PURPOSE: The purpose of this study was to establish optimal imaging acquisition conditions for the GE Advance(TM) PET imaging system by performing the acceptance tests designed by National Electrical Manufacturers Association (NEMA) protocol and General Electric Medical Systems (GEMS) test procedures. MATERIALS AND METHODS: Performance tests were carried out with 18FDG radioactivity source and phantoms by using a standard acquisition mode. Transaxial resolution and scatter fraction tests were performed with a line source and axial resolution with a point source, respectively. A cylindrical phantom made of polymethylmethacrylate (PMMA) was used to measure sensitivity, count rate losses and randoms, uniformity correction, and attenuation inserts were added to measure remaining tests. The test results were acquired in a diagnostic acquisition mode and analyzed mainly on high sensitivity mode. RESULTS: Transaxial resolution and axial resolution were measured as average of 4.65 mm and 3.98 mm at 0 cm, and 6.02 mm and 6.71 mm at 20 cm on high sensitivity mode, respectively. Average scatter fraction was 9.87%, and sensitivity was 225.8 kcps/micronCi/cc of trues. Activity at 50% deadtime was 4.6 Ci/cc, and the error of count rate correction at that activity was from 1.49% to 3.83%. Average nonuniformity for total slice was 8.37%. The accuracy of scatter correction was -0.95%. The accuracies of attenuation correction were 5.68% for air, 0.04% for water and -6.51% for polytetrafluoroethylene (PTFE). CONCLUSION: The results satisfied most acceptance criteria, indicating that the GE AdvanceTM PET system can be optimally used for clinical applications.
Electrons* ; Fluorodeoxyglucose F18 ; Polymethyl Methacrylate ; Polytetrafluoroethylene ; Positron-Emission Tomography* ; Radioactivity ; Water

No abstract available.
Teratoma*

BACKGROUND: Gallstone is one of the most common cause of acute abdominal pain and is increasingly managed by laparoscopic cholecystectomy. Silent gallstones are usually managed expectantly and are considered for surgery only if the characteristic biliary pain occurs. If predictors of stone-related complications such as acute cholecystitis, pancreatitis, and cholangitis can be identified, patients at high risk can be selectively referred for treatment regardless of symptoms development, while those at lower risk may be safely observed. The purpose of this study was to find out the predictors of stone-related complication or biliary pain in patients with gallbladder stones. METHODS: We collected clinical data retrospectively on patients who were diagnosed with gallstone at Asan Medical Center. Total gallstone number was classified into 1, 2~4, over 5. Diameter of the gallstones were subdivided into 20 mm. Statistical analysis was performed using SAS program (Ver 6.11). RESULTS: 918 patients (432 men and 486 women) were included in the analysis. The mean age was 54.3 years; that of men was 55 years and women was 53.8 years. Stone-related complications developed in 201 patients of acute cholecystitis, 78 patients of acute gallstone pancreatitis and 80 patients of acute cholangitis. Biliary pain was occurred in 568 patients. 658 patients were experienced cholecystectomy (158 patients open cholecystectomy and 500 patiens LLC). 377 patients were experiened ERCP, and 289 persons of that were experienced EST. Acute gallstone pancreatitis and acute cholangitis were significantly more frequent in older age and patients experiencing biliary pain. Their gallstone size was significantly smaller and the number was significantly more numerous in the univariate analysis. But, in the multiple logistic regression analysis, only age and the smallest stone size were independent risk factors. Patients who experiencing biliary pain were older and had significantly smaller and multiple gallstones in the univariate analysis. However in the multiple logistic regression analysis only age and stone number were independent variables. Acute cholecystitis was significantly more frequent in the old age group and patients with biliary pain. CONCLUSION: In the multiple logistic regression analysis, old age and small gallstones were predictors of acute gallstone pancreatitis and acute cholangitis. Old age and multiple gallstones were associated with biliary pain. Old age and biliary pain were predictors of acute cholecystitis, but the gallstone size and number were not associated in this study. We suggest that a well-designed prospective study is necessary in the future.
Abdominal Pain ; Cholangiopancreatography, Endoscopic Retrograde ; Cholangitis ; Cholecystectomy ; Cholecystectomy, Laparoscopic ; Cholecystitis ; Cholecystitis, Acute ; Chungcheongnam-do ; Female ; Gallbladder ; Gallstones* ; Humans ; Logistic Models ; Male ; Pancreatitis ; Retrospective Studies ; Risk Factors