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Sample records for 18f-fallypride pet study

  1. Striatal and extrastriatal dopamine release measured with PET and [18F]fallypride

    PubMed Central

    Slifstein, Mark; Kegeles, Lawrence S.; Xu, Xiaoyan; Thompson, Judy L.; Urban, Nina; Castrillon, John; Hackett, Elizabeth; Bae, Sung-A; Laruelle, Marc; Abi-Dargham, Anissa

    2009-01-01

    The amphetamine challenge, in which PET or SPECT radioligand binding following administration of amphetamine is compared to baseline values, has been successfully used in a number of brain imaging studies as an indicator of dopaminergic function, particularly in the striatum. [18F] fallypride is the first PET radioligand that allows measurement of the effects of amphetamine on D2/D3 ligand binding in striatum and extra-striatal brain regions in a single scanning session following amphetamine. We scanned 15 healthy volunteer subjects with [18F] fallypride at baseline and following amphetamine (0.3 mg/kg) using arterial plasma input based modeling as well as reference region methods. We found that amphetamine effect was robustly detected in ventral striatum, globus pallidus and posterior putamen, and with slightly higher variability in other striatal subregions. However, the observed effect sizes in striatum were less than those observed in previous studies in our lab using [11C] raclopride. Robust effect was also detected in limbic extra-striatal regions (hippocampus, amygdala) and substantia nigra, but the signal to noise ratio was too low to allow accurate measurement in cortical regions. We conclude that [18F] fallypride is a suitable ligand for measuring amphetamine effect in striatum and limbic regions, but is not suitable for measuring the effect in cortical regions and may not provide the most powerful way to measure the effect in striatum. PMID:20029833

  2. Psychotic reactivity to daily life stress and the dopamine system: a study combining experience sampling and [18F]fallypride positron emission tomography.

    PubMed

    Hernaus, Dennis; Collip, Dina; Lataster, Johan; Viechtbauer, Wolfgang; Myin, Erik; Ceccarini, Jenny; Van Laere, Koen; van Os, Jim; Myin-Germeys, Inez

    2015-02-01

    Stressful life events increase the risk for psychosis, and the subjective experience of stress related to daily life activities drives moment-to-moment variation in psychotic intensity. Positron emission tomography (PET) studies suggest that dopaminergic (DAergic) activity mediates the behavioral response to an experimental stressor. However, it is not known how alterations in this DAergic stress response relate to the subjective experience of stress in real life situations assessed in momentary assessment studies. This study combined [18F]fallypride PET with an Experience Sampling ambulatory assessment approach to examine the association between the prefrontal DAergic response to experimentally induced stress and real life psychotic reactivity to the subjective experience of stress in daily life. Healthy first-degree relatives of individuals with a psychotic disorder (N = 14) and healthy controls (N = 11) participated in (a) a psychosocial [18F]fallypride PET stress paradigm and (b) an experience sampling study, using a structured diary approach. Mixed multilevel random intercept models revealed that stress-induced [18F]fallypride displacement, indicative of DAergic activity, in ventromedial prefrontal cortex (VMPFC) was associated with psychotic reactivity to daily life stress in the entire sample. Lower levels of [18F]fallypride displacement to stress predicted increased psychotic reactivity to daily life stress. This study combined PET neuroimaging with real life behavioral assessments in the investigation of psychotic symptoms; we showed decreased [18F]fallypride displacement to stress in VMPFC to be associated with increased psychotic reactivity to daily life stress. The preliminary evidence in this study demonstrates that it is possible to acquire a grasp on how brain function is associated with contextualized experience, which has relevance for neuroimaging studies in general.

  3. Delta-9-Tetrahydrocannabinol-Induced Dopamine Release as a Function of Psychosis Risk: 18F-Fallypride Positron Emission Tomography Study

    PubMed Central

    Kuepper, Rebecca; Ceccarini, Jenny; Lataster, Johan; van Os, Jim; van Kroonenburgh, Marinus; van Gerven, Joop M. A.; Marcelis, Machteld; Van Laere, Koen; Henquet, Cécile

    2013-01-01

    Cannabis use is associated with psychosis, particularly in those with expression of, or vulnerability for, psychotic illness. The biological underpinnings of these differential associations, however, remain largely unknown. We used Positron Emission Tomography and 18F-fallypride to test the hypothesis that genetic risk for psychosis is expressed by differential induction of dopamine release by Δ9-THC (delta-9-tetrahydrocannabinol, the main psychoactive ingredient of cannabis). In a single dynamic PET scanning session, striatal dopamine release after pulmonary administration of Δ9-THC was measured in 9 healthy cannabis users (average risk psychotic disorder), 8 patients with psychotic disorder (high risk psychotic disorder) and 7 un-related first-degree relatives (intermediate risk psychotic disorder). PET data were analyzed applying the linear extension of the simplified reference region model (LSRRM), which accounts for time-dependent changes in 18F-fallypride displacement. Voxel-based statistical maps, representing specific D2/3 binding changes, were computed to localize areas with increased ligand displacement after Δ9-THC administration, reflecting dopamine release. While Δ9-THC was not associated with dopamine release in the control group, significant ligand displacement induced by Δ9-THC in striatal subregions, indicative of dopamine release, was detected in both patients and relatives. This was most pronounced in caudate nucleus. This is the first study to demonstrate differential sensitivity to Δ9-THC in terms of increased endogenous dopamine release in individuals at risk for psychosis. PMID:23936196

  4. Evaluation of the early response and mechanism of treatment of Parkinson's disease with L-dopa using 18F-fallypride micro-positron emission tomography scanning

    PubMed Central

    FA, YI-HUA; NI, JIAN-QIANG; WU, XIAO-JIN; TAN, JIA-QING; WU, YI-WEI

    2016-01-01

    The aim of the present study was to investigate the use of 18F-fallypride micro-positron emission tomography (micro-PET) imaging in the evaluation of the early therapeutic efficacy of L-dopa in the treatment of Parkinson's disease (PD) and the underlying mechanism. 18F-fallypride was synthesized and its specific binding with dopamine (DA) receptors in normal mouse brain was studied. Following the establishment of a mouse model of PD, the animals were divided into normal control, PD model and L-dopa treatment groups. General behavior, swimming test, locomotor activity counts, transmission electron microscopy, immunohistochemical analysis, high performance liquid chromatography-electrochemical detection and 18F-fallypride micro-PET imaging were used to study intergroup differences and the correlation between the changes of striatal uptake of 18F-fallypride and the therapeutic efficacy. The general behavioral features of PD model mice were similar to the clinical symptoms of PD patients and were alleviated after treatment. The swimming time, locomotor activity and frequency of standing posture of PD model mice were lower than those of the control mice, but had no difference from those of the control mice after L-dopa treatment. The number of tyrosine hydroxylase-positive neurons and the striatal contents of glutathione peroxidase, superoxide dismutase, DA and its metabolites 3,5-dihydroxyphenylacetic acid and homovanillic acid in the PD group were lower than those in the control group, but were significantly improved following the treatment; the significant reduction in DOPAC/DA and HVA/DA ratios post treatment suggested that the rate of DA metabolism decreased significantly. The striatal malondialdehyde content in the PD group increased compared with that in the control group, but was reduced after L-dopa treatment. Micro-PET imaging indicated that the uptake of 18F-fallypride in the mouse striatum of the PD group was lower than that of the control group and was

  5. 18F-Fallypride binding potential in patients with schizophrenia compared to healthy controls

    PubMed Central

    Lehrer, Douglas S.; Christian, Bradley T.; Kirbas, Cemil; Chiang, Meicheng; Sidhu, Shawn; Short, Holly; Wang, Binquan; Shi, Bingzhi; Chu, King-Wai; Merrill, Brian; Buchsbaum, Monte S.

    2012-01-01

    Background Molecular imaging of dopaminergic parameters has contributed to the dopamine hypothesis of schizophrenia, expanding our understanding of pathophysiology, clinical phenomenology and treatment. Our aim in this study was to compare 18F-fallypride binding potential BPND in a group of patients with schizophrenia-spectrum illness vs. controls, with a particular focus on the cortex and thalamus. Methods We acquired 18F-fallypride positron emission tomography images on 33 patients with schizophrenia spectrum disorder (28 with schizophrenia; 5 with schizoaffective disorder) and 18 normal controls. Twenty-four patients were absolutely neuroleptic naïve and nine were previously medicated, although only four had a lifetime neuroleptic exposure of greater than two weeks. Parametric images of 18F-fallypride BPND were calculated to compare binding across subjects. Results Decreased BPND was observed in the medial dorsal nucleus of the thalamus, prefrontal cortex, lateral temporal lobe and primary auditory cortex. These findings were most marked in subjects who had never previously received medication. Conclusions The regions with decreased BPND tend to match brain regions previously reported to show alterations in metabolic activity and blood flow and areas associated with the symptoms of schizophrenia. PMID:20655709

  6. Use of micro-positron emission tomography with (18)F-fallypride to measure the levels of dopamine receptor-D2 and (18)F-FDG as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 rats.

    PubMed

    Li, Ping; Gui, Songbai; Cao, Lei; Gao, Hua; Bai, Jiwei; Li, Chuzhong; Zhang, Yazhuo

    2016-01-01

    Dopamine receptor-D2 (DRD2) is the most important drug target in prolactinoma. The aim of this current study was to investigate the role of using micro-positron emission tomography (micro-PET) with (18)F-fallypride and (18)F-fluorodeoxyglucose ((18)F-FDG) as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 (F344) rats and detect the difference of the levels of DRD2 in the pituitary glands and prolactinomas of F344 rat prolactinoma models. Female F344 rat prolactinoma models were established by subcutaneous administration of 15 mg 17β-estradiol for 8 weeks. The growth of tumors was monitored by the small-animal magnetic resonance imaging and micro-PET. A series of molecular biological experiments were also performed 4 and 6 weeks after pump implantation. The micro-PET molecular imaging with (18)F-fallypride revealed a decreased expression of DRD2 in F344 rat prolactinoma models, but the micro-PET molecular imaging with (18)F-FDG presented an increased uptake in the prolactinoma compared with the pituitary gland. A decreasing trend of levels of DRD2 in F344 rat prolactinoma models was also detected by molecular biological experiments. From this, we can conclude that micro-PET with (18)F-fallypride and (18)F-FDG can be used to assess tumorigenesis of the prolactinomas in vivo and molecular imaging detection of DRD2 level in prolactinoma may be an indication of treatment effect in the animal experiment.

  7. Use of micro-positron emission tomography with 18F-fallypride to measure the levels of dopamine receptor-D2 and 18F-FDG as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 rats

    PubMed Central

    Li, Ping; Gui, Songbai; Cao, Lei; Gao, Hua; Bai, Jiwei; Li, Chuzhong; Zhang, Yazhuo

    2016-01-01

    Dopamine receptor-D2 (DRD2) is the most important drug target in prolactinoma. The aim of this current study was to investigate the role of using micro-positron emission tomography (micro-PET) with 18F-fallypride and 18F-fluorodeoxyglucose (18F-FDG) as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 (F344) rats and detect the difference of the levels of DRD2 in the pituitary glands and prolactinomas of F344 rat prolactinoma models. Female F344 rat prolactinoma models were established by subcutaneous administration of 15 mg 17β-estradiol for 8 weeks. The growth of tumors was monitored by the small-animal magnetic resonance imaging and micro-PET. A series of molecular biological experiments were also performed 4 and 6 weeks after pump implantation. The micro-PET molecular imaging with 18F-fallypride revealed a decreased expression of DRD2 in F344 rat prolactinoma models, but the micro-PET molecular imaging with 18F-FDG presented an increased uptake in the prolactinoma compared with the pituitary gland. A decreasing trend of levels of DRD2 in F344 rat prolactinoma models was also detected by molecular biological experiments. From this, we can conclude that micro-PET with 18F-fallypride and 18F-FDG can be used to assess tumorigenesis of the prolactinomas in vivo and molecular imaging detection of DRD2 level in prolactinoma may be an indication of treatment effect in the animal experiment. PMID:27103832

  8. Use of micro-positron emission tomography with (18)F-fallypride to measure the levels of dopamine receptor-D2 and (18)F-FDG as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 rats.

    PubMed

    Li, Ping; Gui, Songbai; Cao, Lei; Gao, Hua; Bai, Jiwei; Li, Chuzhong; Zhang, Yazhuo

    2016-01-01

    Dopamine receptor-D2 (DRD2) is the most important drug target in prolactinoma. The aim of this current study was to investigate the role of using micro-positron emission tomography (micro-PET) with (18)F-fallypride and (18)F-fluorodeoxyglucose ((18)F-FDG) as molecular imaging tracer in the pituitary glands and prolactinomas of Fischer-344 (F344) rats and detect the difference of the levels of DRD2 in the pituitary glands and prolactinomas of F344 rat prolactinoma models. Female F344 rat prolactinoma models were established by subcutaneous administration of 15 mg 17β-estradiol for 8 weeks. The growth of tumors was monitored by the small-animal magnetic resonance imaging and micro-PET. A series of molecular biological experiments were also performed 4 and 6 weeks after pump implantation. The micro-PET molecular imaging with (18)F-fallypride revealed a decreased expression of DRD2 in F344 rat prolactinoma models, but the micro-PET molecular imaging with (18)F-FDG presented an increased uptake in the prolactinoma compared with the pituitary gland. A decreasing trend of levels of DRD2 in F344 rat prolactinoma models was also detected by molecular biological experiments. From this, we can conclude that micro-PET with (18)F-fallypride and (18)F-FDG can be used to assess tumorigenesis of the prolactinomas in vivo and molecular imaging detection of DRD2 level in prolactinoma may be an indication of treatment effect in the animal experiment. PMID:27103832

  9. A modified simplified reference tissue model for the quantification of dopamine D2/3 receptors with [18F]fallypride images.

    PubMed

    Tsartsalis, Stergios; Moulin-Sallanon, Marcelle; Dumas, Noé; Tournier, Benjamin B; Ginovart, Nathalie; Millet, Philippe

    2014-01-01

    Defluorination of [18F]fallypride and accumulation of 18F in skull and glands leads to the contamination of brain structures with spillover activity due to partial volume effects, leading to considerable errors in binding potential estimations. Here we propose a modification of the simplified reference tissue model (SRTM) to take into account the contribution of skull activity to the radioactivity kinetic pattern in cerebellum and target regions. It consists of the introduction of an additional parameter for each volume of interest (sT) and one for the cerebellum (sR), corresponding to the fraction of skull activity contaminating these structures. Using five rat positron emission tomography experiments, we applied the modified SRTM (SRTMc), which resulted in excellent fits. As a relative means of comparison of results, we applied factor analysis (FA) to decompose dynamic data into images corresponding to brain and skull activity. With the skull factor images, we estimated the "true" sT and sR values, ultimately permitting us to fix the sR value. Parameters obtained with the SRTMc were closely correlated with values obtained from FA-corrected data. In conclusion, we propose an efficient method for reliable quantification of dopamine D2/3 receptors with single-injection [18F]fallypride scans that is potentially applicable to human studies where 18F skull accumulation compromises binding parameter estimation. PMID:25248453

  10. COMT Val158Met Genotype Selectively Alters Prefrontal [18F]Fallypride Displacement and Subjective Feelings of Stress in Response to a Psychosocial Stress Challenge

    PubMed Central

    Lataster, Johan; Ceccarini, Jenny; Kenis, Gunther; Booij, Linda; Pruessner, Jens; Van Laere, Koen; van Winkel, Ruud; van Os, Jim; Myin-Germeys, Inez

    2013-01-01

    Catechol-O-methyltransferase (COMT) plays an essential role in degradation of extracellular dopamine in prefrontal regions of the brain. Although a polymorphism in this gene, COMT Val158Met, affects human behavior in response to stress little is known about its effect on dopaminergic activity associated with the human stress response, which may be of interest for stress-related psychiatric disorders such as psychosis. We aimed to investigate the effect of variations in COMT genotype on in vivo measures of stress-induced prefrontal cortex (PFC) dopaminergic processing and subjective stress responses. A combined sample of healthy controls and healthy first-degree relatives of psychosis patients (n = 26) were subjected to an [18F]fallypride Positron Emission Tomography scan. Psychosocial stress during the scan was induced using the Montreal Imaging Stress Task and subjective stress was assessed every 12 minutes. Parametric t-maps, generated using the linear extension of the simplified reference region model, revealed an effect of COMT genotype on the spatial extent of [18F]fallypride displacement. Detected effects of exposure to psychosocial stress were unilateral and remained restricted to the left superior and right inferior frontal gyrus, with Met-hetero- and homozygotes showing less [18F]fallypride displacement than Val-homozygotes. Additionally, Met-hetero- and homozygotes experienced larger subjective stress responses than Val-homozygotes. The direction of the effects remained the same when the data was analyzed separately for controls and first-degree relatives. The human stress response may be mediated in part by COMT-dependent dopaminergic PFC activity, providing speculation for the neurobiology underlying COMT-dependent differences in human behaviour following stress. Implications of these results for stress-related psychopathology and models of dopaminergic functioning are discussed. PMID:23799032

  11. Fully automated production of diverse 18F-labeled PET tracers on the ELIXYS multi-reactor radiosynthesizer without hardware modification

    PubMed Central

    Lazari, Mark; Collins, Jeffrey; Shen, Bin; Farhoud, Mohammed; Yeh, Daniel; Maraglia, Brandon; Chin, Frederick T.; Nathanson, David A.; Moore, Melissa; van Dam, R. Michael

    2015-01-01

    Fully-automated radiosynthesizers are continuing to be developed to meet the growing need for the reliable production of positron emission tomography (PET) tracers made under current good manufacturing practice (cGMP) guidelines. There is a current trend towards supporting “kit-like” disposable cassettes that come preconfigured for particular tracers, thus eliminating the need for cleaning protocols between syntheses and enabling quick transitions to synthesizing other tracers. Though ideal for production, these systems are often limited for the development of novel tracers due to pressure, temperature, and chemical compatibility considerations. This study demonstrates the versatile use of the ELIXYS fully-automated radiosynthesizer to adapt and produce eight different 18F-labeled PET tracers of varying complexity. Methods Three reactor syntheses of D-[18F]FAC, L-[18F]FMAU, and D-[18F]FEAU along with the one reactor syntheses of D-[18F]FEAU, [18F]FDG, [18F]FLT, [18F]Fallypride, [18F]FHBG, and [18F]SFB were all produced using ELIXYS without the need for any hardware modifications or reconfiguration. Synthesis protocols were adapted, and slightly modified from literature, but not fully optimized. Furthermore, [18F]FLT, [18F]FDG, and [18F]Fallypride were produced sequentially on the same day and used for preclinical imaging of A431 tumor-bearing SCID mice and wild-type BALB/c mice, respectively. To assess future translation to the clinical setting, several batches of tracers were subjected to a full set of quality control tests. Results All tracers were produced with radiochemical yields comparable to those in literature. [18F]FLT, [18F]FDG, and [18F]Fallypride were successfully used to image the mice with results consistent with literature. All tracers subjected to clinical quality control tests passed. Conclusion The ELIXYS radiosynthesizer facilitates rapid tracer development and is capable of producing multiple 18F-labeled PET tracers suitable for clinical

  12. PET studies in epilepsy

    PubMed Central

    Sarikaya, Ismet

    2015-01-01

    Various PET studies, such as measurements of glucose, serotonin and oxygen metabolism, cerebral blood flow and receptor bindings are availabe for epilepsy. 18Fluoro-2-deoxyglucose (18F-FDG) PET imaging of brain glucose metabolism is a well established and widely available technique. Studies have demonstrated that the sensitivity of interictal FDG-PET is higher than interictal SPECT and similar to ictal SPECT for the lateralization and localization of epileptogenic foci in presurgical patients refractory to medical treatments who have noncontributory EEG and MRI. In addition to localizing epileptogenic focus, FDG-PET provide additional important information on the functional status of the rest of the brain. The main limitation of interictal FDG-PET is that it cannot precisely define the surgical margin as the area of hypometabolism usually extends beyond the epileptogenic zone. Various neurotransmitters (GABA, glutamate, opiates, serotonin, dopamine, acethylcholine, and adenosine) and receptor subtypes are involved in epilepsy. PET receptor imaging studies performed in limited centers help to understand the role of neurotransmitters in epileptogenesis, identify epileptic foci and investigate new treatment approaches. PET receptor imaging studies have demonstrated reduced 11C-flumazenil (GABAA-cBDZ) and 18F-MPPF (5-HT1A serotonin) and increased 11C-cerfentanil (mu opiate) and 11C-MeNTI (delta opiate) bindings in the area of seizure. 11C-flumazenil has been reported to be more sensitive than FDG-PET for identifying epileptic foci. The area of abnormality on GABAAcBDZ and opiate receptor images is usually smaller and more circumscribed than the area of hypometabolism on FDG images. Studies have demonstrated that 11C-alpha-methyl-L-tryptophan PET (to study synthesis of serotonin) can detect the epileptic focus within malformations of cortical development and helps in differentiating epileptogenic from non-epileptogenic tubers in patients with tuberous sclerosis complex

  13. Detecting and estimating head motion in brain PET acquisitions using raw time-of-flight PET data.

    PubMed

    Schleyer, P J; Dunn, J T; Reeves, S; Brownings, S; Marsden, P K; Thielemans, K

    2015-08-21

    Head motion during brain PET imaging is not uncommon and can negatively affect image quality. Motion correction techniques typically either use hardware to prospectively measure head motion, or they divide the acquisition into short fixed-frames and then align and combine these to produce a motion free image. The aim of this work was to retrospectively detect when motion occurred in PET data without the use of motion detection hardware, and then align the frames defined by these motion occurrences. We describe two methods that use either principal component analysis or the motion induced spatial displacements over time to detect motion in raw time-of-flight PET data. The points in time of motion then define the temporal boundaries of frames which are reconstructed without attenuation correction, aligned and combined. Phantom and [18F]-Fallypride patient acquisitions were used to validate and evaluate these approaches, which were compared with motion estimation using 60 s fixed-frames. Both methods identified all motion occurrences in phantom data, and unlike the fixed-frame approach did not exhibit intra-frame motion. With patient acquisitions, images corrected with the motion detection methods increased the average image sharpness by the same amount as the fixed-frame approach, but reduced the number of reconstructions and registrations by a factor of 3.4 on average. Detecting head motion in raw PET data alone is possible, allowing retrospective motion estimation of any listmode brain PET acquisition without additional hardware, subsequently decreasing data processing and potentially reducing intra-frame motion.

  14. Detecting and estimating head motion in brain PET acquisitions using raw time-of-flight PET data

    NASA Astrophysics Data System (ADS)

    Schleyer, P. J.; Dunn, J. T.; Reeves, S.; Brownings, S.; Marsden, P. K.; Thielemans, K.

    2015-08-01

    Head motion during brain PET imaging is not uncommon and can negatively affect image quality. Motion correction techniques typically either use hardware to prospectively measure head motion, or they divide the acquisition into short fixed-frames and then align and combine these to produce a motion free image. The aim of this work was to retrospectively detect when motion occurred in PET data without the use of motion detection hardware, and then align the frames defined by these motion occurrences. We describe two methods that use either principal component analysis or the motion induced spatial displacements over time to detect motion in raw time-of-flight PET data. The points in time of motion then define the temporal boundaries of frames which are reconstructed without attenuation correction, aligned and combined. Phantom and [18F]-Fallypride patient acquisitions were used to validate and evaluate these approaches, which were compared with motion estimation using 60 s fixed-frames. Both methods identified all motion occurrences in phantom data, and unlike the fixed-frame approach did not exhibit intra-frame motion. With patient acquisitions, images corrected with the motion detection methods increased the average image sharpness by the same amount as the fixed-frame approach, but reduced the number of reconstructions and registrations by a factor of 3.4 on average. Detecting head motion in raw PET data alone is possible, allowing retrospective motion estimation of any listmode brain PET acquisition without additional hardware, subsequently decreasing data processing and potentially reducing intra-frame motion.

  15. PET IMAGING STUDIES IN DRUG ABUSE RESEARCH.

    SciTech Connect

    Fowler, J.S.; Volkow, N.D.; Ding, Y.S.; Logan, J.; Wang, G.J.

    2001-01-29

    . This will be followed by highlights of PET studies of the acute effects of the psychostimulant drugs cocaine and methylphenidate (ritalin) and studies of the chronic effects of cocaine and of tobacco smoke on the human brain. This chapter concludes with the description of a study which uses brain imaging coupled with a specific pharmacological challenge to address the age-old question of why some people who experiment with drugs become addicted while others do not.

  16. Towards optimal imaging with PET: an in silico feasibility study

    NASA Astrophysics Data System (ADS)

    McNamara, A. L.; Toghyani, M.; Gillam, J. E.; Wu, K.; Kuncic, Z.

    2014-12-01

    The efficacy of Positron Emission Tomography (PET) imaging relies fundamentally on the ability of the system to accurately identify true coincidence events. With existing systems, this is currently accomplished with an energy acceptance criterion followed by correction techniques to remove suspected false coincidence events. These corrections generally result in signal and contrast loss and thus limit the PET system’s ability to achieve optimum image quality. A key property of annihilation radiation is that the photons are polarised with respect to each other. This polarisation correlation offers a potentially powerful discriminator, independent of energy, to accurately identify true events. In this proof of concept study, we investigate how photon polarisation information can be exploited in PET imaging by developing a method to discriminate true coincidences using the polarisation correlation of annihilation pairs. We implement this method using a Geant4 PET simulation of a GE Advance/Discovery LS system and demonstrate the potential advantages of the polarisation coincidence selection method over a standard energy criterion method. Current PET ring detectors are not capable of exploiting the polarisation correlation of the photon pairs. Compton PET systems, however are promising candidates for this application. We demonstrate the feasibility of a two-component Compton camera system in identifying true coincidences with Monte Carlo simulations. Our study demonstrates the potential of improving signal gain using polarisation, particularly for high photon emission rates. We also demonstrate the ability of the Compton camera at exploiting this polarisation correlation in PET.

  17. Sydenham's chorea: positron emission tomographic (PET) scan studies.

    PubMed

    Aron, Alan M

    2005-10-01

    Two patients with Sydenham's chorea were evaluated with positron emission tomographic (PET) scans in the active phase of the disease. One patient had repeat scanning in the recovery phase. PET scans showed hypermetabolic changes of the caudate nuclei and putamen in the active phase of Sydenham's chorea. The scan reverted to normal in the recovery phase. These changes can afford a basis for comparing concurrent serum antibody studies in the acute and recovery phases of Sydenham's chorea.

  18. Automated image registration for FDOPA PET studies

    NASA Astrophysics Data System (ADS)

    Lin, Kang-Ping; Huang, Sung-Cheng; Yu, Dan-Chu; Melega, William; Barrio, Jorge R.; Phelps, Michael E.

    1996-12-01

    In this study, various image registration methods are investigated for their suitability for registration of L-6-[18F]-fluoro-DOPA (FDOPA) PET images. Five different optimization criteria including sum of absolute difference (SAD), mean square difference (MSD), cross-correlation coefficient (CC), standard deviation of pixel ratio (SDPR), and stochastic sign change (SSC) were implemented and Powell's algorithm was used to optimize the criteria. The optimization criteria were calculated either unidirectionally (i.e. only evaluating the criteria for comparing the resliced image 1 with the original image 2) or bidirectionally (i.e. averaging the criteria for comparing the resliced image 1 with the original image 2 and those for the sliced image 2 with the original image 1). Monkey FDOPA images taken at various known orientations were used to evaluate the accuracy of different methods. A set of human FDOPA dynamic images was used to investigate the ability of the methods for correcting subject movement. It was found that a large improvement in performance resulted when bidirectional rather than unidirectional criteria were used. Overall, the SAD, MSD and SDPR methods were found to be comparable in performance and were suitable for registering FDOPA images. The MSD method gave more adequate results for frame-to-frame image registration for correcting subject movement during a dynamic FDOPA study. The utility of the registration method is further demonstrated by registering FDOPA images in monkeys before and after amphetamine injection to reveal more clearly the changes in spatial distribution of FDOPA due to the drug intervention.

  19. A PET study of visuospatial attention.

    PubMed

    Corbetta, M; Miezin, F M; Shulman, G L; Petersen, S E

    1993-03-01

    Positron emission tomography (PET) was used to identify the neural systems involved in shifting spatial attention to visual stimuli in the left or right visual field along foveofugal or foveocentric directions. Psychophysical evidence indicated that stimuli at validly cued locations were responded to faster than stimuli at invalidly cued locations. Reaction times to invalid probes were faster when they were presented in the same than in the opposite direction of an ongoing attention movement. PET evidence indicated that superior parietal and superior frontal cortex were more active when attention was shifted to peripheral locations than when maintained at the center of gaze. Both regions encoded the visual field and not the direction of an attention shift. In the right superior parietal lobe, two distinct responses were localized for attention to left and right visual field. Finally, the superior parietal region was active when peripheral locations were selected on the basis of cognitive or sensory cues independent of the execution of an overt response. The frontal region was active only when responses were made to stimuli at selected peripheral locations. These findings indicate that parietal and frontal regions control different aspects of spatial selection. The functional asymmetry in superior parietal cortex may be relevant for the pathophysiology of unilateral neglect.

  20. Modification of a medical PET scanner for PEPT studies

    NASA Astrophysics Data System (ADS)

    Sadrmomtaz, Alireza; Parker, D. J.; Byars, L. G.

    2007-04-01

    Over the last 20 years, positron emission tomography (PET) has developed as the most powerful functional imaging modality in medicine. Over the same period the University of Birmingham Positron Imaging Centre has applied PET to study engineering processes and developed the alternative technique of positron emission particle tracking (PEPT) in which a single radioactively labelled tracer particle is tracked by detecting simultaneously the pairs of back-to-back photons arising from positron/electron annihilation. Originally PEPT was performed using a pair of multiwire detectors, and more recently using a pair of digital gamma camera heads. In 2002 the Positron Imaging Centre acquired a medical PET scanner, an ECAT 931/08, previously used at Hammersmith Hospital. This scanner has been rebuilt in a flexible geometry for use in PEPT studies. This paper presents initial results from this system. Fast moving tracer particles can be rapidly and accurately located.

  1. Imaging results and TOF studies with axial PET detectors

    NASA Astrophysics Data System (ADS)

    Joram, Christian

    2013-12-01

    We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (<2 mm FWHM in all three coordinates over the complete field of view) and also demonstrated the ability to include Compton interactions (inter-crystal scatter) in the reconstruction without noticeable performance loss. Our recent studies focus on a TOF extension of the AX-PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.

  2. 18F-FDG PET/CT and PET/MRI Perform Equally Well in Cancer: Evidence from Studies on More Than 2,300 Patients.

    PubMed

    Spick, Claudio; Herrmann, Ken; Czernin, Johannes

    2016-03-01

    (18)F-FDG PET/CT has become the reference standard in oncologic imaging against which the performance of other imaging modalities is measured. The promise of PET/MRI includes multiparametric imaging to further improve diagnosis and phenotyping of cancer. Rather than focusing on these capabilities, many investigators have examined whether (18)F-FDG PET combined with mostly anatomic MRI improves cancer staging and restaging. After a description of PET/MRI scanner designs and a discussion of technical and operational issues, we review the available literature to determine whether cancer assessments are improved with PET/MRI. The available data show that PET/MRI is feasible and performs as well as PET/CT in most types of cancer. Diagnostic advantages may be achievable in prostate cancer and in bone metastases, whereas disadvantages exist in lung nodule assessments. We conclude that (18)F-FDG PET/MRI and PET/CT provide comparable diagnostic information when MRI is used simply to provide the anatomic framework. Thus, PET/MRI could be used in lieu of PET/CT if this approach becomes economically viable and if reasonable workflows can be established. Future studies should explore the multiparametric potential of MRI. PMID:26742709

  3. Intersubject variability and reproducibility of 15O PET studies.

    PubMed

    Coles, Jonathan P; Fryer, Tim D; Bradley, Peter G; Nortje, Jurgens; Smielewski, Peter; Rice, Kenneth; Clark, John C; Pickard, John D; Menon, David K

    2006-01-01

    Oxygen-15 positron emission tomography (15O PET) can provide important data regarding patients with head injury. We provide reference data on intersubject variability and reproducibility of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolism (CMRO2) and oxygen extraction fraction (OEF) in patients and healthy controls, and explored alternative ways of assessing reproducibility within the context of a single PET study. In addition, we used independent measurements of CBF and CMRO2 to investigate the effect of mathematical correlation on the relationship between flow and metabolism. In patients, intersubject coefficients of variation (CoV) for CBF, CMRO2 and OEF were larger than in controls (32.9%+/-2.2%, 23.2%+/-2.0% and 22.5%+/-3.4% versus 13.5%+/-1.4%, 12.8%+/-1.1% and 7.3%+/-1.2%), while CoV for CBV were lower (15.2%+/-2.1% versus 22.5%+/-2.8%) (P<0.001). The CoV for the test-retest reproducibility of CBF, CBV, CMRO2 and OEF in patients were 2.1%+/-1.5%, 3.8%+/-3.0%, 3.7%+/-3.0% and 4.6%+/-3.5%, respectively. These were much lower than the intersubject CoV figures, and were similar to alternative measures of reproducibility obtained by fractionating data from a single study. The physiological relationship between flow and metabolism was preserved even when mathematically independent measures were used for analysis. These data provide a context for the design and interpretation of interventional PET studies. While ideally each centre should develop its own bank of such data, the figures provided will allow initial generic approximations of sample size for such studies.

  4. How to Design PET Experiments to Study Neurochemistry: Application to Alcoholism

    PubMed Central

    Morris, Evan D.; Lucas, Molly V.; Petrulli, J. Ryan; Cosgrove, Kelly P.

    2014-01-01

    Positron Emission Tomography (PET) (and the related Single Photon Emission Computed Tomography) is a powerful imaging tool with a molecular specificity and sensitivity that are unique among imaging modalities. PET excels in the study of neurochemistry in three ways: 1) It can detect and quantify neuroreceptor molecules; 2) it can detect and quantify changes in neurotransmitters; and 3) it can detect and quantify exogenous drugs delivered to the brain. To carry out any of these applications, the user must harness the power of kinetic modeling. Further, the quality of the information gained is only as good as the soundness of the experimental design. This article reviews the concepts behind the three main uses of PET, the rationale behind kinetic modeling of PET data, and some of the key considerations when planning a PET experiment. Finally, some examples of PET imaging related to the study of alcoholism are discussed and critiqued. PMID:24600335

  5. Word and nonword repetition in bilingual subjects: a PET study.

    PubMed

    Klein, Denise; Watkins, Kate E; Zatorre, Robert J; Milner, Brenda

    2006-02-01

    Learning a specific skill during childhood may partly determine the functional organization of the adult brain. This hypothesis led us to study brain activation patterns using positron emission tomography (PET), in which we compared word and nonword repetition in 10 right-handed native English-speakers (L1) who were proficient in their second language, French (L2), which was learned after the age of 5 years. Regional cerebral blood flow (rCBF) was measured by the H2 15O intravenous bolus method with intersubject averaging and coregistration of magnetic resonance and PET images. A comparison of CBF changes when repeating words in L2 with those seen when repeating words in (L1) demonstrated that the pattern of CBF was similar across the two conditions, with several significant CBF differences in the vicinity of the left insular cortex, ventral premotor region, and in the striatum. We hypothesize that these regions are activated when subjects are required to repeat known words, showing increased activity when there are increased articulatory demands imposed by speaking L2. Comparisons of nonword repetition in L1 and L2 revealed increased activity for L2 in the left ventral premotor region and in the cerebellum; rCBF increases were also observed in these regions in both L1 and L2 with increased number of syllables and increased articulatory complexity, suggesting a role for these regions in the complex motor control needed for the production of novel sequences.

  6. Dose fractionation and single subject studies in PET

    NASA Astrophysics Data System (ADS)

    Balakrishnan, Karthikayan

    Conventional positron emission tomography (PET) for cognitive brain studies typically relies on information collected from the distribution of decays following an injection of 15O-labeled water. The number of injections that can be administered to the subject are constrained by radiation dose to the subject and total length of the PET scan. The standard protocol involves 8--10 injections of H152O separated by approximately 5--7 half-lives of 15O. The number of activation conditions that can be realistically studied in a standard PET session is between 8 and 10. This work investigates the physiological response of a simulated subject to H152O injections that are administered in small doses (1--5 mCi) with short inter-injection intervals (40--180 seconds). A larger number of activation conditions are presented to the subject with a wider variation in the activation paradigm. Repeat conditions are studies. Signal averaging methods are feasible with this method of dose administration. Sinograms from scans with similar activation conditions are summed together before reconstruction. The signal in the primary activation region of the brain is shown to increase while suppressing the contribution of secondary activation regions in the brain. The contrast of the final image is similarly increased which leads to easier identification of the primary activation region. An automated H152O -production unit controlled by a PC running LabView software was developed to produce the dose required for the injection sequence by controlling the flow of H152O -vapor that diffuses across a semi-permeable membrane into saline. The unit is capable of producing H152O rapidly for both the standard and the proposed dose administration methods. The system also detects the bolus arrival time at the subject's lungs using a small external plastic detector. Activation sequence commences with the rise in radioactivity observed by the detector. The simulations indicate that inter-injection intervals

  7. Myocardial defect detection using PET-CT: phantom studies.

    PubMed

    Mananga, Eugene S; El Fakhri, Georges; Schaefferkoetter, Joshua; Bonab, Ali A; Ouyang, Jinsong

    2014-01-01

    It is expected that both noise and activity distribution can have impact on the detectability of a myocardial defect in a cardiac PET study. In this work, we performed phantom studies to investigate the detectability of a defect in the myocardium for different noise levels and activity distributions. We evaluated the performance of three reconstruction schemes: Filtered Back-Projection (FBP), Ordinary Poisson Ordered Subset Expectation Maximization (OP-OSEM), and Point Spread Function corrected OSEM (PSF-OSEM). We used the Channelized Hotelling Observer (CHO) for the task of myocardial defect detection. We found that the detectability of a myocardial defect is almost entirely dependent on the noise level and the contrast between the defect and its surroundings.

  8. Using a Popular Pet Fish Species to Study Territorial Behaviour

    ERIC Educational Resources Information Center

    Abante, Maria E.

    2005-01-01

    The colourful, vigorous territorial display behaviour of the Siamese fighting fish, "Betta splendens", has great appeal for both pet enthusiasts and animal behaviourists. Their beauty, longevity, easy maintenance and rearing make them a popular pet and an ideal science laboratory specimen. This investigation utilises "B. splendens" to test for the…

  9. Approaches using molecular imaging technology - use of PET in clinical microdose studies§

    PubMed Central

    Wagner, Claudia C; Langer, Oliver

    2013-01-01

    Positron emission tomography (PET) imaging uses minute amounts of radiolabeled drug tracers and thereby meets the criteria for clinical microdose studies. The advantage of PET, when compared to other analytical methods used in microdose studies, is that the pharmacokinetics (PK) of a drug can be determined in the tissue targeted for drug treatment. PET microdosing already offers interesting applications in clinical oncology and in the development of central nervous system pharmaceuticals and is extending its range of application to many other fields of pharmaceutical medicine. Although requirements for preclinical safety testing for microdose studies have been cut down by regulatory authorities, radiopharmaceuticals increasingly need to be produced under good manufacturing practice (GMP) conditions, which increases the costs of PET microdosing studies. Further challenges in PET microdosing include combining PET with other ultrasensitive analytical methods, such as accelerator mass spectrometry (AMS), to gain plasma PK data of drugs, beyond the short PET examination periods. Finally, conducting clinical PET studies with radiolabeled drugs both at micro- and therapeutic doses is encouraged to answer the question of dose linearity in clinical microdosing. PMID:20887762

  10. The consumption and recycling collection system of PET bottles: a case study of Beijing, China.

    PubMed

    Zhang, Hua; Wen, Zong-Guo

    2014-06-01

    After studying the recycling collection system of polyethylene terephthalate (PET) bottles worldwide, the authors conducted an intercept survey in Beijing. Two separate questionnaires were issued, one questionnaire to PET bottle consumers and one to PET bottle recyclers. In this study, consumers are defined as people that consume PET-bottled beverages in their daily life. Recyclers were defined as those involved in the collection and recycling of PET bottles. These include scavengers, itinerant waste buyers, small community waste-buying depots, medium/large redemption depots, and recycling companies. In total, 580 surveys were completed, including 461 by consumers and 119 by recyclers. The authors found that consumption of PET bottles in Beijing was nearly 100,000 tonnes in 2012. Age, occupation, gender, and education were identified as significant factors linked to PET-bottled beverage consumption, while income was not a significant factor. 90% Of post-consumed PET bottles were collected by informal collectors (i.e., scavengers and itinerant waste buyers). The survey also found that nearly all PET bottles were reprocessed by small factories that were not designed with pollution control equipment, which allows them to offer higher prices for waste recyclable bottles. As Beijing is trying to build a formal recycling collection system for recyclables, subsidies should be given to the formal recycling sector rather than being charged land use fees, and attention should also be given to informal recyclers that make their living from the collection of recyclables. Informal and formal sectors may work together by employing the scavengers and itinerant waste buyers for the formal sectors. In addition to the recycling of PET bottles, concern should also be allocated to reduce consumption, especially among young people, as they, compared to other groups, have a stronger demand for PET-bottled beverages and will be the main body of society.

