• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.476-483
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• 1996

Following radiation therapy for brain tumors, patients often have clinical deterioration due to either radiation necrosis or recurrent tumor progression in the treatment field. The distinction between these entities is important but difficult clinically or even with CT or MRI. T1-201 has been known to accumulate in various tumors and be useful to grade, predict prognosis or detect recurrence of glioma. The aim of this study was to evaluate the usefulness of T1-201 SPECT in the differentiation of recurrent tumor from radiation necrosis. Of 67 patients who did T1-201 brain SPECT imaging with clinically suspected recurrent tumor or radiation necrosis, 20 patients underwent histopathological examination and constituted the study population. T1-201 uptake indices on T1-201 brain SPECT imaging rrere calculated and correlated with histopathological diagnosis. Of 20 patients, 15 were histopathologically confirmed as recurrent original tumor or malignant transformation of benign tumor and 5 were diagnosed as radiation necrosis. On T1-201 SPECT, 18 of 20 had T1-201 index above 2.5 which was regarded as positive indicator for the presence of tumor. Seventeen cases showed concordance, which consisted of 15 true positive and 2 true negative. Discordant 3 cases were all false positive. There was no case of false negative. The sensitivity, specificity, positive and negative predictive value of T1-201 SPECT were 100%, 40%, 83% and 100%. In conclusion, T1-201 brain SPECT is a sensitive diagnostic test in the detection of recurrent tumor following radiation therapy and is useful in the differentiation of recurrent tumor from radiation necrosis. Relatively low specificity should be evaluated further in larger number of patients in consideration of sampling error and referral bias for pathologic examination.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.484-492
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• 1996

To detect ischemic tissue in experimental model of cerebral ischemia made by middle cerebral artery(MCA)-occlusion, we acquired triple image of $^{99m}Tc$-glucarate, [$^{18}F$]fluoro-deoxyglucose (FDG), and 2,3,5- triphenyltetrazolium (TTC) staining. We made cerebral infarction either with reperfusion (after occlusion of 2 hours) or without reperfusion in 10 Sprague-Dawley rats by inserting thread to MCA through internal carotid artery. After 22 hours, we injected 740 MBq of $^{99m}Tc$-glucarate and 55.5 MBq of [$^{18}F$]FDG through tail vein. Each 1 mm slice of rat brains was frozen and exposed to imaging plate for 20 minutes in freezer to get an [$^{18}F$]FDG image. After 20 hours enough to fade radioactivity of [$^{18}F$]FDG, the slices were again imaged by BAS1500 for $^{99m}Tc$-glucarate uptake. Finally, these brain tissues were stained with TTC. Semi-quantitative visual analysis was done by grading 0 to 3 points according to the degree of uptakes($^{99m}Tc$-glucarate) and decreased uptakes([$^{18}F$]FDG and TTC). Ten rats survived with neurologic symptoms. TTC staining confirmed the development of infarction. The size of the infarction was relatively larger in the group without reperfusion. [$^{18}F$]FDG images were similar to TTC-stained images. However, we found regions with intermediate uptake which were not stained with TTC. We found regions with intermediate [$^{18}F$]FDG uptake where TTC staining was normal. $^{99m}Tc$-glucarate uptake was round only in TTC non-stained region. In the TTC stained regions, there were no uptake of $^{99m}Tc$-glucarate. We could not find clear relation between $^{99m}Tc$-glucarate uptake with [$^{18}F$]FDG uptake. This was partly because percent uptake of $^{99m}Tc$-glucarate was so small (less than 1 percent of injected dose) and because there were quite heterogeneity of patterns of [$^{18}F$]FDG uptake and TTC. With these findings, we could conclude that $^{99m}Tc$-glucarate were taken up only in part of ischemic tissues which were proven to be nonviable. The establishment of MCA-occluded rat model with or without reperfusion and triple imaging for $^{99m}Tc,\;^{18}F$ and TTC helped the characterization of $^{99m}Tc$-glucarate uptakes. Further work is needed to clarify the meaning or diversities or [$^{18}F$]FDG and TTC and their relation with $^{99m}Tc$-glucarate.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.384-390
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• 1994

