• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.44-48
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• 2012

Purpose : Arm motion can give rise to striking cold artifact on PET/CT. We investigated that evaluation of scatter-limit correction and correct the patient arm motion artifact in Discovery 600 PET/CT. Materials and Methods : To evaluate a radioactivity uptake (Bq/ml) and a standard uptake value (SUV), the scatter limit correction and scatter correction were compared using 1994 NEMA Phantom$^{TM}$ in Discovery 600 PET/CT (GE Healthcare, Mi, We). Arm motion phantom study was involved a central 20 cm diameter cylinder simulating the neck and 2 peripheral 10 cm diameter cylinders simulating arms. The positions of the arms were altered so as to introduce different amounts of misalignment. The evaluation of arm motion phantom study used the radioactivity uptake and SUV in scatter correction and scatter limit correction. Results : The statistical significance of radioactivity uptake and SUV did not show the differences in comparisons of the scatter limit correction and the scatter correction that not show (p<0.05). Radioactivity uptake of the scatter correction was up to 3.1 kBq/ml in the 0.04 kBq/ml. It was approximately 98.7% undervalued in the arm motion phantom study. However, Radioactivity uptake of the scatter limit correction was up to 3.0 kBq/ml in the 2.11 kBq/ml. It was approximately 30% undervalued in arm motion phantom study. SUV of the scatter correction was 1.05 to 0.006 and underestimated about 98%. However, an applying SUV of the scatter limit correction changed the value as 0.67 which is underestimated about 25%. Radioactivity uptake and SUV of the scatter limit correction was increased approximately 60%, or more than the scatter correction. Conclusion : It is considered that if the patient arm motion artifact was occurred the scatter limit correction will be applicable to give an accurate diagnosis.

• The Journal of the Korean bone and joint tumor society
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• v.20 no.2
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• pp.66-73
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• 2014

Purpose: Various diagnostic imaging modalities have been used to evaluate the effect of neoadjuvant chemotherapy for osteosarcoma early and noninvasively. We evaluated the effectiveness of imaging studies of plain radiographs and positron-emission tomography/computed tomography (PET/CT) in predicting neoadjuvant chemotherapy effect for osteosarcoma and tried to establish a general principle in interpretation of PET/CT parameters. Materials and Methods: Eighteen patients who underwent two cycles of neoadjuvant chemotherapy and surgical excision for osteosarcoma were enrolled. There were 13 males and 5 females, with a median age of 19 (11-63) years. Fifteen patients of 18 had the American Joint Committe on Cancer (AJCC) stage IIB. They had plain radiographs and PET/CT before and after neoadjuvant chemotherapy. The resected tumor specimens were pathologically examined to determine histological response grade using a conventional mapping method. Statistical analysis was performed to evaluate the correlation between histopathological necrosis rate, and radiographic finding category, post-chemotherapy maximum standardized uptake value (SUVmax), average standardized uptake value and metabolic tumor volume (MTV) as well as reduction rates of them. Results: Eight patients were good responders to neoadjuvant chemotherapy based on histological evaluation. Median SUVmax reduction rate was 73 (23-77) % in good responders and 42 (-32-76) % in poor responders. Median MTV reduction rate was 93.5 (62-99) % in good responders and 46 (-81-100) % in poor responders. While radiographic finding category was not different according to histological response (p=1.0), SUVmax reduction rate was significantly different (p=0.041). Difference in MTV reduction rates approached statistical significance as well (p=0.071). Conclusion: While radiographic finding category was not reliable to assess neoadjuvant chemotherapy effect for osteosarcoma, reduction rate of SUVmax was a useful indicator in this study. As parameters of PET/CT can be influenced by various factors of settings, different centers have to make an effort to establish their own standard of judgement with reference of previous studies.