  11. Behavioral health staff's perceptions of pet-assisted therapy: an exploratory study.

    PubMed

    Rossetti, Jeanette; DeFabiis, Susanne; Belpedio, Camille

    2008-09-01

    The purpose and objectives of this exploratory descriptive study were threefold: to assess the impact of pet-assisted therapy on the overall well-being of behavioral health staff, to document whether pet-assisted therapy affected the retention of behavioral health staff, and to explore and describe therapeutic measures behavioral health staff implemented in using pet-assisted therapy in the delivery of mental health patient care. The participants in this study were 10 behavioral health staff members who were involved with the pet-assisted therapy program at a private psychiatric hospital in a Chicago suburb. Themes that emerged from the study included Self-Awareness, Morale, Innovative Therapeutic Strategies, Challenges, and Future Directions. This article describes these themes in detail, provides quotations from participants to further highlight meaning, and discusses the powerful effect of pet-assisted therapy on both patients and staff in the therapeutic milieu. PMID:18822998

  12. Compensation for respiratory motion in cardiac PET - A feasibility study

    SciTech Connect

    Budinger, T.F.; Klein, G.J.; Reed, J.H. |

    1996-05-01

    We characterize respiration-induced motion in the canine myocardium and present preliminary efforts to compensate for the motion in gated PET. An anesthetized dog was injected with 23 mCi FDG-18 and placed in a CTI/Siemens ECAT EXACT HR scanner. The animal was mechanically held at peak inspiration and peak expiration positions for alternate eight-second time periods. Data from each eight-second interval were stored separately, resulting in a total of 32 interleaved volume datasets for each study; half of which represented data during peak inspiration, half represented data during peak expiration. Data from each position were summed and separately reconstructed. The above protocol was repeated four times. Ungated transmission data were acquired while the animal was ventilated normally and were used to correct for the effects of attenuation. Images from each reconstruction were aligned using a cross-correlation technique, which gives the rigid-body transformation necessary to register the two volumes. Over the four sets of data a 10.8 {plus_minus} 0.7 mm magnitude translation and a 6.3 {plus_minus} 0.5 degree rotation were required to align the inspiration data with the expiration data. Consistent registration of the gated data allows summing of the data to improve statistics. Obviously, if one sums the images without regard to misregistration, blurring occurs proportional to the amount of movement over the respiratory cycle. The blurring is markedly decreased by first registering the gated datasets in image space, and then summing according to the transformation parameters. Though cardiac gating was not used in this preliminary study, it indicates that rigid body transformation followed by summation can compensate for a large portion of the image degradations due to respiratory motion. Gated acquisition of PET data using respiratory status signals via a pneumatic bellows will allow separate stages of the respiratory cycle to be collected on the ECAT EXACT HR.

  13. [The elderly and their pets. Supportive and problematic aspects and implications for care. A descriptive study].

    PubMed

    Graf, S

    1999-04-01

    Pet ownership by elderly people is very common. This phenomenological study investigated why elderly people keep pets and what illness of the animals or their loss means to them. Nine women and three men owning either cats, dogs, or birds participated in this study. Their average age was 84. The results confirm on the one hand that elderly people experience happiness and joy thanks to having pets, giving them an ingenious social function as well as helping overcome the frequent passivity of old age. The problems arising with the ownership of animals are accident endangering (falls) and overexertion. An additional concern is the support of the animals during illness of the owner. The loss of animals is often connected with serious grief reaction and disorganisation of daily life. Serious, long-lasting, and pathological grief reactions were shown after a forced separation from the pet. Four recommendations for nursing practice resulted from this study: to approve and support the ownership of pets and domestic animals as a factor of the "good old age"; to accept the pets as part of the 'family' and integrate them into nursing work, to encourage the owner to plan the future of the pet. Finally, to help overcome the loss of pets and animals a specific nursing therapeutic treatment is required. PMID:10437555

  14. [The elderly and their pets. Supportive and problematic aspects and implications for care. A descriptive study].

    PubMed

    Graf, S

    1999-04-01

    Pet ownership by elderly people is very common. This phenomenological study investigated why elderly people keep pets and what illness of the animals or their loss means to them. Nine women and three men owning either cats, dogs, or birds participated in this study. Their average age was 84. The results confirm on the one hand that elderly people experience happiness and joy thanks to having pets, giving them an ingenious social function as well as helping overcome the frequent passivity of old age. The problems arising with the ownership of animals are accident endangering (falls) and overexertion. An additional concern is the support of the animals during illness of the owner. The loss of animals is often connected with serious grief reaction and disorganisation of daily life. Serious, long-lasting, and pathological grief reactions were shown after a forced separation from the pet. Four recommendations for nursing practice resulted from this study: to approve and support the ownership of pets and domestic animals as a factor of the "good old age"; to accept the pets as part of the 'family' and integrate them into nursing work, to encourage the owner to plan the future of the pet. Finally, to help overcome the loss of pets and animals a specific nursing therapeutic treatment is required.

  15. [18F]FDOPA PET as an endophenotype for Parkinson's Disease linkage studies.

    PubMed

    Racette, Brad A; Good, Laura; Antenor, Jo Ann; McGee-Minnich, Lori; Moerlein, Stephen M; Videen, Tom O; Perlmutter, Joel S

    2006-04-01

    Parkinson disease (PD) is a late onset disorder with age-dependent penetrance that may confound genetic studies, since affected individuals may not demonstrate clinical manifestations at the time of evaluation. The use of endophenotypes, biologic surrogates for clinical disease diagnoses, may permit more accurate classification of at-risk subjects. Positron emission tomography (PET) measurements of 6-[18F]fluorodopa ([18F]FDOPA) uptake indicate nigrostriatal neuronal integrity and may provide a useful endophenotype for PD linkage studies. We performed [18F]FDOPA PET in 11 members of a large, multi-incident Amish family with PD, 24 normals and 48 people with clinically definite idiopathic PD (PD controls). Clinical diagnoses in the Amish were clinically definite PD in four, clinically probable in one, clinically possible in five, and normal in one. Abnormal [18F]FDOPA posterior putamen uptake was defined as less than 3 standard deviations below the normal mean. The criteria were applied to the Amish sample to determine a PET endophenotype for each. We performed genetic simulations using SLINK to model the effect phenoconversion with the PET endophenotype had on logarithm of odds (LOD) scores. PET endophenotype confirmed the status of two clinically definite subjects. Two clinically definite Amish PD subjects had normal PETs. Two possible PD were converted to "PET definite PD." The remainder had normal PETs. The average maximum LOD score with the pre-PET was 6.14 +/- 0.84. Simulating phenoconversion of subjects with unknown phenotypes increased the LOD score to 7.36 +/- 1.23. The [18F]FDOPA PET endophenotype permits phenoconversion in multi-incident PD families and may increase LOD score accuracy and power of an informative pedigree. PMID:16528749

  16. [18F]FDOPA PET as an Endophenotype for Parkinson’s Disease Linkage Studies

    PubMed Central

    Racette, Brad A.; Good, Laura; Antenor, Jo Ann; McGee-Minnich, Lori; Moerlein, Stephen M.; Videen, Tom O.; Perlmutter, Joel S.

    2008-01-01

    Parkinson Disease (PD) is a late onset disorder with age-dependent penetrance that may confound genetic studies since affected individuals may not demonstrate clinical manifestations at the time of evaluation. The use of endophenotypes, biologic surrogates for clinical disease diagnoses, may permit more accurate classification of at-risk subjects. Positron emission tomography (PET) measurements of 6-[18F]fluorodopa ([18F]FDOPA) uptake indicate nigrostriatal neuronal integrity and may provide a useful endophenotype for PD linkage studies. We performed [18F]FDOPA PET in 11 members of a large, multi-incident Amish family with PD, 24 normals and 48 people with clinically definite idiopathic PD (PD controls). Clinical diagnoses in the Amish were clinically definite PD in four, clinically probable in one, clinically possible in five, and normal in one. Abnormal [18F]FDOPA posterior putamen uptake was defined as less than three standard deviations below the normal mean. The criteria were applied to the Amish sample to determine a PET endophenotype for each. We performed genetic simulations using SLINK to model the effect phenoconversion with the PET endophenotype had on logarithm of odds (LOD) scores. PET endophenotype confirmed the status of two clinically definite subjects. Two clinically definite Amish PD subjects had normal PETs. Two possible PD were converted to “PET definite PD”. The remainder had normal PETs. The average maximum LOD score with the pre-PET was 6.14±0.84. Simulating phenoconversion of subjects with unknown phenotypes increased the LOD score to 7.36±1.23. The [18F]FDOPA PET endophenotype permits phenoconversion in multi-incident PD families and may increase LOD score accuracy and power of an informative pedigree. PMID:16528749

  17. PET and SPECT studies in children with hemispheric low-grade gliomas.

    PubMed

    Juhász, Csaba; Bosnyák, Edit

    2016-10-01

    Molecular imaging is playing an increasing role in the pretreatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting, and improved detection of tumor recurrence. This review provides a brief overview of single-photon emission computed tomography (SPECT) studies followed by a more detailed review of the clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity, and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pretreatment and post-treatment evaluation of pediatric brain tumors. PMID:27659825

  18. Signal-to-noise ratio in neuro activation PET studies

    SciTech Connect

    Votaw, J.R.

    1996-04-01

    It has become commonplace to compare scanner sensitivity characteristics by comparing noise equivalent count rate curves. However, because a 20-cm diameter uniform phantom is drastically difference from a human brain, these curves give misleading information when planning a neuro activation PET experiment. Signal-to-noise ratio (SNR) calculations have been performed using measured data (Siemens 921 scanner) from the three-dimensional (3-D) Hoffman brain phantom for the purpose of determining the optimal injection and scanning protocol for [{sup 15}O] labeled activation experiments. Region of interest (ROI) values along with the variance due to prompt (trues plus randoms) and random events were determined for various regions and radioactivity concentrations. Calculated attenuation correction was used throughout. Scatter correction was not used when calculating the SNR in activation studies because the number of scattered events is almost identical in each data acquisition and hence cancels. The results indicate that randoms correction should not be performed and that rather than being limited by the scanner capabilities, neuro activation experiments are limited by the amount of radioactivity that can be injected and the length of time the patient can stay in the scanner.

  19. [Extension study and evaluation of the therapeutic response in a patient with metastatic lung adenocarcinoma using sequential study with ¹⁸F-FDG PET-CT and ¹⁸F-fluoride PET-CT].

    PubMed

    Moragas, M; Soler, M; Riera, E; García, J R

    2015-01-01

    We report a case of a patient with lung adenocarcinoma and bone and extraosseus metastases studied with (18)F-FDG PET-CT, (99m)Tc-HMDP and (18)F-fluoride PET-CT. It assesses the usefulness of (18)F-FDG PET-CT for initial staging of the disease and monitoring response to therapy. For the study of the sclerotic bone metastases it shows the superiority of 99mTc-HMDP bone scintigraphy and (18)F-fluoride PET-CT over (18)F-FDG PET-CT, and (18)F-fluoride PET-CT over bone scintigraphy. It also shows the usefulness of (18)F-fluoride PET-CT for monitoring the bone metastases.

  20. Impact of MR based attenuation correction on neurological PET studies

    PubMed Central

    Su, Yi; Rubin, Brian B.; McConathy, Jonathan; Laforest, Richard; Qi, Jing; Sharma, Akash; Priatna, Agus; Benzinger, Tammie L.S.

    2016-01-01

    Hybrid positron emission tomography (PET) and magnetic resonance (MR) scanners have become a reality in recent years with the benefits of reduced radiation exposure, reduction of imaging time, and potential advantages in quantification. Appropriate attenuation correction remains a challenge. Biases in PET activity measurements were demonstrated using the current MR based attenuation correction technique. We aim to investigate the impact of using standard MRAC technique on the clinical and research utility of PET/MR hybrid scanner for amyloid imaging. Methods Florbetapir scans were obtained on 40 participants on a Biograph mMR hybrid scanner with simultaneous MR acquisition. PET images were reconstructed using both MR and CT derived attenuation map. Quantitative analysis was performed for both datasets to assess the impact of MR based attenuation correction to absolute PET activity measurements as well as target to reference ratio (SUVR). Clinical assessment was also performed by a nuclear medicine physician to determine amyloid status based on the criteria in the FDA prescribing information for florbetapir. Results MR based attenuation correction led to underestimation of PET activity for most part of the brain with a small overestimation for deep brain regions. There is also an overestimation of SUVR values with cerebellar reference. SUVR measurements obtained from the two attenuation correction methods were strongly correlated. Clinical assessment of amyloid status resulted in identical classification as positive or negative regardless of the attenuation correction methods. Conclusions MR based attenuation correction cause biases in quantitative measurements. The biases may be accounted for by a linear model, although the spatial variation cannot be easily modelled. The quantitative differences however did not affect clinical assessment as positive or negative. PMID:26823562

  1. Fluorine-18 labeled tracers for PET studies in the neurosciences

    SciTech Connect

    Ding, Yu-Shin; Fowler, J.S.

    1995-12-31

    This chapter focuses on fluorine-18, the positron emitter with the longest half-life, the lowest positron energy and probably, the most challenging chemistry. The incorporation of F-18 into organic compounds presents many challenges, including: the need to synthesize and purify the compound within a 2--3 hour time frame; the limited number of labeled precursor molecules; the need to work on a microscale; and the need to produce radiotracers which are chemically and radiochemically pure, sterile and pyrogen-free, and suitable for intravenous injection. The PET method and F-18 labeling of organic molecules are described followed by highlights of the applications of F-18 labeled compounds in the neurosciences and neuropharmacology. It is important to emphasize the essential and pivotal role that organic synthesis has played in the progression of the PET field over the past twenty years from one in which only a handful of institutions possessed the instrumentation and staff to carry out research to the present-day situation where there are more than 200 PET centers worldwide. During this period PET has become an important scientific tool in the neurosciences, cardiology and oncology. It is important to point out that PET is by no means a mature field. The fact that a hundreds of different F-18 labeled compounds have been developed but only a few possess the necessary selectivity and sensitivity in vivo to track a specific biochemical process illustrates this and underscores a major difficulty in radiotracer development, namely the selection of priority structures for synthesis and the complexities of the interactions between chemical compounds and living systems. New developments in rapid organic synthesis are needed in order to investigate new molecular targets and to improve the quantitative nature of PET experiments.

  2. PET Studies in Nonhuman Primate Models of Cocaine Abuse: Translational Research Related to Vulnerability and Neuroadaptations

    PubMed Central

    Gould, Robert W.; Duke, Angela N.; Nader, Michael A.

    2013-01-01

    The current review highlights the utility of positron emission tomography (PET) imaging to study the neurobiological substrates underlying vulnerability to cocaine addiction and subsequent adaptations following chronic cocaine self-administration in nonhuman primate models of cocaine abuse. Environmental (e.g., social rank) and sex-specific influences on dopaminergic function and sensitivity to the reinforcing effects of cocaine are discussed. Cocaine-related cognitive deficits have been hypothesized to contribute to high rates of relapse and are described in nonhuman primate models. Lastly, the long-term consequences of cocaine on neurobiology are discussed. PET imaging and longitudinal, within-subject behavioral studies in nonhuman primates have provided a strong framework for designing pharmacological and behavioral treatment strategies to aid drug-dependent treatment seekers. Non-invasive PET imaging will allow for individualized treatment strategies. Recent advances in radiochemistry of novel PET ligands and other imaging modalities can further advance our understanding of stimulant use on the brain. PMID:23458573

  3. Netupitant PET imaging and ADME studies in humans

    PubMed Central

    Spinelli, Tulla; Calcagnile, Selma; Giuliano, Claudio; Rossi, Giorgia; Lanzarotti, Corinna; Mair, Stuart; Stevens, Lloyd; Nisbet, Ian

    2014-01-01

    Netupitant is a new, selective NK1 receptor antagonist under development for the prevention of chemotherapy-induced nausea and vomiting. Two studies were conducted to evaluate the brain receptor occupancy (RO) and disposition (ADME) of netupitant in humans. Positron emission tomography (PET) imaging with the NK1 receptor-binding–selective tracer [11C]-GR205171 was used to evaluate the brain penetration of different doses of netupitant (100, 300, and 450 mg) and to determine the NK1-RO duration. A NK1-RO of 90% or higher was achieved with all doses in the majority of the tested brain regions at Cmax, with a long duration of RO. The netupitant minimal plasma concentration predicted to achieve a NK1-RO of 90%, C90%, in the striatum was 225 ng/mL; after administration of netupitant 300 mg, concentrations exceeded the C90%. In the ADME study, a single nominal dose of [14C]-netupitant 300 mg was used to assess its disposition. Absorption was rapid and netupitant was extensively metabolized via Phase I and II hepatic metabolism. Elimination of >90% was predicted at day 29 and was principally via hepatic/biliary route (>85%) with a minor contribution of the renal route (<5%). In conclusion, these studies demonstrate that netupitant is a potent agent targeting NK1 receptors with long lasting RO. In addition, netupitant is extensively metabolized and is mainly eliminated through the hepatic/biliary route and to a lesser extent via the kidneys. PMID:24122871

  4. Pet Bonding and Pet Bereavement among Adolescents.

    ERIC Educational Resources Information Center

    Brown, Brenda H.; And Others

    1996-01-01

    Studied adolescent-pet bonding and bereavement following pet loss (n=55). Hypothesized that highly-bonded adolescents experience more intense grief when a pet dies than do those less bonded; degree of bonding is greater for girls than for boys; and intensity of bereavement is greater for girls than for boys. Results supported the hypotheses. (RB)

  5. Study of the Crystalline Morphology Evolution of PET and PET/PC Blends by Time-resolved Synchrotron Small Angle X-ray Scattering (SAXS) and DSC

    SciTech Connect

    Barbosa, Irineu; Larocca, Nelson M.; Hage, Elias; Plivelic, Tomas S.; Torriani, Iris L.; Mantovani, Gerson L.

    2009-01-29

    Isothermal melt crystallization of poly(ethylene terephthalate)(PET) and PET/PC (polycarbonate) blend, with and without a transesterification catalyst, was studied by time-resolved small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) in order to achieve the variation of the morphological parameters throughout the whole crystallization time. For neat PET, the catalyst promotes a decrease of the crystal lamellar thickness but for the blend no variations were observed. The effect of incorporation of catalyst in crystallization kinetics was very distinct in PET pure and the blend: in the former the catalyst leads to an increase of this kinetics while for the latter it was observed a decreasing.

  6. SU-E-J-270: Study of PET Response to HDR Brachytherapy of Rectal Cancer

    SciTech Connect

    Hobbs, R; Le, Y; Armour, E; Efron, J; Azad, N; Wahl, R; Gearhart, S; Herman, J

    2014-06-01

    Purpose: Dose-response studies in radiation therapy are typically using single response values for tumors across ensembles of tumors. Using the high dose rate (HDR) treatment plan dose grid and pre- and post-therapy FDG-PET images, we look for correlations between voxelized dose and FDG uptake response in individual tumors. Methods: Fifteen patients were treated for localized rectal cancer using 192Ir HDR brachytherapy in conjunction with surgery. FDG-PET images were acquired before HDR therapy and 6–8 weeks after treatment (prior to surgery). Treatment planning was done on a commercial workstation and the dose grid was calculated. The two PETs and the treatment dose grid were registered to each other using non-rigid registration. The difference in PET SUV values before and after HDR was plotted versus absorbed radiation dose for each voxel. The voxels were then separated into bins for every 400 cGy of absorbed dose and the bin average values plotted similarly. Results: Individual voxel doses did not correlate with PET response; however, when group into tumor subregions corresponding to dose bins, eighty percent of the patients showed a significant positive correlation (R2 > 0) between PET uptake difference in the targeted region and the absorbed dose. Conclusion: By considering larger ensembles of voxels, such as organ average absorbed dose or the dose bins considered here, valuable information may be obtained. The dose-response correlations as measured by FDG-PET difference potentially underlines the importance of FDG-PET as a measure of response, as well as the value of voxelized information.

  7. Prospective Study of FLT PET for Early Interim Response Assessment in Advanced Stage B-cell Lymphoma

    PubMed Central

    Schöder, Heiko; Zelenetz, Andrew D.; Hamlin, Paul; Gavane, Somali; Horwitz, Steven; Matasar, Matthew; Moskowitz, Alison; Noy, Ariela; Palomba, Lia; Portlock, Carol; Straus, David; Grewal, Ravinder; Migliacci, Jocelyn C.; Larson, Steven M.; Moskowitz, Craig H.

    2016-01-01

    Purpose Current clinical and imaging tools remain suboptimal for early assessment of prognosis and treatment response in aggressive lymphomas. Positron emission tomography (PET) with 18F-fluorothymidine (FLT) can be used to measure tumor cell proliferation and treatment response. In a prospective study in patients with advanced stage B-cell lymphoma we investigated the prognostic and predictive value of FLT PET in comparison to standard imaging with FDG PET and clinical outcome. Patients and Methods 65 patients were treated with an induction/consolidation regimen consisting of four cycles of R-CHOP-14 followed by 3 cycles of ICE. FLT PET was performed at baseline and at interim (iPET) after 1–2 cycles of therapy. FDG PET was performed at baseline, after cycle 4, and at the end of therapy. The relationship between PET findings, progression free survival (PFS) and overall survival (OS) was investigated. Results With a median follow-up of 51 months, PFS and OS were 71% and 86% respectively. FLT iPET, analyzed visually, using a 5-point score, or semi-quantitatively, using SUV and ΔSUV, predicted both PFS and OS (p<0.01 for all parameters). Residual FLT SUVmax on iPET was associated with an inferior PFS (HR: 1.26, p=0.001) and OS (HR: 1.27, p=0.002). Using FDG PET, findings in the end of treatment scan were better predictors of PFS and OS than findings on interim scan. Baseline PET imaging parameters, including SUV, proliferative or metabolic tumor volume, did not correlate with outcome. Conclusion FLT PET after 1–2 cycles of chemotherapy predicts PFS and OS, and a negative FLT iPET may potentially help design risk-adapted therapies in patients with aggressive lymphomas. In contrast, the positive predictive value of FLT iPET remains too low to justify changes in patient management. PMID:26719374

  8. Design study of a cardiac-dedicated PET system

    NASA Astrophysics Data System (ADS)

    Peng, Hao

    2015-04-01

    The work studies the feasibility of developing a cardiac-dedicated PET system using Monte Carlo simulation tools. The proposed system comprises a dual-panel geometry and both panels utilize fine crystal elements (~2-3 mm) to help improve high spatial resolution. The system performances were studied with respect to photon detection sensitivity, count-rate performances, spatial resolution, depth-of-interaction (DOI) capability, and potential contrast recovery improvement due to time-of-flight (TOF). For a 2:3 dual panel configuration (front panel: 24.0×18.0 cm2 and back panel: 36.0×27.0 cm2), the system is able to achieve a peak photon sensitivity of ~13.0% at the location of the heart. For count-rate performances, the system is able to yield a continuous increase of noise equivalent count rate (NECR) as a function of the total activity of radiotracers between 10 mCi and 50 mCi. When crystal elements of 2×2×20 cm3 are deployed in the front panel and crystal elements of 3×3×20 cm3 are deployed in the back panel, the proposed system is not only able to revolve 2 mm diameter spheres in the image slices parallel to the panels but also demonstrates good resolution uniformity of less than 5%. On the other hand, significant resolution degradation occurs in the direction perpendicular to the panels due to the following two factors: limited angular coverage and finite DOI resolution. Such degradation was quantitatively analyzed for five different DOI resolutions (0 mm, 2.5 mm, 5 mm, 10 mm and 20 mm), as well as three different crystal configurations. Finally, the contrast study with a heart-like phantom (comprising lumen, aortic wall, myocardium and small lesions) indicates that TOF capability (time resolution: 250-500 ps) does not significantly improve image quality and lesion detectability, in terms of contrast-to-noise ratio (CNR).

  9. Towards coronary plaque imaging using simultaneous PET-MR: a simulation study

    NASA Astrophysics Data System (ADS)

    Petibon, Y.; El Fakhri, G.; Nezafat, R.; Johnson, N.; Brady, T.; Ouyang, J.

    2014-03-01

    Coronary atherosclerotic plaque rupture is the main cause of myocardial infarction and the leading killer in the US. Inflammation is a known bio-marker of plaque vulnerability and can be assessed non-invasively using fluorodeoxyglucose-positron emission tomography imaging (FDG-PET). However, cardiac and respiratory motion of the heart makes PET detection of coronary plaque very challenging. Fat surrounding coronary arteries allows the use of MRI to track plaque motion during simultaneous PET-MR examination. In this study, we proposed and assessed the performance of a fat-MR based coronary motion correction technique for improved FDG-PET coronary plaque imaging in simultaneous PET-MR. The proposed methods were evaluated in a realistic four-dimensional PET-MR simulation study obtained by combining patient water-fat separated MRI and XCAT anthropomorphic phantom. Five small lesions were digitally inserted inside the patients coronary vessels to mimic coronary atherosclerotic plaques. The heart of the XCAT phantom was digitally replaced with the patient's heart. Motion-dependent activity distributions, attenuation maps, and fat-MR volumes of the heart, were generated using the XCAT cardiac and respiratory motion fields. A full Monte Carlo simulation using Siemens mMR's geometry was performed for each motion phase. Cardiac/respiratory motion fields were estimated using non-rigid registration of the transformed fat-MR volumes and incorporated directly into the system matrix of PET reconstruction along with motion-dependent attenuation maps. The proposed motion correction method was compared to conventional PET reconstruction techniques such as no motion correction, cardiac gating, and dual cardiac-respiratory gating. Compared to uncorrected reconstructions, fat-MR based motion compensation yielded an average improvement of plaque-to-background contrast of 29.6%, 43.7%, 57.2%, and 70.6% for true plaque-to-blood ratios of 10, 15, 20 and 25:1, respectively. Channelized

  10. Performing 18F-FDG PET studies following injections of 99mTc-sestamibi

    NASA Astrophysics Data System (ADS)

    Smith, R. J.; Karp, J. S.

    1999-06-01

    When SPECT studies are followed by PET studies on the same day, substantial 99mTc activity may be present in patients during the PET scans. Degraded PET camera performance results unless the low-energy gamma rays are absorbed by lead shields. Spatial resolution, camera count rates, energy spectra, image contrast and noise, and image quality have been measured for phantoms with varying levels of 99mTc activity, and both with and without thin lead shields placed in front of the detectors. In addition examples of the results of twelve 18F-FDG PET cardiac studies performed within 6 h of 99mTc-sestamibi injections are reported. The presence of 99mTc (140 keV gamma rays) causes light pile-up with 511 keV photons resulting in distorted energy spectra, degraded spatial resolution, increased Compton background and reduced count-rate capability. These effects are avoided using thin lead shields. Studies performed with 99mTc activity in patients but using lead shields are of comparable quality to studies performed without 99mTc or shields. Thin lead shields effectively filter low-energy gamma rays during PET studies leading to improved count-rate capability, contrast and image quality.

  11. Quantitative, noninvasive, in vivo longitudinal monitoring of gene expression in the brain by co-AAV transduction with a PET reporter gene

    PubMed Central

    Yoon, Sea Young; Gay-Antaki, Carlos; Ponde, Datta E; Poptani, Harish; Vite, Charles H; Wolfe, John H

    2014-01-01

    In vivo imaging of vector transgene expression would be particularly valuable for repetitive monitoring of therapy in the brain, where invasive tissue sampling is contraindicated. We evaluated adeno-associated virus vector expression of a dopamine-2 receptor (D2R) mutant (D2R80A) by positron emission tomography in the brains of mice and cats. D2R80A is inactivated for intracellular signaling and binds subphysiologic amounts of the radioactive [18F]-fallypride analog of dopamine. The [18F]-fallypride signal bound to D2R80A in the injection site was normalized to the signal from endogenous D2R in the striatum and showed stable levels of expression within individual animals. A separate adeno-associated virus type 1 vector with identical gene expression control elements, expressing green fluorescent protein or a therapeutic gene, was coinjected with the D2R80A vector at equal doses into specific sites. Both transgenes had similar levels of gene expression by immunohistochemistry, in situ hybridization, and quantitative PCR assays, demonstrating that D2R80A is a faithful surrogate measure for expression of a gene of interest. This dual vector approach allows the D2R80A gene to be used with any therapeutic gene and to be injected into a single site for monitoring while the therapeutic gene can be distributed more widely as needed in each disease. PMID:26015960

  12. Automated evaluation of setup errors in carbon ion therapy using PET: Feasibility study

    SciTech Connect

    Kuess, Peter Hopfgartner, Johannes; Georg, Dietmar; Helmbrecht, Stephan; Fiedler, Fine; Birkfellner, Wolfgang; Enghardt, Wolfgang

    2013-12-15

    Purpose: To investigate the possibility of detecting patient mispositioning in carbon-ion therapy with particle therapy positron emission tomography (PET) in an automated image registration based manner. Methods: Tumors in the head and neck (H and N), pelvic, lung, and brain region were investigated. Biologically optimized carbon ion treatment plans were created with TRiP98. From these treatment plans, the reference β{sup +}-activity distributions were calculated using a Monte Carlo simulation. Setup errors were simulated by shifting or rotating the computed tomography (CT). The expected β{sup +} activity was calculated for each plan with shifts. Finally, the reference particle therapy PET images were compared to the “shifted” β{sup +}-activity distribution simulations using the Pearson's correlation coefficient (PCC). To account for different PET monitoring options the inbeam PET was compared to three different inroom scenarios. Additionally, the dosimetric effects of the CT misalignments were investigated. Results: The automated PCC detection of patient mispositioning was possible in the investigated indications for cranio-caudal shifts of 4 mm and more, except for prostate tumors. In the rather homogeneous pelvic region, the generated β{sup +}-activity distribution of the reference and compared PET image were too much alike. Thus, setup errors in this region could not be detected. Regarding lung lesions the detection strongly depended on the exact tumor location: in the center of the lung tumor misalignments could be detected down to 2 mm shifts while resolving shifts of tumors close to the thoracic wall was more challenging. Rotational shifts in the H and N and lung region of +6° and more could be detected using inroom PET and partly using inbeam PET. Comparing inroom PET to inbeam PET no obvious trend was found. However, among the inroom scenarios a longer measurement time was found to be advantageous. Conclusions: This study scopes the use of various

  13. Positron range in tissue-equivalent materials: experimental microPET studies.

    PubMed

    Alva-Sánchez, H; Quintana-Bautista, C; Martínez-Dávalos, A; Ávila-Rodríguez, M A; Rodríguez-Villafuerte, M

    2016-09-01

    In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with (18)F, (13)N or (68)Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

  14. Positron range in tissue-equivalent materials: experimental microPET studies

    NASA Astrophysics Data System (ADS)

    Alva-Sánchez, H.; Quintana-Bautista, C.; Martínez-Dávalos, A.; Ávila-Rodríguez, M. A.; Rodríguez-Villafuerte, M.

    2016-09-01

    In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with 18F, 13N or 68Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

  15. PET - A proton/electron telescope for studies of magnetospheric, solar, and galactic particles

    NASA Technical Reports Server (NTRS)

    Cook, Walter R.; Cummings, Alan C.; Cummings, Jay R.; Garrard, Thomas L.; Kecman, Branislav; Mewaldt, Richard A.; Selesnick, Richard S.; Stone, Edward C.; Baker, Daniel N.; Von Rosenvinge, Tycho T.

    1993-01-01

    The Proton/Electron Telescope (PET) on SAMPEX is designed to provide measurements of energetic electrons and light nuclei from solar, galactic, and magnetospheric sources. PET is an all solid-state system that will measure the differential energy spectra of electrons from about 1 to about 30 MeV and H and He nuclei from about 20 to about 300 MeV/nuc, with isotope resolution of H and He extending from about 20 to about 80 MeV/nuc. As SAMPEX scans all local times and geomagnetic cutoffs over the course of its near-polar orbit, PET will characterize precipitating relativistic electron events during periods of declining solar activity, and it will examine whether the production rate of odd nitrogen and hydrogen molecules in the middle atmosphere by precipitating electrons is sufficient to affect O3 depletion. In addition, PET will complement studies of the elemental and isotopic composition of energetic heavy (Z greater than 2) nuclei on SAMPEX by providing measurements of H, He, and electrons. Finally, PET has limited capability to identify energetic positrons from potential natural and man-made sources.

  16. MR-based motion correction for PET imaging using wired active MR microcoils in simultaneous PET-MR: Phantom study

    SciTech Connect

    Huang, Chuan; Brady, Thomas J.; El Fakhri, Georges; Ouyang, Jinsong; Ackerman, Jerome L.; Petibon, Yoann

    2014-04-15

    Purpose: Artifacts caused by head motion present a major challenge in brain positron emission tomography (PET) imaging. The authors investigated the feasibility of using wired active MR microcoils to track head motion and incorporate the measured rigid motion fields into iterative PET reconstruction. Methods: Several wired active MR microcoils and a dedicated MR coil-tracking sequence were developed. The microcoils were attached to the outer surface of an anthropomorphic{sup 18}F-filled Hoffman phantom to mimic a brain PET scan. Complex rotation/translation motion of the phantom was induced by a balloon, which was connected to a ventilator. PET list-mode and MR tracking data were acquired simultaneously on a PET-MR scanner. The acquired dynamic PET data were reconstructed iteratively with and without motion correction. Additionally, static phantom data were acquired and used as the gold standard. Results: Motion artifacts in PET images were effectively removed by wired active MR microcoil based motion correction. Motion correction yielded an activity concentration bias ranging from −0.6% to 3.4% as compared to a bias ranging from −25.0% to 16.6% if no motion correction was applied. The contrast recovery values were improved by 37%–156% with motion correction as compared to no motion correction. The image correlation (mean ± standard deviation) between the motion corrected (uncorrected) images of 20 independent noise realizations and static reference was R{sup 2} = 0.978 ± 0.007 (0.588 ± 0.010, respectively). Conclusions: Wired active MR microcoil based motion correction significantly improves brain PET quantitative accuracy and image contrast.

  17. Cerebral necrosis after radiotherapy and/or intraarterial chemotherapy for brain tumors: PET and neuropathologic studies

    SciTech Connect

    Di Chiro, G.; Oldfield, E.; Wright, D.C.; De Michele, D.; Katz, D.A.; Patronas, N.J.; Doppman, J.L.; Larson, S.M.; Ito, M.; Kufta, C.V.

    1988-01-01

    Cerebral necrosis after radiotherapy for brain tumors is being recognized as a problem more common than previously estimated. Distinction between this iatrogenic complication and tumor recurrence cannot be made by either CT or MR imaging. By using positron emission tomography (PET) with /sup 18/F-deoxyglucose (FDG) we were able to reach a diagnosis of radiation necrosis, later verified, in 10 of 95 patients referred for the purpose of differentiating tumor recurrence from necrosis. The critical PET-FDG feature was focal hypometabolism in the area of necrosis, which contrasted with the hypermetabolism associated with the residual/recurrent tumor. In addition, four cases of cerebral necrosis after supraophthalmic, intraarterial chemotherapy (BCNU) were studied with the PET-FDG method. The area of chemotherapy damage was also characterized by marked hypometabolism. Histology revealed both similarities and differences between radio- and chemonecrosis.

  18. Brain Mapping of Language and Auditory Perception in High-Functioning Autistic Adults: A PET Study.

    ERIC Educational Resources Information Center

    Muller, R-A.; Behen, M. E.; Rothermel, R. D.; Chugani, D. C.; Muzik, O.; Mangner, T. J.; Chugani, H. T.

    1999-01-01

    A study used positron emission tomography (PET) to study patterns of brain activation during auditory processing in five high-functioning adults with autism. Results found that participants showed reversed hemispheric dominance during the verbal auditory stimulation and reduced activation of the auditory cortex and cerebellum. (CR)

  19. Subthalamic Nucleus Stimulation and Dysarthria in Parkinson's Disease: A PET Study

    ERIC Educational Resources Information Center

    Pinto, Serge; Thobois, Stephane; Costes, Nicolas; Le Bars, Didier; Benabid, Alim-Louis; Broussolle, Emmanuel; Pollak, Pierre; Gentil, Michele

    2004-01-01

    In Parkinson's disease, functional imaging studies during limb motor tasks reveal cerebral activation abnormalities that can be reversed by subthalamic nucleus (STN) stimulation. The effect of STN stimulation on parkinsonian dysarthria has not, however, been investigated using PET. The aim of the present study was to evaluate the effect of STN…

  20. Weight Gain following Pallidal Deep Brain Stimulation: A PET Study.

    PubMed

    Sauleau, Paul; Drapier, Sophie; Duprez, Joan; Houvenaghel, Jean-François; Dondaine, Thibaut; Haegelen, Claire; Drapier, Dominique; Jannin, Pierre; Robert, Gabriel; Le Jeune, Florence; Vérin, Marc

    2016-01-01

    The mechanisms behind weight gain following deep brain stimulation (DBS) surgery seem to be multifactorial and suspected depending on the target, either the subthalamic nucleus (STN) or the globus pallidus internus (GPi). Decreased energy expenditure following motor improvement and behavioral and/or metabolic changes are possible explanations. Focusing on GPi target, our objective was to analyze correlations between changes in brain metabolism (measured with PET) and weight gain following GPi-DBS in patients with Parkinson's disease (PD). Body mass index was calculated and brain activity prospectively measured using 2-deoxy-2[18F]fluoro-D-glucose PET four months before and four months after the start of GPi-DBS in 19 PD patients. Dopaminergic medication was included in the analysis to control for its possible influence on brain metabolism. Body mass index increased significantly by 0.66 ± 1.3 kg/m2 (p = 0.040). There were correlations between weight gain and changes in brain metabolism in premotor areas, including the left and right superior gyri (Brodmann area, BA 6), left superior gyrus (BA 8), the dorsolateral prefrontal cortex (right middle gyrus, BAs 9 and 46), and the left and right somatosensory association cortices (BA 7). However, we found no correlation between weight gain and metabolic changes in limbic and associative areas. Additionally, there was a trend toward a correlation between reduced dyskinesia and weight gain (r = 0.428, p = 0.067). These findings suggest that, unlike STN-DBS, motor improvement is the major contributing factor for weight gain following GPi-DBS PD, confirming the motor selectivity of this target. PMID:27070317

  1. Weight Gain following Pallidal Deep Brain Stimulation: A PET Study

    PubMed Central

    Sauleau, Paul; Drapier, Sophie; Duprez, Joan; Houvenaghel, Jean-François; Dondaine, Thibaut; Haegelen, Claire; Drapier, Dominique; Jannin, Pierre; Robert, Gabriel; Le Jeune, Florence; Vérin, Marc

    2016-01-01

    The mechanisms behind weight gain following deep brain stimulation (DBS) surgery seem to be multifactorial and suspected depending on the target, either the subthalamic nucleus (STN) or the globus pallidus internus (GPi). Decreased energy expenditure following motor improvement and behavioral and/or metabolic changes are possible explanations. Focusing on GPi target, our objective was to analyze correlations between changes in brain metabolism (measured with PET) and weight gain following GPi-DBS in patients with Parkinson’s disease (PD). Body mass index was calculated and brain activity prospectively measured using 2-deoxy-2[18F]fluoro-D-glucose PET four months before and four months after the start of GPi-DBS in 19 PD patients. Dopaminergic medication was included in the analysis to control for its possible influence on brain metabolism. Body mass index increased significantly by 0.66 ± 1.3 kg/m2 (p = 0.040). There were correlations between weight gain and changes in brain metabolism in premotor areas, including the left and right superior gyri (Brodmann area, BA 6), left superior gyrus (BA 8), the dorsolateral prefrontal cortex (right middle gyrus, BAs 9 and 46), and the left and right somatosensory association cortices (BA 7). However, we found no correlation between weight gain and metabolic changes in limbic and associative areas. Additionally, there was a trend toward a correlation between reduced dyskinesia and weight gain (r = 0.428, p = 0.067). These findings suggest that, unlike STN-DBS, motor improvement is the major contributing factor for weight gain following GPi-DBS PD, confirming the motor selectivity of this target. PMID:27070317

  2. Cardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study.

    PubMed

    Petibon, Y; Ouyang, J; Zhu, X; Huang, C; Reese, T G; Chun, S Y; Li, Q; El Fakhri, G

    2013-04-01

    Cardiac motion and partial volume effects (PVE) are two of the main causes of image degradation in cardiac PET. Motion generates artifacts and blurring while PVE lead to erroneous myocardial activity measurements. Newly available simultaneous PET-MR scanners offer new possibilities in cardiac imaging as MRI can assess wall contractility while collecting PET perfusion data. In this perspective, we develop a list-mode iterative reconstruction framework incorporating both tagged-MR derived non-rigid myocardial wall motion and position dependent detector point spread function (PSF) directly into the PET system matrix. In this manner, our algorithm performs both motion 'deblurring' and PSF deconvolution while reconstructing images with all available PET counts. The proposed methods are evaluated in a beating non-rigid cardiac phantom whose hot myocardial compartment contains small transmural and non-transmural cold defects. In order to accelerate imaging time, we investigate collecting full and half k-space tagged MR data to obtain tagged volumes that are registered using non-rigid B-spline registration to yield wall motion information. Our experimental results show that tagged-MR based motion correction yielded an improvement in defect/myocardium contrast recovery of 34-206% as compared to motion uncorrected studies. Likewise, lesion detectability improved by respectively 115-136% and 62-235% with MR-based motion compensation as compared to gating and no motion correction and made it possible to distinguish non-transmural from transmural defects, which has clinical significance given the inherent limitations of current single modality imaging in identifying the amount of residual ischemia. The incorporation of PSF modeling within the framework of MR-based motion compensation significantly improved defect/myocardium contrast recovery (5.1-8.5%, p < 0.01) and defect detectability (39-56%, p < 0.01). No statistical difference was found in PET contrast and lesion

  3. Cardiac motion compensation and resolution modeling in simultaneous PET-MR: a cardiac lesion detection study

    NASA Astrophysics Data System (ADS)

    Petibon, Y.; Ouyang, J.; Zhu, X.; Huang, C.; Reese, T. G.; Chun, S. Y.; Li, Q.; El Fakhri, G.

    2013-04-01

    Cardiac motion and partial volume effects (PVE) are two of the main causes of image degradation in cardiac PET. Motion generates artifacts and blurring while PVE lead to erroneous myocardial activity measurements. Newly available simultaneous PET-MR scanners offer new possibilities in cardiac imaging as MRI can assess wall contractility while collecting PET perfusion data. In this perspective, we develop a list-mode iterative reconstruction framework incorporating both tagged-MR derived non-rigid myocardial wall motion and position dependent detector point spread function (PSF) directly into the PET system matrix. In this manner, our algorithm performs both motion ‘deblurring’ and PSF deconvolution while reconstructing images with all available PET counts. The proposed methods are evaluated in a beating non-rigid cardiac phantom whose hot myocardial compartment contains small transmural and non-transmural cold defects. In order to accelerate imaging time, we investigate collecting full and half k-space tagged MR data to obtain tagged volumes that are registered using non-rigid B-spline registration to yield wall motion information. Our experimental results show that tagged-MR based motion correction yielded an improvement in defect/myocardium contrast recovery of 34-206% as compared to motion uncorrected studies. Likewise, lesion detectability improved by respectively 115-136% and 62-235% with MR-based motion compensation as compared to gating and no motion correction and made it possible to distinguish non-transmural from transmural defects, which has clinical significance given the inherent limitations of current single modality imaging in identifying the amount of residual ischemia. The incorporation of PSF modeling within the framework of MR-based motion compensation significantly improved defect/myocardium contrast recovery (5.1-8.5%, p < 0.01) and defect detectability (39-56%, p < 0.01). No statistical difference was found in PET contrast and lesion

  4. Investigation of partial volume correction methods for brain FDG PET studies

    SciTech Connect

    Yang, J.; Huang, S.C.; Mega, M.; Toga, A.W.; Small, G.W.; Phelps, M.E.; Lin, K.P.