Authors retrospectively compared the 99mTc MDP bone scans and corresponding MR imagings in 20 patients with histologically proven malignancy, Mean interval of the two studies was 16.6 days, Cancer diagnosis Included 8 lung, 2 each of colon, breast, stomach, 1 each of prostate, thyroid, malignant lymphoma and 3 adenocarcinoma of unknown primary site. Of the 105 regions compared, :t6 regions were positive for metastases in bone scans or MR imagings. 30 regions(65.2%) were positive by bone scan and 44 regions(95.7%) by MR imaging. 87 regions(82.9%) were concordantly positive or negative by bone scan and MR imaging, but 18 regions(17.1%) were discordant. In the discordant regions, 16 regions positive in MR imaging were negative in bone scan. The greatest number of discordant findings occured in the cervical region and in the patient with stomach cancer. Our results suggest that the sensitivity of MR Imaging is greater than that of bone scan in detecting spinal metastases. And bone scan is useful screening test of metastasis for evaluating entire skeleton including spine.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.507-515
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• 1996

Background : Potassium channel opener (K-opener) opens ATP-sensitive K'-channel located at cell membrane and induces potassium efflux from cytosol, resulting in intracellular hyperpolarization. Newly synthesized K-opener is currently examined for pharmacologic potency by means of rubidium release test from smooth muscle strip pre-incubated with Rb-86. Since in-vivo behavior of thallium is similar to that of rubidium, we hypothesized that K-opener can alter T1-201 kinetics in vivo. Purpose : This study was prepared to investigate the effects of pinacidil (one of potent K-openers) on the T1-201 uptake and clearance in cultured myocyte, and in-vivo biodistribution in mice. Methods : Spontaneous contracting myocytes were prepared to imitate in-vivo condition from 20 hearts of 3-5 days old Sprague-Dawley rat and cultured for 3-5 days before use ($5{\times}10^5$ cells/ml). Pinacidil was dissolved in 10% DMSO solution at a final concentration of 100nM or l0uM and was co-incubated with T1-201 in HBSS buffer for 20-min to evaluate its effect on cellular T1-uptake, or challenged to cell preparation pre-incubated with T1-201 for washout study. Two, 40 or $100{\mu}g$ of pinacidil was injected intravenously into ICR mice at 10 min after $5{\mu}Ci$ T1-201 injection, and organ uptake and whole body retention rate were measured at different time points. Results : Co-incubation of pinacidil with T1-201 resulted in a decrease in T1-201 uptake into cultured myocyte by 1.6 to 2.5 times, depending on pinacidil concentration and activity of T1-201 used. Pinacidil enhanced T1-201 washout by 1.6-3.1 times from myocyte preparations pre-incubated with T1-201. Pinacidil treatment appears to be resulted in mild decreases in blood and liver activity in normal mice, in contrast, renal and cardiac uptake were mildly decreased in a dose dependent manner. Whole body retention ratios of T1-201 were lower at 24 hour after injection with $100{\mu}g$ of pinacidil than control. Conclusion : These results suggest that treatment with K-opener may affect the interpretation of T1-201 myocardial images, due to decreasing thallium accumulation and enhancing washout from myocardium.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.560-569
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• 1996

Background and Purpose : Standardized uptake value(SUV) has been used as a quantitative index for differentiating benign and malignant tumors with F-18-FDG PET In this study, we produced whole body parametric images of SUV(WBPIS) by body weight normalization, and validated the values by comparison with SUV's calculated with regional scans. Subjects and Methods : Whole body scans were followed by regional scans sequentially on 23 patients. In whole body study, transmission and emission scans were acquired for 2 minutes and 6 minutes for each bed position, respectively. In regional study, transmission and emission scans were acquired for 20 minutes. Measured and segmented/ smoothed attenuation correction were applied using these 2 min transmission scans in whole body studies. The effects of attenuation correction on SUVs were evaluated quantitatively using F-18 filled cylindrical phantom. The mean and peak SUVs obtained from WBPIS were compared with SUVs of the regional scans. Results : In phantom studies, with any method of attenuation correction using regional or whole body studies of phantom, SUVs were nearly consistent. In whole body scan, SUV obtained using measured attenuation correction method was a little higher than SUV of regional scan. SUV obtained using segmented/smoothed attenuation correction method was a little lower. In patient studies, WBPIS using segmented/smoothed attenuation correction method was much smoother and more readable. SUVs of WBPIS obtained with both methods of attenuation correction were well correlated with SUVs of regional scans(r=0.9). SUVs of WBPIS with measured attenuation correction method were 5% lower than SUVs of regional scans. SUVs of WBPIS with segmented/smoothed attenuation correction method were 10% lower than SUVs of regional scans. The differences of SUVs of WBPIS by the two attenuation correction methods were relatively small compared with the possible differences derived from biological characteristics of tumors. Conclusion : We concluded that WBPIS could be useful in the quantification of tumor as well as in localization of whole body lesions, which were often outside the field of view in regional scan. WBPIS made using segmented/smoothed attenuation correction method could be used in clinical routines and SUVs from attenuation corrected F-18-FDG PET could be used interchangeably with SUVs of regional studies.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.317-325
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• 1994