• Journal of the Korean Society of Radiology
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• v.8 no.5
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• pp.241-248
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• 2014

The purpose of this study were to analyze the clinical correlation between the thyroid autoimmune antibodies (anti-TPO Ab, anti-TG Ab, and TSH) and the maximum standardized uptake value ($SUV_{max}$) base on the Hashimoto's thyroiditis and the Graves' disease in diffusely $^{18}F-FDG$ uptake of the thyroid gland to the PET/CT image. To achieve this, we was performed the PET/CT examination for the 1,097 subjects from May 2010 to April 2013 in the health screening, and was detected the diffused FDG thyroid uptake, and was additionally performed the thyroid function test (TFT) and the ultrasound (US). As a results, the autoimmune thyroid disease with the diffused FDG thyroid uptake were discovered 39 patients (3.9%), of this, the Hashimoto's thyroiditis was 43.6% and the Graves' disease was 23.1%. Hashimoto's thyroiditis was shown the positive reaction of high titer between the anti-TPO Ab and the anti-TG Ab level, and the correlation coefficient between the $SUV_{max}$ and the anti-TPO Ab was a statistically significant (r>04, p<0.05). Also, Graves' disease was shown the positive reaction of high titer most of the thyroid autoimmune antibodies, and the correlation coefficient between the $SUV_{max}$ and the anti-TPO Ab was a statistically significant (r>05, p<0.01). Therefor, when have a high standard of the $SUV_{max}$ due to the diffusely $^{18}F-FDG$ uptake of the thyroid gland, Hashimoto's thyroiditis and Graves' disease were proportionally increased the anti-TPO Ab and TSH level, respectively. The correlation coefficient between the $SUV_{max}$ and the thyroid autoimmune antibodies will be the most influential criterion that was a standard of judgment for the epihpenomenon of the autoimmune thyroid disease, and it will be available for the clinical application.

• 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.14 no.2
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• pp.50-54
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• 2010

Purpose: The uptake of $^{18}F$-FDG is often observed in normal cell of colon to patients who have non-insulin-dependent diabetes mellitus and had taken anti-diabetic drugs including Metformin in PET/CT scan. In this study, the region of colon was compared between the patients who took anti-diabetic drugs including Metfomin and other patients who took the other anti-diabetic drugs through SUV measurements. Materials and Methods: A hundred eighty patients were studied. 120 patients who have non-insulin-dependent diabetes mellitus (Including Metformin: 60, Excluding Metformin: 60) and 60 patients as a control group were composed. The patient fasted at least 6 hours before receiving an intravenous injection of 370-592 MBq (10-16 mCi) of $^{18}F$-FDG. Scanning from the base of the skull though the mid thigh was performed using the Discovery STe PET/CT Equipment (GE Healthcare, Milwaukee, WI, USA). The highest uptake region was measured SUV among ascending, transverse and descending colon. Results: The values of patients who took the anti-diabetic drugs including Metformin were $6.16{\pm}3.64$ g/mL, $4.41{\pm}2.94$ g/mL, and $5.46{\pm}2.44$ g/mL. The patients who took the anti-diabetic drugs which does not have Metformin were $3.05{\pm}1.39$ g/mL, $2.08{\pm}0.97$ g/mL and $3.15{\pm}1.85$ g/mL. The control group were $2.02{\pm}0.88$ g/mL, $1.68{\pm}0.87$ g/mL and $2.19{\pm}1.88$ g/mL. Conclusion: The effect of the intake of Metformin was observed from the SUV on region of large bowel in this study. Thus, it could be helpful for the results by identifying the ingredient of anti-diabetic drug before the examination and the possibility of interpretation of false positive will be reduced.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.43-48
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• 2014