    1996-12-01

    The use of positron emission tomography (PET) in quantitative fluorodeoxyglucose (FDG) studies of aging and dementia has been limited by partial volume effects. A general method for correction of partial volume effects (PVE) in PET involves the following common procedures; segmentation of MRI brain images into gray matter (GM), white matter (WM), cerebral spinal fluid (CSF), and muscle (MS) components; MRI PET registration; and generation of simulated PET images. Afterward, two different approaches can be taken. The first approach derives first a pixel-by-pixel correction map as the ratio of the measured image to the simulated image [with realistic full-width at half-maximum (FWHM)]. The correction map was applied to the MRI segmentation image. Regions of interest (ROI`s) can then be applied to give results free of partial volume effects. The second approach uses the ROI values of the simulated ``pure`` image (with negligible FWHM) and those of the simulated and the measured PET images to correct for the PVE effect. By varying the ratio of radiotracer concentrations for different tissue components, the in-plane FWHM`s of a three-dimensional point spread function, and the ROI size, the authors evaluated the performance of these two approaches in terms of their accuracy and sensitivity to different simulation configurations. The results showed that both approaches are more robust than the approach developed by Muller-Gartner et al., and the second approach is more accurate and more robust than the first. In conclusion, the authors recommend that the second approach should be used on FDG PET images to correct for partial volume effects and to determine whether an apparent change in GM radiotracer concentration is truly due to metabolic changes.

  5. Imaging and PET-PET/CT imaging.

    PubMed

    Von Schulthess, Gustav K; Hany, Thomas F

    2008-03-01

    PET-CT has grown because the lack of anatomic landmarks in PET makes "hardware-fusion" to anatomic cross-sectional data extremely useful. Addition of CT to PET improves specificity, but also sensitivity, and adding PET to CT adds sensitivity and specificity in tumor imaging. The synergistic advantage of adding CT is that the attenuation correction needed for PET data can also be derived from the CT data. This makes PET-CT 25-30% faster than PET alone, leading to higher patient throughput and a more comfortable examination for patients typically lasting 20 minutes or less. FDG-PET-CT appears to provide relevant information in the staging and therapy monitoring of many tumors, such as lung carcinoma, colorectal cancer, lymphoma, gynaecological cancers, melanoma and many others, with the notable exception of prostatic cancer. For this cancer, choline derivatives may possibly become useful radiopharmaceuticals. The published literature on the applications of FDG-PET-CT in oncology is still limited but several well-designed studies have demonstrated the benefits of PET-CT.

  6. Early assesment of radiation response using a novel functional imaging modality-[18F] Fluorocholine PET (FCH-PET): A pilot study

    PubMed Central

    Parashar, Bhupesh; Wernicke, A. Gabriella; Rice, Samuel; Osborne, Joseph; Singh, Prabhsimranjot; Nori, Dattatreyudu; Vallabhajosula, Shankar; Goldsmith, Stanley; Chao, K.S. Clifford

    2013-01-01

    Purpose [18] Fluoro-deoxyglucose-positron-emission tomography/computerized tomography (FDG-PET) is commonly used to assess response to patients treated with radiation (RT) or Chemotherapy and RT (CRT). The intent of this pilot study is to explore whether FCH-PET can serve as an early predictive biomarker for early detection of RT/CRT response. Materials/Methods Fourteen patients have been accrued and analyzed. The lesions were base of tongue, tonsil, nodes, hypopharynx, maxilla, palate, lung, pancreas, brain, uterine and rectal. There were 16 lesions that were considered target lesion and were followed for correlation between change in FCH-PET SUVmax readings and clinical outcome. Median tumor size was 4.4 cm. Median RT dose was 66Gy. The change in SUVmax (Δ SUVmax) of FCH-PET scans performed before and during RT was correlated with clinical outcome at the last follow-up. Results The median FCH-PET SUVmax for the 1st and 2nd scans was 6.15 and 4.65 respectively. Fourteen (87.5%) lesions showed a reduction in SUVmax in either a CR/PR (complete/partial response) and 2 lesions showed an increase in SUVmax both of which were determined to be NR. The median percentage change between the 1st and 2nd scan was −19.5%. Forty-four percent lesions (7/16) had CR, 44% (7/16) had PR and 12% (2/16) had NR (No response). Median follow-up was 12 months. The results showed a difference between NR and PR, between NR and CR, showed a trend towards significance (p=0.06). Conclusion FCH-PET scan demonstrated changes in SUVmax during RT that were predictive of final outcome PMID:22846199

  7. Evaluation of thoracic tumors with (18)F-FMT and (18)F-FDG PET-CT: a clinicopathological study.

    PubMed

    Kaira, Kyoichi; Oriuchi, Noboru; Shimizu, Kimihiro; Ishikita, Tomohiro; Higuchi, Tetsuya; Imai, Hisao; Yanagitani, Noriko; Sunaga, Noriaki; Hisada, Takeshi; Ishizuka, Tamotsu; Kanai, Yoshikatsu; Endou, Hitoshi; Nakajima, Takashi; Endo, Keigo; Mori, Masatomo

    2009-03-01

    L-[3-(18)F]-alpha-methyltyrosine ((18)F-FMT) is an aminoacid tracer for positron emission tomography (PET). The aim of this study was to determine whether PET-CT with (18)F-FMT provides additional information for the preoperative diagnostic workup as compared with (18)F-FDG PET. PET-CT studies with (18)F-FMT and (18)F-FDG were performed as a part of the preoperative workup in 36 patients with histologically confirmed bronchial carcinoma, 6 patients with benign lesions and a patient with atypical carcinoid. Expression of L-type amino acid transporter 1 (LAT1), CD98, Ki-67 labeling index, VEGF, CD31 and CD34 of the resected tumors were analyzed by immunohistochemical staining, and correlated with the uptake of PET tracers. For the detection of pulmonary malignant tumors, (18)F-FMT PET exhibited a sensitivity of 84% whereas the sensitivity for (18)F-FDG PET was 89% (p = 0.736). (18)F-FMT PET-CT and (18)F-FDG PET-CT agreed with pathological staging in 85 and 68%, respectively (p = 0.151). (18)F-FMT uptake was closely correlated with LAT1, CD98, cell proliferation and angiogenesis. The specificity of (18)F-FMT PET for diagnosing thoracic tumors was higher than that of (18)F-FDG PET. Our results suggest that coexpression of LAT1 and CD98 in addition to cell proliferation and angiogenesis is relavant for the progression and metastasis of lung cancer.

  8. Discovery of Phosphodiesterase 10A (PDE10A) PET Tracer AMG 580 to Support Clinical Studies.

    PubMed

    Hu, Essa; Chen, Ning; Kunz, Roxanne K; Hwang, Dah-Ren; Michelsen, Klaus; Davis, Carl; Ma, Ji; Shi, Jianxia; Lester-Zeiner, Dianna; Hungate, Randall; Treanor, James; Chen, Hang; Allen, Jennifer R

    2016-07-14

    We report the discovery of PDE10A PET tracer AMG 580 developed to support proof of concept studies with PDE10A inhibitors in the clinic. To find a tracer with higher binding potential (BPND) in NHP than our previously reported tracer 1, we implemented a surface plasmon resonance assay to measure the binding off-rate to identify candidates with slower washout rate in vivo. Five candidates (2-6) from two structurally distinct scaffolds were identified that possessed both the in vitro characteristics that would favor central penetration and the structural features necessary for PET isotope radiolabeling. Two cinnolines (2, 3) and one keto-benzimidazole (5) exhibited PDE10A target specificity and brain uptake comparable to or better than 1 in the in vivo LC-MS/MS kinetics distribution study in SD rats. In NHP PET imaging study, [(18)F]-5 produced a significantly improved BPND of 3.1 and was nominated as PDE10A PET tracer clinical candidate for further studies. PMID:27437084

  9. Another breed of "service" animals: STARS study findings about pet ownership and recovery from serious mental illness.

    PubMed

    Wisdom, Jennifer P; Saedi, Goal Auzeen; Green, Carla A

    2009-07-01

    This study elucidates the role of pets in recovery processes among adults with serious mental illness. Data derive from interviews with 177 HMO members with serious mental illness (52.2% women, average age 48.8 years) in the Study of Transitions and Recovery Strategies (STARS). Interviews and questionnaires addressed factors affecting recovery processes and included questions about pet ownership. Data were analyzed using a modified grounded theory method to identify the roles pets play in the recovery process. Primary themes indicate pets assist individuals in recovery from serious mental illness by (a) providing empathy and "therapy"; (b) providing connections that can assist in redeveloping social avenues; (c) serving as "family" in the absence of or in addition to human family members; and (d) supporting self-efficacy and strengthening a sense of empowerment. Pets appear to provide more benefits than merely companionship. Participants' reports of pet-related contributions to their well-being provide impetus to conduct more formal research on the mechanisms by which pets contribute to recovery and to develop pet-based interventions. PMID:19839680

  10. 18F-FET-PET in Primary Hyperparathyroidism: A Pilot Study

    PubMed Central

    Krakauer, Martin; Kjaer, Andreas; Bennedbæk, Finn N.

    2016-01-01

    Preoperative localisation of the diseased parathyroid gland(s) in primary hyperparathyroidism (PHP) is a prerequisite for subsequent minimally invasive surgery. Recently, as alternatives to conventional sestamibi parathyroid scintigraphy, the 11C-based positron emission tomography (PET) tracers methionine and choline have shown promise for this purpose. We evaluated the feasibility of using the 18F-based PET tracer fluoroethyl-l-tyrosine (FET), as the longer half-life of 18F makes it logistically more favourable. As a proof-of-concept study, we included two patients with PHP in which dual-isotope parathyroid subtraction single photon emission computed tomography had determined the exact location of the parathyroid adenoma. A dynamic FET PET/CT scan was performed with subsequent visual evaluation and calculation of target-to-background (TBR; parathyroid vs. thyroid). The maximum TBR in the two patients under study was achieved approximately 30 min after the injection of the tracer and was 1.5 and 1.7, respectively. This ratio was too small to allow for confident visualisation of the adenomas. FET PET/CT seems not feasible as a preoperative imaging modality in PHP. PMID:27548229

  11. (18)F-FET-PET in Primary Hyperparathyroidism: A Pilot Study.

    PubMed

    Krakauer, Martin; Kjaer, Andreas; Bennedbæk, Finn N

    2016-01-01

    Preoperative localisation of the diseased parathyroid gland(s) in primary hyperparathyroidism (PHP) is a prerequisite for subsequent minimally invasive surgery. Recently, as alternatives to conventional sestamibi parathyroid scintigraphy, the (11)C-based positron emission tomography (PET) tracers methionine and choline have shown promise for this purpose. We evaluated the feasibility of using the (18)F-based PET tracer fluoroethyl-l-tyrosine (FET), as the longer half-life of (18)F makes it logistically more favourable. As a proof-of-concept study, we included two patients with PHP in which dual-isotope parathyroid subtraction single photon emission computed tomography had determined the exact location of the parathyroid adenoma. A dynamic FET PET/CT scan was performed with subsequent visual evaluation and calculation of target-to-background (TBR; parathyroid vs. thyroid). The maximum TBR in the two patients under study was achieved approximately 30 min after the injection of the tracer and was 1.5 and 1.7, respectively. This ratio was too small to allow for confident visualisation of the adenomas. FET PET/CT seems not feasible as a preoperative imaging modality in PHP. PMID:27548229

  12. A Factor-Image Framework to Quantification of Brain Receptor Dynamic PET Studies

    PubMed Central

    Wang, Z. Jane; Szabo, Zsolt; Lei, Peng; Varga, József; Liu, K. J. Ray

    2007-01-01

    The positron emission tomography (PET) imaging technique enables the measurement of receptor distribution or neurotransmitter release in the living brain and the changes of the distribution with time and thus allows quantification of binding sites as well as the affinity of a radioligand. However, quantification of receptor binding studies obtained with PET is complicated by tissue heterogeneity in the sampling image elements (i.e., voxels, pixels). This effect is caused by a limited spatial resolution of the PET scanner. Spatial heterogeneity is often essential in understanding the underlying receptor binding process. Tracer kinetic modeling also often requires an intrusive collection of arterial blood samples. In this paper, we propose a likelihood-based framework in the voxel domain for quantitative imaging with or without the blood sampling of the input function. Radioligand kinetic parameters are estimated together with the input function. The parameters are initialized by a subspace-based algorithm and further refined by an iterative likelihood-based estimation procedure. The performance of the proposed scheme is examined by simulations. The results show that the proposed scheme provides reliable estimation of factor time-activity curves (TACs) and the underlying parametric images. A good match is noted between the result of the proposed approach and that of the Logan plot. Real brain PET data are also examined, and good performance is observed in determining the TACs and the underlying factor images. PMID:18769527

  13. Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

    NASA Astrophysics Data System (ADS)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

  14. Dopamine D2/D3 receptor availability and venturesomeness.

    PubMed

    Bernow, Nina; Yakushev, Igor; Landvogt, Christian; Buchholz, Hans-Georg; Smolka, Michael N; Bartenstein, Peter; Lieb, Klaus; Gründer, Gerhard; Vernaleken, Ingo; Schreckenberger, Mathias; Fehr, Christoph

    2011-08-30

    The construct of impulsivity is considered as a major trait of personality. There is growing evidence that the mesolimbic dopamine system plays an important role in the modulation of impulsivity and venturesomeness, the two key components within the impulsivity-construct. The aim of the present study was to explore an association between trait impulsivity measured with self-assessment and the dopaminergic neurotransmission as measured by positron emission tomography (PET) in a cohort of healthy male subjects. In vivo D2/D3 receptor availability was determined with [(18)F]fallypride PET in 18 non-smoking healthy subjects. The character trait impulsivity was measured using the Impulsiveness-Venturesomeness-Empathy questionnaire (I7). Image processing and statistical analysis was performed on a voxel-by-voxel basis using statistical parametric mapping (SPM) software. The I7 subscale venturesomeness correlated positively with the D2/D3 receptor availability within the left temporal cortex and the thalamus. Measures on the I7 subscale impulsiveness and empathy did not correlate with the D2/D3 receptor availability in any brain region investigated. Our results suggest the involvement of extrastriatal dopaminergic neurotransmission in venturesomeness, a component of impulsivity. PMID:21689908

  15. (68)Ga-PRGD2 PET/CT in the evaluation of Glioma: a prospective study.

    PubMed

    Li, Deling; Zhao, Xiaobin; Zhang, Liwei; Li, Fang; Ji, Nan; Gao, Zhixian; Wang, Jisheng; Kang, Peng; Liu, Zhaofei; Shi, Jiyun; Chen, Xiaoyuan; Zhu, Zhaohui

    2014-11-01

    Integrin αvβ3 is overexpressed in both neovasculature and glioma cells. We aimed to evaluate (68)gallium-BNOTA-PRGD2 ((68)Ga-PRGD2) as a new reagent for noninvasive integrin αvβ3 imaging in glioma patients. With informed consent, 12 patients with suspicious brain glioma, as diagnosed by enhanced magnetic resonance imaging (MRI) scanning, were enrolled to undergo (68)Ga-PRGD2 PET/CT and (18)F-FDG PET/CT scans before surgery. The preoperative images were compared and correlated with the pathologically determined WHO grade. Next, the expression of integrin αvβ3, CD34, and Ki-67 were determined by immunohistochemical staining of the resected brain tumor tissue. Our findings demonstrated that (68)Ga-PRGD2 specifically accumulated in the brain tumors that were rich of integrin αvβ3 and other neovasculature markers, but not in the brain parenchyma other than the choroid plexus. Therefore, (68)Ga-PRGD2 PET/CT was able to evaluate the glioma demarcation more specifically than (18)F-FDG PET/CT. The maximum standardized uptake values (SUVmax) of (68)Ga-PRGD2, rather than those of (18)F-FDG, were significantly correlated with the glioma grading. The maximum tumor-to-brain ratios (TBRmax) of both tracers were significantly correlated with glioma grading, whereas (68)Ga-PRGD2 seemed to be more superior to (18)F-FDG in differentiating high-grade glioma (HGG) from low-grade glioma (LGG). Moreover, (68)Ga-PRGD2 PET/CT showed different accumulation patterns for HGG of WHO grades III and IV. This is the first noninvasive integrin imaging study, to the best of our knowledge, conducted in preoperative patients with different grades of glioma, and it preliminarily indicated the effectiveness of this novel method for evaluating glioma grading and demarcation.

  16. Comparison of 18F SPECT with PET in myocardial imaging: A realistic thorax-cardiac phantom study

    PubMed Central

    Knešaurek, Karin; Machac, Josef

    2006-01-01

    Background Positron emission tomography (PET) imaging with fluorine-18 (18F) Fluorodeoxyglucose (FDG) and flow tracer such as Rubidium-82 (82Rb) is an established method for evaluating an ischemic but viable myocardium. However, the high cost of PET imaging restricts its wider clinical use. Therefore, less expensive 18F FDG single photon emission computed tomography (SPECT) imaging has been considered as an alternative to 18F FDG PET imaging. The purpose of the work is to compare SPECT with PET in myocardial perfusion/viability imaging. Methods A nonuniform RH-2 thorax-heart phantom was used in the SPECT and PET acquisitions. Three inserts, 3 cm, 2 cm and 1 cm in diameter, were placed in the left ventricular (LV) wall to simulate infarcts. The phantom acquisition was performed sequentially with 7.4 MBq of 18F and 22.2 MBq of Technetium-99m (99mTc) in the SPECT study and with 7.4 MBq of 18F and 370 MBq of 82Rb in the PET study. SPECT and PET data were processed using standard reconstruction software provided by vendors. Circumferential profiles of the short-axis slices, the contrast and viability of the inserts were used to evaluate the SPECT and PET images. Results The contrast for 3 cm, 2 cm and 1 cm inserts were for 18F PET data, 1.0 ± 0.01, 0.67 ± 0.02 and 0.25 ± 0.01, respectively. For 82Rb PET data, the corresponding contrast values were 0.61 ± 0.02, 0.37 ± 0.02 and 0.19 ± 0.01, respectively. For 18F SPECT the contrast values were, 0.31 ± 0.03 and 0.20 ± 0.05 for 3 cm and 2 cm inserts, respectively. For 99mTc SPECT the contrast values were, 0.63 ± 0.04 and 0.24 ± 0.05 for 3 cm and 2 cm inserts respectively. In SPECT, the 1 cm insert was not detectable. In the SPECT study, all three inserts were falsely diagnosed as "viable", while in the PET study, only the 1 cm insert was diagnosed falsely "viable". Conclusion For smaller defects the 99mTc/18F SPECT imaging cannot entirely replace the more expensive 82Rb/18F PET for myocardial perfusion

  17. Study of oxygen scavenging PET-based films activated by water

    NASA Astrophysics Data System (ADS)

    Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana

    2016-05-01

    In this work an active barrier system consisting of a thin and transparent film based on polyethylene terephthalate (PET) was studied. Dynamic oxygen absorption measurements were performed at different values of relative humidity and temperature, pointing out that humidity is a key factor in activating the oxidation of the polymer sample. Moreover, the thermal and optical properties of the films were investigated and a good correlation was found between the crystallinity increase and the consequent transparency reduction occurring after the oxygen absorption.

  18. Methods for the correction of vascular artifacts in PET O-15 water brain-mapping studies

    SciTech Connect

    Chen, K.; Reiman, E.M. |; Lawson, M.; Yun, L.S.; Bandy, D.

    1996-12-01

    While positron emission tomographic (PET) measurements of regional cerebral blood flow (rCBF) can be used to map brain regions that are involved in normal and pathological human behaviors, measurements in the anteromedial temporal lobe can be confounded by the combined effects of radiotracer activity in neighboring arteries and partial-volume averaging. The authors now describe two simple methods to address this vascular artifact. One method utilizes the early frames of a dynamic PET study, while the other method utilizes a coregistered magnetic resonance image (MRI) to characterize the vascular region of interest (VROI). Both methods subsequently assign a common value to each pixel in the VROI for the control scan and the activation scan. To study the vascular artifact and to demonstrate the ability of the proposed methods correcting the vascular artifact, four dynamic PET scans were performed in a single subject during the same behavioral state. For each of the four scans, a vascular scan containing vascular activity was computed as the summation of the images acquired 0--60 s after radiotracer administrations, and a control scan containing minimal vascular activity was computed as the summation of the images acquired 20--80 s after radiotracer administration. t-score maps calculated from the four pairs of vascular and control scans were used to characterize regional blood flow differences related to vascular activity before and after the applications of each vascular artifact correction method. Both methods eliminated the observed differences in vascular activity, as well as the vascular artifact observed in the anteromedial temporal lobes. Using PET data from a study of normal human emotion, these methods permitted us to identify rCBF increases in the anteromedial temporal lobe free from the potentially confounding, combined effects of vascular activity and partial-volume averaging.

  19. Flow optimization study of a batch microfluidics PET tracer synthesizing device

    PubMed Central

    Elizarov, Arkadij M.; Meinhart, Carl; van Dam, R. Michael; Huang, Jiang; Daridon, Antoine; Heath, James R.; Kolb, Hartmuth C.

    2010-01-01

    We present numerical modeling and experimental studies of flow optimization inside a batch microfluidic micro-reactor used for synthesis of human-scale doses of Positron Emission Tomography (PET) tracers. Novel techniques are used for mixing within, and eluting liquid out of, the coin-shaped reaction chamber. Numerical solutions of the general incompressible Navier Stokes equations along with time-dependent elution scalar field equation for the three dimensional coin-shaped geometry were obtained and validated using fluorescence imaging analysis techniques. Utilizing the approach presented in this work, we were able to identify optimized geometrical and operational conditions for the micro-reactor in the absence of radioactive material commonly used in PET related tracer production platforms as well as evaluate the designed and fabricated micro-reactor using numerical and experimental validations. PMID:21072595

  20. RADIOSYNTHESIS AND CHIRAL SEPARATION OF C-11 LABELED BORONOPHENYLALANINE FOR BNCT STUDIES WITH PET.

    SciTech Connect

    STUDENOV,A.; DING,Y.S.; FERRIERI,R.; MIURA,M.; CODERRE,J.; FOWLER,J.S.

    2001-06-10

    The overall goal of this research is to combine two powerful methodologies, boron neutron capture therapy (BNCT) and positron emission tomography (PET), to advance the treatment of patients with malignant brain tumors. BNCT is a method to selectively deliver lethal alpha radiation to a tumor through the administration of a boron-10 containing drug, and irradiation of the tumor area with neutrons [1]. L-Boronophenylalanine (L-{sup 10}BPA) is a boron-10 containing amino acid currently used for BNCT [4]. In order to perform neutron dosimetry, it is essential to determine tumor boron-10 levels in the course of the therapy. PET has the ability to measure the concentration of drugs labeled with positron-emitting isotopes in the human body [2]. 2-Fluoro-4-borono-phenylalanine ([{sup 18}F]FBPA) has been labeled as a surrogate marker for L-BPA for pharmacokinetic studies in brain tumor patients [3]. However, [{sup 18}F]FBPA is a different drug than L-BPA because it contains a fluorine atom. We report here the labeling of L-BPA with C-11, which has the advantage of being chemically identical to L-BPA. Carbon-11 is also well suited to repeated studies within the same PET scanning session.

  1. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    SciTech Connect

    Huang, Chuan; Petibon, Yoann; Ouyang, Jinsong; El Fakhri, Georges; Reese, Timothy G.; Ahlman, Mark A.; Bluemke, David A.

    2015-02-15

    relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies.

  2. Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

    PubMed Central

    Huang, Chuan; Petibon, Yoann; Ouyang, Jinsong; Reese, Timothy G.; Ahlman, Mark A.; Bluemke, David A.; El Fakhri, Georges

    2015-01-01

    relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies. PMID:25652521

  3. Study of CT-based positron range correction in high resolution 3D PET imaging

    NASA Astrophysics Data System (ADS)

    Cal-González, J.; Herraiz, J. L.; España, S.; Vicente, E.; Herranz, E.; Desco, M.; Vaquero, J. J.; Udías, J. M.

    2011-08-01

    Positron range limits the spatial resolution of PET images and has a different effect for different isotopes and positron propagation materials. Therefore it is important to consider it during image reconstruction, in order to obtain optimal image quality. Positron range distributions for most common isotopes used in PET in different materials were computed using the Monte Carlo simulations with PeneloPET. The range profiles were introduced into the 3D OSEM image reconstruction software FIRST and employed to blur the image either in the forward projection or in the forward and backward projection. The blurring introduced takes into account the different materials in which the positron propagates. Information on these materials may be obtained, for instance, from a segmentation of a CT image. The results of introducing positron blurring in both forward and backward projection operations was compared to using it only during forward projection. Further, the effect of different shapes of positron range profile in the quality of the reconstructed images with positron range correction was studied. For high positron energy isotopes, the reconstructed images show significant improvement in spatial resolution when positron range is taken into account during reconstruction, compared to reconstructions without positron range modeling.

  4. Quality control for quantitative multicenter whole-body PET/MR studies: A NEMA image quality phantom study with three current PET/MR systems

    SciTech Connect

    Boellaard, Ronald; Rausch, Ivo; Beyer, Thomas; Delso, Gaspar; Yaqub, Maqsood; Quick, Harald H.; Sattler, Bernhard

    2015-10-15

    Purpose: Integrated positron emission tomography/magnetic resonance (PET/MR) systems derive the PET attenuation correction (AC) from dedicated MR sequences. While MR-AC performs reasonably well in clinical patient imaging, it may fail for phantom-based quality control (QC). The authors assess the applicability of different protocols for PET QC in multicenter PET/MR imaging. Methods: The National Electrical Manufacturers Association NU 2 2007 image quality phantom was imaged on three combined PET/MR systems: a Philips Ingenuity TF PET/MR, a Siemens Biograph mMR, and a GE SIGNA PET/MR (prototype) system. The phantom was filled according to the EANM FDG-PET/CT guideline 1.0 and scanned for 5 min over 1 bed. Two MR-AC imaging protocols were tested: standard clinical procedures and a dedicated protocol for phantom tests. Depending on the system, the dedicated phantom protocol employs a two-class (water and air) segmentation of the MR data or a CT-based template. Differences in attenuation- and SUV recovery coefficients (RC) are reported. PET/CT-based simulations were performed to simulate the various artifacts seen in the AC maps (μ-map) and their impact on the accuracy of phantom-based QC. Results: Clinical MR-AC protocols caused substantial errors and artifacts in the AC maps, resulting in underestimations of the reconstructed PET activity of up to 27%, depending on the PET/MR system. Using dedicated phantom MR-AC protocols, PET bias was reduced to −8%. Mean and max SUV RC met EARL multicenter PET performance specifications for most contrast objects, but only when using the dedicated phantom protocol. Simulations confirmed the bias in experimental data to be caused by incorrect AC maps resulting from the use of clinical MR-AC protocols. Conclusions: Phantom-based quality control of PET/MR systems in a multicenter, multivendor setting may be performed with sufficient accuracy, but only when dedicated phantom acquisition and processing protocols are used for

  5. Feasibility Study of Myocardial Perfusion and Oxygenation by Non-Contrast MRI: Comparison with PET Study in a Canine Model

    PubMed Central

    McCommis, Kyle S.; Zhang, Haosen; Herrero, Pilar; Gropler, Robert J.; Zheng, Jie

    2008-01-01

    The purpose of this study was to examine the feasibility of quantifying myocardial blood flow (MBF) and rate of myocardial oxygen consumption (MVO2) during pharmacologically induced stress without using a contrast agent. The former was measured by the arterial spin labeling (ASL) method and the later was obtained by measuring the oxygen extraction fraction (OEF) with the magnetic resonance imaging (MRI) blood oxygenation level-dependent (BOLD) effect and Fick's law. The MRI results were compared with the established positron emission tomography (PET) methods. Six mongrel dogs with induced acute moderate left coronary artery stenosis were scanned using a clinical PET and a 1.5T MRI system, in the same day. Regional MBF, myocardial OEF, and MVO2 were measured with both imaging modalities. Correlation coefficients (R2) of the three myocardial indexes (MBF, OEF, and MVO2) between MRI and PET methods ranged from 0.70 to 0.93. Bland-Altman statistics demonstrated that the estimated precision of the limits of agreement between MRI and PET measurements varied from 18% (OEF), to 37% (MBF), and 45% (MVO2). The detected changes in these indexes, at rest and during dobutamine stress, were similar between two image modalities. The proposed non-contrast MRI technique is a promising method to quantitatively assess myocardial perfusion and oxygenation. PMID:17566684

  6. ESR studies on pet irradiated with high energy ions

    NASA Astrophysics Data System (ADS)

    Chipară, Mircea Ioan; Bunget, Ion; Georgescu, Rodica; Georgescu, Edith; Vîlcov, Isabela

    1983-05-01

    Electron spin resonance studies on polyethylene terephtalate films, irradiated with high energy oxygen and sulphur ions are reported. The dependence of the resonance line parameters on time, temperature and on UV postirradiation time is investigated.

  7. First in situ TOF-PET study using digital photon counters for proton range verification

    NASA Astrophysics Data System (ADS)

    Cambraia Lopes, P.; Bauer, J.; Salomon, A.; Rinaldi, I.; Tabacchini, V.; Tessonnier, T.; Crespo, P.; Parodi, K.; Schaart, D. R.

    2016-08-01

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong 15O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  108 protons s-1, and 1010 total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results also

  8. First in situ TOF-PET study using digital photon counters for proton range verification.

    PubMed

    Cambraia Lopes, P; Bauer, J; Salomon, A; Rinaldi, I; Tabacchini, V; Tessonnier, T; Crespo, P; Parodi, K; Schaart, D R

    2016-08-21

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong (15)O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  10(8) protons s(-1), and 10(10) total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results

  9. First in situ TOF-PET study using digital photon counters for proton range verification

    NASA Astrophysics Data System (ADS)

    Cambraia Lopes, P.; Bauer, J.; Salomon, A.; Rinaldi, I.; Tabacchini, V.; Tessonnier, T.; Crespo, P.; Parodi, K.; Schaart, D. R.

    2016-08-01

    Positron emission tomography (PET) is the imaging modality most extensively tested for treatment monitoring in particle therapy. Optimal use of PET in proton therapy requires in situ acquisition of the relatively strong 15O signal due to its relatively short half-life (~2 min) and high oxygen content in biological tissues, enabling shorter scans that are less sensitive to biological washout. This paper presents the first performance tests of a scaled-down in situ time-of-flight (TOF) PET system based on digital photon counters (DPCs) coupled to Cerium-doped Lutetium Yttrium Silicate (LYSO:Ce) crystals, providing quantitative results representative of a dual-head tomograph that complies with spatial constraints typically encountered in clinical practice (2  ×  50°, of 360°, transaxial angular acceptance). The proton-induced activity inside polymethylmethacrylate (PMMA) and polyethylene (PE) phantoms was acquired within beam pauses (in-beam) and immediately after irradiation by an actively-delivered synchrotron pencil-beam, with clinically relevant 125.67 MeV/u, 4.6  ×  108 protons s‑1, and 1010 total protons. 3D activity maps reconstructed with and without TOF information are compared to FLUKA simulations, demonstrating the benefit of TOF-PET to reduce limited-angle artefacts using a 382 ps full width at half maximum coincidence resolving time. The time-dependent contributions from different radionuclides to the total count-rate are investigated. We furthermore study the impact of the acquisition time window on the laterally integrated activity depth-profiles, with emphasis on 2 min acquisitions starting at different time points. The results depend on phantom composition and reflect the differences in relative contributions from the radionuclides originating from carbon and oxygen. We observe very good agreement between the shapes of the simulated and measured activity depth-profiles for post-beam protocols. However, our results also

  10. Experimental Study of Sliding Friction for PET Track Membranes

    NASA Astrophysics Data System (ADS)

    Filippova, E. O.; Filippov, A. V.; Shulepov, I. A.

    2016-04-01

    The article is presented results of a study of the process for a dry friction metal-polymer couple on scheme disc-finger. Track membrane from polyethylene terephthalate was a research material. Membrane had pores with 0.4 and 0.8 μm diameters. The effect of the sliding velocity for membranes with pores of 0.8 microns was determined. Research was shown that increasing pore’s diameter caused a reduction of the friction coefficient and downturn its magnitude vibrations. The study showed that track membrane have adequate resistance to wear and can be successfully used in surgical procedures in the layers of the cornea.

  11. Specification and estimation of sources of bias affecting neurological studies in PET/MR with an anatomical brain phantom

    NASA Astrophysics Data System (ADS)

    Teuho, J.; Johansson, J.; Linden, J.; Saunavaara, V.; Tolvanen, T.; Teräs, M.

    2014-01-01

    Selection of reconstruction parameters has an effect on the image quantification in PET, with an additional contribution from a scanner-specific attenuation correction method. For achieving comparable results in inter- and intra-center comparisons, any existing quantitative differences should be identified and compensated for. In this study, a comparison between PET, PET/CT and PET/MR is performed by using an anatomical brain phantom, to identify and measure the amount of bias caused due to differences in reconstruction and attenuation correction methods especially in PET/MR. Differences were estimated by using visual, qualitative and quantitative analysis. The qualitative analysis consisted of a line profile analysis for measuring the reproduction of anatomical structures and the contribution of the amount of iterations to image contrast. The quantitative analysis consisted of measurement and comparison of 10 anatomical VOIs, where the HRRT was considered as the reference. All scanners reproduced the main anatomical structures of the phantom adequately, although the image contrast on the PET/MR was inferior when using a default clinical brain protocol. Image contrast was improved by increasing the amount of iterations from 2 to 5 while using 33 subsets. Furthermore, a PET/MR-specific bias was detected, which resulted in underestimation of the activity values in anatomical structures closest to the skull, due to the MR-derived attenuation map that ignores the bone. Thus, further improvements for the PET/MR reconstruction and attenuation correction could be achieved by optimization of RAMLA-specific reconstruction parameters and implementation of bone to the attenuation template.

  12. Derivation of input function from FDG-PET studies in small hearts

    SciTech Connect

    Wu, Hsiao-Ming; Huang, Sung-Cheng; Allada, V.

    1996-10-01

    The extraction of pure arterial time-activity curves (TACs) from dynamic PET images of a small animal heart using factor analysis of dynamic structures (FADS) was found to be unsuccessful due to the small size of the cardiac chamber that causes extensive mixture of TACs of different structures. In this study, we used digital phantoms of the left ventricle (LV cavity size: 1-2 cm) and small monkey (LV cavity size: {approx} 2 cm) dynamic FDG PET studies to evaluate FADS for extracting the pure blood-pool TACs by adding a single blood sample (taken at a late scan time) constraint. In the digital phantom studies, spillover fractions in the extracted blood-pool TACs using FADS without a blood sample constraint (FADS(-)) and with a blood sample constraint (FADS(+)) were 3%-91% and < 3%, respectively. In the monkey studies (n = 4), FADS(+) extracted blood-pool TACs matched well with the arterialized well counter measurements (% differences of curve integration: FADS(-) < 82%; FADS(+) < 9%). The microparameters (K*{sub 1}, k*{sub 2}, k*{sub 3}, k*{sub 4}) and macroparameters (K{sub nlr}), obtained from the FADS(+) blood-pool TACs, were similar to those obtained from plasma samples in a three-compartment model fitting (% differences of K{sub nlr}: phantom studies < 5%; monkey studies < 9%). The FADS technique with a single-blood sample has the potential to extract the pure blood-pool TACs directly from dynamic PET images of a small animal without multiple blood sampling, region of interest definition or spillover correction. 14 refs., 5 figs., 3 tabs.

  13. A comparative study between evaluation methods for quality control procedures for determining the accuracy of PET/CT registration

    NASA Astrophysics Data System (ADS)

    Cha, Min Kyoung; Ko, Hyun Soo; Jung, Woo Young; Ryu, Jae Kwang; Choe, Bo-Young

    2015-08-01

    The Accuracy of registration between positron emission tomography (PET) and computed tomography (CT) images is one of the important factors for reliable diagnosis in PET/CT examinations. Although quality control (QC) for checking alignment of PET and CT images should be performed periodically, the procedures have not been fully established. The aim of this study is to determine optimal quality control (QC) procedures that can be performed at the user level to ensure the accuracy of PET/CT registration. Two phantoms were used to carry out this study: the American college of Radiology (ACR)-approved PET phantom and National Electrical Manufacturers Association (NEMA) International Electrotechnical Commission (IEC) body phantom, containing fillable spheres. All PET/CT images were acquired on a Biograph TruePoint 40 PET/CT scanner using routine protocols. To measure registration error, the spatial coordinates of the estimated centers of the target slice (spheres) was calculated independently for the PET and the CT images in two ways. We compared the images from the ACR-approved PET phantom to that from the NEMA IEC body phantom. Also, we measured the total time required from phantom preparation to image analysis. The first analysis method showed a total difference of 0.636 ± 0.11 mm for the largest hot sphere and 0.198 ± 0.09 mm for the largest cold sphere in the case of the ACR-approved PET phantom. In the NEMA IEC body phantom, the total difference was 3.720 ± 0.97 mm for the largest hot sphere and 4.800 ± 0.85 mm for the largest cold sphere. The second analysis method showed that the differences in the x location at the line profile of the lesion on PET and CT were (1.33, 1.33) mm for a bone lesion, (-1.26, -1.33) mm for an air lesion and (-1.67, -1.60) mm for a hot sphere lesion for the ACR-approved PET phantom. For the NEMA IEC body phantom, the differences in the x location at the line profile of the lesion on PET and CT were (-1.33, 4.00) mm for the air

  14. Pet Health

    MedlinePlus

    ... Before getting a pet, think carefully about which animal is best for your family. What is each ... Does anyone have pet allergies? What type of animal suits your lifestyle and budget? Once you own ...

  15. Estimated radiation dose to the newborn in FDG-PET studies

    SciTech Connect

    Ruotsalainen, U.; Suhonen-Polvi, H.; Eronen, E.; Kinnala, A.

    1996-02-01

    The aim of this study was to estimate the radiation dose due to intravenous injection of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose (FDG) for infants studied with PET. The radioactivity concentration in the brain and bladder content was measured with PET to determine the cumulated activity in these organs in 21 infant FDG studies. The individual organ masses were estimated according to the whole-body and brain masses, and they were used to calculate the absorbed dose per unit cumulated activity (S values). For organs other than brain and bladder, the cumulated activity was defined from adult studies. For each individual patient, the absorbed dose to the brain, bladder wall and selected organs were calculated. An estimation of the effective dose was determined. Whole-body distribution of FDG in the infants differed from adults: a greater proportion of the injected activity accumulated into the brain (9% versus 7%) and less was excreted to urine (7% versus 20% respectively). The measured cumulated activity in the brain was 0.25 MBq {center_dot} h/MBq and in the bladder content 0.04 MBq {center_dot}h/MBq with a large individual variation in latter. The calculated absorbed dose was 0.24 mGy/MBq to the brain and 1.03 mGy/MBq to the bladder wall. The estimated effective dose was 0.43 mSv/MBq. The dose to the bladder wall was lower in infants as compared to adults with ordinary amounts of injected activity. The greater amount of activity remaining in the body may increase the dose to other organs. The effective dose was lower compared to adults and conventional nuclear medicine studies of infants. PET can be a valuable tool in pediatric nuclear medicine because of good resolution images, sensitive radiation measurement and a variety of tracers labeled with short-lived isotopes. 27 refs., 4 figs., 2 tabs.

  16. Simulation study of PET detector limitations using continuous crystals

    NASA Astrophysics Data System (ADS)

    Cabello, Jorge; Etxebeste, Ane; Llosá, Gabriela; Ziegler, Sibylle I.

