Simplified Dynamic Phantom for Pediatric Renography: A Description of Instrument and Its Performance

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

Nuclear medicine practice in Japan: a report of the seventh nationwide survey in 2012

Objective The Subcommittee on the Survey of Nuclear Medical Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. Methods The subcommittee sent questionnaires, including the number and category of examinations as well as the kind and dose of the radiopharmaceuticals during the 30 days of June 2012, to all the nuclear medicine institutes. The total numbers for the year 2012 were then estimated. Results A total of 1,167 institutes responded to the survey, including the 14 in vitro assay institutes and 266 PET centers. The recovery rate was 92 %. The number of gamma cameras installed was 1,425 in total, with 9 % decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 84 and 10.5 %, respectively. The number of single-photon tracer studies in 2012 was 1.15 million which means decrease in 19 % in 5 years and 29 % in 10 years. All but cerebral perfusion study and sentinel lymphoscintigraphy have decreased. Bone scintigraphy was a leading examination (38.7 %), followed by cardiac studies (29.4 %) and cerebral perfusion study (18.5 %) in order. SPECT studies showed an increase from 42.3 to 47.2 %. PET centers have also increased from 212 to 295, as compared to the last survey. The 135 PET centers have installed one or two in-house cyclotrons. PET studies showed 25.5 % increase in 5 years, with oncology accounting for 96.3 %. 18F-FDG accounted for 98.2 % (505,990 examinations). PET examinations using 11C-methionine have been increasing, with 3,352 examinations in 2012. The number of new PET studies using 11C-PIB PET was 695. 131I-radioiodine targeted therapies showed an increase, including 3,644 patients (53.6 %) for thyroid cancer and 4,889 patients (17.9 %) for hyperthyroidism. Out-patient thyroid bed ablation therapy with 30 mCi of 131I accounted for 21.0 % of cancer patients. The number of admission rooms decreased from 158 to 135 in 5 years. In vitro radioassays have been declining continuously since 1992, with the number of studies of 9.0 million in 2012. Conclusions Single-photon examinations showed a continuous tendency toward a decline in the survey. In contrast, the number of hybrid SPECT/CT scanner examinations has increased. PET/CT study in the oncology field and radionuclide targeted therapy have steadily increased. © 2014 The Japanese Society of Nuclear Medicine

Different Characteristics of Cognitive Impairment in Elderly Schizophrenia and Alzheimer's Disease in the Mild Cognitive Impairment Stage

We compared indices of the revised version of the Wechsler Memory Scale (WMS-R) and scaled scores of the five subtests of the revised version of the Wechsler Adult Intelligence Scale (WAIS-R) in 30 elderly schizophrenia (ES) patients and 25 Alzheimer's disease (AD) patients in the amnestic mild cognitive impairment (aMCI) stage (AD-aMCI). In the WMS-R, attention/concentration was rated lower and delayed recall was rated higher in ES than in AD-aMCI, although general memory was comparable in the two groups. In WAIS-R, digit symbol substitution, similarity, picture completion, and block design scores were significantly lower in ES than in AD-aMCI, but the information scores were comparable between the two groups. Delayed recall and forgetfulness were less impaired, and attention, working memory and executive function were more impaired in ES than in AD-aMCI. These results should help clinicians to distinguish ES combined with AD-aMCI from ES alone

Data from: Increase in extraction of I-123 iomazenil in patients with chronic cerebral ischemia

Background: Cerebral extraction of diffusively distributed substances like oxygen has been suggested to change according to the cerebral blood flow (CBF) and status of the microvasculature. The relationships between the cerebral extraction of diffusively distributed lipophilic tracers and the severity of cerebral ischemia has not yet been clarified. In the present study, we attempted to elucidate the association between the extraction fraction of the lipophilic tracer I-123 iomazenil (IMZ) (IMZ-EF) and the oxygen extraction fraction (OEF) derived from O-15 PET in patients with chronic steno-occlusive disease of internal carotid artery (ICA) or middle cerebral artery (MCA). Methods: Seven patients with unilateral chronic severe stenosis or occlusion of the middle cerebral/internal cerebral artery were prospectively recruited for this study. All the patients underwent both O-15 PET and quantitative I-123 IMZ SPECT. Parametric images derived from the PET and SPECT scans were anatomically normalized and evaluated by automated image analysis based on the volume-of-interest template. Results: The asymmetry index (AI) of IMZ-EF was shown to significantly correlated with the AI of OEF (r = 0.562, P < 0.001) in the internal carotid artery perfusion area. Strong and significant correlation between the AI of the influx rate constant K1 of IMZ and the AI of the cerebral metabolic rate of oxygen (r = 0.552, P = 0.001) was clarified. Conclusions: Our results suggested that the transportation efficiency of I-123 IMZ into the brain tissue was an indicator for evaluating severity of cerebral ischemia in patients with chronic steno-occlusive disease of ICA or MCA. Cerebral metabolic state can possibly be estimated by I-123 IMZ SPECT without cyclotron

Image data of figure3A

Asymmetry maps of the patient with left ICA occlusion accompanied by old cerebral infarction in the left medial frontal lobe (Case 2 in Table 1); Image format is NIfTI.　These images were overlayed on the template MRI

Data for figure2

The AI of the parameters in the 35 VOI pairs from the 7 patient

Image data of figure3B

Asymmetry maps of the patient with near-occlusion of the left ICA (Case 5 in Table 1); Image format is NIfTI. These images were overlayed on the template MRI