Purpose: In the PET/CT images, The SUV (standardized uptake value) enables the quantitative assessment according to the biological changes of organs as the index of distinction whether lesion is malignant or not. Therefore, It is too important to enter parameters correctly that affect to the SUV. The purpose of this study is to evaluate an allowable error range of SUV as measuring the difference of results according to input errors of Activity, Weight, uptake Time among the parameters. Materials and Methods: Three inserts, Hot, Teflon and Air, were situated in the 1994 NEMA Phantom. Phantom was filled with 27.3 MBq/mL of 18F-FDG. The ratio of hotspot area activity to background area activity was regulated as 4:1. After scanning, Image was re-reconstructed after incurring input errors in Activity, Weight, uptake Time parameters as ${\pm}5%$, 10%, 15%, 30%, 50% from original data. ROIs (region of interests) were set one in the each insert areas and four in the background areas. $SUV_{mean}$ and percentage differences were calculated and compared in each areas. Results: $SUV_{mean}$ of Hot. Teflon, Air and BKG (Background) areas of original images were 4.5, 0.02. 0.1 and 1.0. The min and max value of $SUV_{mean}$ according to change of Activity error were 3.0 and 9.0 in Hot, 0.01 and 0.04 in Teflon, 0.1 and 0.3 in Air, 0.6 and 2.0 in BKG areas. And percentage differences were equally from -33% to 100%. In case of Weight error showed $SUV_{mean}$ as 2.2 and 6.7 in Hot, 0.01 and 0.03 in Tefron, 0.09 and 0.28 in Air, 0.5 and 1.5 in BKG areas. And percentage differences were equally from -50% to 50% except Teflon area's percentage deference that was from -50% to 52%. In case of uptake Time error showed $SUV_{mean}$ as 3.8 and 5.3 in Hot, 0.01 and 0.02 in Teflon, 0.1 and 0.2 in Air, 0.8 and 1.2 in BKG areas. And percentage differences were equally from 17% to -14% in Hot and BKG areas. Teflon area's percentage difference was from -50% to 52% and Air area's one was from -12% to 20%. Conclusion: As shown in the results, It was applied within ${\pm}5%$ of Activity and Weight errors if the allowable error range was configured within 5%. So, The calibration of dose calibrator and weighing machine has to conduct within ${\pm}5%$ error range because they can affect to Activity and Weight rates. In case of Time error, it showed separate error ranges according to the type of inserts. It showed within 5% error when Hot and BKG areas error were within ${\pm}15%$. So we have to consider each time errors if we use more than two clocks included scanner's one during the examinations.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.13-20
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• 2011

Purpose: The limited FOV(Field of View) of CT (Computed Tomography) can cause truncation artifact at external DFOV (Display Field of View) in PET/CT image. In our study, we measured the difference of SUV and compared the influence affecting to the image reconstructed with the extended DFOV. Materials and Methods: NEMA 1994 PET Phantom was filled with $^{18}F$(FDG) of 5.3 kBq/mL and placed at the center of FOV. Phantom images were acquired through emission scan. Shift the phantom's location to the external edge of DFOV and images were acquired with same method. All of acquired data through each experiment were reconstructed with same method, DFOV was applied 50 cm and 70 cm respectively. Then ROI was set up on the emission image, performed the comparative analysis SUV. In the clinical test, patient group shown truncation artifact was selected. ROI was set up at the liver of patient's image and performed the comparative analysis SUV according to the change of DFOV. Results: The pixel size was increase from 3.91 mm to 5.47 mm according to the DFOV increment in the centered location phantom study. When extended DFOV was applied, $_{max}SUV$ of ROI was decreased from 1.49 to 1.35. In case of shifted the center of phantom location study, $_{max}SUV$ was decreased from 1.30 to 1.20. The $_{max}SUV$ was 1.51 at the truncated region in the extended DFOV. The difference of the $_{max}SUV$ was 25.9% higher at the outside of the truncated region than inside. When the extended DFOV was applied, $_{max}SUV$ was decreased from 3.38 to 3.13. Conclusion: When the extended DFOV was applied, $_{max}SUV$ decreasing phenomenon can cause pixel to pixel noise by increasing of pixel size. In this reason, $_{max}SUV$ was underestimated. Therefore, We should consider the underestimation of quantitative result in the whole image plane in case of patient study applied extended DFOV protocol. Consequently, the result of the quantitative analysis may show more higher than inside at the truncated region.

• Exercise Science
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• v.21 no.2
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• pp.231-242
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• 2012