    2015-05-01

    Continuous crystals can potentially obtain better intrinsic detector spatial resolution compared to pixelated crystals, additionally providing depth of interaction (DoI) information from the light distribution. To achieve high performance sophisticated interaction position estimation algorithms are required. There are a number of algorithms in the literature applied to different crystal dimensions and different photodetectors. However, the different crystal properties and photodetector array geometries have an impact on the algorithm performance. In this work we analysed, through Monte Carlo simulations, different combinations of realistic crystals and photodetector parameters to better understand their influence on the interaction position estimation accuracy, with special emphasis on the DoI. We used an interaction position estimation based on an analytical model for the present work. Different photodetector granulation schemes were investigated. The impact of the number of crystal faces readout by photodetectors was studied by simulating scenarios with one and two photodetectors. In addition, crystals with different levels of reflection and aspect ratios (AR) were analysed. Results showed that the impact of photodetector granularity is mainly shown near the edges and specially in the corners of the crystal. The resulting intrinsic spatial resolution near the centre with a 12 × 12 × 10 mm3 LYSO crystal was 0.7-0.9 mm, while the average spatial resolution calculated on the entire crystal was 0.77 ± 0.18 mm for all the simulated geometries with one and two photodetectors. Having front and back photodetectors reduced the DoI bias (Euclidean distance between estimated DoI and real DoI) and improved the transversal resolution near the corners. In scenarios with one photodetector, small AR resulted in DoI inaccuracies for absorbed events at the entrance of the crystal. These inaccuracies were slightly reduced either by increasing the AR or reducing the amount of

  17. Simulation study of PET detector limitations using continuous crystals.

    PubMed

    Cabello, Jorge; Etxebeste, Ane; Llosá, Gabriela; Ziegler, Sibylle I

    2015-05-01

    Continuous crystals can potentially obtain better intrinsic detector spatial resolution compared to pixelated crystals, additionally providing depth of interaction (DoI) information from the light distribution. To achieve high performance sophisticated interaction position estimation algorithms are required. There are a number of algorithms in the literature applied to different crystal dimensions and different photodetectors. However, the different crystal properties and photodetector array geometries have an impact on the algorithm performance. In this work we analysed, through Monte Carlo simulations, different combinations of realistic crystals and photodetector parameters to better understand their influence on the interaction position estimation accuracy, with special emphasis on the DoI. We used an interaction position estimation based on an analytical model for the present work. Different photodetector granulation schemes were investigated. The impact of the number of crystal faces readout by photodetectors was studied by simulating scenarios with one and two photodetectors. In addition, crystals with different levels of reflection and aspect ratios (AR) were analysed. Results showed that the impact of photodetector granularity is mainly shown near the edges and specially in the corners of the crystal. The resulting intrinsic spatial resolution near the centre with a 12 × 12 × 10 mm(3) LYSO crystal was 0.7-0.9 mm, while the average spatial resolution calculated on the entire crystal was 0.77 ± 0.18 mm for all the simulated geometries with one and two photodetectors. Having front and back photodetectors reduced the DoI bias (Euclidean distance between estimated DoI and real DoI) and improved the transversal resolution near the corners. In scenarios with one photodetector, small AR resulted in DoI inaccuracies for absorbed events at the entrance of the crystal. These inaccuracies were slightly reduced either by increasing the AR or reducing the amount

  18. Brain metabolic changes in Hodgkin disease patients following diagnosis and during the disease course: An 18F-FDG PET/CT study

    PubMed Central

    CHIARAVALLOTI, AGOSTINO; PAGANI, MARCO; CANTONETTI, MARIA; DI PIETRO, BARBARA; TAVOLOZZA, MARIO; TRAVASCIO, LAURA; DI BIAGIO, DANIELE; DANIELI, ROBERTA; SCHILLACI, ORAZIO

    2015-01-01

    The aim of the present study was to investigate brain glucose metabolism in patients with Hodgkin disease (HD) after diagnosis and during chemotherapy treatment. Following the administration of first-line doxorubicin, bleomycin, vinblastine and dacarbazine (ABVD) chemotherapy, 74 HD patients underwent 18F-fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography (PET)/computed tomography brain scans, both baseline (PET0) and interim (PET2) at the Department of Biomedicine and Prevention, University of Rome Tor Vergata (Rome, Italy). Fifty-seven patients were further evaluated 15±6 days after four additional cycles (PET6). Furthermore, a control group (CG) of 40 chemotherapy-naïve subjects was enrolled. Differences in brain 18F-FDG uptake between the CG, PET0, PET2 and PET6 scans were analyzed using statistical parametric mapping. Compared with the PET0 and CG scans, the PET2 scan demonstrated a higher metabolic activity in Brodmann area (BA) 39, and a metabolic reduction in BA 11 bilaterally and in left BA 32. All of these changes disappeared at PET6. The results of the present study indicate that ABVD chemotherapy has a limited impact on brain metabolism. PMID:25621038

  19. The ADNI PET Core: 2015

    PubMed Central

    Jagust, William J.; Landau, Susan M.; Koeppe, Robert A.; Reiman, Eric M.; Chen, Kewei; Mathis, Chester A.; Price, Julie C.; Foster, Norman L.; Wang, Angela Y.

    2015-01-01

    INTRODUCTION This paper reviews the work done in the ADNI PET core over the past 5 years, largely concerning techniques, methods, and results related to amyloid imaging in ADNI. METHODS The PET Core has utilized [18F]florbetapir routinely on ADNI participants, with over 1600 scans available for download. Four different laboratories are involved in data analysis, and have examined factors such as longitudinal florbetapir analysis, use of FDG-PET in clinical trials, and relationships between different biomarkers and cognition. RESULTS Converging evidence from the PET Core has indicated that cross-sectional and longitudinal florbetapir analyses require different reference regions. Studies have also examined the relationship between florbetapir data obtained immediately after injection, which reflects perfusion, and FDG-PET results. Finally, standardization has included the translation of florbetapir PET data to a centiloid scale. CONCLUSION The PET Core has demonstrated a variety of methods for standardization of biomarkers such as florbetapir PET in a multicenter setting. PMID:26194311

  20. A study of non-invasive Patlak quantification for whole-body dynamic FDG-PET studies of mice

    PubMed Central

    Zheng, Xiujuan; Wen, Lingfeng; Yu, Shu-Jung; Huang, Sung-Cheng; Feng, David Dagan

    2012-01-01

    Physiological changes in dynamic PET images can be quantitatively estimated by kinetic modeling technique. The process of PET quantification usually requires an input function in the form of a plasma-time activity curve (PTAC), which is generally obtained by invasive arterial blood sampling. However, invasive arterial blood sampling poses many challenges especially for small animal studies, due to the subjects’ limited blood volume and small blood vessels. A simple non-invasive quantification method based on Patlak graphical analysis (PGA) has been recently proposed to use a reference region to derive the relative influx rate for a target region without invasive blood sampling, and evaluated by using the simulation data of human brain FDG-PET studies. In this study, the non-invasive Patlak (nPGA) method was extended to whole-body dynamic small animal FDG-PET studies. The performance of nPGA was systematically investigated by using experimental mouse studies and computer simulations. The mouse studies showed high linearity of relative influx rates between the nPGA and PGA for most pairs of reference and target regions, when an appropriate underlying kinetic model was used. The simulation results demonstrated that the accuracy of the nPGA method was comparable to that of the PGA method, with a higher reliability for most pairs of reference and target regions. The results proved that the nPGA method could provide a non-invasive and indirect way for quantifying the FDG kinetics of tumor in small animal studies. PMID:22956982

  1. Study of a high-resolution PET system using a silicon detector probe.

    PubMed

    Brzeziński, K; Oliver, J F; Gillam, J; Rafecas, M

    2014-10-21

    A high-resolution silicon detector probe, in coincidence with a conventional PET scanner, is expected to provide images of higher quality than those achievable using the scanner alone. Spatial resolution should improve due to the finer pixelization of the probe detector, while increased sensitivity in the probe vicinity is expected to decrease noise. A PET-probe prototype is being developed utilizing this principle. The system includes a probe consisting of ten layers of silicon detectors, each a 80 × 52 array of 1 × 1 × 1 mm(3) pixels, to be operated in coincidence with a modern clinical PET scanner. Detailed simulation studies of this system have been performed to assess the effect of the additional probe information on the quality of the reconstructed images. A grid of point sources was simulated to study the contribution of the probe to the system resolution at different locations over the field of view (FOV). A resolution phantom was used to demonstrate the effect on image resolution for two probe positions. A homogeneous source distribution with hot and cold regions was used to demonstrate that the localized improvement in resolution does not come at the expense of the overall quality of the image. Since the improvement is constrained to an area close to the probe, breast imaging is proposed as a potential application for the novel geometry. In this sense, a simplified breast phantom, adjacent to heart and torso compartments, was simulated and the effect of the probe on lesion detectability, through measurements of the local contrast recovery coefficient-to-noise ratio (CNR), was observed. The list-mode ML-EM algorithm was used for image reconstruction in all cases. As expected, the point spread function of the PET-probe system was found to be non-isotropic and vary with position, offering improvement in specific regions. Increase in resolution, of factors of up to 2, was observed in the region close to the probe. Images of the resolution phantom

  2. Study of a high-resolution PET system using a Silicon detector probe

    NASA Astrophysics Data System (ADS)

    Brzeziński, K.; Oliver, J. F.; Gillam, J.; Rafecas, M.

    2014-10-01

    A high-resolution silicon detector probe, in coincidence with a conventional PET scanner, is expected to provide images of higher quality than those achievable using the scanner alone. Spatial resolution should improve due to the finer pixelization of the probe detector, while increased sensitivity in the probe vicinity is expected to decrease noise. A PET-probe prototype is being developed utilizing this principle. The system includes a probe consisting of ten layers of silicon detectors, each a 80 × 52 array of 1 × 1 × 1 mm3 pixels, to be operated in coincidence with a modern clinical PET scanner. Detailed simulation studies of this system have been performed to assess the effect of the additional probe information on the quality of the reconstructed images. A grid of point sources was simulated to study the contribution of the probe to the system resolution at different locations over the field of view (FOV). A resolution phantom was used to demonstrate the effect on image resolution for two probe positions. A homogeneous source distribution with hot and cold regions was used to demonstrate that the localized improvement in resolution does not come at the expense of the overall quality of the image. Since the improvement is constrained to an area close to the probe, breast imaging is proposed as a potential application for the novel geometry. In this sense, a simplified breast phantom, adjacent to heart and torso compartments, was simulated and the effect of the probe on lesion detectability, through measurements of the local contrast recovery coefficient-to-noise ratio (CNR), was observed. The list-mode ML-EM algorithm was used for image reconstruction in all cases. As expected, the point spread function of the PET-probe system was found to be non-isotropic and vary with position, offering improvement in specific regions. Increase in resolution, of factors of up to 2, was observed in the region close to the probe. Images of the resolution phantom showed

  3. Right prefrontal activation produced by arterial baroreceptor stimulation: a PET study.

    PubMed

    Weisz, J; Emri, M; Fent, J; Lengyel, Z; Márián, T; Horváth, G; Bogner, P; Trón, L; Adám, G

    2001-10-29

    This study was performed to test the hypothesis of greater right hemispheric involvement in the processing of baroreceptor stimuli. Carotid sinus baroreceptors were stimulated by rhythmically decreasing air pressure in a neck chamber, and under control conditions the thorax was stimulated in a similar manner. Changes in regional cerebral blood flow (rCBF) were measured by PET. Baroreceptor stimulation resulted in rCBF increase in the right anterior-inferior prefrontal cortex (Brodmann areas (BA) 10/44/47) and bilaterally in BA 6/8. We conclude that in at least some stages of baroreceptor information processing the right hemisphere plays a greater role than the left hemisphere. PMID:11711862

  4. Study of an image-derived SUV and a modified SUV using mouse FDG-PET

    PubMed Central

    Zheng, Xiujuan; Yu, Chin-Lung; Sha, Wei; Radu, Caius; Huang, Sung-Cheng; Feng, Dagan

    2010-01-01

    Introduction Standard uptake value (SUV) is calculated without consideration of the differences in plasma FDG clearance. Its variability can be affected by changes of the amount of excreted FDG by renal function. Moreover, the estimation of SUV is quite sensitive to errors in the measurements of body weight and injected dose. This study aims to develop an image-based method to obtain an image-derived SUV (iSUV) and a modified SUV (mSUV) to overcome these problems. Methods 31 tumor-planted SCID mice were scanned in microPET at ~60min post FDG injection, and then scanned in microCT. Using image-based method, the body weight and injected dose were derived from the microPET/CT images to calculate iSUV. The volumes and the total activities of FDG within the bladder and the whole-body were also obtained to calculate mSUV. For the selected targets, the iSUVs and mSUVs were compared against their corresponding SUVs. Results Compared with SUV factor (injected dose/body weight), iSUV factor had an average percentage error of −0.7%. The linear regressions between SUV and iSUV had a slope of 0.99 with correlation coefficient of 0.95. Compared with SUV and iSUV, CV% of mSUV decreased while the tumor-to-background separation of mSUV increased. Conclusions Using this image-based method, the iSUV can replace SUV when the actual measurements were missing or unreliable. The mSUV can reduce the inter-subject variability and enhance the tumor-to-background separation in mouse FDG-PET studies. PMID:21492784

  5. A positron emission tomography study of nigro-striatal dopaminergic mechanisms underlying attention: implications for ADHD and its treatment.

    PubMed

    del Campo, Natalia; Fryer, Tim D; Hong, Young T; Smith, Rob; Brichard, Laurent; Acosta-Cabronero, Julio; Chamberlain, Samuel R; Tait, Roger; Izquierdo, David; Regenthal, Ralf; Dowson, Jonathan; Suckling, John; Baron, Jean-Claude; Aigbirhio, Franklin I; Robbins, Trevor W; Sahakian, Barbara J; Müller, Ulrich

    2013-11-01

    Through the combined use of (18)F-fallypride positron emission tomography and magnetic resonance imaging this study examined the neural mechanisms underlying the attentional deficits associated with attention deficit/hyperactivity disorder and their potential reversal with a single therapeutic dose of methylphenidate. Sixteen adult patients with attention deficit/hyperactivity disorder and 16 matched healthy control subjects were positron emission tomography and magnetic resonance imaging scanned and tested on a computerized sustained attention task after oral methylphenidate (0.5 mg/kg) and placebo administration in a within-subject, double-blind, cross-over design. Although patients with attention deficit/hyperactivity disorder as a group showed significant attentional deficits and reduced grey matter volume in fronto-striato-cerebellar and limbic networks, they had equivalent D2/D3 receptor availability and equivalent increases in endogenous dopamine after methylphenidate treatment to that observed in healthy control subjects. However, poor attentional performers drawn from both the attention deficit/hyperactivity disorder and the control groups had significantly reduced left caudate dopamine activity. Methylphenidate significantly increased dopamine levels in all nigro-striatal regions, thereby normalizing dopamine levels in the left caudate in low performers. Behaviourally, methylphenidate improved sustained attention in a baseline performance-dependent manner, irrespective of diagnosis. This finding was accompanied by an equally performance-dependent effect of the drug on dopamine release in the midbrain, whereby low performers showed reduced dopamine release in this region. Collectively, these findings support a dimensional model of attentional deficits and underlying nigro-striatal dopaminergic mechanisms of attention deficit/hyperactivity disorder that extends into the healthy population. Moreover, they confer midbrain dopamine autoreceptors a hitherto

  6. Design Study of a Whole-Body PET Scanner with Improved Spatial and Timing Resolution

    PubMed Central

    Surti, S.; Shore, Adam R.; Karp, Joel S.

    2013-01-01

    Current state-of-art whole-body PET scanners achieve a system spatial resolution of 4–5 mm with limited sensitivity. Since the reconstructed spatial resolution and image quality are limited by the count statistics, there has not been a significant push for developing higher resolution whole-body PET scanners. Our goal in this study is to investigate the impact of improved spatial resolution together with time-of-flight (TOF) capability on lesion uptake estimation and lesion detectability, two important tasks in whole-body oncologic studies. The broader goal of this project is the development of a new state-of-art TOF PET scanner operating within an MRI while pushing the technology in PET system design. We performed Monte Carlo simulations to test the effects of crystal size (4 mm and 2.6 mm wide crystals), TOF timing resolution (300ps and 600ps), and 2-level depth-of-interaction (DOI) capability. Spatial resolution was calculated by simulating point sources in air at multiple positions. Results show that smaller crystals produced improved resolution, while degradation of resolution due to parallax error could be reduced with a 2-level DOI detector. Lesion phantoms were simulated to measure the contrast recovery coefficient (CRC) and area under the LROC curve (ALROC) for 0.5 cm diameter lesions with 6:1 activity uptake relative to the background. Smaller crystals produce higher CRC, leading to increased ALROC values or a reduction in scan time. Improved timing resolution provides faster CRC convergence and once again leads to an increase in ALROC value or reduced scan time. Based on our choice of timing resolution and crystal size, improved timing resolution (300ps) with larger crystals (4 mm wide) has similar ALROC as smaller crystals (2.6 mm wide) with 600ps timing resolution. A 2-level DOI measurement provides some CRC and ALROC improvement for lesions further away from the center, leading to a more uniform performance within the imaging field-of-view (FOV

  7. Study and optimization of positioning algorithms for monolithic PET detectors blocks

    NASA Astrophysics Data System (ADS)

    Garcia de Acilu, P.; Sarasola, I.; Canadas, M.; Cuerdo, R.; Rato Mendes, P.; Romero, L.; Willmott, C.

    2012-06-01

    We are developing a PET insert for existing MRI equipment to be used in clinical PET/MR studies of the human brain. The proposed scanner is based on annihilation gamma detection with monolithic blocks of cerium-doped lutetium yttrium orthosilicate (LYSO:Ce) coupled to magnetically-compatible avalanche photodiodes (APD) matrices. The light distribution generated on the LYSO:Ce block provides the impinging position of the 511 keV photons by means of a positioning algorithm. Several positioning methods, from the simplest Anger Logic to more sophisticate supervised-learning Neural Networks (NN), can be implemented to extract the incidence position of gammas directly from the APD signals. Finally, an optimal method based on a two-step Feed-Forward Neural Network has been selected. It allows us to reach a resolution at detector level of 2 mm, and acquire images of point sources using a first BrainPET prototype consisting of two monolithic blocks working in coincidence. Neural networks provide a straightforward positioning of the acquired data once they have been trained, however the training process is usually time-consuming. In order to obtain an efficient positioning method for the complete scanner it was necessary to find a training procedure that reduces the data acquisition and processing time without introducing a noticeable degradation of the spatial resolution. A grouping process and posterior selection of the training data have been done regarding the similitude of the light distribution of events which have one common incident coordinate (transversal or longitudinal). By doing this, the amount of training data can be reduced to about 5% of the initial number with a degradation of spatial resolution lower than 10%.

  8. Mild traumatic brain injury results in depressed cerebral glucose uptake: An (18)FDG PET study.

    PubMed

    Selwyn, Reed; Hockenbury, Nicole; Jaiswal, Shalini; Mathur, Sanjeev; Armstrong, Regina C; Byrnes, Kimberly R

    2013-12-01

    Moderate to severe traumatic brain injury (TBI) in humans and rats induces measurable metabolic changes, including a sustained depression in cerebral glucose uptake. However, the effect of a mild TBI on brain glucose uptake is unclear, particularly in rodent models. This study aimed to determine the glucose uptake pattern in the brain after a mild lateral fluid percussion (LFP) TBI. Briefly, adult male rats were subjected to a mild LFP and positron emission tomography (PET) imaging with (18)F-fluorodeoxyglucose ((18)FDG), which was performed prior to injury and at 3 and 24 h and 5, 9, and 16 days post-injury. Locomotor function was assessed prior to injury and at 1, 3, 7, 14, and 21 days after injury using modified beam walk tasks to confirm injury severity. Histology was performed at either 10 or 21 days post-injury. Analysis of function revealed a transient impairment in locomotor ability, which corresponds to a mild TBI. Using reference region normalization, PET imaging revealed that mild LFP-induced TBI depresses glucose uptake in both the ipsilateral and contralateral hemispheres in comparison with sham-injured and naïve controls from 3 h to 5 days post-injury. Further, areas of depressed glucose uptake were associated with regions of glial activation and axonal damage, but no measurable change in neuronal loss or gross tissue damage was observed. In conclusion, we show that mild TBI, which is characterized by transient impairments in function, axonal damage, and glial activation, results in an observable depression in overall brain glucose uptake using (18)FDG-PET. PMID:23829400

  9. Preliminary study: fibre content in pet rabbit diets, crude fibre versus total dietary fibre.

    PubMed

    Molina, J; Martorell, J; Hervera, M; Pérez-Accino, J; Fragua, V; Villaverde, C

    2015-04-01

    Fibre is an important nutrient for rabbit health, and, on commercial pet rabbit packaging, it is labelled as crude fibre (CF). In several species, it is considered that CF is not an accurate representation of the fibre content in feedstuffs. The objective of this study was to compare the CF stated on the label (CFL) with laboratory analysis of CF (CFA) and the analysed content of total dietary fibre (TDF) in different commercial pet rabbit feeds. We selected 15 commercial diets and analysed CF and TDF. A mixed model was used to evaluate differences between CFL, CFA and TDF, and linear regression was performed to study the correlation between CFL and CFA with TDF. CFA and CFL were not significantly different (p = 0.836) in the feeds studied, and both were lower than TDF (p < 0.001). The correlations between TDF and both CFA and CFL were significant (p < 0.001 and p = 0.02, respectively), but the correlation was better with CFA (R = 0.86) than with CFL (R = 0.53). As expected, TDF content was higher than CF content, an average of two times. These results suggest that the CF content in rabbit diets reported on the label is not an appropriate indicator of their total fibre content, although further work with a larger sample size is required to confirm these results.

  10. PET/CT-guided treatment planning for paediatric cancer patients: a simulation study of proton and conventional photon therapy

    PubMed Central

    Brodin, N P; Björk-Eriksson, T; Birk Christensen, C; Kiil-Berthelsen, A; Aznar, M C; Hollensen, C; Markova, E; Munck af Rosenschöld, P

    2015-01-01

    Objective: To investigate the impact of including fluorine-18 fludeoxyglucose (18F-FDG) positron emission tomography (PET) scanning in the planning of paediatric radiotherapy (RT). Methods: Target volumes were first delineated without and subsequently re-delineated with access to 18F-FDG PET scan information, on duplicate CT sets. RT plans were generated for three-dimensional conformal photon RT (3DCRT) and intensity-modulated proton therapy (IMPT). The results were evaluated by comparison of target volumes, target dose coverage parameters, normal tissue complication probability (NTCP) and estimated risk of secondary cancer (SC). Results: Considerable deviations between CT- and PET/CT-guided target volumes were seen in 3 out of the 11 patients studied. However, averaging over the whole cohort, CT or PET/CT guidance introduced no significant difference in the shape or size of the target volumes, target dose coverage, irradiated volumes, estimated NTCP or SC risk, neither for IMPT nor 3DCRT. Conclusion: Our results imply that the inclusion of PET/CT scans in the RT planning process could have considerable impact for individual patients. There were no general trends of increasing or decreasing irradiated volumes, suggesting that the long-term morbidity of RT in childhood would on average remain largely unaffected. Advances in knowledge: 18F-FDG PET-based RT planning does not systematically change NTCP or SC risk for paediatric cancer patients compared with CT only. 3 out of 11 patients had a distinct change of target volumes when PET-guided planning was introduced. Dice and mismatch metrics are not sufficient to assess the consequences of target volume differences in the context of RT. PMID:25494657

  11. A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

    NASA Astrophysics Data System (ADS)

    Jung An, Su; Beak, Cheol-Ha; Lee, Kisung; Hyun Chung, Yong

    2013-01-01

    The application of hadrons such as carbon ions is being developed for the treatment of cancer. The effectiveness of such a technique is due to the eligibility of charged particles in delivering most of their energy near the end of the range, called the Bragg peak. However, accurate verification of dose delivery is required since misalignment of the hadron beam can cause serious damage to normal tissue. PET scanners can be utilized to track the carbon beam to the tumor by imaging the trail of the hadron-induced positron emitters in the irradiated volume. In this study, we designed and evaluated (through Monte Carlo simulations) an in-beam PET scanner for monitoring patient dose in carbon beam therapy. A C-shaped PET and a partial-ring PET were designed to avoid interference between the PET detectors and the therapeutic carbon beam delivery. Their performance was compared with that of a full-ring PET scanner. The C-shaped, partial-ring, and full-ring scanners consisted of 14, 12, and 16 detector modules, respectively, with a 30.2 cm inner diameter for brain imaging. Each detector module was composed of a 13×13 array of 4.0 mm×4.0 mm×20.0 mm LYSO crystals and four round 25.4 mm diameter PMTs. To estimate the production yield of positron emitters such as 10C, 11C, and 15O, a cylindrical PMMA phantom (diameter, 20 cm; thickness, 20 cm) was irradiated with 170, 290, and 350 AMeV 12C beams using the GATE code. Phantom images of the three types of scanner were evaluated by comparing the longitudinal profile of the positron emitters, measured along the carbon beam as it passed a simulated positron emitter distribution. The results demonstrated that the development of a C-shaped PET scanner to characterize carbon dose distribution for therapy planning is feasible.

  12. Parallax error in long-axial field-of-view PET scanners—a simulation study

    NASA Astrophysics Data System (ADS)

    Schmall, Jeffrey P.; Karp, Joel S.; Werner, Matt; Surti, Suleman

    2016-07-01

    There is a growing interest in the design and construction of a PET scanner with a very long axial extent. One critical design challenge is the impact of the long axial extent on the scanner spatial resolution properties. In this work, we characterize the effect of parallax error in PET system designs having an axial field-of-view (FOV) of 198 cm (total-body PET scanner) using fully-3D Monte Carlo simulations. Two different scintillation materials were studied: LSO and LaBr3. The crystal size in both cases was 4  ×  4  ×  20 mm3. Several different depth-of-interaction (DOI) encoding techniques were investigated to characterize the improvement in spatial resolution when using a DOI capable detector. To measure spatial resolution we simulated point sources in a warm background in the center of the imaging FOV, where the effects of axial parallax are largest, and at several positions radially offset from the center. Using a line-of-response based ordered-subset expectation maximization reconstruction algorithm we found that the axial resolution in an LSO scanner degrades from 4.8 mm to 5.7 mm (full width at half max) at the center of the imaging FOV when extending the axial acceptance angle (α) from  ±12° (corresponding to an axial FOV of 18 cm) to the maximum of  ±67°—a similar result was obtained with LaBr3, in which the axial resolution degraded from 5.3 mm to 6.1 mm. For comparison we also measured the degradation due to radial parallax error in the transverse imaging FOV; the transverse resolution, averaging radial and tangential directions, of an LSO scanner was degraded from 4.9 mm to 7.7 mm, for a measurement at the center of the scanner compared to a measurement with a radial offset of 23 cm. Simulations of a DOI detector design improved the spatial resolution in all dimensions. The axial resolution in the LSO-based scanner, with α  =  ± 67°, was improved from 5.7 mm to 5.0 mm by

  13. Regularized ML reconstruction for time/dose reduction in 18F-fluoride PET/CT studies

    NASA Astrophysics Data System (ADS)

    De Bernardi, Elisabetta; Magnani, Patrizia; Gianolli, Luigi; Carla Gilardi, Maria; Bettinardi, Valentino

    2015-01-01

    We are proposing a regularized reconstruction strategy for the detection of bone lesions in 18F-fluoride whole body PET images obtained with 1 min/bed using the anatomical information provided by co-registered CT images. Bones are recognized on CT images and then transposed into the PET volume framework. During PET reconstruction, two different priors are used for bone and non-bone voxels: the relative difference prior in bone and the P-Gaussian prior in non-bone. After a tuning of the priors’ parameters, the reconstruction strategy has been tested on 6 18F-fluoride PET/CT studies, on a total of 67 lesions. Regularized images provided results comparable to the standard 3 min/bed images, in terms image quality, lesion activity, noise level and noise correlation. The proposed strategy therefore appears to be a useful tool to reduce the acquisition time or the injected dose in 18F-fluoride PET studies.

  14. A feasibility study of ortho-positronium decays measurement with the J-PET scanner based on plastic scintillators

    NASA Astrophysics Data System (ADS)

    Kamińska, D.; Gajos, A.; Czerwiński, E.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Korcyl, G.; Kowalski, P.; Krzemień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Pawlik-Niedźwiecka, M.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wieczorek, A.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

    2016-08-01

    We present a study of the application of the Jagiellonian positron emission tomograph (J-PET) for the registration of gamma quanta from decays of ortho-positronium (o-Ps). The J-PET is the first positron emission tomography scanner based on organic scintillators in contrast to all current PET scanners based on inorganic crystals. Monte Carlo simulations show that the J-PET as an axially symmetric and high acceptance scanner can be used as a multi-purpose detector well suited to pursue research including e.g. tests of discrete symmetries in decays of ortho-positronium in addition to the medical imaging. The gamma quanta originating from o-Ps decay interact in the plastic scintillators predominantly via the Compton effect, making the direct measurement of their energy impossible. Nevertheless, it is shown in this paper that the J-PET scanner will enable studies of the { o-Ps }→ 3γ decays with angular and energy resolution equal to σ (θ ) ≈ {0.4°} and σ (E) ≈ 4.1 {keV}, respectively. An order of magnitude shorter decay time of signals from plastic scintillators with respect to the inorganic crystals results not only in better timing properties crucial for the reduction of physical and instrumental background, but also suppresses significantly the pile-ups, thus enabling compensation of the lower efficiency of the plastic scintillators by performing measurements with higher positron source activities.

  15. Antidepressant response to aripiprazole augmentation associated with enhanced FDOPA utilization in striatum: a preliminary PET study.

    PubMed

    Conway, Charles R; Chibnall, John T; Cumming, Paul; Mintun, Mark A; Gebara, Marie Anne I; Perantie, Dana C; Price, Joseph L; Cornell, Martha E; McConathy, Jonathan E; Gangwani, Sunil; Sheline, Yvette I

    2014-03-30

    Several double blind, prospective trials have demonstrated an antidepressant augmentation efficacy of aripiprazole in depressed patients unresponsive to standard antidepressant therapy. Although aripiprazole is now widely used for this indication, and much is known about its receptor-binding properties, the mechanism of its antidepressant augmentation remains ill-defined. In vivo animal studies and in vitro human studies using cloned dopamine dopamine D2 receptors suggest aripiprazole is a partial dopamine agonist; in this preliminary neuroimaging trial, we hypothesized that aripiprazole's antidepressant augmentation efficacy arises from dopamine partial agonist activity. To test this, we assessed the effects of aripiprazole augmentation on the cerebral utilization of 6-[(18)F]-fluoro-3,4-dihydroxy-l-phenylalanine (FDOPA) using positron emission tomography (PET). Fourteen depressed patients, who had failed 8 weeks of antidepressant therapy with selective serotonin reuptake inhibitors, underwent FDOPA PET scans before and after aripiprazole augmentation; 11 responded to augmentation. Whole brain, voxel-wise comparisons of pre- and post-aripiprazole scans revealed increased FDOPA trapping in the right medial caudate of augmentation responders. An exploratory analysis of depressive symptoms revealed that responders experienced large improvements only in putatively dopaminergic symptoms of lassitude and inability to feel. These preliminary findings suggest that augmentation of antidepressant response by aripiprazole may be associated with potentiation of dopaminergic activity.

  16. Bio-inspired surface modification of PET for cardiovascular applications: Case study of gelatin.

    PubMed

    Giol, E Diana; Schaubroeck, David; Kersemans, Ken; De Vos, Filip; Van Vlierberghe, Sandra; Dubruel, Peter

    2015-10-01

    An aqueous-based bio-inspired approach was applied to chemically bind a bio compatible and cell-interactive gelatin layer on poly(ethylene terephthalate) (PET) for cardiovascular applications. The protein layer was immobilized after an initial surface activation via a dopamine coating. The individual and synergetic effect of the dopamine deposition procedure and the substrate nature (pristine versus plasma-treated) was investigated via XPS, AFM, SEM and contact angle measurements. Dependent on the applied parameters, the post dopamine coating presented various surface roughnesses ranging between 96 nm and 210 nm. Subsequent gelatin immobilization mostly induced a smoothening effect, but the synergetic influence of the deposition protocol and plasma treatment resulted in different gelatin conformations. In addition, a comprehensive comparative study between chemically-modified (via dopamine) and physically-modified (physisorption) PET with gelatin was developed within the present study. All investigated samples were submitted to preliminary haemocompatibility tests, which clearly indicated the direct link between blood platelet behaviour and final protein arrangement. PMID:26163974

  17. Bio-inspired surface modification of PET for cardiovascular applications: Case study of gelatin.

    PubMed

    Giol, E Diana; Schaubroeck, David; Kersemans, Ken; De Vos, Filip; Van Vlierberghe, Sandra; Dubruel, Peter

    2015-10-01

    An aqueous-based bio-inspired approach was applied to chemically bind a bio compatible and cell-interactive gelatin layer on poly(ethylene terephthalate) (PET) for cardiovascular applications. The protein layer was immobilized after an initial surface activation via a dopamine coating. The individual and synergetic effect of the dopamine deposition procedure and the substrate nature (pristine versus plasma-treated) was investigated via XPS, AFM, SEM and contact angle measurements. Dependent on the applied parameters, the post dopamine coating presented various surface roughnesses ranging between 96 nm and 210 nm. Subsequent gelatin immobilization mostly induced a smoothening effect, but the synergetic influence of the deposition protocol and plasma treatment resulted in different gelatin conformations. In addition, a comprehensive comparative study between chemically-modified (via dopamine) and physically-modified (physisorption) PET with gelatin was developed within the present study. All investigated samples were submitted to preliminary haemocompatibility tests, which clearly indicated the direct link between blood platelet behaviour and final protein arrangement.

  18. Positron emission tomography (PET) studies of dopaminergic/cholinergic interactions in the baboon brain

    SciTech Connect

    Dewey, S.L.; Brodie, J.D.; Fowler, J.S.; MacGregor, R.R.; Schlyer, D.J.; King, P.T.; Alexoff, D.L.; Volkow, N.D.; Shiue, C.Y.; Wolf, A.P. )

    1990-01-01

    Interactions between the dopaminergic D2 receptor system and the muscarinic cholinergic system in the corpus striatum of adult female baboons (Papio anubis) were examined using positron emission tomography (PET) combined with (18F)N-methylspiroperidol (( 18F)NMSP) (to probe D2 receptor availability) and (N-11C-methyl)benztropine (to probe muscarinic cholinergic receptor availability). Pretreatment with benztropine, a long-lasting anticholinergic drug, bilaterally reduced the incorporation of radioactivity in the corpus striatum but did not alter that observed in the cerebellum or the rate of metabolism of (18F)NMSP in plasma. Pretreatment with unlabelled NMSP, a potent dopaminergic antagonist, reduced the incorporation of (N-11C-methyl)benztropine in all brain regions, with the greatest effect being in the corpus striatum greater than cortex greater than thalamus greater than cerebellum, but did not alter the rate of metabolism of the labelled benztropine in the plasma. These reductions in the incorporation of either (18F)NMSP or (N-11C-methyl)benztropine exceeded the normal variation in tracer incorporation in repeated studies in the same animal. This study demonstrates that PET can be used as a tool for investigating interactions between neurochemically different yet functionally linked neurotransmitters systems in vivo and provides insight into the consequences of multiple pharmacologic administration.

  19. Initial studies using the RatCAP conscious animal PET tomograph

    NASA Astrophysics Data System (ADS)

    Woody, C.; Vaska, P.; Schlyer, D.; Pratte, J.-F.; Junnarkar, S.; Park, S.-J.; Stoll, S.; Purschke, M.; Southekal, S.; Kriplani, A.; Krishnamoorthy, S.; Maramraju, S.; Lee, D.; Schiffer, W.; Dewey, S.; Neill, J.; Kandasamy, A.; O'Connor, P.; Radeka, V.; Fontaine, R.; Lecomte, R.

    2007-02-01

    The RatCAP is a small, head-mounted PET tomograph designed to image the brain of a conscious rat without the use of anesthesia. The detector is a complete, high-performance 3D tomograph consisting of a 3.8 cm inside-diameter ring containing 12 block detectors, each of which is comprised of a 4×8 array of 2.2×2.2×5 mm 3 LSO crystals readout with a matching APD array and custom ASIC, and has a 1.8 cm axial field of view. Construction of the first working prototype detector has been completed and its performance characteristics have been measured. The results show an intrinsic spatial resolution of 2.1 mm, a time resolution of ˜14 ns FWHM, and a sensitivity of 0.7% at an energy threshold of 150 keV. First preliminary images have been obtained using 18F-FDG and 11C-methamphetamine, which show comparable image quality to those obtained from a commercial MicroPET R4 scanner. Initial studies have also been carried out to study stress levels in rats wearing the RatCAP.

  20. Subthalamic nucleus stimulation affects orbitofrontal cortex in facial emotion recognition: a pet study

    PubMed Central

    Le Jeune, F.; Péron, J.; Biseul, I.; Fournier, S.; Sauleau, P.; Drapier, S.; Haegelen, C.; Drapier, D.; Millet, B.; Garin, E.; Herry, J.-Y.; Malbert, C.-H.

    2008-01-01

    Deep brain stimulation (DBS) of the bilateral subthalamic nucleus (STN) in Parkinson's disease is thought to produce adverse events such as emotional disorders, and in a recent study, we found fear recognition to be impaired as a result. These changes have been attributed to disturbance of the STN's limbic territory and would appear to confirm that the negative emotion recognition network passes through the STN. In addition, it is now widely acknowledged that damage to the orbitofrontal cortex (OFC), especially the right side, can result in impaired recognition of facial emotions (RFE). In this context, we hypothesized that this reduced recognition of fear is correlated with modifications in the cerebral glucose metabolism of the right OFC. The objective of the present study was first, to reinforce our previous results by demonstrating reduced fear recognition in our Parkinson's disease patient group following STN DBS and, second, to correlate these emotional performances with glucose metabolism using 18FDG-PET. The 18FDG-PET and RFE tasks were both performed by a cohort of 13 Parkinson's disease patients 3 months before and 3 months after surgery for STN DBS. As predicted, we observed a significant reduction in fear recognition following surgery and obtained a positive correlation between these neuropsychological results and changes in glucose metabolism, especially in the right OFC. These results confirm the role of the STN as a key basal ganglia structure in limbic circuits. PMID:18490359

  1. Clinical impact of time-of-flight and point response modeling in PET reconstructions: a lesion detection study

    NASA Astrophysics Data System (ADS)

    Schaefferkoetter, Joshua; Casey, Michael; Townsend, David; El Fakhri, Georges

    2013-03-01

    Time-of-flight (TOF) and point spread function (PSF) modeling have been shown to improve PET reconstructions, but the impact on physicians in the clinical setting has not been thoroughly investigated. A lesion detection and localization study was performed using simulated lesions in real patient images. Four reconstruction schemes were considered: ordinary Poisson OSEM (OP) alone and combined with TOF, PSF, and TOF + PSF. The images were presented to physicians experienced in reading PET images, and the performance of each was quantified using localization receiver operating characteristic. Numerical observers (non-prewhitening and Hotelling) were used to identify optimal reconstruction parameters, and observer SNR was compared to the performance of the physicians. The numerical models showed good agreement with human performance, and best performance was achieved by both when using TOF + PSF. These findings suggest a large potential benefit of TOF + PSF for oncology PET studies, especially in the detection of small, low-intensity, focal disease in larger patients.

  2. Sound Richness of Music Might Be Mediated by Color Perception: A PET Study

    PubMed Central

    Satoh, Masayuki; Nagata, Ken; Tomimoto, Hidekazu

    2015-01-01

    Objects. We investigated the role of the fusiform cortex in music processing with the use of PET, focusing on the perception of sound richness. Method. Musically naïve subjects listened to familiar melodies with three kinds of accompaniments: (i) an accompaniment composed of only three basic chords (chord condition), (ii) a simple accompaniment typically used in traditional music text books in elementary school (simple condition), and (iii) an accompaniment with rich and flowery sounds composed by a professional composer (complex condition). Using a PET subtraction technique, we studied changes in regional cerebral blood flow (rCBF) in simple minus chord, complex minus simple, and complex minus chord conditions. Results. The simple minus chord, complex minus simple, and complex minus chord conditions regularly showed increases in rCBF at the posterior portion of the inferior temporal gyrus, including the LOC and fusiform gyrus. Conclusions. We may conclude that certain association cortices such as the LOC and the fusiform cortex may represent centers of multisensory integration, with foreground and background segregation occurring at the LOC level and the recognition of richness and floweriness of stimuli occurring in the fusiform cortex, both in terms of vision and audition. PMID:26525171

  3. Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

    PubMed Central

    Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

    2011-01-01

    This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

  4. WAXS studies of heat - mechanically modified amorphous PET fibers. Role of the tensile stress

    NASA Astrophysics Data System (ADS)

    Velev, V.; Popov, A.; Kyurkchiev, P.; Veleva, L.; Pencheva, M.

    2014-12-01

    The present work is devoted to the investigation of the structure developments in as- spun amorphous poly (ethylene terephthalate) (PET) filaments occurred as a result of heat mechanically modification. The degree of crystallinity of the untreated samples was 1,7 %. The thermal deformation experiments were carried out under isothermal conditions. PET yarn was annealed during 10 min at constant temperature of 80°C after which the sample is subjected to a well-defined constant tensile stress for 120 s at the same temperature. The mechanical load is gravitationally in the range from 0 MPa to 30 MPa and with increment step of 3 MPa. Using of wide angle X-ray scattering (WAXS) were investigated the structural rearrangements in the studied samples caused by the fibers treatments. Dependences between the strain force values and the running in the specimen's structure development are established. And in particular, it was found that a small increase of the tensile stress from 3 MPa to 6 MPa leads to a massive increase in the fibers degree of crystallinity with more than 33%.

  5. Low-carbohydrate diet versus euglycemic hyperinsulinemic clamp for the assessment of myocardial viability with 18F-fluorodeoxyglucose-PET: a pilot study.

