dose to workers.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.3
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• pp.111-115
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• 2011

PET/CT(Positron Emission Tomography/Computed Tomography) is an examination combining morphological and functional information in one examination. The purpose of this study is to see the lowest CT dose for attenuation correction in the PET/CT maintaining good image quality when considering CT scan dose to the patients. We injected $^{18}F$-FDG and water into the cylinder shaped phantom, and obtained emission images for 3 mins and transmission images(140 kVp, 8 sec, 10~200 mA for transmission images), and reconstructed the images to PET/CT images with Iterative method. Data(Maximum, Minimum, Average, Standard Deviation) were obtained by drawing a circular ROI(Region Of Interest) on each sphere in each image set with Image J program. And then described SD according to the CT and PEC/CT images as graphes. Through the graphes, we got the relationships of mA and quality of images. SDs according to CT graph were 16.25 at 10 mA, 7.26 at 50 mA, 5.5 at 100 mA, 4.29 at 150 mA, and 3.83 at 200 mA, i.e. the higer mA, the better image quality was presented. SDs according to PET/CT graph were 1823.2 at 10 mA, 1825.1 at 50 mA, 1828.4 at 100 mA, 1813.8 at 150 mA, and 1811.3 at 200 mA. Calculated SDs at PET/CT images were maintained. This means images quality is maintained having nothing to do with mA of high and low.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.47-52
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• 2011

Purpose: Facilities use own sever or mini PACS system for storage and analysis of the PET/CT data. Mini PACS can storage scan data as well as measuring SUV. Therefore, the study was performed to confirm whether or not measured SUV on mini PACS is measured equally on PET/CT workstation. Materials and Methods: In February 2011, 30 patients who were performed $^{18}F$-FDG wholebody PET/CT scan in Biograph 16, Biograph 40 and Discovery Ste 8 were enrolled. First, using each workstation, SUV in liver and aorta of mediastinum level was measured. Second, using mini PACS, SUV was measured by same method. Result: The correlation coefficient of SUV in liver between PET/CT scanner and min PACS in Biograph 16, Biograph 40, Discovery Ste 8 was 0.99, 0.98, 0.64 respectably, the correlation coefficient of SUV in aorta was 0.98, 0.98, 0.66, and these were showed positive correlation coefficient. Difference of SUV between Biograph workstation and mini PACS was not showed statistical significant difference at 5% level of significance. Difference of SUV between Discovery Ste 8 workstation and mini PACS was showed statistical significant difference at 5% level of significance. Conclusion: In case that patient was scanned by the other scanner, if the correction of SUV formula in mini PACS for each scanners is performed, mini PACS will be usefully used to provide consistently quantitative assessment.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.44-49
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• 2012

Purpose: In the whole body PET/CT scan, it is natural to lift the patient's arm for its quality improvement. However, when the lesion is located in head and neck, the arms should be located lower. This study was designed to compare the CT effective dose for each arm position applying Automatic Exposure Control (AEC). Materials and Methods: 45 patients who had $^{18}F$-FDG whole body PET/CT scan were studied with Biograph Truepoint 40 (SIEMENS, GERMANY), Biograph Sensation 16 (SIEMENS, GERMANY), Discovery STe 8 (GE healthcare, USA). The CT effective dose of 15 patients for each equipment was measured and comparatively analyzed in both arm-lifted position and lower-arm position. ImPACT v1.0 program was used as the method of measurement for CT effective dose. For the statistics analysis, Paired t-test which paired with SPSS 18.0 statistic program was applied. Results: In the case of arm-lifted, it was measured as $6.33{\pm}0.93mSv$ for Biograph Sensation 16, $8.01{\pm}1.34mSv$ for Biograph Truepoint 40, and $9.69{\pm}2.32mSv$ for Discovery STe 8. When arms are located lower position, it was measure as $6.97{\pm}0.76mSv$, $8.95{\pm}1.85mSv$, $13.07{\pm}2.87mSv$ for each. CT effective dose according to the arm position was 9.2% for Biograph Truepoint 40, 10.5% for Biograph Sensation 16, and 25.9% for Discovery Ste 8. The statistics analysis showed the meaningful difference ($p$<0.05). Conclusion: For the whole body PET/CT case, CT effective dose applying AEC was decreased the radiation exposure of the patients when the arm was lifted for 15.2% of average value. The patient who has no lesion in head and neck would decrease the artifact occurrence in objective part and lower the CT effective dose. Also, for the patient who had lesion in head and neck, the artifact in objective part can be lower by putting the arms down, the fact that CT effective dose increases should be concerned in its whole body PET/CT scan.