The purpose of this study was to develop the prediction model of VO₂max using submaximal metabolic responses from the Bruce protocol, HR responses at several stages and 1,200 m running record, and to compare and analyse the validity of these prediction models. The subjects were consisted of 255 male(133 male for 1,200 m running). They were participated maximal exercise testing with Bruce protocol, and the metabolic responses were measured in the end of the first(3 minute), second stage(6 minute), and 1,200 m running record. Measurement items were VO₂(㎖/kg/min), VCO₂(㎖/kg/min), VE(L/min), HR(bpm) of 3 and 6 minute, time to HR 150 bpm and 170 bpm, HR difference between Bruce protocol 6 and 3 minute, 1,200 m running record. Analyzing with all variables using enter method, the multiple R of total variable model was 0.642(p<.01), SEE was 4.38 ㎖/kg/min, CV was 10.8 %, but multicolinearity was appeared. The multiple R of 3 minutes model 1 and model 2 were 0.341 and 0.461, SEE was 6.05 and 5.72 ㎖/kg/min, CV was 14.9 and 14.1%, and multicolinearity did not appeared. The multiple R of 6 minutes model 1 and model 2 were 0.350 and 0.456, SEE was 6.03 and 5.74 ㎖/kg/min, CV was 14.9 and 14.2%, and multicolinearity did not appeared. The R of HR 170 and HR 170 model were 0.151 and 0.154, SEE were 6.36~6.37 ㎖/kg/min, CV were 15.7%. The R of 1,200 m running model was 0.444, SEE was 4.82 ㎖/kg/min, CV were 11.9%. In conclusion, with considering usefulness and convenience through the validity of these prediction models, the prediction model of VO₂max recommended 6 and 3 minute model, and the validity of HR model and 1,200 m running model were moderately low.

• Journal of Biomedical Engineering Research
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• v.39 no.2
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• pp.80-86
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• 2018

The aim of this study were to establish the clinical references and guidelines for the maximum standardized uptake ($SUV_{max}$) value of pancreatic cancer, pancreatitis, and normal pancreas in $^{18}F-FDG$ PET-CT examinations for pancreatic disease. For this purpose, we performed the statistical analysis on the descriptive statistics, percentiles and inter quartiles range (IQR), normal distribution, and using the probability density function for pancreatic cancer, pancreatitis, and normal pancreas. As a result, the clinical reference of $SUV_{max}$ for the pancreatic cancer, pancreatitis, and normal pancreas was more than 3.45, 1.91 to 2.62, and less than 1.91, respectively. Also, optimal cut-off value for applying the dual time point PET-CT examination was determined to be 2.62. The results of this study are summarized as follows: first, we suggests the clinical reference and guideline for the pancreatic cancer, pancreatitis, and normal pancreas, and second, suggests a scientific approach to improve diagnostic accuracy of pancreatic disease by deviating from an approximate experience approach.

• The Korean Journal of Nuclear Medicine
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• v.33 no.5
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• pp.439-451
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• 1999

Purpose : It is important to differentiate malignant from benign lesions of intraocular masses in choosing therapeutic plan. Biopsy of intraocular tumor is not recommended due to the risk of visual damage. We evaluated the usefulness of F-18-FDG PET imaging in diagnosing intraocular neoplasms. Materials and Methods: F-18-FDG PET scan was performed in 13 patients (15 lesions) suspected to have malignant intraocular tumors. There were 3 benign lesions (retinal detachment, choroidal effusion and hemorrhage) and 10 patients with 12 malignant lesions (3 melanomas, 7 retinoblastomas and 2 metastatic cancers). Regional eye images ($256{\times}256$ and $128{\times}128$ matrices) were obtained with or without attenuation correction. Whole body scan was also performed in eight patients (3 benign and 6 malignant lesions). Results: All malignant lesions were visualized while all benign lesions were not visualized. The mean peak standardized uptake value (SUV) of malignant lesions was $2.64{\pm}0.57g/ml$. There was no correlations between peak SUV and tumor volume. Two large malignant lesions ($> 1000 mm^3$) showed hot uptake on whole body scan. But two medium-sized lesions ($100-1000mm^3$) looked faint and two small ($<100mm^3$) lesions were not visualized. The images reconstructed with $256{\times}256$ matrix showed lesions more clearly than those with $128{\times}128$ matrix Conclusion: F-18-FDG PET scan is highly sensitivity in detecting malignant intraocular tumor For the evaluation of small-sized intraocular lesions, whole body scan is not appropriate because of low sensitivity. A regional scan with sufficient acquisition time is recommended for that purpose. Image reconstruction in matrix size of $256{\times}256$ produced clearer images than the ones in $128{\times}128$, but it does not affect the diagnostic sensitivity.