    PubMed

    Soares, José; Rodrigues Filho, Filadelfo; Izaki, Marisa; Giorgi, Maria Clementina P; Catapirra, Rosa M A; Abe, Rubens; Vinagre, Carmen G C M; Cerri, Giovanni G; Meneghetti, José Cláudio

    2014-02-01

    Positron emission tomography with (18)F-fluorodeoxyglucose (FDG-PET) is considered the gold standard for myocardial viability. A pilot study was undertaken to compare FDG-PET using euglycemic hyperinsulinemic clamp before (18)F-fluorodeoxyglucose ((18)F-FDG) administration (PET-CLAMP) with a new proposed technique consisting of a 24-h low-carbohydrate diet before (18)F-FDG injection (PET-DIET), for the assessment of hypoperfused but viable myocardium (hibernating myocardium). Thirty patients with previous myocardial infarction were subjected to rest (99m)Tc-sestamibi-SPECT and two (18)F-FDG studies (PET-CLAMP and PET-DIET). Myocardial tracer uptake was visually scored using a 5-point scale in a 17-segment model. Hibernating myocardium was defined as normal or mildly reduced metabolism ((18)F-FDG uptake) in areas with reduced perfusion ((99m)Tc-sestamibi uptake) since (18)F-FDG uptake was higher than the degree of hypoperfusion-perfusion/metabolism mismatch indicating a larger flow defect. PET-DIET identified 79 segments and PET-CLAMP 71 as hibernating myocardium. Both methods agreed in 61 segments (agreement = 94.5 %, κ = 0.78). PET-DIET identified 230 segments and PET-CLAMP 238 as nonviable. None of the patients had hypoglycemia after DIET, while 20 % had it during CLAMP. PET-DIET compared with PET-CLAMP had a good correlation for the assessment of hibernating myocardium. To our knowledge, these data provide the first evidence of the possibility of myocardial viability assessment with this technique. PMID:24253855

  6. PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants

    PubMed Central

    Parodi, Katia; Paganetti, Harald; Cascio, Ethan; Flanz, Jacob B.; Bonab, Ali A.; Alpert, Nathaniel M.; Lohmann, Kevin; Bortfeld, Thomas

    2008-01-01

    The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of

  7. PET/CT imaging for treatment verification after proton therapy: A study with plastic phantoms and metallic implants

    SciTech Connect

    Parodi, Katia; Paganetti, Harald; Cascio, Ethan; Flanz, Jacob B.; Bonab, Ali A.; Alpert, Nathaniel M.; Lohmann, Kevin; Bortfeld, Thomas

    2007-02-15

    The feasibility of off-line positron emission tomography/computed tomography (PET/CT) for routine three dimensional in-vivo treatment verification of proton radiation therapy is currently under investigation at Massachusetts General Hospital in Boston. In preparation for clinical trials, phantom experiments were carried out to investigate the sensitivity and accuracy of the method depending on irradiation and imaging parameters. Furthermore, they addressed the feasibility of PET/CT as a robust verification tool in the presence of metallic implants. These produce x-ray CT artifacts and fluence perturbations which may compromise the accuracy of treatment planning algorithms. Spread-out Bragg peak proton fields were delivered to different phantoms consisting of polymethylmethacrylate (PMMA), PMMA stacked with lung and bone equivalent materials, and PMMA with titanium rods to mimic implants in patients. PET data were acquired in list mode starting within 20 min after irradiation at a commercial luthetium-oxyorthosilicate (LSO)-based PET/CT scanner. The amount and spatial distribution of the measured activity could be well reproduced by calculations based on the GEANT4 and FLUKA Monte Carlo codes. This phantom study supports the potential of millimeter accuracy for range monitoring and lateral field position verification even after low therapeutic dose exposures of 2 Gy, despite the delay between irradiation and imaging. It also indicates the value of PET for treatment verification in the presence of metallic implants, demonstrating a higher sensitivity to fluence perturbations in comparison to a commercial analytical treatment planning system. Finally, it addresses the suitability of LSO-based PET detectors for hadron therapy monitoring. This unconventional application of PET involves countrates which are orders of magnitude lower than in diagnostic tracer imaging, i.e., the signal of interest is comparable to the noise originating from the intrinsic radioactivity of

  8. Sensitivity study of voxel-based PET image comparison to image registration algorithms

    SciTech Connect

    Yip, Stephen Chen, Aileen B.; Berbeco, Ross; Aerts, Hugo J. W. L.

    2014-11-01

    Purpose: Accurate deformable registration is essential for voxel-based comparison of sequential positron emission tomography (PET) images for proper adaptation of treatment plan and treatment response assessment. The comparison may be sensitive to the method of deformable registration as the optimal algorithm is unknown. This study investigated the impact of registration algorithm choice on therapy response evaluation. Methods: Sixteen patients with 20 lung tumors underwent a pre- and post-treatment computed tomography (CT) and 4D FDG-PET scans before and after chemoradiotherapy. All CT images were coregistered using a rigid and ten deformable registration algorithms. The resulting transformations were then applied to the respective PET images. Moreover, the tumor region defined by a physician on the registered PET images was classified into progressor, stable-disease, and responder subvolumes. Particularly, voxels with standardized uptake value (SUV) decreases >30% were classified as responder, while voxels with SUV increases >30% were progressor. All other voxels were considered stable-disease. The agreement of the subvolumes resulting from difference registration algorithms was assessed by Dice similarity index (DSI). Coefficient of variation (CV) was computed to assess variability of DSI between individual tumors. Root mean square difference (RMS{sub rigid}) of the rigidly registered CT images was used to measure the degree of tumor deformation. RMS{sub rigid} and DSI were correlated by Spearman correlation coefficient (R) to investigate the effect of tumor deformation on DSI. Results: Median DSI{sub rigid} was found to be 72%, 66%, and 80%, for progressor, stable-disease, and responder, respectively. Median DSI{sub deformable} was 63%–84%, 65%–81%, and 82%–89%. Variability of DSI was substantial and similar for both rigid and deformable algorithms with CV > 10% for all subvolumes. Tumor deformation had moderate to significant impact on DSI for progressor

  9. Cardiac applications of PET.

    PubMed

    Sarikaya, Ismet

    2015-10-01

    Routine use of cardiac positron emission tomography (PET) applications has been increasing but has not replaced cardiac single-photon emission computerized tomography (SPECT) studies yet. The majority of cardiac PET tracers, with the exception of fluorine-18 fluorodeoxyglucose (18F-FDG), are not widely available, as they require either an onsite cyclotron or a costly generator for their production. 18F-FDG PET imaging has high sensitivity for the detection of hibernating/viable myocardium and has replaced Tl-201 SPECT imaging in centers equipped with a PET/CT camera. PET myocardial perfusion imaging with various tracers such as Rb-82, N-13 ammonia, and O-15 H2O has higher sensitivity and specificity than myocardial perfusion SPECT for the detection of coronary artery disease (CAD). In particular, quantitative PET measurements of myocardial perfusion help identify subclinical coronary stenosis, better define the extent and severity of CAD, and detect ischemia when there is balanced reduction in myocardial perfusion due to three-vessel or main stem CAD. Fusion images of PET perfusion and CT coronary artery calcium scoring or CT coronary angiography provide additional complementary information and improve the detection of CAD. PET studies with novel 18F-labeled perfusion tracers such as 18F-flurpiridaz and 18F-FBnTP have yielded high sensitivity and specificity in the diagnosis of CAD. These tracers are still being tested in humans, and, if approved for clinical use, they will be commercially and widely available. In addition to viability studies, 18F-FDG PET can also be utilized to detect inflammation/infection in various conditions such as endocarditis, sarcoidosis, and atherosclerosis. Some recent series have obtained encouraging results for the detection of endocarditis in patients with intracardiac devices and prosthetic valves. PET tracers for cardiac neuronal imaging, such as C-11 HED, help assess the severity of heart failure and post-transplant cardiac

  10. Effect of pet ownership on respiratory responses to air pollution in Chinese children: The Seven Northeastern Cities (SNEC) study

    NASA Astrophysics Data System (ADS)

    Qian, Zhengmin (Min); Dong, Guang-Hui; Ren, Wan-Hui; Simckes, Maayan; Wang, Jing; Zelicoff, Alan; Trevathan, Edwin

    2014-04-01

    Previous studies examining pet ownership as a risk factor for respiratory conditions have yielded inconsistent results. Little is known about whether or not pet ownership modifies the relationship between air pollutants and respiratory symptoms and asthma in children. In order to evaluate the interaction between pet and air pollution on respiratory health in children, we recruited 30,149 children, aged 2-12 years, from 25 districts of seven cities in northeast China. Parents of the children completed questionnaires that characterized the children's histories of respiratory symptoms and illnesses and associated risk factors. Average ambient annual exposures to particulate matter with an aerodynamic diameter ≤10 μm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were estimated from monitoring stations in each of the 25 study districts. The results showed that among children without pets at home, there were statistically significant associations between both recent exacerbations of asthma among physician-diagnosed asthmatics and respiratory symptoms and all pollutants examined. Odds ratios (ORs) ranged from 1.12 [95% confidence interval (CI), 1.00-1.26] to 1.41 (95% CI, 1.24-1.61) per 31 μg m-3 for PM10, whereas, among children with pets at home, there were no effects or small effects for either asthma or the symptoms. The interactions between dog ownership and PM10, SO2, NO2, and O3 were statistically significant, such that children with a dog at home had lower reporting of both current asthma and current wheeze. In conclusion, this study suggests that pet ownership decreased the effects of air pollution on respiratory symptoms and asthma among Chinese children.

  11. FDG-PET and Neuropsychiatric Symptoms among Cognitively Normal Elderly Persons: The Mayo Clinic Study of Aging.

    PubMed

    Krell-Roesch, Janina; Ruider, Hanna; Lowe, Val J; Stokin, Gorazd B; Pink, Anna; Roberts, Rosebud O; Mielke, Michelle M; Knopman, David S; Christianson, Teresa J; Machulda, Mary M; Jack, Clifford R; Petersen, Ronald C; Geda, Yonas E

    2016-07-14

    One of the key research agenda of the field of aging is investigation of presymptomatic Alzheimer's disease (AD). Furthermore, abnormalities in brain glucose metabolism (as measured by FDG-PET) have been reported among cognitively normal elderly persons. However, little is known about the association of FDG-PET abnormalities with neuropsychiatric symptoms (NPS) in a population-based setting. Thus, we conducted a cross-sectional study derived from the ongoing population-based Mayo Clinic Study of Aging in order to examine the association between brain glucose metabolism and NPS among cognitively normal (CN) persons aged > 70 years. Participants underwent FDG-PET and completed the Neuropsychiatric Inventory Questionnaire (NPI-Q), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). Cognitive classification was made by an expert consensus panel. We conducted multivariable logistic regression analyses to compute odds ratios (OR) and 95% confidence intervals after adjusting for age, sex, and education. For continuous variables, we used linear regression and Spearman rank-order correlations. Of 668 CN participants (median 78.1 years, 55.4% males), 205 had an abnormal FDG-PET (i.e., standardized uptake value ratio < 1.32 in AD-related regions). Abnormal FDG-PET was associated with depression as measured by NPI-Q (OR = 2.12; 1.23-3.64); the point estimate was further elevated for APOE ɛ4 carriers (OR = 2.59; 1.00-6.69), though marginally significant. Additionally, we observed a significant association between abnormal FDG-PET and depressive and anxiety symptoms when treated as continuous measures. These findings indicate that NPS, even in community-based samples, can be an important additional tool to the biomarker-based investigation of presymptomatic AD. PMID:27447426

  12. FDG-PET and Neuropsychiatric Symptoms among Cognitively Normal Elderly Persons: The Mayo Clinic Study of Aging

    PubMed Central

    Krell-Roesch, Janina; Ruider, Hanna; Lowe, Val J.; Stokin, Gorazd B.; Pink, Anna; Roberts, Rosebud O.; Mielke, Michelle M.; Knopman, David S.; Christianson, Teresa J.; Machulda, Mary M.; Jack, Clifford R.; Petersen, Ronald C.; Geda, Yonas E.

    2016-01-01

    One of the key research agenda of the field of aging is investigation of presymptomatic Alzheimer’s disease (AD). Furthermore, abnormalities in brain glucose metabolism (as measured by FDG-PET) have been reported among cognitively normal elderly persons. However, little is known about the association of FDG-PET abnormalities with neuropsychiatric symptoms (NPS) in a population-based setting. Thus, we conducted a cross-sectional study derived from the ongoing population-based Mayo Clinic Study of Aging in order to examine the association between brain glucose metabolism and NPS among cognitively normal (CN) persons aged > 70 years. Participants underwent FDG-PET and completed the Neuropsychiatric Inventory Questionnaire (NPI-Q), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). Cognitive classification was made by an expert consensus panel. We conducted multivariable logistic regression analyses to compute odds ratios (OR) and 95% confidence intervals after adjusting for age, sex, and education. For continuous variables, we used linear regression and Spearman rank-order correlations. Of 668 CN participants (median 78.1 years, 55.4% males), 205 had an abnormal FDG-PET (i.e., standardized uptake value ratio < 1.32 in AD-related regions). Abnormal FDG-PET was associated with depression as measured by NPI-Q (OR = 2.12; 1.23–3.64); the point estimate was further elevated for APOE ɛ4 carriers (OR = 2.59; 1.00–6.69), though marginally significant. Additionally, we observed a significant association between abnormal FDG-PET and depressive and anxiety symptoms when treated as continuous measures. These findings indicate that NPS, even in community-based samples, can be an important additional tool to the biomarker-based investigation of presymptomatic AD. PMID:27447426

  13. Longitudinal Study of the Excretion Patterns of Thermophilic Campylobacter spp. in Young Pet Dogs in Denmark

    PubMed Central

    Hald, Birthe; Pedersen, Karl; Wainø, Michael; Jørgensen, Jens Christian; Madsen, Mogens

    2004-01-01

    The Campylobacter excretion patterns of 26 domestic pet dogs were described in a longitudinal study. The dogs entered the study between 3 and 8 months of age and were monitored until 2 years of age. They were tested monthly for Campylobacter carriage in stool samples that were cultured on the Campylobacter-selective media CAT and modified CCDA agar at 37 and 42°C. This study comprised 366 fecal swab samples, of which 278 (76.2%) were found to be Campylobacter positive, with the following distribution of species: 75.0% Campylobacter upsaliensis, 19.4% Campylobacter jejuni, 2.1% Campylobacter lari, 0.7% Campylobacter coli, and 2.8% Campylobacter spp. Isolates were typed by pulsed-field gel electrophoresis (PFGE) to elucidate the strain excretion pattern. All study dogs excreted Campylobacter spp. during the study period. At 3 months of age, 60% of the dogs carried Campylobacter, increasing to nearly 100% carriers at 1 year of age, whereafter the carriage rate decreased to 67% at 24 months of age. The PFGE types showed that individual dogs were often colonized by unique strains of C. upsaliensis for several months, up to 21 months or longer. These C. upsaliensis strains were either clonal (or underwent concurrent minor mutative changes) or independent strains. In contrast, the excreted C. jejuni isolates were much more diverse and, in most cases, only seen in one sample from each dog. A high degree of diversity among different dogs was seen. We conclude that young domestic pet dogs excreted Campylobacter spp. during the majority of their puppyhood and adolescent period. In general C. upsaliensis strains were excreted for months, with short-term interruptions by or cocolonization with other transitory Campylobacter spp., predominantly C. jejuni. C. jejuni was more prevalent in dogs between 3 months and 1 year of age than in dogs between 1 and 2 years of age. PMID:15131162

  14. Extrastriatal monoamine neuron function in Parkinson's disease: an 18F-dopa PET study.

    PubMed

    Moore, Robert Y; Whone, Alan L; Brooks, David J

    2008-03-01

    The early motor manifestations of Parkinson's disease (PD) reflect degeneration of nigrostriatal dopamine neurons projecting to the caudal putamen. However, extrastriatal dopamine and other monoamine systems are also involved, particularly in later disease. We used (18)F-dopa PET in a cross-sectional study to characterize extrastriatal monoamine neuronal dysfunction in PD. 16 Controls and 41 patients underwent investigation. We found that (18)F-dopa uptake was decreased in cortical motor areas, particularly the motor cortex, even in early disease. Frontal association areas were also affected in later disease but limbic areas were spared except for hypothalamus. The substantia nigra, midbrain raphe and locus coeruleus showed normal or increased (18)F-dopa uptake until PD was advanced, indicating compensatory responses in intact monoamine neuron perikarya. The red nucleus, subthalamus, ventral thalamus and pineal gland were also eventually involved. These findings provide a further basis for understanding the complex pathophysiology of PD in vivo and complement pathological studies.

  15. Extended amygdala and emotional salience: a PET activation study of positive and negative affect.

    PubMed

    Liberzon, Israel; Phan, K Luan; Decker, Laura R; Taylor, Stephan F

    2003-04-01

    Functional neuroimaging studies have implicated amygdaloid and basal forebrain regions, including sublenticular extended amygdala (SLEA), in the mediation of aversive emotional responses. However, it is not clear whether SLEA responds to 'aversiveness' or to general stimulus salience. We predicted that both pleasant and aversive stimuli would activate this region. Using [(15)O] water PET, we studied 10 healthy subjects while viewing pleasant, aversive, neutral, and blank images. Each subject underwent eight scans, which were processed and averaged with standard statistical methods. Both positive and negative stimuli activated regions in SLEA. Both positive and negative content activated the visual cortex, relative to neutral content. Aversive stimuli deactivated the left frontal pole, relative to positive and neutral stimuli. These findings demonstrate that both positive and negative emotional content evokes processing in the sublenticular/extended amygdala region, suggesting that this region is involved in general emotional processing, such as detection or attribution of salience.

  16. Study conformational dynamics of intrinsically disordered protein by PET-FCS (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Enderlein, Joerg; Zhou, Man; Van, Qui; Gregor, Ingo

    2016-02-01

    Intrinsically disordered proteins (IDP) form a large and functionally important class of proteins that lack an ordered three-dimensional structure. IDPs play an important role in cell signaling, transcription, or chromatin remodeling. The discovery of IDPs has challenged the traditional paradigm of protein structure which states that protein function depends on a well-defined three-dimensional structure. Due to their high conformational flexibility and the lack of ordered secondary structure, it is challenging to study the flexible structure, dynamics and energetics of these proteins with conventional methods. In our work, we employ photoinduced electron transfer (PET) combined with fluorescence correlation spectroscopy (FCS) for studying the conformational dynamics of one specific class of IDPs: phenylalanine-glycine rich protein domains (FG repeats) which are dominant building blocks within the pore of nuclear pore complexes. Nuclear pore complexes are large protein assemblies that cross the nuclear envelope and form selective barrier, which regulate bidirectional exchange between nucleus and cytoplasm.

  17. Correction for FDG PET dose extravasations: Monte Carlo validation and quantitative evaluation of patient studies

    SciTech Connect

    Silva-Rodríguez, Jesús Aguiar, Pablo; Sánchez, Manuel; Mosquera, Javier; Luna-Vega, Víctor; Cortés, Julia; Garrido, Miguel; Pombar, Miguel; Ruibal, Álvaro

    2014-05-15

    Purpose: Current procedure guidelines for whole body [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) state that studies with visible dose extravasations should be rejected for quantification protocols. Our work is focused on the development and validation of methods for estimating extravasated doses in order to correct standard uptake value (SUV) values for this effect in clinical routine. Methods: One thousand three hundred sixty-seven consecutive whole body FDG-PET studies were visually inspected looking for extravasation cases. Two methods for estimating the extravasated dose were proposed and validated in different scenarios using Monte Carlo simulations. All visible extravasations were retrospectively evaluated using a manual ROI based method. In addition, the 50 patients with higher extravasated doses were also evaluated using a threshold-based method. Results: Simulation studies showed that the proposed methods for estimating extravasated doses allow us to compensate the impact of extravasations on SUV values with an error below 5%. The quantitative evaluation of patient studies revealed that paravenous injection is a relatively frequent effect (18%) with a small fraction of patients presenting considerable extravasations ranging from 1% to a maximum of 22% of the injected dose. A criterion based on the extravasated volume and maximum concentration was established in order to identify this fraction of patients that might be corrected for paravenous injection effect. Conclusions: The authors propose the use of a manual ROI based method for estimating the effectively administered FDG dose and then correct SUV quantification in those patients fulfilling the proposed criterion.

  18. Synthesis and PET studies of [11C-cyano]letrozole (Femara), an aromatase inhibitor drug

    SciTech Connect

    kil K. E.; Biegon A.; Kil, K.-E.; Biegon, A.; Ding, Y.-S.; Fischer, A.; Ferrieri, R.A.; Kim, S.-W.; Pareto, D.; Schueller, M.J.; Fowler, J.S.

    2008-11-10

    Aromatase, a member of the cytochrome P450 family, converts androgens such as androstenedione and testosterone to estrone and estradiol respectively. Letrozole (1-[bis-(4-cyanophenyl)methyl]-1H-1,2,4-triazole, Femara{reg_sign}) is a high affinity aromatase inhibitor (K{sub i}=11.5 nM) which has FDA approval for breast cancer treatment. Here we report the synthesis of carbon-11 labeled letrozole and its assessment as a radiotracer for brain aromatase in the baboon. Letrozole and its precursor (4-[(4-bromophenyl)-1H-1,2,4-triazol-1-ylmethyl]benzonitrile, 3) were prepared in two-step syntheses from 4-cyanobenzyl bromide and 4-bromobenzyl bromide, respectively. The [{sup 11}C]cyano group was introduced via the tetrakis(triphenylphosphine)palladium(0) catalyzed coupling of [{sup 11}C]cyanide with the bromo-precursor (3). PET studies in the baboon brain were carried out to assess regional distribution and kinetics, reproducibility of repeated measures and saturability. The free fraction of letrozole in the plasma, log D, and the [{sup 11}C-cyano]letrozole fraction in the arterial plasma were also measured. [{sup 11}C-cyano]Letrozole was synthesized in 60 min with a radiochemical yield of 79-80%, with a radiochemical purity greater than 98% and a specific activity of 4.16 {+-} 2.21 Ci/{micro}mol at the end of bombardment (n=4). PET studies in the baboon revealed initial rapid and high uptake and initial rapid clearance followed by slow clearance of carbon-11 from the brain with no difference between brain regions. The brain kinetics was not affected by co-injection of unlabeled letrozole (0.1 mg/kg). The free fraction of letrozole in plasma was 48.9% and log D was 1.84. [{sup 11}C-cyano]Letrozole is readily synthesized via a palladium catalyzed coupling reaction with [{sup 11}C]cyanide. Although it is unsuitable as a PET radiotracer for brain aromatase as revealed by the absence of regional specificity and saturability in brain regions, such as amygdala, which are known

  19. A FEASIBILITY STUDY EXAMINING THE POTENTIAL FOR HUMAN EXPOSURE TO PET-BORNE DIAZINON RESIDUES FOLLOWING RESIDENTIAL TURF APPLICATIONS

    EPA Science Inventory

    The domestic dog may be a vehicle for translocation of pesticide residues following residential applications to turf. In addition, human occupants may be exposed to residues deposited inside homes by pets or by intimate contacts with them. This study examines the potential of ...

  20. A FEASIBILITY STUDY EXAMINING THE POTENTIAL FOR HUMAN HEALTH EXPOSURE TO PET-BORNE DIAZINON RESIDUES FOLLOWING RESIDENTIAL TURF APPLICATIONS

    EPA Science Inventory

    The domestic dog may be a vehicle for translocation of pesticide residues following residential applications to turf. In addition, human occupants may be exposed to residues deposited inside homes by pets or by intimate contacts with them. This study examines the potential of a...

  1. PILOT STUDY OF THE POTENTIAL FOR HUMAN EXPOSURES TO PET-BORNE DIAZINON RESIDUES FOLLOWING LAWN APPLICATIONS IN NORTH CAROLINA

    EPA Science Inventory

    This study examined the potential for indoor/outdoor pet dogs to be an important pathway for transporting diazinon residues into homes and onto occupants following residential lawn applications. The primary objective was to investigate the potential exposures of children and thei...

  2. Preclinical studies of [61Cu]ATSM as a PET radiopharmaceutical for fibrosarcoma imaging.

    PubMed

    Jalilian, Amir R; Rostampour, Nima; Rowshanfarzad, Pejman; Shafaii, Kamaleddin; Kamali-Dehghan, Mohsen; Akhlaghi, Mehdi

    2009-03-01

    [61Cu]diacetyl-bis(N4-methylthiosemicarbazone) ([61Cu] ATSM) was prepared using in house-made diacetyl-bis(N4-methylthiosemicarbazone) (ATSM) ligand and [61Cu]CuCl2 produced via the natZn(p, x)61Cu (180 muA proton irradiation, 22 MeV, 3.2 h) and purified by a ion chromatography method. [61Cu]ATSM radiochemical purity was >98 %, as shown by HPLC and RTLC methods. [61Cu]ATSM was administered into normal and tumor bearing rodents for up to 210 minutes, followed by biodistribution and co-incidence imaging studies. Significant tumor/non-tumor accumulation was observed either by animal sacrification or imaging. [61Cu]ATSM is a positron emission tomography (PET) radiotracer for tumor hypoxia imaging.

  3. Effects of a 902 MHz mobile phone on cerebral blood flow in humans: a PET study.

    PubMed

    Haarala, Christian; Aalto, Sargo; Hautzel, Hubertus; Julkunen, Laura; Rinne, Juha O; Laine, Matti; Krause, Bernd; Hämäläinen, Heikki

    2003-11-14

    Fourteen healthy right-handed subjects were scanned using PET with a [15O]water tracer during exposure to electromagnetic field (EMF) emitted by a mobile phone and a sham-exposure under double-blind conditions. During scanning, the subjects performed a visual working memory task. Exposure to an active mobile phone produced a relative decrease in regional cerebral blood flow (rCBF) bilaterally in the auditory cortex but no rCBF changes were observed in the area of maximum EMF. It is possible that these remote findings were caused by the EMF emitted by the active mobile phone. A more likely interpretation of the present findings were a result of an auditory signal from the active mobile phone. Therefore, it is not reasoned to attribute this finding to the EMF emitted by the phone. Further study on human rCBF during exposure to EMF of a mobile phone is needed.

  4. Neural responses of rats in the forced swimming test: [F-18]FDG micro PET study.

    PubMed

    Jang, Dong-Pyo; Lee, So-Hee; Lee, Sang-Yoon; Park, Chan-Woong; Cho, Zang-Hee; Kim, Young-Bo

    2009-10-12

    The forced swimming test (FST) is a widely used tool in the assessment of behavioral despair and prediction of response to antidepressants. However, the neural mechanisms underlying behavioral changes between pretest and test sessions of the FST remain unclear. In this study, we investigated changes in rat brain activity during the FST using [F-18]Fluorodeoxyglucose micro PET. In both pretest and test sessions, the activity of the cerebellum and striatum increased, whereas significant deactivation was observed in the hippocampus, inferior colliculus, orbital cortex, and insula. The periaqueductal gray (PAG) region activated markedly in the pretest session, but did not activate in the test session. There was a significant increase in immobility and a decrease in climbing during the behavioral analysis test session. These results suggest that the PAG region may play an important role in the modulation of FST coping strategies subsequent to failure of the escape response during the pretest session.

  5. SU-E-J-263: Repeatability of SUV and Texture Parameters in Serial PET Studies

    SciTech Connect

    Schwartz, J; Humm, J; Nehmeh, S; Schoder, H

    2015-06-15

    Purpose: Standardized uptake values (SUV) are standard quantitative PET measures of FDG tumor uptake used,and are used as a tool to monitor response to therapy. Textural analysis is emerging as a new tool for assessing intratumoral heterogeneity which may allow better tissue characterization and improved prediction of response and survival rate.Understanding what variations may be expected in these parameters is key in order to make decisions based on how the change throughout the course of treatment. The aim of this study was to assess repeatability in SUV measures and texture parameters,and establish criteria that differentiate changes associated with treatment rather than statistical variability. Methods: Eighty patients,167 random lesions total,were scanned in a GE Discovery STE PET/CT Scanner. One field-of-view was chosen centered on the largest lesion observed in a clinical whole-body FDG PET.Immediately following,a gated 9 min scan was acquired in list mode,without changing the patient’s position between any scans. Data was replayed into 3 time bins,3 min each,in order to insure equivalent noise characteristics in each replicate.Data was reconstructed into 128×128×47 square matrices.One VOI was drawn over each lesion for each patient and used to segment all 3 replicates. The mean.max and peak SUV were calculated for each VOI and replicate. First-order textural features were also calculated (skewness and kurtosis). Repeatability was calculated as the average standard deviation over the mean for the 3 repeated measurements for each lesion. Results: The average percent error in the SUV max,peak and mean were 3.4%(0– 12.9%),1.9% (0–7.5%),2.8% (0–12.2%),respectively.For skewness and kurtosis they were 10.9% and 17.8%. Conclusion: We have shown that there is a large variation in %error in SUV measures across patients. SUVpeak is the least variable and kurtosis and skewness parameters are less reliable thatn SUVs.Higher order textures are be.

  6. Designing a compact high performance brain PET scanner-simulation study.

    PubMed

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E; Harrison, Robert L; Elston, Brian F; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V; Brefczynski-Lewis, Julie A; Qi, Jinyi

    2016-05-21

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér-Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact 'helmet' design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging. PMID

  7. Designing a compact high performance brain PET scanner—simulation study

    NASA Astrophysics Data System (ADS)

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E.; Harrison, Robert L.; Elston, Brian F.; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V.; Brefczynski-Lewis, Julie A.; Qi, Jinyi

    2016-05-01

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér–Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging.

  8. Carbon-11-cocaine binding compared at subpharmacological and pharmacological doses: A PET study

    SciTech Connect

    Volkow, N.D.; Fowler, J.S.; Logan, J. |

    1995-07-01

    The authors have characterized cocaine binding in the brain to a high-affinity site on the dopamine transporter using PET and tracer doses of [{sup 11}C]cocaine in the baboon in vivo. The binding pattern, however, of cocaine at tracer (subpharmacological) doses may differ from that observed when the drug is taken in behaviorally active doses, particularly since in vitro studies have shown that cocaine also binds to low affinity binding sites. PET was used to compare and characterize [{sup 11}C]cocaine binding in the baboon brain at low subpharmacological (18 {mu}g average dose) and at pharmacological (8000 {mu}g) doses. Serial studies on the same day in the same baboon were used to assess the reproducibility of repeated measures and to assess the effects of drugs which inhibit the dopamine, norepinephrine and serotonin transporters. Time-activity curves from brain and the arterial plasma input function were used to calculate the steady-state distribution volume (DV). At subpharmacological doses, [{sup 11}C]cocaine had a more homogeneous distribution. Bmax/Kd for sub-pharmacological [{sup 11}C]cocaine corresponded to 0.5-0.6 and for pharmacological [{sup 11}C]cocaine it corresponded to 0.1-0.2. Two-point Scatchard analysis gave Bmax = 2300 pmole/g and Kd = 3600 nM. Bmax/Kd for sub-pharmacological doses of [{sup 11}C]cocaine was decreased by cocaine and drugs that inhibit the dopamine transporter, to 0.1-0.2, but not by drugs that inhibit the serotonin or the norepinephrine transporter. None of these drugs changed Bmax/Kd for a pharmacological dose of [{sup 11}C]cocaine. At subpharmacological doses, [{sup 11}C]cocaine binds predominantly to a high-affinity site on the dopamine transporter. 36 refs., 4 figs., 5 tabs.

  9. Study of electrode pattern design for a CZT-based PET detector

    PubMed Central

    Gu, Y; Levin, C S

    2014-01-01

    We are developing a 1 mm resolution small animal positron emission tomography (PET) system using 3-D positioning Cadmium Zinc Telluride (CZT) photon detectors comprising 40 mm × 40 mm × 5 mm crystals metalized with a cross-strip electrode pattern with a 1 mm anode strip pitch. We optimized the electrode pattern design for intrinsic sensitivity and spatial, energy and time resolution performance using a test detector comprising cathode and steering electrode strips of varying dimensions. The study found 3 mm and 5 mm width cathode strips locate charge-shared photon interactions near cathode strip boundaries with equal precision. 3 mm width cathode strips exhibited large time resolution variability as a function of photon interaction location between the anode and cathode planes (~26 ns to ~127.5 ns FWHM for 0.5 mm and 4.2 mm depths, respectively). 5 mm width cathode strips by contrast exhibited more stable time resolution for the same interaction locations (~34 ns to ~83 ns FWHM), provided more linear spatial positioning in the direction orthogonal to the electrode planes, and as much as 68.4% improvement in photon sensitivity over the 3 mm wide cathode strips. The results were understood by analyzing the cathode strips’ weighting functions, which indicated a stronger “small pixel” effect in the 3 mm wide cathode strips. Photon sensitivity and anode energy resolution were seen to improve with decreasing steering electrode bias from 0 V to −80 V w.r.t the anode potential. A slight improvement in energy resolution was seen for wider steering electrode strips (400 μm vs. 100 μm) for charge-shared photon interactions. Although this study successfully focused on electrode pattern features for PET performance, the results are generally applicable to semiconductor photon detectors employing cross-trip electrode patterns. PMID:24786208

  10. Designing a compact high performance brain PET scanner—simulation study

    NASA Astrophysics Data System (ADS)

    Gong, Kuang; Majewski, Stan; Kinahan, Paul E.; Harrison, Robert L.; Elston, Brian F.; Manjeshwar, Ravindra; Dolinsky, Sergei; Stolin, Alexander V.; Brefczynski-Lewis, Julie A.; Qi, Jinyi

    2016-05-01

    The desire to understand normal and disordered human brain function of upright, moving persons in natural environments motivates the development of the ambulatory micro-dose brain PET imager (AMPET). An ideal system would be light weight but with high sensitivity and spatial resolution, although these requirements are often in conflict with each other. One potential approach to meet the design goals is a compact brain-only imaging device with a head-sized aperture. However, a compact geometry increases parallax error in peripheral lines of response, which increases bias and variance in region of interest (ROI) quantification. Therefore, we performed simulation studies to search for the optimal system configuration and to evaluate the potential improvement in quantification performance over existing scanners. We used the Cramér-Rao variance bound to compare the performance for ROI quantification using different scanner geometries. The results show that while a smaller ring diameter can increase photon detection sensitivity and hence reduce the variance at the center of the field of view, it can also result in higher variance in peripheral regions when the length of detector crystal is 15 mm or more. This variance can be substantially reduced by adding depth-of-interaction (DOI) measurement capability to the detector modules. Our simulation study also shows that the relative performance depends on the size of the ROI, and a large ROI favors a compact geometry even without DOI information. Based on these results, we propose a compact ‘helmet’ design using detectors with DOI capability. Monte Carlo simulations show the helmet design can achieve four-fold higher sensitivity and resolve smaller features than existing cylindrical brain PET scanners. The simulations also suggest that improving TOF timing resolution from 400 ps to 200 ps also results in noticeable improvement in image quality, indicating better timing resolution is desirable for brain imaging.

  11. Brain areas involved in the acupuncture treatment of AD model rats: a PET study

    PubMed Central

    2014-01-01

    Background Acupuncture may effectively treat certain symptoms of Alzheimer’s disease (AD). Although several studies have used functional brain imaging to investigate the mechanisms of acupuncture treatment on AD, these mechanisms are still poorly understood. We therefore further explored the mechanism by which needling at ST36 may have a therapeutic effect in a rat AD model. Methods A total of 80 healthy Wistar rats were divided into healthy control (n = 15) and pre-model (n = 65) groups. After inducing AD-like disease, a total of 45 AD model rats were randomly divided into three groups: the model group (n = 15), the sham-point group (n = 15), and the ST36 group (n = 15). The above three groups underwent PET scanning. PET images were processed with SPM2. Results The brain areas that were activated in the sham-point group relative to the model group were primarily centred on the bilateral limbic system, the right frontal lobe, and the striatum, whereas the activated areas in the ST36 group were primarily centred on the bilateral limbic system (pyriform cortex), the bilateral temporal lobe (olfactory cortex), the right amygdala and the right hippocampus. Compared with the sham-point group, the ST36 group showed greater activation in the bilateral amygdalae and the left temporal lobe. Conclusion We concluded that needling at a sham point or ST36 can increase blood perfusion and glycol metabolism in certain brain areas, and thus may have a positive influence on the cognition of AD patients. PMID:24886495

  12. Central modulation in cluster headache patients treated with occipital nerve stimulation: an FDG-PET study

    PubMed Central

    2011-01-01

    Background Occipital nerve stimulation (ONS) has raised new hope for drug-resistant chronic cluster headache (drCCH), a devastating condition. However its mode of action remains elusive. Since the long delay to meaningful effect suggests that ONS induces slow neuromodulation, we have searched for changes in central pain-control areas using metabolic neuroimaging. Methods Ten drCCH patients underwent an 18FDG-PET scan after ONS, at delays varying between 0 and 30 months. All were scanned with ongoing ONS (ON) and with the stimulator switched OFF. Results After 6-30 months of ONS, 3 patients were pain free and 4 had a ≥ 90% reduction of attack frequency (responders). In all patients compared to controls, several areas of the pain matrix showed hypermetabolism: ipsilateral hypothalamus, midbrain and ipsilateral lower pons. All normalized after ONS, except for the hypothalamus. Switching the stimulator ON or OFF had little influence on brain glucose metabolism. The perigenual anterior cingulate cortex (PACC) was hyperactive in ONS responders compared to non-responders. Conclusions Metabolic normalization in the pain neuromatrix and lack of short-term changes induced by the stimulation might support the hypothesis that ONS acts in drCCH through slow neuromodulatory processes. Selective activation in responders of PACC, a pivotal structure in the endogenous opioid system, suggests that ONS could restore balance within dysfunctioning pain control centres. That ONS is nothing but a symptomatic treatment might be illustrated by the persistent hypothalamic hypermetabolism, which could explain why autonomic attacks may persist despite pain relief and why cluster attacks recur shortly after stimulator arrest. PET studies on larger samples are warranted to confirm these first results. PMID:21349186

  13. A study of shape-dependent partial volume correction in pet imaging using ellipsoidal phantoms fabricated via rapid prototyping

    NASA Astrophysics Data System (ADS)

    Mille, Matthew M.

    Positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) is being increasingly recognized as an important tool for quantitative assessment of tumor response because of its ability to capture functional information about the tumor's metabolism. However, despite many advances in PET technology, measurements of tumor radiopharmaceutical uptake in PET are still challenged by issues of accuracy and consistency, thereby compromising the use of PET as a surrogate endpoint in clinical trials. One limiting component of the overall uncertainty in PET is the relatively poor spatial resolution of the images which directly affects the accuracy of the tumor radioactivity measurements. These spatial resolution effects, colloquially known as the partial volume effect (PVE), are a function of the characteristics of the scanner as well as the tumor being imaged. Previous efforts have shown that the PVE depends strongly on the tumor volume and the background-to-tumor activity concentration ratio. The PVE is also suspected to be a function of tumor shape, although to date no systematic study of this effect has been performed. This dissertation seeks to help fill the gap in the current knowledge about the shape-dependence of the PVE by attempting to quantify, through both theoretical calculation and experimental measurement, the magnitude of the shape effect for ellipsoidal tumors. An experimental investigation of the tumor shape effect necessarily requires tumor phantoms of multiple shapes. Hence, a prerequisite for this research was the design and fabrication of hollow tumor phantoms which could be filled uniformly with radioactivity and imaged on a PET scanner. The phantom fabrication was achieved with the aid of stereolithography and included prolate ellipsoids of various axis ratios. The primary experimental method involved filling the tumor phantoms with solutions of 18F whose activity concentrations were known and traceable to primary radioactivity standards

  14. A Prospective Study of {sup 18}FDG-PET With CT Coregistration for Radiation Treatment Planning of Lymphomas and Other Hematologic Malignancies

    SciTech Connect

    Terezakis, Stephanie A.; Schöder, Heiko; Kowalski, Alexander; McCann, Patrick; Lim, Remy; Turlakov, Alla; Gonen, Mithat; Barker, Chris; Goenka, Anuj; Lovie, Shona; Yahalom, Joachim

    2014-06-01

    Purpose: This prospective single-institution study examined the impact of positron emission tomography (PET) with the use of 2-[{sup 18}F] fluoro-2-deoxyglucose and computed tomography (CT) scan radiation treatment planning (TP) on target volume definition in lymphoma. Methods and Materials: 118 patients underwent PET/CT TP during June 2007 to May 2009. Gross tumor volume (GTV) was contoured on CT-only and PET/CT studies by radiation oncologists (ROs) and nuclear medicine physicians (NMPs) for 95 patients with positive PET scans. Treatment plans and dose-volume histograms were generated for CT-only and PET/CT for 95 evaluable sites. Paired t test statistics and Pearson correlation coefficients were used for analysis. Results: 70 (74%) patients had non-Hodgkin lymphoma, 10 (11%) had Hodgkin lymphoma, 12 (10%) had plasma-cell neoplasm, and 3 (3%) had other hematologic malignancies. Forty-three (45%) presented with relapsed/refractory disease. Forty-five (47%) received no prior chemotherapy. The addition of PET increased GTV as defined by ROs in 38 patients (median, 27%; range, 5%-70%) and decreased GTV in 41 (median, 39.5%; range, 5%-80%). The addition of PET increased GTV as defined by NMPs in 27 patients (median, 26.5%; range, 5%-95%) and decreased GTV in 52 (median, 70%; range, 5%-99%). The intraobserver correlation between CT-GTV and PET-GTV was higher for ROs than for NMPs (0.94, P<.01 vs 0.89, P<.01). On the basis of Bland-Altman plots, the PET-GTVs defined by ROs were larger than those defined by NMPs. On evaluation of clinical TPs, only 4 (4%) patients had inadequate target coverage (D95 <95%) of the PET-GTV defined by NMPs. Conclusions: Significant differences between the RO and NMP volumes were identified when PET was coregistered to CT for radiation planning. Despite this, the PET-GTV defined by ROs and NMPs received acceptable prescription dose in nearly all patients. However, given the potential for a marginal miss, consultation with an experienced PET

  15. 4D offline PET-based treatment verification in scanned ion beam therapy: a phantom study

    NASA Astrophysics Data System (ADS)

    Kurz, Christopher; Bauer, Julia; Unholtz, Daniel; Richter, Daniel; Stützer, Kristin; Bert, Christoph; Parodi, Katia

    2015-08-01

    At the Heidelberg Ion-Beam Therapy Center, patient irradiation with scanned proton and carbon ion beams is verified by offline positron emission tomography (PET) imaging: the {β+} -activity measured within the patient is compared to a prediction calculated on the basis of the treatment planning data in order to identify potential delivery errors. Currently, this monitoring technique is limited to the treatment of static target structures. However, intra-fractional organ motion imposes considerable additional challenges to scanned ion beam radiotherapy. In this work, the feasibility and potential of time-resolved (4D) offline PET-based treatment verification with a commercial full-ring PET/CT (x-ray computed tomography) device are investigated for the first time, based on an experimental campaign with moving phantoms. Motion was monitored during the gated beam delivery as well as the subsequent PET acquisition and was taken into account in the corresponding 4D Monte-Carlo simulations and data evaluation. Under the given experimental conditions, millimeter agreement between the prediction and measurement was found. Dosimetric consequences due to the phantom motion could be reliably identified. The agreement between PET measurement and prediction in the presence of motion was found to be similar as in static reference measurements, thus demonstrating the potential of 4D PET-based treatment verification for future clinical applications.