The accuracy of dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial imaging for detection of ischemia depends on reproducible image interpretation. To evaluate the reproducibility of visual assessment, agreement in interpretation among two independent observers, blind-ed to clinical data, was evaluated in SPECT images of 131 patients (94 males, 38 females; mean age $58{\pm}7yr$) with suspected coronary artery disease who underwent both dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial SPECT and coronary angiography. The left ventricle was divided into twenty-nine segments in stress and rest SPECT images and each segment was visually graded according to a five-point scale (segmental score : 0=normal, 1=equivocal, 2=mild decrease, 3=severe decrease and 4=absent uptake). Overall concordance of segmental scoring between the two observers was 80%. The Pear-son's correlation coefficient (r) of the segmental scores for stress and rest images were 0.67 and 0.65, respectively, while the difference in score between the two images showed a correlation of 0.45 (all p<0.001). Agreement between two observers in final SPECT diagnosis as absence or presence of disease was 93%. The degree of agreement in segmental scoring showed no difference between patients with or without agreement as to the presence of disease. Therefore it appeared that cases with inconcordant diagnosis between the 2 observers were mainly due to a difference in individual threshold for interpretating the significance of a particular decreased uptake area rather than to a difference in perceiving the degree of the hypoactivity Thus, establishment of individual optimum thresholds in visual interpretation of myocardial SPECT may be helpful to improve reproducibility and accuracy of scan diagnosis.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.478-486
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• 2009

Purpose: 5-iododeoxyuridine analogues have been exclusively developed for the potential antiviral and antitumor therapeutic agents. In this study, we synthesized carbocyclic radioiododeoxyuridineanalogue (ddIVDU) and carbocyclic intermediate as efficient carbocyclic radiopharmaceuticals. Materials and Methods: The synthesis is LAH reduction, hetero Diels-Alder reaction as key reactions including Pd(0)-catalyzed coupling reaction together with organotin. MCA-RH7777 (MCA) and MCA-tk (HSV1-tk positive) cells were treated with various concentration of carbocyclic ddIVDU, and GCV. Cytotoxicity was measured by the MTS methods. For in vitro uptake study, MCA and MCA-tk cells were incubated with 1uCi of [$^{125}I$]carbocyclic ddIVDU. Accumulated radioactivity was measured after various incubation times. Results: The synthesis of ddIVDU and precursor for radioiodination were achieved from cyclopentadiene in good overall yield, respectively. The radioiododemetallation for radiolabeling gave more than 80% yield with > 95% radiochemical purity. GCV was more toxic than carbocyclic ddIVDU in MCA-tk cells. Accumulation of [$^{125}I$]carbocyclic ddIVDU was higher in MCA-tk cells than MCA cells. Conclusion: Biological data reveal that ddIVDU is stable in vitro, less toxic than ganciclovir (GCV), and selective in HSV1-tk expressed cells. Thus, this new carbocyclic nucleoside, referred to in this paper as carbocyclic 2',3'-didehydro-2',3'-dideoxy-5- iodovinyluridine (carbocyclic ddIVDU), is a potential imaging probe for HSV1-tk.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.4
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• pp.280-286
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• 2009

Purpose: The aim of this study was to evaluate the hemodynamic changes after endovascular stenting in patients with unilateral middle cerebral artery (MCA) stenosis using statistical probabilistic anatomical mapping (SPAM) analysis of basal/acetazolamide (ACZ) Tc-99m ECD brain perfusion SPECT. Materials and Methods: Eight patients (3 men and 5 women, 64.8$\pm$10.5 years) who underwent endovascular stenting for unilateral MCA stenosis were enrolled. Basal/ACZ Tc-99m ECD brain perfusion SPECT studies were performed by one-day protocol before and after stenting. Using SPAM analysis, we compared basal cerebral perfusion (BCP) counts and cerebrovascular reserve (CVR) index of the MCA territory before stenting with those after stenting. Results: After stenting, no patient had any complication nor additional stroke. In SPAM analysis, 7 out of the 8 patients had improved BCP counts of the MCA territory and 7 out of the 8 patients had improved CVR index of the MCA territory after stenting. Before stenting, the mean BCP counts and CVR index in the affected MCA territory were 47.1$\pm$2.2 ml/min/100 g and -2.1$\pm$2.9%, respectively. After stenting, the mean BCP counts and CVR index in the affected MCA territory were improved significantly (48.3$\pm$2.9 ml/min/100 g, p =0.025 and 0.1$\pm$1.3%, p =0.036). Conclusion: This study revealed that SPAM analysis of basal/ACZ brain perfusion SPEG would be helpful to evaluate hemodynamic efficacy of endovascular stenting in unilateral MCA stenosis.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.1
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• pp.122-126
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• 2014

