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Objective(s): Renography is used for the diagnostic evaluation of pediatric patients with a suspected obstruction of urinary tract or impaired renal function. The recommended dose for children have been released by the European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and Japanese Society of Nuclear Medicine. Since acquisition counts in dynamic scintigraphy are affected by the administered doses and sensitivity of the scintillation camera, the scan procedure should be determined independently. In this study, we constructed simplified dynamic phantom imitating pediatric renography and tested its performance.Methods: Simplified dynamic phantom consisted of three components (i.e.,infusion, imitated kidney, and drainage sections). The infusion rates (mL/min) were determined by comparing the time activity curves obtained from patientswith normal renal function. The time-points of the maximum counts (Tmax), as well as the two-thirds and one-half of the maximum counts (T2/3 and T1/2) were measured in different doses using the phantom with the best-match infusion rateand duration, and low-energy general-purpose (LEGP) or low-energy highresolution (LEHR) collimators and applying different attenuations.Results: The best-match infusion rates of the phantom to imitate the time activity curve of the normal renal function were 42.0, 1.0, 0.6, and 0.3 mL/min in the arterial, secretory, early-excretory, and late-excretory phases, respectively. When 30 MBq, LEHR collimator and non-water-equivalent phantom were applied, Tmax, T2/3, and T1/2 were 242±15.3, 220±10.0 and 317±25.2 seconds, respectively. Using LEGP collimator and (3 MBq of activity) 5-cm water-equivalent phantom, Tmax, T2/3, and T1/2 values were estimated as 242±5.8, 213±11.5, and 310±17.3 sec, respectively.Conclusion: Our simplified dynamic phantom for pediatric renography could imitate the time activity curves obtained from patients with normal renal function. Tmax, T2/3, and T1/2 could be measured under various settings of dose,collimator, and tissue attenuation.

Objective(s): This study aimed to evaluate the role of pretreatment SUVmax and volumetric FDG positron emission tomography (PET) parameters in the differentiation between benign and malignant mediastinal tumors. In addition, we investigated whether pretreatment SUVmax and volumetric FDG-PET parameters could distinguish thymomas from thymic carcinomas, and low-risk from high-risk thymomas.Methods: This study was conducted on 52 patients with mediastinal tumors undergoing FDG-PET/CT. Histological examination indicated that 29 mediastinal tumors were benign, and 23 cases were malignant. To obtain quantitative PET/CT parameters, we determined the maximum standardized uptake value (SUVmax), volumetric parameters, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumors using SUVmax cut-off value of 2.5. SUVmax, MTV and TLG of benign and malignant tumors were comparedusing the Mann-Whitney U test. Moreover, receiver-operating curve (ROC) analysis was applied to identify the cut-off values of SUVmax, MTV and TLG for the accurate differentiation of benign and malignant tumors. SUVmax, MTV and TLG were compared between thymomas and thymic carcinomas, as well as low-risk and high-risk thymomas.Results: Mean SUVmax, MTV and TLG of malignant mediastinal tumors were significantly higher compared to benign tumors (P

Objective(s): It is difficult to investigate the whole-body distribution of an orally administered drug by means of positron emission tomography (PET), owing to the short physical half-life of radionuclides, especially when 11C-labeled compounds are tested. Therefore, we aimed to examine the whole-body distribution of donepezil (DNP) as an acetylcholinesterase inhibitor by means of 11C-DNP PET imaging, combined with the oral administration of pharmacological doses of DNP.Methods: We studied 14 healthy volunteers, divided into group A (n=4) and group B (n=10). At first, we studied four females (mean age: 57.3±4.5 y), three of whom underwent 11C-DNP PET scan at 2.5 h after the oral administration of 1 mg and 30 μg of DNP, respectively, while one patient was scanned following the oral administration of 30 μg of DNP (group A). Then, we studied five females and five males (48.3±6.1 y), who underwent 11C-DNP PET scan, without the oral administration of DNP (group B). Plasma DNP concentration upon scanning was measured by tandem mass spectrometry. Arterialized venous blood samples were collected periodically to measure plasma radioactivity and metabolites. In group A, 11C-DNP PET scan of the brain and whole body continued for 60 and 20 min, respectively. Subjects in group B underwent sequential whole-body scan for 60 min. The regional uptake of 11C-DNP was analyzed by measuring the standard uptake value (SUV) through setting regions of interest on major organs with reference CT.Results: In group A, plasma DNP concentration was significantly correlated with the orally administered dose of DNP. The mean plasma concentration was 2.00 nM (n=3) after 1 mg oral administration and 0.06 nM (n=4) after 30 μg oral administration. No significant difference in plasma radioactivity or fraction of metabolites was found between groups A and B. High 11C-DNP accumulation was found in the liver, stomach, pancreas, brain, salivary glands, bone marrow, and myocardium in groups A and B, in this order. No significant difference in SUV value was found among 11C-DNP PET studies after the oral administration of 1 mg of DNP, 30 μg of DNP, or no DNP.Conclusion: The present study demonstrated that the whole-body distribution of DNP after the oral administration of pharmacological doses could be evaluated by 11C-DNP PET studies, combined with the oral administration of DNP.

Objective(s): Post-treatment evaluations by CT/MRI (based on the International Working Group/ Cotswolds meeting guidelines) and PET (based on Revised Response Criteria), were examined in terms of progression-free survival (PFS) in patients with malignant lymphoma (ML). Methods: 79 patients, undergoing CT/MRI for the examination of suspected lesions and whole-body PET/CT before and after therapy, were included in the study during April 2007-January 2013. The relationship between post-treatment evaluations (CT/MRI and PET) and PFS during the follow-up period was examined, using Kaplan-Meier survival analysis. The patients were grouped according to the histological type into Hodgkin’s lymphoma (HL), diffuse large B-cell lymphoma (DLBCL), and other histological types. The association between post-treatment evaluations (PET or PET combined with CT/ MRI) and PFS was examined separately. Moreover, the relationship between disease recurrence and serum soluble interleukin-2 receptor, lactic dehydrogenase, and C-reactive protein levels was evaluated before and after the treatment. Results: Patients with incomplete remission on both CT/MRI and PET had a significantly shorter PFS, compared to patients with complete remission on both CT/MRI and PET and those exhibiting incomplete remission on CT/MRI and complete remission on PET (P