  16. Preclinical TSPO Ligand PET to Visualize Human Glioma Xenotransplants: A Preliminary Study.

    PubMed

    Buck, Jason R; McKinley, Eliot T; Fu, Allie; Abel, Ty W; Thompson, Reid C; Chambless, Lola; Watchmaker, Jennifer M; Harty, James P; Cooper, Michael K; Manning, H Charles

    2015-01-01

    Current positron emission tomography (PET) imaging biomarkers for detection of infiltrating gliomas are limited. Translocator protein (TSPO) is a novel and promising biomarker for glioma PET imaging. To validate TSPO as a potential target for molecular imaging of glioma, TSPO expression was assayed in a tumor microarray containing 37 high-grade (III, IV) gliomas. TSPO staining was detected in all tumor specimens. Subsequently, PET imaging was performed with an aryloxyanilide-based TSPO ligand, [18F]PBR06, in primary orthotopic xenograft models of WHO grade III and IV gliomas. Selective uptake of [18F]PBR06 in engrafted tumor was measured. Furthermore, PET imaging with [18F]PBR06 demonstrated infiltrative glioma growth that was undetectable by traditional magnetic resonance imaging (MRI). Preliminary PET with [18F]PBR06 demonstrated a preferential tumor-to-normal background ratio in comparison to 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG). These results suggest that TSPO PET imaging with such high-affinity radiotracers may represent a novel strategy to characterize distinct molecular features of glioma growth, as well as better define the extent of glioma infiltration for therapeutic purposes.

  17. 4D offline PET-based treatment verification in scanned ion beam therapy: a phantom study.

    PubMed

    Kurz, Christopher; Bauer, Julia; Unholtz, Daniel; Richter, Daniel; Stützer, Kristin; Bert, Christoph; Parodi, Katia

    2015-08-21

    At the Heidelberg Ion-Beam Therapy Center, patient irradiation with scanned proton and carbon ion beams is verified by offline positron emission tomography (PET) imaging: the β+-activity measured within the patient is compared to a prediction calculated on the basis of the treatment planning data in order to identify potential delivery errors. Currently, this monitoring technique is limited to the treatment of static target structures. However, intra-fractional organ motion imposes considerable additional challenges to scanned ion beam radiotherapy. In this work, the feasibility and potential of time-resolved (4D) offline PET-based treatment verification with a commercial full-ring PET/CT (x-ray computed tomography) device are investigated for the first time, based on an experimental campaign with moving phantoms. Motion was monitored during the gated beam delivery as well as the subsequent PET acquisition and was taken into account in the corresponding 4D Monte-Carlo simulations and data evaluation. Under the given experimental conditions, millimeter agreement between the prediction and measurement was found. Dosimetric consequences due to the phantom motion could be reliably identified. The agreement between PET measurement and prediction in the presence of motion was found to be similar as in static reference measurements, thus demonstrating the potential of 4D PET-based treatment verification for future clinical applications. PMID:26237315

  18. Acute and sustained effects of methylphenidate on cognition and presynaptic dopamine metabolism: an [18F]FDOPA PET study.

    PubMed

    Schabram, Ina; Henkel, Karsten; Mohammadkhani Shali, Siamak; Dietrich, Claudia; Schmaljohann, Jörn; Winz, Oliver; Prinz, Susanne; Rademacher, Lena; Neumaier, Bernd; Felzen, Marc; Kumakura, Yoshitaka; Cumming, Paul; Mottaghy, Felix M; Gründer, Gerhard; Vernaleken, Ingo

    2014-10-29

    Methylphenidate (MPH) inhibits the reuptake of dopamine and noradrenaline. PET studies with MPH challenge show increased competition at postsynaptic D2/3-receptors, thus indirectly revealing presynaptic dopamine release. We used [(18)F]fluorodopamine ([(18)F]FDOPA)-PET in conjunction with the inlet-outlet model (IOM) of Kumakura et al. (2007) to investigate acute and long-term changes in dopamine synthesis capacity and turnover in nigrostriatal fibers of healthy subjects with MPH challenge. Twenty healthy human females underwent two dynamic [(18)F]FDOPA PET scans (124 min; slow bolus-injection; arterial blood sampling), with one scan in untreated baseline condition and the other after MPH administration (0.5 mg/kg, p.o.), in randomized order. Subjects underwent cognitive testing at each PET session. Time activity curves were obtained for ventral putamen and caudate and were analyzed according to the IOM to obtain the regional net-uptake of [(18)F]FDOPA (K; dopamine synthesis capacity) as well as the [(18)F]fluorodopamine washout rate (kloss, index of dopamine turnover). MPH substantially decreased kloss in putamen (-22%; p = 0.003). In the reversed treatment order group (MPH/no drug), K was increased by 18% at no drug follow-up. The magnitude of K at the no drug baseline correlated with cognitive parameters. Furthermore, individual kloss changes correlated with altered cognitive performance under MPH. [(18)F]FDOPA PET in combination with the IOM detects an MPH-evoked decrease in striatal dopamine turnover, in accordance with the known acute pharmacodynamics of MPH. Furthermore, the scan-ordering effect on K suggested that a single MPH challenge persistently increased striatal dopamine synthesis capacity. Attenuation of dopamine turnover by MPH is linked to enhanced cognitive performance in healthy females.

  19. Motion compensation for brain PET imaging using wireless MR active markers in simultaneous PET-MR: phantom and non-human primate studies

    PubMed Central

    Huang, Chuan; Ackerman, Jerome L.; Petibon, Yoann; Normandin, Marc D.; Brady, Thomas J.; El Fakhri, Georges; Ouyang, Jinsong

    2014-01-01

    Brain PET scanning plays an important role in the diagnosis, prognostication and monitoring of many brain diseases. Motion artifacts from head motion are one of the major hurdles in brain PET. In this work, we propose to use wireless MR active markers to track head motion in real time during a simultaneous PET-MR brain scan and incorporate the motion measured by the markers in the listmode PET reconstruction. Several wireless MR active markers and a dedicated fast MR tracking pulse sequence module were built. Data were acquired on an ACR Flangeless PET phantom with multiple spheres and a non-human primate with and without motion. Motions of the phantom and monkey’s head were measured with the wireless markers using a dedicated MR tracking sequence module. The motion PET data were reconstructed using list-mode reconstruction with and without motion correction. Static reference was used as gold standard for quantitative analysis. The motion artifacts, which were prominent on the images without motion correction, were eliminated by the wireless marker based motion correction in both the phantom and monkey experiments. Quantitative analysis was performed on the phantom motion data from 24 independent noise realizations. The reduction of bias of sphere-to-background PET contrast by active marker based motion correction ranges from 26% to 64% and 17% to 25% for hot (i.e., radioactive) and cold (i.e., non-radioactive) spheres, respectively. The motion correction improved the channelized Hotelling observer signal-to-noise ratio of the spheres by 1.2 to 6.9 depending on their locations and sizes. The proposed wireless MR active marker based motion correction technique removes the motion artifacts in the reconstructed PET images and yields accurate quantitative values. PMID:24418501

  20. Motion compensation for brain PET imaging using wireless MR active markers in simultaneous PET-MR: phantom and non-human primate studies.

    PubMed

    Huang, Chuan; Ackerman, Jerome L; Petibon, Yoann; Normandin, Marc D; Brady, Thomas J; El Fakhri, Georges; Ouyang, Jinsong

    2014-05-01

    Brain PET scanning plays an important role in the diagnosis, prognostication and monitoring of many brain diseases. Motion artifacts from head motion are one of the major hurdles in brain PET. In this work, we propose to use wireless MR active markers to track head motion in real time during a simultaneous PET-MR brain scan and incorporate the motion measured by the markers in the listmode PET reconstruction. Several wireless MR active markers and a dedicated fast MR tracking pulse sequence module were built. Data were acquired on an ACR Flangeless PET phantom with multiple spheres and a non-human primate with and without motion. Motions of the phantom and monkey's head were measured with the wireless markers using a dedicated MR tracking sequence module. The motion PET data were reconstructed using list-mode reconstruction with and without motion correction. Static reference was used as gold standard for quantitative analysis. The motion artifacts, which were prominent on the images without motion correction, were eliminated by the wireless marker based motion correction in both the phantom and monkey experiments. Quantitative analysis was performed on the phantom motion data from 24 independent noise realizations. The reduction of bias of sphere-to-background PET contrast by active marker based motion correction ranges from 26% to 64% and 17% to 25% for hot (i.e., radioactive) and cold (i.e., non-radioactive) spheres, respectively. The motion correction improved the channelized Hotelling observer signal-to-noise ratio of the spheres by 1.2 to 6.9 depending on their locations and sizes. The proposed wireless MR active marker based motion correction technique removes the motion artifacts in the reconstructed PET images and yields accurate quantitative values.

  1. Delineation of Gross Tumor Volume (GTV) for Radiation Treatment Planning of Locally Advanced Rectal Cancer Using Information From MRI or FDG-PET/CT: A Prospective Study

    SciTech Connect

    Braendengen, Morten; Hansson, Karl; Radu, Calin; Siegbahn, Albert; Jacobsson, Hans; Glimelius, Bengt

    2011-11-15

    Purpose: Accurate delineation of target volumes is important to maximize radiation dose to the tumor and minimize it to nontumor tissue. Computed tomography (CT) and magnetic resonance imaging (MRI) are standard imaging modalities in rectal cancer. The aim was to explore whether functional imaging with F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET), combined with CT (FDG-PET/CT) gives additional information to standard pretreatment evaluation and changes the shape and size of the gross tumor volume (GTV). Methods and Materials: From 2007 to 2009, 77 consecutive patients with locally advanced rectal cancer were prospectively screened for inclusion in the study at two university hospitals in Sweden, and 68 patients were eligible. Standard GTV was delineated using information from clinical examination, CT, and MRI (GTV-MRI). Thereafter, a GTV-PET was defined in the fused PET-CT, and the target volume delineations were compared for total volume, overlap, and mismatch. Pathologic uptake suspect of metastases was also registered. Results: The median volume of GTV-MRI was larger than that of GTV-PET: 111 cm{sup 3} vs. 87 cm{sup 3} (p < 0.001). In many cases, the GTV-MRI contained the GTV defined on the PET/CT images as subvolumes, but when a GTV total was calculated after the addition of GTV-PET to GTV-MRI, the volume increased, with median 11% (range, 0.5-72%). New lesions were seen in 15% of the patients for whom PET/CT was used. Conclusions: FDG-PET/CT facilitates and adds important information to the standard delineation procedure of locally advanced rectal cancer, mostly resulting in a smaller GTV, but a larger total GTV using the union of GTV-MRI and GTV-PET. New lesions were sometimes seen, potentially changing the treatment strategy.

  2. Uncoupling of fatty acid and glucose metabolism in malignant lymphoma: a PET study

    PubMed Central

    Nuutinen, J; Minn, H; Bergman, J; Haaparanta, M; Ruotsalainen, U; Laine, H; Knuuti, J

    1999-01-01

    Increased use of glucose through glycolysis is characteristic for neoplastic growth while the significance of serum-free fatty acids for regulation of energy metabolism in cancer is poorly understood. We studied whether serum-free fatty acids (FFA) interfere with glycolytic metabolism of lymphoproliferative neoplasms as assessed with 2-F18-fluoro-2-deoxy-D-glucose ([F18]FDG) and positron emission tomography (PET). Twelve patients with newly diagnosed non-Hodgkin's lymphoma (n = 9) or Hodgkin's disease (n = 3) participated in this study before start of oncologic treatment. Each patient underwent two [F18]FDG PET studies within 1 week after overnight fast: once during high fasting serum FFA concentrations and once after reduction of serum FFA by administration of acipimox. Acipimox is a nicotinic acid derivative that inhibits lipolysis in peripheral tissues and induces a striking reduction in circulating FFA concentration. In all cases, dynamic PET imaging over the tumour area was performed for 60 min after injection of [F18]FDG. Both graphical analysis (rMRFDG) and single scan approach (SUV) were used to compare tumour uptake of [F18]FDG under high fasting FFA concentrations and after pharmacologically decreased FFA concentrations. Serum FFA concentrations were reduced significantly from 0.92 ± 0.42 mmol l−1 at baseline to 0.26 ± 0.31 mmol l−1 after acipimox administration (P = 0.0003). Plasma glucose, serum insulin and lactate concentrations were similar during both approaches. The retention of glucose analogue [F18]FDG in tumour was similar between baseline and acipimox studies. Median rMRFDG of a total of 12 involved lymph nodes in 12 patients was 21.9 μmol 100 g−1 min−1 (range 8.7–82.5) at baseline and 20.1 μmol 100 g−1 min−1 (range 10.7–81.7) after acipimox. The respective values for median SUV were 7.8 (range 3.6–18.6) and 6.0 (range 4.1–20.2). As expected, [F18]FDG uptake in myocardium was clearly enhanced by acipimox due to reduction

  3. Dipyridamole-induced stress - variability in {sup 82}Rb PET kinetic studies in the anesthetized canine

    SciTech Connect

    Coxson, P.G.; Brennan, K.M.; Taylor, S.E.

    1996-05-01

    Reproducibility and variability of dipyridamole-induced stress in the myocardium as measured with {sup 82}Rb PET kinetics was tested in a series of replicated studies on six dogs using the Donner 600-Crystal Positron Tomograph (4.5mm FWHM with {sup 82}Rb). A single lateral slice through the myocardium was imaged in a baseline resting state, and again immediately after an infusion of dipyridamole (0.6 mg/kg over 4 min). Blood samples taken at 1 minute intervals were assayed with HPLC. A two compartment model with parameters k{sub 1} (uptake rate), k{sub 2} (wash-out rate), and f{sub v} (vascular fraction) was fit to the data. Stress-state k{sub 1} estimates were compared with rest-state k{sub 1} estimates and dipyridamole levels in the blood to ascertain any dependencies between them. In a multiple regression of the stress-k{sub 1} on both the rest-k{sub 1} and the mean dipyridamole concentration (0-4 min), the rest-k{sub 1} is significant (p=0.032) as a predictor and the dipyridamole concentration is borderline significant (p=0.060). Together they explain about 35% of the variability in the stress-k{sub 1}. Analysis of variance shows no significant between-animal effects for either the rest-k{sub 1} or the stress-k{sub 1} estimates but a significant (p=0.032) between-animal effect for the dipyridamole concentration. Dipyridamole is routinely used to induce stress for kinetic PET cardiac studies, but its contribution to variability in the rest-stress test has not been examined. These studies show that dipyridamole pharmacokinetic variability within and between animals has an effect on the stress-k{sub 1} estimate, but the effect is small. The statistically significant correlation of the rest- and stress-k{sub 1} values suggests that the ratio of K{sub 1} (stress/rest) is a more stable indicator of the stress response than the stress-k{sub 1} values alone.

  4. A feasibility study of PETiPIX: an ultra high resolution small animal PET scanner

    NASA Astrophysics Data System (ADS)

    Li, K.; Safavi-Naeini, M.; Franklin, D. R.; Petasecca, M.; Guatelli, S.; Rosenfeld, A. B.; Hutton, B. F.; Lerch, M. L. F.

    2013-12-01

    PETiPIX is an ultra high spatial resolution positron emission tomography (PET) scanner designed for imaging mice brains. Four Timepix pixellated silicon detector modules are placed in an edge-on configuration to form a scanner with a field of view (FoV) 15 mm in diameter. Each detector module consists of 256 × 256 pixels with dimensions of 55 × 55 × 300 μm3. Monte Carlo simulations using GEANT4 Application for Tomographic Emission (GATE) were performed to evaluate the feasibility of the PETiPIX design, including estimation of system sensitivity, angular dependence, spatial resolution (point source, hot and cold phantom studies) and evaluation of potential detector shield designs. Initial experimental work also established that scattered photons and recoil electrons could be detected using a single edge-on Timepix detector with a positron source. Simulation results estimate a spatial resolution of 0.26 mm full width at half maximum (FWHM) at the centre of FoV and 0.29 mm FWHM overall spatial resolution with sensitivity of 0.01%, and indicate that a 1.5 mm thick tungsten shield parallel to the detectors will absorb the majority of non-coplanar annihilation photons, significantly reducing the rates of randoms. Results from the simulated phantom studies demonstrate that PETiPIX is a promising design for studies demanding high resolution images of mice brains.

  5. A retrospective molecular study of select intestinal protozoa in healthy pet cats from Italy.

    PubMed

    Mancianti, Francesca; Nardoni, Simona; Mugnaini, Linda; Zambernardi, Lucia; Guerrini, Alessandro; Gazzola, Valentina; Papini, Roberto Amerigo

    2015-02-01

    The feline gut can harbour a number of protozoan parasites. Recent genetic studies have highlighted new epidemiological findings about species of Cryptosporidium, assemblages of Giardia duodenalis and Toxoplasma gondii. Furthermore, epidemiological studies suggest the occurrence of Tritrichomonas foetus in cats is on the increase worldwide. The prevalence of selected intestinal protozoa was determined by PCR using DNA previously extracted from the faeces of 146 privately owned healthy cats from Italy. Molecular genotyping on T gondii, G duodenalis and Cryptosporidium DNA was achieved. PCR assays were positive in 32 (22.9%) samples. Three animals (2.0%) were positive for T foetus and Cryptosporidium DNA, 15 specimens (10.3%) were positive for T gondii and 11 (7.5%) for G duodenalis. Co-infections were never observed. Results of the typing analysis allowed the identification of Cryptosporidium felis in all cases. The specimens positive for T gondii hinted at clonal genotype I (n = 7), genotype II (n = 1) and genotype III (n = 7). The G duodenalis isolates were referable to assemblages F (n = 9) and C (n = 2). In conclusion, the results obtained in this study add to the literature regarding the epidemiology of these parasites by confirming their presence in the faeces of healthy pet cats.

  6. Pre-symptomatic diagnosis in fatal familial insomnia: serial neurophysiological and 18FDG-PET studies.

    PubMed

    Cortelli, Pietro; Perani, Daniela; Montagna, Pasquale; Gallassi, Roberto; Tinuper, Paolo; Provini, Federica; Federica, Provini; Avoni, Patrizia; Ferrillo, Franco; Anchisi, Davide; Moresco, Rosa Maria; Fazio, Ferruccio; Parchi, Piero; Baruzzi, Agostino; Lugaresi, Elio; Gambetti, Pierluigi

    2006-03-01

    Knowing how and when the degenerative process starts is important in neurodegenerative diseases. We have addressed this issue in fatal familial insomnia (FFI) measuring the cerebral metabolic rate of glucose (CMRglc) with 2-[18F]fluoro-2-deoxy-D-glucose PET in parallel with detailed clinical, neuropsychological examinations and polysomnography with EEG spectral analyses. Nine asymptomatic carriers of the D178N mutation, 10 non-carriers belonging to the same family, and 19 age-matched controls were studied over several years. The CMRglc as well as clinical and electrophysiological examinations were normal in all cases at the beginning of the study. Four of the mutation carriers developed typical FFI during the study but CMRglc and the clinical and electrophysiological examinations remained normal 63, 56, 32 and 21 months, respectively before disease onset. The carrier whose tests were normal 32 months before disease onset was re-examined 13 months before the onset. At that time, selective hypometabolism was detected in the thalamus while spectral-EEG analysis disclosed an impaired thalamic sleep spindle formation. Following clinical disease onset, CRMglc was reduced in the thalamus in all 3 patients examined. Our data indicate that the neurodegenerative process associated with FFI begins in the thalamus between 13 and 21 months before the clinical presentation of the disease.

  7. The MINDView brain PET detector, feasibility study based on SiPM arrays

    NASA Astrophysics Data System (ADS)

    González, Antonio J.; Majewski, Stan; Sánchez, Filomeno; Aussenhofer, Sebastian; Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F.; Pani, Roberto; Bettiol, Marco; Fabbri, Andrea; Bert, Julien; Visvikis, Dimitris; Jackson, Carl; Murphy, John; O'Neill, Kevin; Benlloch, Jose M.

    2016-05-01

    The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm2 active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

  8. An observational study of the potential for human exposures to pet-borne diazinon residues following lawn applications

    SciTech Connect

    Morgan, Marsha K. Stout, Daniel M.; Jones, Paul A.; Barr, Dana B.

    2008-07-15

    This study examined the potential for pet dogs to be an important pathway for transporting diazinon residues into homes and onto its occupants following residential lawn applications. The primary objectives were to investigate the potential exposures of occupants and their pet dogs to diazinon after an application to turf at their residences and to determine if personal contacts between occupants and their pet dogs resulted in measurable exposures. It was conducted from April to August 2001 before the Agency phased out all residential uses of diazinon in December 2004. Six families and their pet dogs were recruited into the study. Monitoring was conducted at pre-, 1, 2, 4, and 8 days post-application of a commercial, granular formulation of diazinon to the lawn by the homeowner. Environmental samples collected included soil, indoor air, carpet dust, and transferable residues from lawns and floors. Samples collected from the pet dogs consisted of paw wipes, fur clippings, and transferable residues from the fur by a technician or child wearing a cotton glove(s). First morning void (FMV) urine samples were collected from each child and his/her parent on each sampling day. Diazinon was analyzed in all samples, except urine, by GC-MS. The metabolite 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy) was analyzed in the urine samples by HPLC-MS/MS. Mean airborne residues of diazinon on day 1 post-application were at least six times higher in both the living rooms (235{+-}267 ng/m{sup 3}) and children's bedrooms (179{+-}246 ng/m{sup 3}) than at pre-application. Mean loadings of diazinon in carpet dust samples were at least 20 times greater on days 2, 4, and 8 post-application than mean loadings (0.03{+-}0.04 ng/cm{sup 2}) at pre-application. The pet dogs had over 900 times higher mean loadings of diazinon residues on their paws on day 1 post-application (88.1{+-}100.1 ng/cm{sup 2}) compared to mean loadings (<0.09 ng/cm{sup 2}) at pre-application. The mean diazinon loadings

  9. Uncoupling cognitive workload and prefrontal cortical physiology: a PET rCBF study.

    PubMed

    Goldberg, T E; Berman, K F; Fleming, K; Ostrem, J; Van Horn, J D; Esposito, G; Mattay, V S; Gold, J M; Weinberger, D R

    1998-05-01

    Working memory is a fundamental cognitive building block involved in the short-term maintenance and transformation of information. In neuropsychological studies, working memory has been shown to be of limited capacity; however, the neurophysiological concomitants of this capacity limitation have not been explored. In this study we used the [15O] water PET rCBF technique and statistical parametric mapping to examine normal subjects while they performed two cognitive tasks, both individually and simultaneously. One task was the Wisconsin Card Sorting Test, a complex reasoning task involving working memory, and the other was a rapidly paced auditory verbal shadowing task. When both tasks were performed simultaneously, there were significant decrements in performance compared with the individual task performance scores, indicating that cognitive workload had been increased. Analysis of the rCBF maps showed that when the two tasks were performed together, in contrast to when they were performed separately, there was less prefrontal activation. These results suggest that increases in cognitive workload do not necessarily recruit and then sustain cortical neurophysiological resources to a maximum, but rather may actually be accompanied by a diminution in cortical activity.

  10. The effects of case mixing on word recognition: evidence from a PET study.

    PubMed

    Mayall, K; Humphreys, G W; Mechelli, A; Olson, A; Price, C J

    2001-08-15

    The early stages of visual word recognition were investigated by scanning participants using PET as they took part in implicit and explicit reading tasks with visually disrupted stimuli. CaSe MiXiNg has been shown in behavioral studies to increase reaction times (RTs) in naming and other word recognition tasks. In this study, we found that during both an implicit (feature detection) task and an explicit word-naming task, mixed-case words compared to same-case words produced increased activation in an area of the right parietal cortex previously associated with visual attention. No effect of case was found in this area for pseudowords or consonant strings. Further, lowering the contrast of the stimuli slowed RTs as much as case mixing, but did not lead to the same increase in right parietal activation. No significant effect of case mixing was observed in left-hemisphere language areas. The results suggest that reading mixed-case words requires increased attentional processing. However, later word recognition processes may be relatively unaffected by the disruption in presentation.

  11. STRATEGIES FOR QUANTIFYING PET IMAGING DATA FROM TRACER STUDIES OF BRAIN RECEPTORS AND ENZYMES.

    SciTech Connect

    Logan, J.

    2001-04-02

    A description of some of the methods used in neuroreceptor imaging to distinguish changes in receptor availability has been presented in this chapter. It is necessary to look beyond regional uptake of the tracer since uptake generally is affected by factors other than the number of receptors for which the tracer has affinity. An exception is the infusion method producing an equilibrium state. The techniques vary in complexity some requiring arterial blood measurements of unmetabolized tracer and multiple time uptake data. Others require only a few plasma and uptake measurements and those based on a reference region require no plasma measurements. We have outlined some of the limitations of the different methods. Laruelle (1999) has pointed out that test/retest studies to which various methods can be applied are crucial in determining the optimal method for a particular study. The choice of method will also depend upon the application. In a clinical setting, methods not involving arterial blood sampling are generally preferred. In the future techniques for externally measuring arterial plasma radioactivity with only a few blood samples for metabolite correction will extend the modeling options of clinical PET. Also since parametric images can provide information beyond that of ROI analysis, improved techniques for generating such images will be important, particularly for ligands requiring more than a one-compartment model. Techniques such as the wavelet transform proposed by Turkheimer et al. (2000) may prove to be important in reducing noise and improving quantitation.

  12. The neural basis of autobiographical and semantic memory: new evidence from three PET studies.

    PubMed

    Graham, Kim S; Lee, Andy C H; Brett, Matthew; Patterson, Karalyn

    2003-09-01

    A novel, neuropsychologically informed paradigm (extended retrieval of events in response to a cue word) was used to investigate the neural basis of autobiographical and semantic memory. Contrasting retrieval of autobiographical memories with retrieval of semantic facts (ABM-SEM) in 24 subjects across three PET studies revealed bilateral involvement of the middle temporal gyrus (BA 21) and medial frontal cortex (BA 9/10). The opposite contrast, SEM-ABM, resulted in increased regional cerebral blood flow in left posterior temporal regions (BA 37) and left prefrontal cortex (BA 45/46). Laterality maps suggest that the bilateral pattern seen in our studies, but not often in other neuroimaging investigations, reflects the use of a task stressing retrieval of specific personal events. Further comparisons revealed that the activation in the right anterior temporal lobe during autobiographical recall was virtually identical to that seen during retrieval of information about famous people or events in contrast with retrieval of general semantic facts. These findings suggest that the retrieval of an autobiographical event requires participation from conceptual knowledge, and that this type of knowledge is bilaterally distributed in the temporal lobes. PMID:14672158

  13. PARAQUAT IS EXCLUDED BY THE BLOOD BRAIN BARRIER IN RHESUS MACAQUE: AN IN VIVO PET STUDY

    PubMed Central

    Bartlett, Rachel M.; Holden, James E.; Nickles, R. Jerome; Murali, Dhanabalan; Barbee, David L.; Barnhart, Todd E.; Christian, Bradley C.; DeJesus, Onofre T.

    2009-01-01

    Environmental factors have long been thought to have a role in the etiology of idiopathic Parkinson’s Disease (PD). Since the discovery of the selective neurotoxicity of MPTP to dopamine cells, suspicion has focused on paraquat, a common herbicide with chemical structure similar to 1-methyl-4-phenylpyridinium (MPP+), the MPTP metabolite responsible for its neurotoxicity. Although in vitro evidence for paraquat neurotoxicity to dopamine cells is well established, its in vivo effects have been ambiguous because paraquat is di-cationic in plasma, which raises questions about its ability to cross the blood brain barrier. This study assessed the brain uptake of [11C]-paraquat in adult male rhesus macaques using quantitative PET imaging. Results showed minimal uptake of [11C]-paraquat in the macaque brain. The highest concentrations of paraquat was seen in the pineal gland and the lateral ventricles. Global brain concentrations including those in known dopamine areas were consistent with the blood volume in those structures. This acute exposure study found that paraquat is excluded from the brain by the blood brain barrier and thus does not readily support the causative role of paraquat exposure in idiopathic Parkinson’s Disease. PMID:19135428

  14. Positron Emission Tomography (PET)

    SciTech Connect

    Welch, M.J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET. 22 figs.

  15. Positron Emission Tomography (PET)

    DOE R&D Accomplishments Database

    Welch, M. J.

    1990-01-01

    Positron emission tomography (PET) assesses biochemical processes in the living subject, producing images of function rather than form. Using PET, physicians are able to obtain not the anatomical information provided by other medical imaging techniques, but pictures of physiological activity. In metaphoric terms, traditional imaging methods supply a map of the body's roadways, its, anatomy; PET shows the traffic along those paths, its biochemistry. This document discusses the principles of PET, the radiopharmaceuticals in PET, PET research, clinical applications of PET, the cost of PET, training of individuals for PET, the role of the United States Department of Energy in PET, and the futures of PET.

  16. Imaging Neuroinflammation in Gray and White Matter in Schizophrenia: An In-Vivo PET Study With [18F]-FEPPA

    PubMed Central

    Kenk, Miran; Selvanathan, Thiviya; Rao, Naren; Suridjan, Ivonne; Rusjan, Pablo; Remington, Gary; Meyer, Jeffrey H.; Wilson, Alan A.; Houle, Sylvain; Mizrahi, Romina

    2015-01-01

    Neuroinflammation and abnormal immune responses have been implicated in schizophrenia (SCZ). Past studies using positron emission tomography (PET) that examined neuroinflammation in patients with SCZ in vivo using the translocator protein 18kDa (TSPO) target were limited by the insensitivity of the first-generation imaging agent [11C]-PK11195, scanners used, and the small sample sizes studied. Present study uses a novel second-generation TSPO PET radioligand N-acetyl-N-(2-[18F]fluoroethoxybenzyl)-2-phenoxy-5-pyridinamine ([18F]-FEPPA) to evaluate whether there is increased neuroinflammation in patients with SCZ. A cross-sectional study was performed using [18F]-FEPPA and a high-resolution research tomograph (HRRT). Eighteen patients with SCZ with ongoing psychotic symptoms and 27 healthy volunteers (HV) were recruited from a tertiary psychiatric clinical setting and the community, respectively. All participants underwent [18F]-FEPPA PET and magnetic resonance imaging, and PET data were analyzed to obtain [18F]-FEPPA total volume of distribution (V T) using a 2-tissue compartment model with an arterial plasma input function, as previously validated. All subjects were classified as high-, medium- or low-affinity [18F]-FEPPA binders on the basis of rs6971 polymorphism, and genotype information was incorporated into the analyses of imaging outcomes. No significant differences in neuroinflammation indexed as [18F]-FEPPA V T were observed between groups in either gray (F (1,39) = 0.179, P = .674) or white matter regions (F (1,38) = 0.597, P = .445). The lack of significant difference in neuroinflammation in treated patients with SCZ in the midst of a psychotic episode and HV suggests that neuroinflammatory processes may take place early in disease progression or are affected by antipsychotic treatment. PMID:25385788

  17. Imaging neuroinflammation in gray and white matter in schizophrenia: an in-vivo PET study with [18F]-FEPPA.

    PubMed

    Kenk, Miran; Selvanathan, Thiviya; Rao, Naren; Suridjan, Ivonne; Rusjan, Pablo; Remington, Gary; Meyer, Jeffrey H; Wilson, Alan A; Houle, Sylvain; Mizrahi, Romina

    2015-01-01

    Neuroinflammation and abnormal immune responses have been implicated in schizophrenia (SCZ). Past studies using positron emission tomography (PET) that examined neuroinflammation in patients with SCZ in vivo using the translocator protein 18kDa (TSPO) target were limited by the insensitivity of the first-generation imaging agent [(11)C]-PK11195, scanners used, and the small sample sizes studied. Present study uses a novel second-generation TSPO PET radioligand N-acetyl-N-(2-[(18)F]fluoroethoxybenzyl)-2-phenoxy-5-pyridinamine ([(18)F]-FEPPA) to evaluate whether there is increased neuroinflammation in patients with SCZ. A cross-sectional study was performed using [(18)F]-FEPPA and a high-resolution research tomograph (HRRT). Eighteen patients with SCZ with ongoing psychotic symptoms and 27 healthy volunteers (HV) were recruited from a tertiary psychiatric clinical setting and the community, respectively. All participants underwent [(18)F]-FEPPA PET and magnetic resonance imaging, and PET data were analyzed to obtain [(18)F]-FEPPA total volume of distribution (VT) using a 2-tissue compartment model with an arterial plasma input function, as previously validated. All subjects were classified as high-, medium- or low-affinity [(18)F]-FEPPA binders on the basis of rs6971 polymorphism, and genotype information was incorporated into the analyses of imaging outcomes. No significant differences in neuroinflammation indexed as [(18)F]-FEPPA VT were observed between groups in either gray (F(1,39) = 0.179, P = .674) or white matter regions (F(1,38) = 0.597, P = .445). The lack of significant difference in neuroinflammation in treated patients with SCZ in the midst of a psychotic episode and HV suggests that neuroinflammatory processes may take place early in disease progression or are affected by antipsychotic treatment. PMID:25385788

  18. Is there any complimentary role of F-18 NaF PET/CT in detecting of osseous involvement of multiple myeloma? A comparative study for F-18 FDG PET/CT and F-18 FDG NaF PET/CT.

    PubMed

    Ak, İlknur; Onner, Hasan; Akay, Olga Meltem

    2015-09-01

    Multiple myeloma (MM) is a disease characterized by a monoclonal plasma cell population in the bone marrow whereby osseous involvement is a predominant feature. The aim of this prospective study was to investigate the combined use of F-18 FDG and F-18 NaF PET/CT in the skeletal assessment of patients with MM and to compare the efficacy of these two PET tracers regarding detection of myeloma-indicative osseous lesions. A total of 26 patients (14 females and 12 males, mean age 61.8 ± 1.8 years (range 40-81 years)) with MM diagnosed according to standard criteria. All patients underwent both F-18 FDG PET/CT and F-18 NaF PET/CT scans within 1 week after the completion of the usual staging workup for MM. In total, approximately 128 focal F-18 FDG avid skeletal lesions were detected; the stage I (n = 5) patients had 10 bone lesions, the stage II (n = 11) patients had 43 lesions, and the stage III (n = 10) patients demonstrated 75 focal bone lesions. F-18 NaF PET/CTs demonstrated fewer myeloma indicative lesions than F-18 FDG PET/CTs. Totally, 57 focal bone lesions were detected with whole body F-18 NaF PET/CT (mean 2.19 ± 0.34, between 1 and 9 lesions); the five stage I patients had 6 bone lesions, the 11 stage II pts had 18 lesions, and the ten stage III patients demonstrated 33 focal bone lesions. On the other hand, F-18 NaF PET/CT demonstrated additional 135 bone lesions defined as rib fractures and other findings due to degenerative changes. In conclusion, our study implies that F-18 NaF PET/CT scan did not actually aid for assessing the myelomatous bone lesions in patients with MM. Therefore, a complementary F-18 NaF PET/CT may be an accurate modality for detecting of bone fracture in patients with MM.

  19. Is there any complimentary role of F-18 NaF PET/CT in detecting of osseous involvement of multiple myeloma? A comparative study for F-18 FDG PET/CT and F-18 FDG NaF PET/CT.

    PubMed

    Ak, İlknur; Onner, Hasan; Akay, Olga Meltem

    2015-09-01

    Multiple myeloma (MM) is a disease characterized by a monoclonal plasma cell population in the bone marrow whereby osseous involvement is a predominant feature. The aim of this prospective study was to investigate the combined use of F-18 FDG and F-18 NaF PET/CT in the skeletal assessment of patients with MM and to compare the efficacy of these two PET tracers regarding detection of myeloma-indicative osseous lesions. A total of 26 patients (14 females and 12 males, mean age 61.8 ± 1.8 years (range 40-81 years)) with MM diagnosed according to standard criteria. All patients underwent both F-18 FDG PET/CT and F-18 NaF PET/CT scans within 1 week after the completion of the usual staging workup for MM. In total, approximately 128 focal F-18 FDG avid skeletal lesions were detected; the stage I (n = 5) patients had 10 bone lesions, the stage II (n = 11) patients had 43 lesions, and the stage III (n = 10) patients demonstrated 75 focal bone lesions. F-18 NaF PET/CTs demonstrated fewer myeloma indicative lesions than F-18 FDG PET/CTs. Totally, 57 focal bone lesions were detected with whole body F-18 NaF PET/CT (mean 2.19 ± 0.34, between 1 and 9 lesions); the five stage I patients had 6 bone lesions, the 11 stage II pts had 18 lesions, and the ten stage III patients demonstrated 33 focal bone lesions. On the other hand, F-18 NaF PET/CT demonstrated additional 135 bone lesions defined as rib fractures and other findings due to degenerative changes. In conclusion, our study implies that F-18 NaF PET/CT scan did not actually aid for assessing the myelomatous bone lesions in patients with MM. Therefore, a complementary F-18 NaF PET/CT may be an accurate modality for detecting of bone fracture in patients with MM. PMID:26068066

  20. Study of the ion beam induced amorphisation, bond breaking and optical gap change processes in PET

    NASA Astrophysics Data System (ADS)

    Papaléo, R. M.; de Araújo, M. A.; Livi, R. P.

    1992-03-01

    Ion beam bombardment induced effects on the crystalline and chemical structures, as well as in the thermal, optical, and electrical properties of PET (Mylar) were studied. The induced modifications were followed by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-VIS), X-ray diffractometry, differential scanning calorimetry (DSC), and electrical resistance measurements. The melting temperature and the crystalline fraction started to decrease at fluences where the chemical degradation was not significant. The hydrogen and oxygen losses led preferentially to new carbon-carbon bonds within the polymer chains and gradually increased the aliphatic and aromatic conjugation. Simultaneously, a decrease in the optical gap as function of the ion fluencc is observed. For 40Ar 2+-bombarded samples the optical gap saturates around 0.7 eV lor f'luences of the order of 10 15 cm -2, At those fluences the electrical resistivity is relatively high (τ ≫ 10 6 Ω cm) , but for higher fluences it decreases by several orders of magnitude before saturation. The cross sections for the amorphisation, for the optical gap change and for the ester group bond reorganization processes were extracted.

  1. Reference region modeling approaches for amphetamine challenge studies with [11C]FLB 457 and PET.

    PubMed

    Sandiego, Christine M; Gallezot, Jean-Dominique; Lim, Keunpoong; Ropchan, Jim; Lin, Shu-fei; Gao, Hong; Morris, Evan D; Cosgrove, Kelly P

    2015-04-01

    Detecting fluctuations in synaptic dopamine levels in extrastriatal brain regions with [(11)C]FLB 457 and positron emission tomography (PET) is a valuable tool for studying dopaminergic dysfunction in psychiatric disorders. The evaluation of reference region modeling approaches would eliminate the need to obtain arterial input function data. Our goal was to explore the use of reference region models to estimate amphetamine-induced changes in [(11)C]FLB 457 dopamine D2/D3 binding. Six healthy tobacco smokers were imaged with [(11)C]FLB 457 at baseline and at 3 hours after amphetamine (0.4 to 0.5 mg/kg, per os) administration. Simplified reference tissue models, SRTM and SRTM2, were evaluated against the 2-tissue compartmental model (2TC) to estimate [(11)C]FLB 457 binding in extrastriatal regions of interest (ROIs), using the cerebellum as a reference region. No changes in distribution volume were observed in the cerebellum between scan conditions. SRTM and SRTM2 underestimated binding, compared with 2TC, in ROIs by 26% and 9%, respectively, with consistent bias between the baseline and postamphetamine scans. Postamphetamine, [(11)C]FLB 457 binding significantly decreased across several brain regions as measured with SRTM and SRTM2; no significant change was detected with 2TC. These data support the sensitivity of [(11)C]FLB 457 for measuring amphetamine-induced dopamine release in extrastriatal regions with SRTM and SRTM2. PMID:25564239

  2. Generalized decrease in brain glucose metabolism during fasting in humans studied by PET

    SciTech Connect

    Redies, C.; Hoffer, L.J.; Beil, C.; Marliss, E.B.; Evans, A.C.; Lariviere, F.; Marrett, S.; Meyer, E.; Diksic, M.; Gjedde, A.

    1989-06-01

    In prolonged fasting, the brain derives a large portion of its oxidative energy from the ketone bodies, beta-hydroxybutyrate and acetoacetate, thereby reducing whole body glucose consumption. Energy substrate utilization differs regionally in the brain of fasting rat, but comparable information has hitherto been unavailable in humans. We used positron emission tomography (PET) to study regional brain glucose and oxygen metabolism, blood flow, and blood volume in four obese subjects before and after a 3-wk total fast. Whole brain glucose utilization fell to 54% of control (postabsorptive) values (P less than 0.002). The whole brain rate constant for glucose tracer phosphorylation fell to 51% of control values (P less than 0.002). Both parameters decreased uniformly throughout the brain. The 2-fluoro-2-deoxy-D-glucose lumped constant decreased from a control value of 0.57 to 0.43 (P less than 0.01). Regional blood-brain barrier transfer coefficients for glucose tracer, regional oxygen utilization, blood flow, and blood volume were unchanged.

  3. Effects of emotion and reward motivation on neural correlates of episodic memory encoding: a PET study.

    PubMed

    Shigemune, Yayoi; Abe, Nobuhito; Suzuki, Maki; Ueno, Aya; Mori, Etsuro; Tashiro, Manabu; Itoh, Masatoshi; Fujii, Toshikatsu

    2010-05-01

    It is known that emotion and reward motivation promote long-term memory formation. It remains unclear, however, how and where emotion and reward are integrated during episodic memory encoding. In the present study, subjects were engaged in intentional encoding of photographs under four different conditions that were made by combining two factors (emotional valence, negative or neutral; and monetary reward value, high or low for subsequent successful recognition) during H2 15O positron emission tomography (PET) scanning. As for recognition performance, we found significant main effects of emotional valence (negative>neutral) and reward value (high value>low value), without an interaction between the two factors. Imaging data showed that the left amygdala was activated during the encoding conditions of negative pictures relative to neutral pictures, and the left orbitofrontal cortex was activated during the encoding conditions of high reward pictures relative to low reward pictures. In addition, conjunction analysis of these two main effects detected right hippocampal activation. Although we could not find correlations between recognition performance and activity of these three regions, we speculate that the right hippocampus may integrate the effects of emotion (processed in the amygdala) and monetary reward (processed in the orbitofrontal cortex) on episodic memory encoding.