Purpose: The new reconstruction algorithms (NRA) provided by vendor aim to shorten the acquisition scan time. Whereas depending on the installed version AutoQuant program used for myocardial SPECT quantitative analysis did not contain the normal data that NRA is applied. Thus, the purpose of this paper is to compare the results according to AutoQuant versions in myocardial SPECT applied NRA and half-time scan (HT). Materials and Methods: Rest Tl and stress MIBI data of total 80 (40 men, 40 women) patients were gathered. Data were applied HT acquisition and ASTONISH (Philips) software which is NRA. Modified autoquant of SNUH and old version of AutoQuant (full-time scan) provided by company were compared. Comparison groups were classified as coronary artery disease (CAD), 24 hrs delay and almost normal patients who have a simple pain patient. Perfusion distribution aspect, summed stress score (SSS), summed rest score (SRS), extent and total perfusion deficit (TPD) of each 25 patient who have above diseases were compared and evaluated. Results: The case of CAD, when using re-edited AutoQuant (HT) SSS and SRS showed about 30% reduction (P<0.0001), Extent showed about 38% reduction and TPD showed about 30% reduction in the tendency (P<0.0001). In the score of the perfusion, especially on the part of infero-medium, infero-apical, lateral-medium and lateral-apical regions were the biggest change. The case of the 24 hrs delay patient SRS (P=0.042), Extent (P=0.018) and TPD (P=0.0024) showed about 13-18% reduction. And the case of simple pain patient, comparison of 4 results showed about 5-7% reduction. Conclusion: This study was started based on expectation that results could be affected by normal patient data. Normal patient data is possible to change by race and gender. It was proved that combination of new reconstruction algorithm for reducing scan time and analysis program according to scan protocol with NRA could also be affected to results. Clinical usefulness of gated myocardial SPECT is possibly increased if each hospital properly collects normal patient data for their scan acquisition protocol.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.3
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• pp.184-191
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• 2008

Purpose: To evaluate the degree of malignancy of incident thyroid lesion found in $^{18}F$-FDG PET/CT findings and the usefulness of the method suggested in this study, we applicate the Delay Scan Method that differentiate a false positive benign tumor, inflammation and malignancy, as well as make the criteria of SUV. Materials and Methods: A retrograde study was conducted of 800 patients who were admitted in E hospital to receive $^{18}F$-FDG PET/CT examination. One patient who was diagnosed as primary thyroid cancer and received $^{18}F$-FDG PET/CT examination was excluded. The number of final patients of this study was 799, the reasons of $^{18}F$-FDG PET/CT examination of these patients were follow-up of old cancer or suspicious tumorous lesion in 696 and disease screening in 103. $^{18}F$-FDG PET/CT image photographing was taken in Biograph-Duo made by SIEMENS, after taking normal $^{18}F$-FDG PET/CT image (1 hr) and then 1 hr later we took the thyroid 1 bed-delayed image for the patients who showed abnormal thyroid $^{18}F$-FDG uptake and above 2.0 SUV for 2 minutes every 1 bed. For the patients who showed abnormal thyroid uptake and above 2.0 SUV, 1 hr later, we took a 1 bed-delayed image and then made a comparative study between measured $SUV_{max}$ of 1 hr-abnormal uptake image and that of 2 hr-delayed image. Results and Conclusion: In this $^{18}F$-FDG PET/CT study among the patients who showed incidental $^{18}F$-FDG thyroidal uptake the number of thyroid incidentaloma was 5 (0.63%), all of then showed benign findings. And in the case of incidental $^{18}F$-FDG uptake in thyroid, $SUV_{max}$ variance obtained from 2 hr delayed image can be a indirect criteria in differentiating benign tumor from malignancy and decrease finding error. In the cases found thyroid incidentaloma when 1) $SUV_{max}$ of focal thyroid lesion is above 5.0 and 2) $SUV_{max}$ variance between normal $^{18}F$-FDG PET/CT exam and 2 hr delayed is $1.0{\pm}0.5$, they are suspected as malignancy and confirming biopsy is to be followed. Otherwise, I also think that distinct follow-up PET or CT image study is a reasonable diagnostic method.