  4. FDG PET imaging in sarcoidosis.

    PubMed

    Sobic-Saranovic, Dragana; Artiko, Vera; Obradovic, Vladimir

    2013-11-01

    The objective of this review is to highlight the clinical utility of FDG-PET/CT for evaluation of patients with chronic sarcoidosis. The emphasis was on the potential advantages and disadvantages of this technique in these patients based on which recommendations were made. The advantage of FDG-PET/CT technique is that it can visualize FDG accumulation in activated inflammatory cells and simultaneously provide PET and CT images. Of particular interest is the use of FDG-PET/CT for the staging and identification of occult sites and sites suitable for biopsy and for the assessment of inflammatory active sarcoidosis in patients with prolonged symptoms, especially when other markers of the disease are within normal values. FDG-PET/CT also provides a better visualization of extrathoracic sites of active sarcoidosis, such as in the bones, liver, spleen, and retroperitoneal lymph nodes. The use of FDG-PET/CT is of special interest in cardiac sarcoidosis because this potentially life-threatening disease is sometimes present in asymptomatic patients. FDG-PET/CT also has a role in the clinical management of patients with chronic persistent sarcoidosis, such as for planning treatment, monitoring response, and long-term follow-up. The limitations of FDG-PET/CT in patients with sarcoidosis are discussed in the context of a "sarcoidosis-lymphoma syndrome" and potentially excessive radiation exposure. Further prospective multicentre studies are needed to refine the clinical applications of FDG-PET/CT in patients with sarcoidosis and drive the field forward.

  5. Design of Infusion Schemes for Neuroreceptor Imaging: Application to [11C]Flumazenil-PET Steady-State Study

    PubMed Central

    Feng, Ling; Svarer, Claus; Madsen, Karine; Ziebell, Morten; Dyssegaard, Agnete; Ettrup, Anders; Hansen, Hanne Demant; Lehel, Szabolcs; Yndgaard, Stig; Paulson, Olaf Bjarne; Knudsen, Gitte Moos; Pinborg, Lars Hageman

    2016-01-01

    This study aims at developing a simulation system that predicts the optimal study design for attaining tracer steady-state conditions in brain and blood rapidly. Tracer kinetics was determined from bolus studies and used to construct the system. Subsequently, the system was used to design inputs for bolus infusion (BI) or programmed infusion (PI) experiments. Steady-state quantitative measurements can be made with one short scan and venous blood samples. The GABAA receptor ligand [11C]Flumazenil (FMZ) was chosen for this purpose, as it lacks a suitable reference region. Methods. Five bolus [11C]FMZ-PET scans were conducted, based on which population-based PI and BI schemes were designed and tested in five additional healthy subjects. The design of a PI was assisted by an offline feedback controller. Results. The system could reproduce the measurements in blood and brain. With PI, [11C]FMZ steady state was attained within 40 min, which was 8 min earlier than the optimal BI (B/I ratio = 55 min). Conclusions. The system can design both BI and PI schemes to attain steady state rapidly. For example, subjects can be [11C]FMZ-PET scanned after 40 min of tracer infusion for 40 min with venous sampling and a straight-forward quantification. This simulation toolbox is available for other PET-tracers. PMID:27123457

  6. Elevated serotonin transporter binding in depressed patients with Parkinson's disease: a preliminary PET study with [11C]DASB.

    PubMed

    Boileau, Isabelle; Warsh, Jerry J; Guttman, Mark; Saint-Cyr, Jean A; McCluskey, Tina; Rusjan, Pablo; Houle, Sylvain; Wilson, Alan A; Meyer, Jeffrey H; Kish, Stephen J

    2008-09-15

    This study investigated whether abnormalities in serotonin transporter binding occur in Parkinson's disease (PD) patients with concurrent depression. We estimated serotonin transporter levels in seven clinically depressed early-stage PD patients and in seven healthy matched-control subjects during a single positron emission tomography (PET) scan with the serotonin transporter radioligand, [(11)C]DASB. Depressed PD patients displayed a wide-spread increase (8-68%) in [(11)C]DASB specific binding outside of the striatum, which was significant in dorsolateral (37%) and prefrontal (68%) cortices. Elevated [(11)C]DASB binding was positively correlated with depressive symptoms but not with disease severity or duration. Compatible with recent PET/[(11)C]DASB findings in major depression, the present preliminary data suggest that increased [(11)C]DASB binding, possibly reflecting greater serotonin transporter density (up-regulation), might be a pathological feature of depression in Parkinson's disease-and possibly a characteristic of depressive illness in general.

  7. Comparison of 18F-FDG PET/CT and PET/MRI in patients with multiple myeloma

    PubMed Central

    Sachpekidis, Christos; Hillengass, Jens; Goldschmidt, Hartmut; Mosebach, Jennifer; Pan, Leyun; Schlemmer, Heinz-Peter; Haberkorn, Uwe; Dimitrakopoulou-Strauss, Antonia

    2015-01-01

    PET/MRI represents a promising hybrid imaging modality with several potential clinical applications. Although PET/MRI seems highly attractive in the diagnostic approach of multiple myeloma (MM), its role has not yet been evaluated. The aims of this prospective study are to evaluate the feasibility of 18F-FDG PET/MRI in detection of MM lesions, and to investigate the reproducibility of bone marrow lesions detection and quantitative data of 18F-FDG uptake between the functional (PET) component of PET/CT and PET/MRI in MM patients. The study includes 30 MM patients. All patients initially underwent 18F-FDG PET/CT (60 min p.i.), followed by PET/MRI (120 min p.i.). PET/CT and PET/MRI data were assessed and compared based on qualitative (lesion detection) and quantitative (SUV) evaluation. The hybrid PET/MRI system provided good image quality in all cases without artefacts. PET/MRI identified 65 of the 69 lesions, which were detectable with PET/CT (94.2%). Quantitative PET evaluations showed the following mean values in MM lesions: SUVaverage=5.5 and SUVmax=7.9 for PET/CT; SUVaverage=3.9 and SUVmax=5.8 for PET/MRI. Both SUVaverage and SUVmax were significantly higher on PET/CT than on PET/MRI. Spearman correlation analysis demonstrated a strong correlation between both lesional SUVaverage (r=0.744) and lesional SUVmax (r=0.855) values derived from PET/CT and PET/MRI. Regarding detection of myeloma skeletal lesions, PET/MRI exhibited equivalent performance to PET/CT. In terms of tracer uptake quantitation, a significant correlation between the two techniques was demonstrated, despite the statistically significant differences in lesional SUVs between PET/CT and PET/MRI. PMID:26550538

  8. Study on heat transfer coefficients during cooling of PET bottles for food beverages

    NASA Astrophysics Data System (ADS)

    Liga, Antonio; Montesanto, Salvatore; Mannella, Gianluca A.; La Carrubba, Vincenzo; Brucato, Valerio; Cammalleri, Marco

    2016-08-01

    The heat transfer properties of different cooling systems dealing with Poly-Ethylene-Terephthalate (PET) bottles were investigated. The heat transfer coefficient (Ug) was measured in various fluid dynamic conditions. Cooling media were either air or water. It was shown that heat transfer coefficients are strongly affected by fluid dynamics conditions, and range from 10 W/m2 K to nearly 400 W/m2 K. PET bottle thickness effect on Ug was shown to become relevant under faster fluid dynamics regimes.

  9. High-resolution PET (positron emission tomography) for medical science studies

    SciTech Connect

    Budinger, T.F.; Derenzo, S.E.; Huesman, R.H.; Jagust, W.J.; Valk, P.E. )

    1989-09-01

    One of the unexpected fruits of basic physics research and the computer revolution is the noninvasive imaging power available to today's physician. Technologies that were strictly the province of research scientists only a decade or two ago now serve as the foundations for such standard diagnostic tools as x-ray computer tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), ultrasound, single photon emission computed tomography (SPECT), and positron emission tomography (PET). Furthermore, prompted by the needs of both the practicing physician and the clinical researcher, efforts to improve these technologies continue. This booklet endeavors to describe the advantages of achieving high resolution in PET imaging. 6 refs., 21 figs.

  10. High-resolution PET [Positron Emission Tomography] for Medical Science Studies

    DOE R&D Accomplishments Database

    Budinger, T. F.; Derenzo, S. E.; Huesman, R. H.; Jagust, W. J.; Valk, P. E.

    1989-09-01

    One of the unexpected fruits of basic physics research and the computer revolution is the noninvasive imaging power available to today's physician. Technologies that were strictly the province of research scientists only a decade or two ago now serve as the foundations for such standard diagnostic tools as x-ray computer tomography (CT), magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), ultrasound, single photon emission computed tomography (SPECT), and positron emission tomography (PET). Furthermore, prompted by the needs of both the practicing physician and the clinical researcher, efforts to improve these technologies continue. This booklet endeavors to describe the advantages of achieving high resolution in PET imaging.

  11. Differential dopamine function in fibromyalgia.

    PubMed

    Albrecht, Daniel S; MacKie, Palmer J; Kareken, David A; Hutchins, Gary D; Chumin, Evgeny J; Christian, Bradley T; Yoder, Karmen K

    2016-09-01

    Approximately 30 % of Americans suffer from chronic pain disorders, such as fibromyalgia (FM), which can cause debilitating pain. Many pain-killing drugs prescribed for chronic pain disorders are highly addictive, have limited clinical efficacy, and do not treat the cognitive symptoms reported by many patients. The neurobiological substrates of chronic pain are largely unknown, but evidence points to altered dopaminergic transmission in aberrant pain perception. We sought to characterize the dopamine (DA) system in individuals with FM. Positron emission tomography (PET) with [(18)F]fallypride (FAL) was used to assess changes in DA during a working memory challenge relative to a baseline task, and to test for associations between baseline D2/D3 availability and experimental pain measures. Twelve female subjects with FM and 11 female controls completed study procedures. Subjects received one FAL PET scan while performing a "2-back" task, and one while performing a "0-back" (attentional control, "baseline") task. FM subjects had lower baseline FAL binding potential (BP) in several cortical regions relative to controls, including anterior cingulate cortex. In FM subjects, self-reported spontaneous pain negatively correlated with FAL BP in the left orbitofrontal cortex and parahippocampal gyrus. Baseline BP was significantly negatively correlated with experimental pain sensitivity and tolerance in both FM and CON subjects, although spatial patterns of these associations differed between groups. The data suggest that abnormal DA function may be associated with differential processing of pain perception in FM. Further studies are needed to explore the functional significance of DA in nociception and cognitive processing in chronic pain.

  12. (C-11)-thymidine PET imaging as a measure of DNA synthesis rate: A preliminary quantitative study of human brain glioblastoma

    SciTech Connect

    Wong, C.Y.O.; Yung, B.C.Y.; Conti, P.

    1994-05-01

    (C-11)-Thymidine (TdR) PET imaging can potentially be used to measure the tumor proliferation in-vivo and monitor treatment. Twenty-four stereotactic brain biopsies (SBB) following in-vivo bromodeoxyuridine (BUDR) under MRI guidance were obtained to correlate with TdR PET imaging of primary glioblastoma in human brain. Following data acquisition, standard 4 by 4 pixel (2mm/pixel) regions of interest (ROIs) were placed over the tumor site based on SBB and the corresponding homologous region of contralateral normal cortices. After correcting input function for major metabolites and subtracting TdR activity in the normal side from the tumor side of the brain, 2- and 3- compartmental analysis was performed for all the ROIs. Akaike :(AIC) and Bayes (BIC) information criteria was calculated to compare these 2 kinetic models for differentiating pure blood pool effects from TdR incorporation into DNA. Of 24 SBB regions, 20 non-overlapping and corresponding ROIs in PET were identified and quantified. Eight ROIs were selected based on the AIC, BIC and root-mean-square errors (RMSE < 0.1) (4 couldn`t be modelled and 8 most likely represented blood flow effects). The percentage (%) of BUDR per high power field area %BUDR labelling. The k3, the forward phosphorylation rate (hence an index of DNA synthesis), was categorized into 2 groups according to a threshold value of %BUDR/hpfa - 5%. The tumor regions with low proliferative index (%BUDR/hpfa<5%) have significantly lower k3 than those with high proliferative index (p<0.005). We also find that k4 is at least an order less than k3, suggesting minimal effects of dephosphorylation and efflux of metabolites. We conclude that 3-compartmental, 4-parameter modeling is adequate for TdR PET studies and k3 correlates with DNA synthesis rate.

  13. Pet therapy: dogs de-stress students.

    PubMed

    Young, Judith S

    2012-01-01

    Research supports the efficacy of the human-animal bond and pet therapy in a variety of settings. At nursing students' request at one school, the author began offering pet therapy prior to examinations. Anecdotal evidence of a study with the author's Golden Retriever, Goldilocks, demonstrates that pet therapy can reduce test anxiety and improve nursing student performance. PMID:23082615

  14. Lexical learning of the English language: a PET study in healthy French subjects.

    PubMed

    Raboyeau, Gaëlle; Marie, Nathalie; Balduyck, Sébastien; Gros, Hélène; Démonet, Jean-François; Cardebat, Dominique

    2004-08-01

    To investigate the neural correlates of word learning in adults, 10 right-handed French subjects who had learned English without mastering it performed an English and a French naming task during two PET sessions, one before (PET1) and the second after (PET2) a 4-week lexical training in English. Behavioral performance was collected during the two PET exams and 2 months after (T3). At T2, performance on English naming increased in all subjects; this improvement persisted at T3, with no correlation between English performance at T2 and T3. Cerebral activation during French naming mainly showed a left frontal temporal network. The pattern specifically associated with English lexical learning included, in addition to the anterior cingulate cortex involved in attentional processing and BAs 4/6 reflecting speech output, the right cerebellum and the left insular cortex that are linked to speech gesture learning, and the right medial temporal regions, likely to reflect the involvement of episodic memory during verbal learning. Correlations between English T2/T1 performance and English T2/T1 rCBF changes reinforced the hypothesis of intervention of episodic memory since they interested right frontal, hippocampal, and lateral temporal regions. 'Predictive' correlations between English T3/T2 performance and English T2/T1 rCBF changes showed, in good reminders, increased activities in the left posterior superior temporal sulcus and middle temporal cortex probably related to efficient semantic storage of learned words.

  15. In search of autobiographical memories: A PET study in the frontal variant of frontotemporal dementia.

    PubMed

    Piolino, Pascale; Chételat, Gaël; Matuszewski, Vanessa; Landeau, Brigitte; Mézenge, Florence; Viader, Fausto; de la Sayette, Vincent; Eustache, Francis; Desgranges, Béatrice

    2007-09-20

    Patients suffering from frontal variant of frontotemporal dementia (fv-FTD) undergo autobiographical amnesia encompassing all time periods. We previously demonstrated in a group of 20 fv-FTD patients that this impairment involved deficits in executive function and semantic memory for all periods as well as new episodic learning and behavioural changes for the most recent period covering the last 12 months [Matuszewski, V., Piolino, P., de la Sayette, V., Lalevée, C., Pélerin, A., Dupuy, B., et al. (2006). Retrieval mechanisms for autobiographical memories: Insights from the frontal variant of frontotemporal dementia, Neuropsychologia, 44, 2386-2397]. The aim of the present study was to unravel the neural bases of this impairment by mapping in a subgroup of patients correlations between resting-state brain glucose utilization measured by FDG-PET and measures of autobiographical memory (AM) using the TEMPau task which is designed to gauge personal event recollection across five life time periods. Like in our previous report, the group of patients was impaired regardless of time periods compared to healthy subjects providing generic memories instead of event specific sensory-perceptual-affective details, i.e., episodic memories. New data showed that the patients were also impaired in sense of reliving and self-perspective during retrieval. The cognitivo-metabolic correlations between the AM score and resting normalized FDG-Uptake were computed using statistical parametric mapping (SPM2) and controlling for age and dementia severity. They revealed that AM deficits were mainly subserved by the dysfunction of left-sided orbitofrontal and also temporal neocortical areas whatever the period. Additional analysis showed that specific memories were associated with left orbitofrontal areas whereas generic memories were mainly associated with the left temporal pole. This study supports the view that fv-FTD patients undergo a breakdown of generative processes which relies

  16. A FDG-PET Study of Metabolic Networks in Apolipoprotein E ε4 Allele Carriers.

    PubMed

    Yao, Zhijun; Hu, Bin; Zheng, Jiaxiang; Zheng, Weihao; Chen, Xuejiao; Gao, Xiang; Xie, Yuanwei; Fang, Lei

    2015-01-01

    Recently, some studies have applied the graph theory in brain network analysis in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). However, relatively little research has specifically explored the properties of the metabolic network in apolipoprotein E (APOE) ε4 allele carriers. In our study, all the subjects, including ADs, MCIs and NCs (normal controls) were divided into 165 APOE ε4 carriers and 165 APOE ε4 noncarriers. To establish the metabolic network for all brain regions except the cerebellum, cerebral glucose metabolism data obtained from FDG-PET (18F-fluorodeoxyglucose positron emission tomography) were segmented into 90 areas with automated anatomical labeling (AAL) template. Then, the properties of the networks were computed to explore the between-group differences. Our results suggested that both APOE ε4 carriers and noncarriers showed the small-world properties. Besides, compared with APOE ε4 noncarriers, the carriers showed a lower clustering coefficient. In addition, significant changes in 6 hub brain regions were found in between-group nodal centrality. Namely, compared with APOE ε4 noncarriers, significant decreases of the nodal centrality were found in left insula, right insula, right anterior cingulate, right paracingulate gyri, left cuneus, as well as significant increases in left paracentral lobule and left heschl gyrus in APOE ε4 carriers. Increased local short distance interregional correlations and disrupted long distance interregional correlations were found, which may support the point that the APOE ε4 carriers were more similar with AD or MCI in FDG uptake. In summary, the organization of metabolic network in APOE ε4 carriers indicated a less optimal pattern and APOE ε4 might be a risk factor for AD.

  17. Abnormal functional activation during a simple word repetition task: A PET study of adult dyslexics.

    PubMed

    McCrory, E; Frith, U; Brunswick, N; Price, C

    2000-09-01

    Eight dyslexic subjects, impaired on a range of tasks requiring phonological processing, were matched for age and general ability with six control subjects. Participants were scanned using positron emission tomography (PET) during three conditions: repeating real words, repeating pseudowords, and rest. In both groups, speech repetition relative to rest elicited widespread bilateral activation in areas associated with auditory processing of speech; there were no significant differences between words and pseudowords. However, irrespective of word type, the dyslexic group showed less activation than the control group in the right superior temporal and right post-central gyri and also in the left cerebellum. Notably, the right anterior superior temporal cortex (Brodmann's area 22 [BA 22]) was less activated in each of the eight dyslexic subjects, compared to each of the six control subjects. This deficit appears to be specific to auditory repetition as it was not detected in a previous study of reading which used the same sets of stimuli (Brunswick, N., McCrory, E., Price, C., Frith, C.D., & Frith, U. [1999]. Explicit and implicit processing of words and pseudowords by adult developmental dyslexics: A search for Wernicke's Wortschatz? Brain, 122, 1901-1917). This implies that the observed neural manifestation of developmental dyslexia is task-specific (i.e., functional rather than structural). Other studies of normal subjects indicate that attending to the phonetic structure of speech leads to a decrease in right-hemisphere processing. Lower right hemisphere activation in the dyslexic group may therefore indicate less processing of non-phonetic aspects of speech, allowing greater salience to be accorded to phonological aspects of attended speech. PMID:11054918

  18. Preclinical Study on GRPR-Targeted (68)Ga-Probes for PET Imaging of Prostate Cancer.

    PubMed

    Sun, Yao; Ma, Xiaowei; Zhang, Zhe; Sun, Ziyan; Loft, Mathias; Ding, Bingbing; Liu, Changhao; Xu, Liying; Yang, Meng; Jiang, Yuxin; Liu, Jianfeng; Xiao, Yuling; Cheng, Zhen; Hong, Xuechuan

    2016-08-17

    Gastrin-releasing peptide receptor (GRPR) targeted positron emission tomography (PET) is a highly promising approach for imaging of prostate cancer (PCa) in small animal models and patients. Developing a GRPR-targeted PET probe with excellent in vivo performance such as high tumor uptake, high contrast, and optimal pharmacokinetics is still very challenging. Herein, a novel bombesin (BBN) analogue (named SCH1) based on JMV594 peptide modified with an 8-amino octanoic acid spacer (AOC) was thus designed and conjugated with the metal chelator 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA). The resulting NODAGA-SCH1 was then radiolabeled with (68)Ga and evaluated for PET imaging of PCa. Compared with (68)Ga-NODAGA-JMV594 probe, (68)Ga-NODAGA-SCH1 exhibited excellent PET/CT imaging properties on PC-3 tumor-bearing nude mice, such as high tumor uptake (5.80 ± 0.42 vs 3.78 ± 0.28%ID/g, 2 h) and high tumor/muscle contrast (16.6 ± 1.50 vs 8.42 ± 0.61%ID/g, 2 h). Importantly, biodistribution data indicated a relatively similar accumulation of (68)Ga-NODAGA-SCH1 was observed in the liver (4.21 ± 0.42%ID/g) and kidney (3.41 ± 0.46%ID/g) suggesting that the clearance is through both the kidney and the liver. Overall, (68)Ga-NODAGA-SCH1 showed promising in vivo properties and is a promising candidate for translation into clinical PET-imaging of PCa patients.

  19. Preclinical Study on GRPR-Targeted (68)Ga-Probes for PET Imaging of Prostate Cancer.

    PubMed

    Sun, Yao; Ma, Xiaowei; Zhang, Zhe; Sun, Ziyan; Loft, Mathias; Ding, Bingbing; Liu, Changhao; Xu, Liying; Yang, Meng; Jiang, Yuxin; Liu, Jianfeng; Xiao, Yuling; Cheng, Zhen; Hong, Xuechuan

    2016-08-17

    Gastrin-releasing peptide receptor (GRPR) targeted positron emission tomography (PET) is a highly promising approach for imaging of prostate cancer (PCa) in small animal models and patients. Developing a GRPR-targeted PET probe with excellent in vivo performance such as high tumor uptake, high contrast, and optimal pharmacokinetics is still very challenging. Herein, a novel bombesin (BBN) analogue (named SCH1) based on JMV594 peptide modified with an 8-amino octanoic acid spacer (AOC) was thus designed and conjugated with the metal chelator 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA). The resulting NODAGA-SCH1 was then radiolabeled with (68)Ga and evaluated for PET imaging of PCa. Compared with (68)Ga-NODAGA-JMV594 probe, (68)Ga-NODAGA-SCH1 exhibited excellent PET/CT imaging properties on PC-3 tumor-bearing nude mice, such as high tumor uptake (5.80 ± 0.42 vs 3.78 ± 0.28%ID/g, 2 h) and high tumor/muscle contrast (16.6 ± 1.50 vs 8.42 ± 0.61%ID/g, 2 h). Importantly, biodistribution data indicated a relatively similar accumulation of (68)Ga-NODAGA-SCH1 was observed in the liver (4.21 ± 0.42%ID/g) and kidney (3.41 ± 0.46%ID/g) suggesting that the clearance is through both the kidney and the liver. Overall, (68)Ga-NODAGA-SCH1 showed promising in vivo properties and is a promising candidate for translation into clinical PET-imaging of PCa patients. PMID:27399868

  20. Comparison of Cell Proliferation, Protein, and Glucose Metabolism in Musculoskeletal Tumors in a PET Study

    PubMed Central

    Tian, Mei; Zhang, Hong; Endo, Keigo

    2011-01-01

    11C-choline and 18F-FAMT are known to correlate with tumor cell proliferation and amino acid metabolism. We investigated the ability of 11C-Choline and 18F-FAMT PET in diagnosis of musculoskeletal tumors in thirty-six patients in comparison of 18F-FDG PET. 11C-Choline and 18F-FDG PET were positive in all the malignant tumors (n = 13), whereas 18F-FAMT was positive in 11 tumors. The mean SUVs for malignant tumors were significantly higher than those for benign lesions in all three tracers imaging. A moderate correlation was found between 11C-Choline and 18F-FDG (r = 0.540, P < .05), or 18F-FAMT and FDG (r = 0.596, P < .05). The diagnostic sensitivity and specificity for malignancy were 91.7% and 71.4%, respectively, using 11C-choline with a SUV cut-off of 2.69. The sensitivity and specificity of 18F-FAMT for malignancy were 66.7% and 85.7%, respectively, using a SUV cut-off of 1.26. For 18F-FDG, using a SUV cut-off of 2.77, the sensitivity and specificity were 83.3% and 71.4%, respectively. According to ROC analysis, the ROC curves for 11C-Choline, 18F-FAMT, and 18F-FDG were 0.855, 0.734, and 0.847, respectively. 11C-Choline PET is superior in the visualization of musculoskeletal tumors with high contrast imaging, whereas the combination of 18F-FAMT and 18F-FDG PET provides valuable information for the preoperative planning in patients with musculoskeletal tumors. PMID:21738405

  1. A study of response of a LuYAP:Ce array with innovative assembling for PET

    NASA Astrophysics Data System (ADS)

    Pani, Roberto; Cinti, Maria Nerina; Scafè, Raffaele; Bennati, Paolo; Lo Meo, Sergio; Preziosi, Enrico; Pellegrini, Rosanna; De Vincentis, Giuseppe; Sacco, Donatella; Fabbri, Andrea

    2015-09-01

    We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2 mm×2 mm×10 mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015 mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2 mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated 99mTc radioisotope (140 keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4. Although the dielectric coating pixel insulator cannot overcome the inherent limitations of LuYAP crystal due to its self-absorption of light (still present), this study demonstrated that the new coating treatment allows better light collection (nearly close to the expected one) with in addition a very good uniformity between different pixels. These results confirm the high potentiality of this coating for any other crystal array suited for imaging application and new expectations for the use of LuYAP for PET systems.

  2. Attenuation correction for freely moving small animal brain PET studies based on a virtual scanner geometry

    NASA Astrophysics Data System (ADS)

    Angelis, G. I.; Kyme, A. Z.; Ryder, W. J.; Fulton, R. R.; Meikle, S. R.

    2014-10-01

    Attenuation correction in positron emission tomography brain imaging of freely moving animals is a very challenging problem since the torso of the animal is often within the field of view and introduces a non negligible attenuating factor that can degrade the quantitative accuracy of the reconstructed images. In the context of unrestrained small animal imaging, estimation of the attenuation correction factors without the need for a transmission scan is highly desirable. An attractive approach that avoids the need for a transmission scan involves the generation of the hull of the animal’s head based on the reconstructed motion corrected emission images. However, this approach ignores the attenuation introduced by the animal’s torso. In this work, we propose a virtual scanner geometry which moves in synchrony with the animal’s head and discriminates between those events that traversed only the animal’s head (and therefore can be accurately compensated for attenuation) and those that might have also traversed the animal’s torso. For each recorded pose of the animal’s head a new virtual scanner geometry is defined and therefore a new system matrix must be calculated leading to a time-varying system matrix. This new approach was evaluated on phantom data acquired on the microPET Focus 220 scanner using a custom-made phantom and step-wise motion. Results showed that when the animal’s torso is within the FOV and not appropriately accounted for during attenuation correction it can lead to bias of up to 10% . Attenuation correction was more accurate when the virtual scanner was employed leading to improved quantitative estimates (bias < 2%), without the need to account for the attenuation introduced by the extraneous compartment. Although the proposed method requires increased computational resources, it can provide a reliable approach towards quantitatively accurate attenuation correction for freely moving animal studies.

  3. Comparative study of ¹⁸F-FDG-PET/CT imaging and serum hTERT mRNA quantification in cancer diagnosis.

    PubMed

    Ping, Bingqiong; Tsuno, Satoshi; Wang, Xinhui; Ishihara, Yoshitaka; Yamashita, Taro; Miura, Keigo; Miyoshi, Fuminori; Shinohara, Yuki; Matsuki, Tsutomu; Tanabe, Yoshio; Tanaka, Noriaki; Ogawa, Toshihide; Shiota, Goshi; Miura, Norimasa

    2015-10-01

    We have reported on the clinical usefulness of human telomerase reverse transcriptase (hTERT) mRNA quantification in sera in patients with several cancers. Positron emission tomography-computed tomography (PET/CT) using ¹⁸F-fluorodeoxyglucose (FDG) has recently become an excellent modality for detecting cancer. We performed a diagnostic comparative study of FDG-PET/CT and hTERT mRNA quantification in patients with cancer. Four hundred seventy subjects, including 125 healthy individuals and 345 outpatients with cancer who had received medical treatments for cancer in their own or other hospitals, were enrolled. The subjects were diagnosed by FDG-PET/CT, and we measured their serum hTERT mRNA levels using real-time RT-PCR, correlating the quantified values with the clinical course. In this prospective study, we statistically assessed the sensitivity and specificity, and their clinical significance. hTERT mRNA and FDG-PET/CT were demonstrated to be correlated with the clinical parameters of metastasis and recurrence (P < 0.001), and of recurrence and tumor number in cancer compared with noncancer patients, respectively. A multivariate analysis showed a significant difference in the detection by FDG-PET/CT, ¹⁸F-FDG uptake, the detection by hTERT mRNA, and age. The use of both FDG-PET/CT and hTERT mRNA resulted in a positivity of 94.4% (221/234) for the detection of viable tumor cells. FDG-PET/CT is superior to hTERT mRNA quantification in the early detection of cancer and combinative use of FDG-PET/CT and hTERT mRNA may improve the diagnostic accuracy of cancer.

  4. Pet Therapy.

    ERIC Educational Resources Information Center

    Kavanagh, Kim

    1994-01-01

    This resource guide presents information on a variety of ways that animals can be used as a therapeutic modality with people having disabilities. Aspects addressed include: pet ownership and selection criteria; dogs (including service dogs, hearing/signal dogs, seeing leader dogs, and social/specialty dogs); horseriding for both therapy and fun;…

  5. Comparison of prone versus supine 18F-FDG-PET of locally advanced breast cancer: Phantom and preliminary clinical studies

    SciTech Connect

    Williams, Jason M.; Rani, Sudheer D.; Li, Xia; Whisenant, Jennifer G.; Abramson, Richard G.; Arlinghaus, Lori R.; Lee, Tzu-Cheng; MacDonald, Lawrence R.; Partridge, Savannah C.; Kang, Hakmook; Linden, Hannah M.; Kinahan, Paul E.; Yankeelov, Thomas E.

    2015-07-15

    Purpose: Previous studies have demonstrated how imaging of the breast with patients lying prone using a supportive positioning device markedly facilitates longitudinal and/or multimodal image registration. In this contribution, the authors’ primary objective was to determine if there are differences in the standardized uptake value (SUV) derived from [{sup 18}F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in breast tumors imaged in the standard supine position and in the prone position using a specialized positioning device. Methods: A custom positioning device was constructed to allow for breast scanning in the prone position. Rigid and nonrigid phantom studies evaluated differences in prone and supine PET. Clinical studies comprised 18F-FDG-PET of 34 patients with locally advanced breast cancer imaged in the prone position (with the custom support) followed by imaging in the supine position (without the support). Mean and maximum values (SUV{sub peak} and SUV{sub max}, respectively) were obtained from tumor regions-of-interest for both positions. Prone and supine SUV were linearly corrected to account for the differences in 18F-FDG uptake time. Correlation, Bland–Altman, and nonparametric analyses were performed on uptake time-corrected and uncorrected data. Results: SUV from the rigid PET breast phantom imaged in the prone position with the support device was 1.9% lower than without the support device. In the nonrigid PET breast phantom, prone SUV with the support device was 5.0% lower than supine SUV without the support device. In patients, the median (range) difference in uptake time between prone and supine scans was 16.4 min (13.4–30.9 min), which was significantly—but not completely—reduced by the linear correction method. SUV{sub peak} and SUV{sub max} from prone versus supine scans were highly correlated, with concordance correlation coefficients of 0.91 and 0.90, respectively. Prone SUV{sub peak} and SUV{sub max} were

  6. SU-D-201-05: Phantom Study to Determine Optimal PET Reconstruction Parameters for PET/MR Imaging of Y-90 Microspheres Following Radioembolization

    SciTech Connect

    Maughan, N; Conti, M; Parikh, P; Faul, D; Laforest, R

    2015-06-15

    Purpose: Imaging Y-90 microspheres with PET/MRI following hepatic radioembolization has the potential for predicting treatment outcome and, in turn, improving patient care. The positron decay branching ratio, however, is very small (32 ppm), yielding images with poor statistics even when therapy doses are used. Our purpose is to find PET reconstruction parameters that maximize the PET recovery coefficients and minimize noise. Methods: An initial 7.5 GBq of Y-90 chloride solution was used to fill an ACR phantom for measurements with a PET/MRI scanner (Siemens Biograph mMR). Four hot cylinders and a warm background activity volume of the phantom were filled with a 10:1 ratio. Phantom attenuation maps were derived from scaled CT images of the phantom and included the MR phased array coil. The phantom was imaged at six time points between 7.5–1.0 GBq total activity over a period of eight days. PET images were reconstructed via OP-OSEM with 21 subsets and varying iteration number (1–5), post-reconstruction filter size (5–10 mm), and either absolute or relative scatter correction. Recovery coefficients, SNR, and noise were measured as well as total activity in the phantom. Results: For the 120 different reconstructions, recovery coefficients ranged from 0.1–0.6 and improved with increasing iteration number and reduced post-reconstruction filter size. SNR, however, improved substantially with lower iteration numbers and larger post-reconstruction filters. From the phantom data, we found that performing 2 iterations, 21 subsets, and applying a 5 mm Gaussian post-reconstruction filter provided optimal recovery coefficients at a moderate noise level for a wide range of activity levels. Conclusion: The choice of reconstruction parameters for Y-90 PET images greatly influences both the accuracy of measurements and image quality. We have found reconstruction parameters that provide optimal recovery coefficients with minimized noise. Future work will include the effects

  7. Monitoring of anti-cancer treatment with (18)F-FDG and (18)F-FLT PET: a comprehensive review of pre-clinical studies.

    PubMed

    Jensen, Mette Munk; Kjaer, Andreas

    2015-01-01

    Functional imaging of solid tumors with positron emission tomography (PET) imaging is an evolving field with continuous development of new PET tracers and discovery of new applications for already implemented PET tracers. During treatment of cancer patients, a general challenge is to measure treatment effect early in a treatment course and by that to stratify patients into responders and non-responders. With 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) and 3'-deoxy-3'-[(18)F]fluorothymidine((18)F-FLT) two of the cancer hallmarks, altered energy metabolism and increased cell proliferation, can be visualized and quantified non-invasively by PET. With (18)F-FDG and (18)F-FLT PET changes in energy metabolism and cell proliferation can thereby be determined after initiation of cancer treatment in both clinical and pre-clinical studies in order to predict, at an early time-point, treatment response. It is hypothesized that decreases in glycolysis and cell proliferation may occur in tumors that are sensitive to the applied cancer therapeutics and that tumors that are resistant to treatment will show unchanged glucose metabolism and cell proliferation. Whether (18)F-FDG and/or (18)F-FLT PET can be used for prediction of treatment response has been analyzed in many studies both following treatment with conventional chemotherapeutic agents but also following treatment with different targeted therapies, e.g. monoclonal antibodies and small molecules inhibitors. The results from these studies have been most variable; in some studies early changes in (18)F-FDG and (18)F-FLT uptake predicted later tumor regression whereas in other studies no change in tracer uptake was observed despite the treatment being effective. The present review gives an overview of pre-clinical studies that have used (18)F-FDG and/or (18)F-FLT PET for response monitoring of cancer therapeutics.

  8. Monitoring of anti-cancer treatment with 18F-FDG and 18F-FLT PET: a comprehensive review of pre-clinical studies

    PubMed Central

    Jensen, Mette Munk; Kjaer, Andreas

    2015-01-01

    Functional imaging of solid tumors with positron emission tomography (PET) imaging is an evolving field with continuous development of new PET tracers and discovery of new applications for already implemented PET tracers. During treatment of cancer patients, a general challenge is to measure treatment effect early in a treatment course and by that to stratify patients into responders and non-responders. With 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) and 3’-deoxy-3’-[18F]fluorothymidine(18F-FLT) two of the cancer hallmarks, altered energy metabolism and increased cell proliferation, can be visualized and quantified non-invasively by PET. With 18F-FDG and 18F-FLT PET changes in energy metabolism and cell proliferation can thereby be determined after initiation of cancer treatment in both clinical and pre-clinical studies in order to predict, at an early time-point, treatment response. It is hypothesized that decreases in glycolysis and cell proliferation may occur in tumors that are sensitive to the applied cancer therapeutics and that tumors that are resistant to treatment will show unchanged glucose metabolism and cell proliferation. Whether 18F-FDG and/or 18F-FLT PET can be used for prediction of treatment response has been analyzed in many studies both following treatment with conventional chemotherapeutic agents but also following treatment with different targeted therapies, e.g. monoclonal antibodies and small molecules inhibitors. The results from these studies have been most variable; in some studies early changes in 18F-FDG and 18F-FLT uptake predicted later tumor regression whereas in other studies no change in tracer uptake was observed despite the treatment being effective. The present review gives an overview of pre-clinical studies that have used 18F-FDG and/or 18F-FLT PET for response monitoring of cancer therapeutics. PMID:26550536

  9. Varenicline-Induced Elevation of Dopamine in Smokers: A Preliminary [(11)C]-(+)-PHNO PET Study.

    PubMed

    Di Ciano, Patricia; Guranda, Mihail; Lagzdins, Dina; Tyndale, Rachel F; Gamaleddin, Islam; Selby, Peter; Boileau, Isabelle; Le Foll, Bernard

    2016-05-01

    Varenicline, a nicotinic partial agonist, is the most effective treatment for tobacco use disorder. However, its mechanism of action is still unclear and may involve stimulating dopaminergic transmission. Here we used PET imaging with [(11)C]-(+)-PHNO to explore for the first time the impact of varenicline on dopamine transmission in the D2-rich striatum and D3-rich extra-striatal regions and its relationship with craving, withdrawal and smoking. Eleven treatment-seeking smokers underwent two PET scans with [(11)C]-(+)-PHNO, each following 12-h overnight smoking abstinence both prior to receiving varenicline and following 10-11 days of varenicline treatment (ie, at steady-state drug levels). Subjective measures of craving and urges to smoke were also assessed on the days of the PET scans. Varenicline treatment significantly reduced [(11)C]-(+)-PHNO binding in the dorsal caudate (p=0.008) and reduced some craving measures. These findings provide the first evidence that varenicline is able to increase DA levels in the human brain, a factor that may contribute to its therapeutic efficacy. PMID:26442600

  10. Quantitative simultaneous PET-MR imaging

    NASA Astrophysics Data System (ADS)

    Ouyang, Jinsong; Petibon, Yoann; Huang, Chuan; Reese, Timothy G.; Kolnick, Aleksandra L.; El Fakhri, Georges

    2014-06-01

    Whole-body PET is currently limited by the degradation due to patient motion. Respiratory motion degrades imaging studies of the abdomen. Similarly, both respiratory and cardiac motions significantly hamper the assessment of myocardial ischemia and/or metabolism in perfusion and viability cardiac PET studies. Based on simultaneous PET-MR, we have developed robust and accurate MRI methods allowing the tracking and measurement of both respiratory and cardiac motions during abdominal or cardiac studies. Our list-mode iterative PET reconstruction framework incorporates the measured motion fields into PET emission system matrix as well as the time-dependent PET attenuation map and the position dependent point spread function. Our method significantly enhances the PET image quality as compared to conventional methods.

  11. Recent Developments in PET Instrumentation

    PubMed Central

    Peng, Hao; Levin, Craig S.

    2013-01-01

    Positron emission tomography (PET) is used in the clinic and in vivo small animal research to study molecular processes associated with diseases such as cancer, heart disease, and neurological disorders, and to guide the discovery and development of new treatments. This paper reviews current challenges of advancing PET technology and some of newly developed PET detectors and systems. The paper focuses on four aspects of PET instrumentation: high photon detection sensitivity; improved spatial resolution; depth-of-interaction (DOI) resolution and time-of-flight (TOF). Improved system geometry, novel non-scintillator based detectors, and tapered scintillation crystal arrays are able to enhance the photon detection sensitivity of a PET system. Several challenges for achieving high resolution with standard scintillator-based PET detectors are discussed. Novel detectors with 3-D positioning capability have great potential to be deployed in PET for achieving spatial resolution better than 1 mm, such as cadmium-zinc-telluride (CZT) and position-sensitive avalanche photodiodes (PSAPDs). DOI capability enables a PET system to mitigate parallax error and achieve uniform spatial resolution across the field-of-view (FOV). Six common DOI designs, as well as advantages and limitations of each design, are discussed. The availability of fast scintillation crystals such as LaBr3, and the silicon photomultiplier (SiPM) greatly advances TOF-PET development. Recent instrumentation and initial results of clinical trials are briefly presented. If successful, these technology advances, together with new probe molecules, will substantially enhance the molecular sensitivity of PET and thus increase its role in preclinical and clinical research as well as evaluating and managing disease in the clinic. PMID:20497121

  12. Variance of Standardized Uptake Values for FDG-PET/CT Greater in Clinical Practice than Under Ideal Study Settings

    PubMed Central

    Kumar, Virendra; Nath, Kavindra; Berman, Claudia G.; Kim, Jongphil; Tanvetyanon, Tawee; Chiappori, Alberto A; Gatenby, Robert A.; Gillies, Robert J.; Eikman, Edward A.

    2012-01-01

    Purpose Measurement variance affects the clinical effectiveness of PET-based measurement as a semi-quantitative imaging biomarker for cancer response in individual patients and for planning clinical trials. In this study, we measured test-retest reproducibility of SUV measurements under clinical practice conditions, and recorded recognized deviations from protocol compliance. Methods Instrument performance calibration, display and analyses conformed to manufacture recommendations. Baseline clinical 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET/CT examinations were performed and then repeated at 1 – 7 days. Intended scan initiation uptake period was to repeat the examinations at the same time for each study after injection of 12 mCi FDG tracer. Avidity of uptake was measured in 62 tumors in 21 patients as standardized uptake value for maximum voxel (SUVmax) and for a mean of sampled tumor voxels (SUVmean). Results The range of SUVmax and SUVmean was 1.07–21.47 and 0.91–14.69, respectively. Intraclass correlation coefficient (ICC) between log of SUVmax and log of SUVmean was 0.93 (95% CI: 0.88–0.95) and 0.92 (95% CI: 0.87–0.95), respectively. Correlation analysis failed to show an effect on uptake period variation on SUV measurements between the two examinations, suggesting additional sources of noise. The threshold criteria for relative difference from baseline for the 95% confidence interval were ±49% or ±44% for SUVmax or SUVmean, respectively. Conclusion Variance of SUV for FDG-PET/CT in current clinical practice in a single institution was greater than expected when compared to benchmarks reported under stringent efficacy study settings. Under comparable clinical practice conditions, interpretation of changes in tumor avidity in individuals, and assumptions in planning clinical trials may be affected. PMID:23354032

  13. Can technical characteristics predict clinical performance in PET/CT imaging? A correlation study for thyroid cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Kallergi, Maria; Menychtas, Dimitrios; Georgakopoulos, Alexandros; Pianou, Nikoletta; Metaxas, Marinos; Chatziioannou, Sofia

    2013-03-01

    The purpose of this study was to determine whether image characteristics could be used to predict the outcome of ROC studies in PET/CT imaging. Patients suspected for recurrent thyroid cancer underwent a standard whole body (WB) examination and an additional high-resolution head-and-neck (HN) F18-FDG PET/CT scan. The value of the latter was determined with an ROC study, the results of which showed that the WB+HN combination was better than WB alone for thyroid cancer detection and diagnosis. Following the ROC experiment, the WB and HN images of confirmed benign or malignant thyroid disease were analyzed and first and second order textural features were determined. Features included minimum, mean, and maximum intensity, as well as contrast in regions of interest encircling the thyroid lesions. Lesion size and standard uptake values (SUV) were also determined. Bivariate analysis was applied to determine relationships between WB and HN features and between observer ROC responses and the various feature values. The two sets showed significant associations in the values of SUV, contrast, and lesion size. They were completely different when the intensities were considered; no relationship was found between the WB minimum, maximum, and mean ROI values and their HN counterparts. SUV and contrast were the strongest predictors of ROC performance on PET/CT examinations of thyroid cancer. The high resolution HN images seem to enhance these relationships but without a single dramatic effect as was projected from the ROC results. A combination of features from both WB and HN datasets may possibly be a more robust predictor of ROC performance.

  14. High-resolution imaging of the large non-human primate brain using microPET: a feasibility study

    NASA Astrophysics Data System (ADS)

    Naidoo-Variawa, S.; Hey-Cunningham, A. J.; Lehnert, W.; Kench, P. L.; Kassiou, M.; Banati, R.; Meikle, S. R.

    2007-11-01

    The neuroanatomy and physiology of the baboon brain closely resembles that of the human brain and is well suited for evaluating promising new radioligands in non-human primates by PET and SPECT prior to their use in humans. These studies are commonly performed on clinical scanners with 5 mm spatial resolution at best, resulting in sub-optimal images for quantitative analysis. This study assessed the feasibility of using a microPET animal scanner to image the brains of large non-human primates, i.e. papio hamadryas (baboon) at high resolution. Factors affecting image accuracy, including scatter, attenuation and spatial resolution, were measured under conditions approximating a baboon brain and using different reconstruction strategies. Scatter fraction measured 32% at the centre of a 10 cm diameter phantom. Scatter correction increased image contrast by up to 21% but reduced the signal-to-noise ratio. Volume resolution was superior and more uniform using maximum a posteriori (MAP) reconstructed images (3.2-3.6 mm3 FWHM from centre to 4 cm offset) compared to both 3D ordered subsets expectation maximization (OSEM) (5.6-8.3 mm3) and 3D reprojection (3DRP) (5.9-9.1 mm3). A pilot 18F-2-fluoro-2-deoxy-d-glucose ([18F]FDG) scan was performed on a healthy female adult baboon. The pilot study demonstrated the ability to adequately resolve cortical and sub-cortical grey matter structures in the baboon brain and improved contrast when images were corrected for attenuation and scatter and reconstructed by MAP. We conclude that high resolution imaging of the baboon brain with microPET is feasible with appropriate choices of reconstruction strategy and corrections for degrading physical effects. Further work to develop suitable correction algorithms for high-resolution large primate imaging is warranted.

  15. A pilot study of the prognostic significance of metabolic tumor size measurements in PET/CT imaging of lymphomas

    NASA Astrophysics Data System (ADS)

    Kallergi, Maria; Botsivali, Maria; Politis, Nikolaos; Menychtas, Dimitrios; Georgakopoulos, Alexandros; Chatziioannou, Sofia

    2015-03-01

    This study explores changes in metabolic tumor volume, metabolic tumor diameter, and maximum standardized uptake value (SUVmax), for earlier and more accurate identification of lymphomas' response to treatment using 18F- FDG PET/CT. Pre- and post-treatment PET/CT studies of 20 patients with Hodgkin disease (HL) and 7 patients with non- Hodgkin lymphoma (NHL) were retrospectively selected for this study. The diameter and volume of the metabolic tumor was determined by an in-house developed adaptive local thresholding technique based on a 50% threshold of the maximum pixel value within a region. Statistical analysis aimed at exploring associations between metabolic size measurements and SUVmax and the ability of the three biomarkers to predict the patients' response to treatment as defined by the four classes in the European Organization for Research and Treatment of Cancer (EORTC) guidelines. Results indicated moderate correlations between % change in metabolic tumor volume and % change in metabolic tumor maximum diameter (R=0.51) and between % change in maximum diameter and % change in SUVmax (R=0.52). The correlation between % change in tumor volume and % change in SUVmax was weak (R=0.24). The % change in metabolic tumor size, either volume or diameter, was a "very strong" predictor of response to treatment (R=0.89), stronger than SUVmax (R=0.63). In conclusion, metabolic tumor volume could have important prognostic value, possibly higher than maximum metabolic diameter or SUVmax that are currently the standard of practice. Volume measurements, however, should be based on robust and standardized segmentation methodologies to avoid variability. In addition, SUV-peak or lean body mass corrected SUV-peak may be a better PET biomarker than SUVmax when SUV-volume combinations are considered.

  16. Preclinical acute toxicity, biodistribution, pharmacokinetics, radiation dosimetry and microPET imaging studies of [(18)F]fluorocholine in mice.

    PubMed

    Silveira, Marina B; Ferreira, Soraya M Z M D; Nascimento, Leonardo T C; Costa, Flávia M; Mendes, Bruno M; Ferreira, Andrea V; Malamut, Carlos; Silva, Juliana B; Mamede, Marcelo

    2016-10-01

    [(18)F]Fluorocholine ([(18)F]FCH) has been proven to be effective in prostate cancer. Since [(18)F]FCH is classified as a new radiopharmaceutical in Brazil, preclinical safety and efficacy data are required to support clinical trials and to obtain its approval. The aim of this work was to perform acute toxicity, biodistribution, pharmacokinetics, radiation dosimetry and microPET imaging studies of [(18)F]FCH. The results could support its use in nuclear medicine as an important piece of work for regulatory in Brazil.

  17. Preclinical acute toxicity, biodistribution, pharmacokinetics, radiation dosimetry and microPET imaging studies of [(18)F]fluorocholine in mice.

    PubMed

    Silveira, Marina B; Ferreira, Soraya M Z M D; Nascimento, Leonardo T C; Costa, Flávia M; Mendes, Bruno M; Ferreira, Andrea V; Malamut, Carlos; Silva, Juliana B; Mamede, Marcelo

    2016-10-01

    [(18)F]Fluorocholine ([(18)F]FCH) has been proven to be effective in prostate cancer. Since [(18)F]FCH is classified as a new radiopharmaceutical in Brazil, preclinical safety and efficacy data are required to support clinical trials and to obtain its approval. The aim of this work was to perform acute toxicity, biodistribution, pharmacokinetics, radiation dosimetry and microPET imaging studies of [(18)F]FCH. The results could support its use in nuclear medicine as an important piece of work for regulatory in Brazil. PMID:27509594

  18. Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies

    NASA Astrophysics Data System (ADS)

    Xiong, Guoming; Cumming, Paul; Todica, Andrei; Hacker, Marcus; Bartenstein, Peter; Böning, Guido

    2012-12-01

    Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [18F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach.

  19. Noninvasive image derived heart input function for CMRglc measurements in small animal slow infusion FDG PET studies.

    PubMed

    Xiong, Guoming; Paul, Cumming; Todica, Andrei; Hacker, Marcus; Bartenstein, Peter; Böning, Guido

    2012-12-01

    Absolute quantitation of the cerebral metabolic rate for glucose (CMRglc) can be obtained in positron emission tomography (PET) studies when serial measurements of the arterial [(18)F]-fluoro-deoxyglucose (FDG) input are available. Since this is not always practical in PET studies of rodents, there has been considerable interest in defining an image-derived input function (IDIF) by placing a volume of interest (VOI) within the left ventricle of the heart. However, spill-in arising from trapping of FDG in the myocardium often leads to progressive contamination of the IDIF, which propagates to underestimation of the magnitude of CMRglc. We therefore developed a novel, non-invasive method for correcting the IDIF without scaling to a blood sample. To this end, we first obtained serial arterial samples and dynamic FDG-PET data of the head and heart in a group of eight anaesthetized rats. We fitted a bi-exponential function to the serial measurements of the IDIF, and then used the linear graphical Gjedde-Patlak method to describe the accumulation in myocardium. We next estimated the magnitude of myocardial spill-in reaching the left ventricle VOI by assuming a Gaussian point-spread function, and corrected the measured IDIF for this estimated spill-in. Finally, we calculated parametric maps of CMRglc using the corrected IDIF, and for the sake of comparison, relative to serial blood sampling from the femoral artery. The uncorrected IDIF resulted in 20% underestimation of the magnitude of CMRglc relative to the gold standard arterial input method. However, there was no bias with the corrected IDIF, which was robust to the variable extent of myocardial tracer uptake, such that there was a very high correlation between individual CMRglc measurements using the corrected IDIF with gold-standard arterial input results. Based on simulation, we furthermore find that electrocardiogram-gating, i.e. ECG-gating is not necessary for IDIF quantitation using our approach. PMID:23160517

  20. Competitive advantage of PET/MRI.

    PubMed

    Jadvar, Hossein; Colletti, Patrick M

    2014-01-01

    Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved.

  1. Measuring cigarette smoking-induced cortical dopamine release: A [¹¹C]FLB-457 PET study.

    PubMed

    Wing, Victoria C; Payer, Doris E; Houle, Sylvain; George, Tony P; Boileau, Isabelle

    2015-05-01

    Striatal dopamine (DA) is thought to have a fundamental role in the reinforcing effects of tobacco smoking and nicotine. Microdialysis studies indicate that nicotine also increases DA in extrastriatal brain areas, but much less is known about its role in addiction. High-affinity D2/3 receptor radiotracers permit the measurement of cortical DA in humans using positron emission tomography (PET). [(11)C]FLB-457 PET scans were conducted in 10 nicotine-dependent daily smokers after overnight abstinence and reinstatement of smoking. Voxel-wise [(11)C]-FLB-457-binding potential (BPND) in the frontal lobe, insula, and limbic regions was estimated in the two conditions. Paired t-tests showed BPND values were reduced following smoking (an indirect index of DA release). The overall peak t was located in the cingulate gyrus, which was part of a larger medial cluster (BPND change -12.1±9.4%) and this survived false discovery rate correction for multiple comparisons. Clusters were also identified in the left anterior cingulate cortex/medial frontal gyrus, bilateral prefrontal cortex (PFC), bilateral amygdala, and the left insula. This is the first demonstration of tobacco smoking-induced cortical DA release in humans; it may be the result of both pharmacological (nicotine) and non-pharmacological factors (tobacco cues). Abstinence increased craving but had minimal cognitive effects, thus limiting correlation analyses. However, given that the cingulate cortex, PFC, insula, and amygdala are thought to have important roles in tobacco craving, cognition, and relapse, these associations warrant investigation in a larger sample. [(11)C]FLB-457 PET imaging may represent a useful tool to investigate individual differences in tobacco addiction severity and treatment response. PMID:25502631

  2. Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain

    SciTech Connect

    Jung, Jin Ho; Choi, Yong Jung, Jiwoong; Kim, Sangsu; Lim, Hyun Keong; Im, Ki Chun; Oh, Chang Hyun; Park, Hyun-wook; Kim, Kyung Min; Kim, Jong Guk

    2015-05-15

    Purpose: The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. Methods: The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 array LYSO coupled to a 4 × 4 Geiger-mode avalanche photodiode (GAPD) array. The PET insert consisted of 18 detector blocks, circularly mounted on a custom-made plastic base to form a ring with an inner diameter of 390 mm and axial length of 60 mm. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with a thickness of 0.24 mm. The position decoder circuit and field programmable gate array-embedded DAQ modules were enclosed in an aluminum box with a thickness of 10 mm and located at the rear of the MR bore inside the MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and inner bore diameter of 60 cm was used as the PET/MRI hybrid system. A custom-made radio frequency (RF) coil with an inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside the MRI scanner using echo planar imaging, spin echo, turbo spin echo, and gradient echo sequences. MRI performance was also evaluated with and without the PET insert. The stability of the newly developed PET insert was evaluated and simultaneous PET and MR images of a brain phantom were acquired. Results: No significant degradation of the PET performance caused by MR was observed when the PET was operated using various MR imaging sequences. The signal-to-noise ratio of MR images was slightly degraded due to the PET insert installed inside the MR bore while the homogeneity was

  3. A non-linear mixed effect modelling approach for metabolite correction of the arterial input function in PET studies.

    PubMed

    Veronese, Mattia; Gunn, Roger N; Zamuner, Stefano; Bertoldo, Alessandra

    2013-02-01

    Quantitative PET studies with arterial blood sampling usually require the correction of the measured total plasma activity for the presence of metabolites. In particular, if labelled metabolites are found in the plasma in significant amounts their presence has to be accounted for, because it is the concentration of the parent tracer which is required for data quantification. This is achieved by fitting a Parent Plasma fraction (PPf) model to discrete metabolite measurements. The commonly used method is based on an individual approach, i.e. for each subject the PPf model parameters are estimated from its own metabolite samples, which are, in general, sparse and noisy. This fact can compromise the quality of the reconstructed arterial input functions, and, consequently, affect the quantification of tissue kinetic parameters. In this study, we proposed a Non-Linear Mixed Effect Modelling (NLMEM) approach to describe metabolite kinetics. Since NLMEM has been developed to provide robust parameter estimates in the case of sparse and/or noisy data, it has the potential to be a reliable method for plasma metabolite correction. Three different PET datasets were considered: [11C]-(+)-PHNO (54 scans), [11C]-PIB (22 scans) and [11C]-DASB (30 scans). For each tracer both simulated and measured data were considered and NLMEM performance was compared with that provided by individual analysis. Results showed that NLMEM provided improved estimates of the plasma parent input function over the individual approach when the metabolite data were sparse or contained outliers.

  4. Polarisation-based coincidence event discrimination: an in silico study towards a feasible scheme for Compton-PET.

    PubMed

    Toghyani, M; Gillam, J E; McNamara, A L; Kuncic, Z

    2016-08-01

    Current positron emission tomography (PET) systems use temporally localised coincidence events discriminated by energy and time-of-flight information. The two annihilation photons are in an entangled polarisation state and, in principle, additional information from the polarisation correlation of photon pairs could be used to improve the accuracy of coincidence classification. In a previous study, we demonstrated that in principle, the polarisation correlation information could be transferred to an angular correlation in the distribution of scattered photon pairs in a planar Compton camera system. In the present study, we model a source-phantom-detector system using Geant4 and we develop a coincidence classification scheme that exploits the angular correlation of scattered annihilation quanta to improve the accuracy of coincidence detection. We find a [Formula: see text] image quality improvement in terms of the peak signal-to-noise ratio when scattered coincidence events are discriminated solely by their angular correlation, thus demonstrating the feasibility of this novel classification scheme. By integrating scatter events (both single-single and single-only) with unscattered coincidence events discriminated using conventional methods, our results suggest that Compton-PET may be a promising candidate for optimal emission tomographic imaging. PMID:27405797

  5. Impact of patient weight on tumor visibility based on human-shaped phantom simulation study in PET imaging system

    NASA Astrophysics Data System (ADS)

    Musarudin, M.; Saripan, M. I.; Mashohor, S.; Saad, W. H. M.; Nordin, A. J.; Hashim, S.

    2015-10-01

    Energy window technique has been implemented in all positron emission tomography (PET) imaging protocol, with the aim to remove the unwanted low energy photons. Current practices in our institution however are performed by using default energy threshold level regardless of the weight of the patient. Phantom size, which represents the size of the patient's body, is the factor that determined the level of scatter fraction during PET imaging. Thus, the motivation of this study is to determine the optimum energy threshold level for different sizes of human-shaped phantom, to represent underweight, normal, overweight and obese patients. In this study, the scanner was modeled by using Monte Carlo code, version MCNP5. Five different sizes of elliptical-cylinder shaped of human-sized phantoms with diameter ranged from 15 to 30 cm were modeled. The tumor was modeled by a cylindrical line source filled with 1.02 MeV positron emitters at the center of the phantom. Various energy window widths, in the ranged of 10-50% were implemented to the data. In conclusion, the phantom mass volume did influence the scatter fraction within the volume. Bigger phantom caused more scattering events and thus led to coincidence counts lost. We evaluated the impact of phantom sizes on the sensitivity and visibility of the simulated models. Implementation of wider energy window improved the sensitivity of the system and retained the coincidence photons lost. Visibility of the tumor improved as an appropriate energy window implemented for the different sizes of phantom.

  6. Polarisation-based coincidence event discrimination: an in silico study towards a feasible scheme for Compton-PET

    NASA Astrophysics Data System (ADS)

    Toghyani, M.; Gillam, J. E.; McNamara, A. L.; Kuncic, Z.

    2016-08-01

    Current positron emission tomography (PET) systems use temporally localised coincidence events discriminated by energy and time-of-flight information. The two annihilation photons are in an entangled polarisation state and, in principle, additional information from the polarisation correlation of photon pairs could be used to improve the accuracy of coincidence classification. In a previous study, we demonstrated that in principle, the polarisation correlation information could be transferred to an angular correlation in the distribution of scattered photon pairs in a planar Compton camera system. In the present study, we model a source-phantom-detector system using Geant4 and we develop a coincidence classification scheme that exploits the angular correlation of scattered annihilation quanta to improve the accuracy of coincidence detection. We find a 22% image quality improvement in terms of the peak signal-to-noise ratio when scattered coincidence events are discriminated solely by their angular correlation, thus demonstrating the feasibility of this novel classification scheme. By integrating scatter events (both single-single and single-only) with unscattered coincidence events discriminated using conventional methods, our results suggest that Compton-PET may be a promising candidate for optimal emission tomographic imaging.

  7. Optimizing light transport in scintillation crystals for time-of-flight PET: an experimental and optical Monte Carlo simulation study

    PubMed Central

    Berg, Eric; Roncali, Emilie; Cherry, Simon R.

    2015-01-01

    Achieving excellent timing resolution in gamma ray detectors is crucial in several applications such as medical imaging with time-of-flight positron emission tomography (TOF-PET). Although many factors impact the overall system timing resolution, the statistical nature of scintillation light, including photon production and transport in the crystal to the photodetector, is typically the limiting factor for modern scintillation detectors. In this study, we investigated the impact of surface treatment, in particular, roughening select areas of otherwise polished crystals, on light transport and timing resolution. A custom Monte Carlo photon tracking tool was used to gain insight into changes in light collection and timing resolution that were observed experimentally: select roughening configurations increased the light collection up to 25% and improved timing resolution by 15% compared to crystals with all polished surfaces. Simulations showed that partial surface roughening caused a greater number of photons to be reflected towards the photodetector and increased the initial rate of photoelectron production. This study provides a simple method to improve timing resolution and light collection in scintillator-based gamma ray detectors, a topic of high importance in the field of TOF-PET. Additionally, we demonstrated utility of our Monte Carlo simulation tool to accurately predict the effect of altering crystal surfaces on light collection and timing resolution. PMID:26114040

  8. Pet ownership among homeless youth: associations with mental health, service utilization and housing status.

    PubMed

    Rhoades, Harmony; Winetrobe, Hailey; Rice, Eric

    2015-04-01

    As many as 25 % of homeless persons have pets. To our knowledge, pet ownership has not been studied quantitatively with homeless youth. This study examined pet ownership among 398 homeless youth utilizing two Los Angeles drop-in centers. Twenty-three percent of homeless youth had a pet. The majority of pet owners reported that their pets kept them company and made them feel loved; nearly half reported that their pets made it more difficult to stay in a shelter. Pet owners reported fewer symptoms of depression and loneliness than their non-pet owning peers. Pet ownership was associated with decreased utilization of housing and job-finding services, and decreased likelihood of currently staying in a shelter. These findings elucidate many of the positive benefits of pet ownership for homeless youth, but importantly highlight that pet ownership may negatively impact housing options. Housing and other services must be sensitive to the needs of homeless youth with pets. PMID:24728815

  9. Pet ownership among homeless youth: associations with mental health, service utilization and housing status.

    PubMed

    Rhoades, Harmony; Winetrobe, Hailey; Rice, Eric

    2015-04-01

    As many as 25 % of homeless persons have pets. To our knowledge, pet ownership has not been studied quantitatively with homeless youth. This study examined pet ownership among 398 homeless youth utilizing two Los Angeles drop-in centers. Twenty-three percent of homeless youth had a pet. The majority of pet owners reported that their pets kept them company and made them feel loved; nearly half reported that their pets made it more difficult to stay in a shelter. Pet owners reported fewer symptoms of depression and loneliness than their non-pet owning peers. Pet ownership was associated with decreased utilization of housing and job-finding services, and decreased likelihood of currently staying in a shelter. These findings elucidate many of the positive benefits of pet ownership for homeless youth, but importantly highlight that pet ownership may negatively impact housing options. Housing and other services must be sensitive to the needs of homeless youth with pets.

  10. Radiomics Analysis on FLT-PET/MRI for Characterization of Early Treatment Response in Renal Cell Carcinoma: A Proof-of-Concept Study.

    PubMed

    Antunes, Jacob; Viswanath, Satish; Rusu, Mirabela; Valls, Laia; Hoimes, Christopher; Avril, Norbert; Madabhushi, Anant

    2016-04-01

    Studying early response to cancer treatment is significant for patient treatment stratification and follow-up. Although recent advances in positron emission tomography (PET) and magnetic resonance imaging (MRI) allow for evaluation of tumor response, a quantitative objective assessment of treatment-related effects offers localization and quantification of structural and functional changes in the tumor region. Radiomics, the process of computerized extraction of features from radiographic images, is a new strategy for capturing subtle changes in the tumor region that works by quantifying subvisual patterns which might escape human identification. The goal of this study was to demonstrate feasibility for performing radiomics analysis on integrated PET/MRI to characterize early treatment response in metastatic renal cell carcinoma (RCC) undergoing sunitinib therapy. Two patients with advanced RCC were imaged using an integrated PET/MRI scanner. [18 F] fluorothymidine (FLT) was used as the PET radiotracer, which can measure the degree of cell proliferation. Image acquisitions included test/retest scans before sunitinib treatment and one scan 3 weeks into treatment using [18 F] FLT-PET, T2-weighted (T2w), and diffusion-weighted imaging (DWI) protocols, where DWI yielded an apparent diffusion coefficient (ADC) map. Our framework to quantitatively characterize treatment-related changes involved the following analytic steps: 1) intraacquisition and interacquisition registration of protocols to allow voxel-wise comparison of changes in radiomic features, 2) correction and pseudoquantification of T2w images to remove acquisition artifacts and examine tissue-specific response, 3) characterization of information captured by T2w MRI, FLT-PET, and ADC via radiomics, and 4) combining multiparametric information to create a map of integrated changes from PET/MRI radiomic features. Standardized uptake value (from FLT-PET) and ADC textures ranked highest for reproducibility in a

  11. Morbidity and disease management in pet rats: a study of 375 cases.

    PubMed

    Rey, F; Bulliot, C; Bertin, N; Mentré, V

    2015-04-11

    Typical diseases are well described in pet rats, but their prevalence and management are largely unknown. During a six-month period, standardised records were obtained for 375 rats presenting in three French centres to determine the diagnoses made and the treatments prescribed. Rhinitis, healthy animal and mammary gland tumours accounted for the majority of diagnoses. The 10 most common diagnoses accounted for 66.9 per cent of all cases. Inappropriate environment was a risk factor for respiratory disease (P<0.001). Mean age of presentation of rats with respiratory disease was lower for rats living in non-appropriate environment (P=0.049). Twenty-two per cent of animals underwent surgery, with a significant difference according to sex because of the higher rate of mammary gland tumours in females (P=0.006). Tumourectomy, ovariohysterectomy or castration accounted for 70 per cent of all procedures. Training veterinarians on 10 clinical situations, 3 surgical procedures and 3 therapeutic classes would improve the management of most of the pet rats. An early visit to provide owners with all recommendations and information on appropriate maintenance, and one visit around 15 months of age to detect any mass at an early stage, could help to reduce respiratory disease and improve clinical outcomes.

  12. Design study of a 9 MeV compact cyclotron system for PET

    NASA Astrophysics Data System (ADS)

    Lee, Byeong-No; Shin, Seung-Wook; Song, Hoseung; Kim, Hyun-Wook; Chai, Jong-Seo

    2013-06-01

    A cyclotron is an accelerator which can be applied to both cancer diagnosis and treatment. Among commercially sold cyclotrons, the major energy is used for positron emission tomography (PET) ranges from 10 to 20 MeV. In this research, 9 MeV compact cyclotron for PET was designed. The research was conducted on the response cross section and the yield for the energy distribution to decide the design features. Also, it was determined the specifications on the basis of the fluoro-deoxy-glucose (FDG) maximum dose. The machine, which has a 20 uA beam current, is designed to be installed in small-to-medium-sized hospitals in local cities because of its relatively light weight (6 tons). This compact cyclotron, which provides 9-MeV proton beams, is composed of a azimuthally varying field (AVF) electromagnet, 83-MHz RF systems with a 20 kW amplifier, a panning ion gauge (PIG) type ion-source for negative hydrogen, and a double-stage high-vacuum system. The basic model design was done by using 3-D CAD program, CATIA and all the field calculations were performed using commercial electromagnetic field analysis code, OPERA-3D TOSCA. From this research, we expect a time reduction for FDG production, a decrease of radioactive exposure for workers, and an equipment cost reduction.

  13. Reversal of brain metabolic abnormalities following treatment of AIDS dementia complex with 3'-azido-2',3'-dideoxythymidine (AZT, zidovudine): a PET-FDG study

    SciTech Connect

    Brunetti, A.; Berg, G.; Di Chiro, G.; Cohen, R.M.; Yarchoan, R.; Pizzo, P.A.; Broder, S.; Eddy, J.; Fulham, M.J.; Finn, R.D.

    1989-05-01

    Brain glucose metabolism was evaluated in four patients with acquired immunodeficiency syndrome (AIDS) dementia complex using (/sup 18/F)fluorodeoxyglucose (FDG) and positron emission tomography (PET) scans at the beginning of therapy with 3'-azido-2',3'-dideoxythymidine (AZT, zidovudine), and later in the course of therapy. In two patients, baseline, large focal cortical abnormalities of glucose utilization were reversed during the course of therapy. In the other two patients, the initial PET study did not reveal pronounced focal alterations, while the post-treatment scans showed markedly increased cortical glucose metabolism. The improved cortical glucose utilization was accompanied in all patients by immunologic and neurologic improvement. PET-FDG studies can detect cortical metabolic abnormalities associated with AIDS dementia complex, and may be used to monitor the metabolic improvement in response to AZT treatment.

  14. Estimation of patient radiation dose from whole body 18F- FDG PET/CT examination in cancer imaging: a preliminary study

    NASA Astrophysics Data System (ADS)

    Mahmud, M. H.; Nordin, A. J.; Saad, F. F. Ahmad; Fattah Azman, A. Z.

    2014-11-01

    This study aims to estimate the radiation effective dose resulting from whole body fluorine-18 flourodeoxyglucose Positron Emission Tomography (18F-FDG PET) scanning as compared to conservative Computed Tomography (CT) techniques in evaluating oncology patients. We reviewed 19 oncology patients who underwent 18F-FDG PET/CT at our centre for cancer staging. Internal and external doses were estimated using radioactivity of injected FDG and volume CT Dose Index (CTDIvol), respectively with employment of the published and modified dose coefficients. The median differences of dose among the conservative CT and PET protocols were determined using Kruskal Wallis test with p < 0.05 considered as significant. The median (interquartile range, IQR) effective doses of non-contrasted CT, contrasted CT and PET scanning protocols were 7.50 (9.35) mSv, 9.76 (3.67) mSv and 6.30 (1.20) mSv, respectively, resulting in the total dose of 21.46 (8.58) mSv. Statistically significant difference was observed in the median effective dose between the three protocols (p < 0.01). The effective doses of whole body 18F-FDG PET technique may be effective the lowest amongst the conventional CT imaging techniques.

  15. The Predictive Value of Early Behavioural Assessments in Pet Dogs – A Longitudinal Study from Neonates to Adults

    PubMed Central

    Riemer, Stefanie; Müller, Corsin; Virányi, Zsófia; Huber, Ludwig; Range, Friederike

    2014-01-01

    Studies on behavioural development in domestic dogs are of relevance for matching puppies with the right families, identifying predispositions for behavioural problems at an early stage, and predicting suitability for service dog work, police or military service. The literature is, however, inconsistent regarding the predictive value of tests performed during the socialisation period. Additionally, some practitioners use tests with neonates to complement later assessments for selecting puppies as working dogs, but these have not been validated. We here present longitudinal data on a cohort of Border collies, followed up from neonate age until adulthood. A neonate test was conducted with 99 Border collie puppies aged 2–10 days to assess activity, vocalisations when isolated and sucking force. At the age of 40–50 days, 134 puppies (including 93 tested as neonates) were tested in a puppy test at their breeders' homes. All dogs were adopted as pet dogs and 50 of them participated in a behavioural test at the age of 1.5 to 2 years with their owners. Linear mixed models found little correspondence between individuals' behaviour in the neonate, puppy and adult test. Exploratory activity was the only behaviour that was significantly correlated between the puppy and the adult test. We conclude that the predictive validity of early tests for predicting specific behavioural traits in adult pet dogs is limited. PMID:25003341

  16. A 15O-H2O PET study of meditation and the resting state of normal consciousness.

    PubMed

    Lou, H C; Kjaer, T W; Friberg, L; Wildschiodtz, G; Holm, S; Nowak, M

    1999-01-01

    The aim of the present study was to examine whether the neural structures subserving meditation can be reproducibly measured, and, if so, whether they are different from those supporting the resting state of normal consciousness. Cerebral blood flow distribution was investigated with the 15O-H20 PET technique in nine young adults, who were highly experienced yoga teachers, during the relaxation meditation (Yoga Nidra), and during the resting state of normal consciousness. In addition, global CBF was measured in two of the subjects. Spectral EEG analysis was performed throughout the investigations. In meditation, differential activity was seen, with the noticeable exception of V1, in the posterior sensory and associative cortices known to participate in imagery tasks. In the resting state of normal consciousness (compared with meditation as a baseline), differential activity was found in dorso-lateral and orbital frontal cortex, anterior cingulate gyri, left temporal gyri, left inferior parietal lobule, striatal and thalamic regions, pons and cerebellar vermis and hemispheres, structures thought to support an executive attentional network. The mean global flow remained unchanged for both subjects throughout the investigation (39+/-5 and 38+/-4 ml/100 g/min, uncorrected for partial volume effects). It is concluded that the (H2)15O PET method may measure CBF distribution in the meditative state as well as during the resting state of normal consciousness, and that characteristic patterns of neural activity support each state. These findings enhance our understanding of the neural basis of different aspects of consciousness.

  17. The predictive value of early behavioural assessments in pet dogs--a longitudinal study from neonates to adults.

    PubMed

    Riemer, Stefanie; Müller, Corsin; Virányi, Zsófia; Huber, Ludwig; Range, Friederike

    2014-01-01

    Studies on behavioural development in domestic dogs are of relevance for matching puppies with the right families, identifying predispositions for behavioural problems at an early stage, and predicting suitability for service dog work, police or military service. The literature is, however, inconsistent regarding the predictive value of tests performed during the socialisation period. Additionally, some practitioners use tests with neonates to complement later assessments for selecting puppies as working dogs, but these have not been validated. We here present longitudinal data on a cohort of Border collies, followed up from neonate age until adulthood. A neonate test was conducted with 99 Border collie puppies aged 2-10 days to assess activity, vocalisations when isolated and sucking force. At the age of 40-50 days, 134 puppies (including 93 tested as neonates) were tested in a puppy test at their breeders' homes. All dogs were adopted as pet dogs and 50 of them participated in a behavioural test at the age of 1.5 to 2 years with their owners. Linear mixed models found little correspondence between individuals' behaviour in the neonate, puppy and adult test. Exploratory activity was the only behaviour that was significantly correlated between the puppy and the adult test. We conclude that the predictive validity of early tests for predicting specific behavioural traits in adult pet dogs is limited.

  18. Effect of anatomical variability, reconstruction algorithms and scattered photons on the SPM output of brain PET studies.

    PubMed

    Aguiar, P; Pareto, D; Gispert, J D; Crespo, C; Falcón, C; Cot, A; Lomeña, F; Pavía, J; Ros, D

    2008-02-01

    Statistical parametric mapping (SPM) has become the standard technique to statistically evaluate differences between functional images. The aim of this paper was to assess the effect of anatomical variability of skull, the reconstruction algorithm and the scattering of photons in the brain on the output of an SPM analysis of brain PET studies. To this end, Monte Carlo simulation was used to generate suitable PET sinograms and bootstrap techniques were employed to increase the reliability of the conclusions. Activity distribution maps were obtained by segmenting thirty nine T1-weighted magnetic resonance images. Foci were placed on the posterior cingulate cortex (PCC) and the superior temporal cortex (STC) and activation factors ranging between -25% and +25% were simulated. Preprocessing of the reconstructed images and statistical analysis were performed using SPM2. Our findings show that intersubject anatomical differences can cause the minimum sample size to increase between 10 and 42% for posterior cingulate Cortex and between 40 and 80% for superior temporal cortex. Ideal scatter correction (ISC) allowed us to diminish the sample size up to 18% and fully 3D reconstruction reduced the minimum sample size between 8 and 33%. Detection sensitivity was higher for hypo-activation than for hyper-activation situations and higher for superior temporal cortex than for posterior cingulate cortex.

  19. Pet Problems at Home: Pet Problems in the Community.

    ERIC Educational Resources Information Center

    Soltow, Willow

    1984-01-01

    Discusses problems of pets in the community, examining the community's role related to disruptive pets and pet overpopulation. Also discusses pet problems at home, offering advice on selecting a pet, meeting a pet's needs, and disciplining pets. Includes a list of books, films/filmstrips, teaching materials, and various instructional strategies.…

  20. Pilot study assessing 18F-fluorothymidine PET/CT in cervical and vaginal cancers before and after external beam radiation☆

    PubMed Central

    Cho, Linda P.; Kim, Chun K.; Viswanathan, Akila N.

    2015-01-01

    Objective The role of F-18-fluorothymidine (FLT) PET-CT imaging in the evaluation of gynecologic cancers has not been established. We sought to evaluate (FLT) PET-CT imaging in gynecologic cancers by comparing standard uptake values (SUVs) of FLT with F-18-fluorodeoxyglucose (FDG) PET in the primary tumor at diagnosis, and assess FLT uptake immediately following concurrent chemoradiotherapy (chemoRT). Methods In this pilot study, patients treated for cervical (5) or vaginal (1) cancer underwent FLT-PET and FDG-PET scanning at diagnosis (FLT1 and FDG1). Five patients (4 cervical and 1 vaginal) also underwent FLT-PET within 1–3 weeks after chemoRT before brachytherapy (FLT2). Wilcoxon rank-sum test was used to compare the FLT1 and FDG1 parameters. Results Median age at diagnosis was 61-years (range, 33–72). Cervical cancers were staged as IB2 (n = 1, 20%), IIB (n = 1, 20%), IIIB (n = 1, 20%) and IVA (n = 2, 40%) and the single vaginal cancer was staged IIIB. The most common histology was squamous cell carcinoma (n = 3, 50%) followed by adenocarcinoma (n = 2, 33%) and clear-cell adenosquamous carcinoma (n = 1, 17%). Median tumor SUVmax at diagnosis was 7.8 on FLT1-PET (3.9–14.2) versus 11.6 (5.9–23.2) on FDG1-PET (p = 0.15). Tumor SUVmax of FLT declined 54%–100% after chemoRT. Conclusion The tumor SUV of FLT at diagnosis was lower than that of FDG-PET. FLT uptake was markedly decreased after chemoRT. Results indicate that there may not be a significant effect of inflammation on FLT uptake in gynecologic cancers. FLT may be a useful tool when assessing the effects of chemoRT on gynecologic malignancies and planning for postchemoRT brachytherapy treatments. PMID:26793770

  1. A Comparative Study of Noninvasive Hypoxia Imaging with 18F-Fluoroerythronitroimidazole and 18F-Fluoromisonidazole PET/CT in Patients with Lung Cancer

    PubMed Central

    Huang, Yong; Yu, Qingxi; Zhu, Shouhui; Wang, Suzhen; Zhao, Shuqiang; Hu, Xudong; Yu, Jinming; Yuan, Shuanghu

    2016-01-01

    Purpose This is a clinical study to compare noninvasive hypoxia imaging using 18F-fluoroerythronitroimidazole (18F-FETNIM) and 18F-fluoromisonidazole (18F-FMISO) positron emission tomography/computed tomography (PET/CT) in patients with inoperable stages III–IV lung cancer. Methods A total of forty-two patients with inoperable stages III–IV lung cancer underwent 18F-FETNIM PET/CT (n = 18) and 18F-FMISO PET/CT (n = 24) before chemo/radiation therapy. The standard uptake values (SUVs) of malignant and normal tissues depict 18F-FETNIM PET/CT and 18F-FMISO PET/CT uptake. Tumor-to-blood ratios (T/B) were used to quantify hypoxia. Results All patients with lung cancer underwent 18F-FETNIM PET/CT and 18F-FMISO PET/CT successfully. Compared to 18F-FMISO, 18F-FETNIM showed similar uptake in muscle, thyroid, spleen, pancreas, heart, lung and different uptake in blood, liver, and kidney. Significantly higher SUV and T/B ratio with 18F-FMISO (2.56±0.77, 1.98±0.54), as compared to 18F-FETNIM (2.12±0.56, 1.42±0.33) were seen in tumor, P = 0.022, <0.001. For the patients with different histopathological subtypes, no significant difference of SUV (or T/B ratio) was observed both in 18F-FMISO and 18F-FETNIM in tumor. A significantly different SUV (or T/B ratio) was detected between < = 2cm, 2~5cm, and >5cm groups in 18F-FMISO PET/CT, P = 0.015 (or P = 0.029), whereas no difference was detected in 18F-FMISO PET/CT, P = 0.446 (or P = 0.707). Both 18F-FETNIM and 18F-FMISO showed significantly higher SUVs (or T/B ratios) in stage IV than stage III, P = 0.021, 0.013 (or P = 0.032, 0.02). Conclusion 18F-FMISO showed significantly higher uptake than 18F-FETNIM in tumor/non-tumor ratio and might be a better hypoxia tracer in lung cancer. PMID:27322586

  2. (99m)Tc-DMSA (V) in Evaluation of Osteosarcoma: Comparative Studies with (18)F-FDG PET/CT in Detection of Primary and Malignant Lesions.

    PubMed

    Bandopadhyaya, G P; Gupta, Priyanka; Singh, Archana; Shukla, Jaya; Rastogi, S; Kumar, Rakesh; Malhotra, Arun

    2012-01-01

    To evaluate the role of (99m)Tc-DMSA (V) and [(18)F]FDG PET-CT in management of patients with osteosarcoma, 22 patients were included in our study. All patients underwent both (99m)Tc-DMSA (V) and whole-body [(18)F]FDG PET-CT scans within an interval of 1 week. 555-740 MBq of (99m)Tc-DMSA (V) was injected i.v. the whole-body planar, SPECT images of primary site and chest were performed after 3-4 hours. [(18)F]FDG PET-CT images were obtained 60 minutes after i.v. injection of 370 MBq of F-18 FDG. Both FDG PET-CT (mean SUV(max) = 7.1) and DMSA (V) scans showed abnormal uptake at primary site in all the 22 patients (100% sensitivity for both). Whole-body PET-CT detected metastasis in 11 pts (lung mets in 10 and lung + bone mets in 1 patient). Whole-body planar DMSA (V) and SPECT detected bone metastasis in one patient, lung mets in 7 patients and LN in 1 patient. HRCT of chest confirmed lung mets in 10 patients and inflammatory lesion in one patient. 7 patients positive for mets on DMSA (V) scan had higher uptake in lung lesions as compared to FDG uptake on PET-CT. Three patients who did not show any DMSA uptake had subcentimeter lung nodule. Resuts of both (99m)Tc-DMSA (V) (whole-body planar and SPECT imaging) and [(18)F]FDG PET-CT were comparable in evaluation of primary site lesions and metastatic lesions greater than 1 cm. Though (99m)Tc-DMSA (V) had higher uptake in the lesions as compared to [(18)F]FDG PET-CT, the only advantage [(18)F]FDG PET-CT had was that it could also detect subcentimeter lesions.

  3. The involvement of organic anion transporting polypeptide in the hepatic uptake of telmisartan in rats: PET studies with [¹¹C]telmisartan.

    PubMed

    Takashima, Tadayuki; Hashizume, Yoshinobu; Katayama, Yumiko; Murai, Machiko; Wada, Yasuhiro; Maeda, Kazuya; Sugiyama, Yuichi; Watanabe, Yasuyoshi

    2011-10-01

    Telmisartan, a selective angiotensin II receptor antagonist, is primarily excreted via hepatobiliary transport. The predominant contribution of organic anion transporting polypeptide (OATP) 1B3 in its hepatic uptake of telmisartan has been demonstrated by in vitro transport studies. In the present study, a quantitative positron emission tomography (PET) methodology was developed for in vivo kinetic assessment of hepatobiliary transport of telmisartan. Serial abdominal PET scans were performed in rats following intravenous administration of [(11)C]telmisartan as a radiotracer. PET scans revealed that [(11)C]telmisartan was localized primarily in the liver and some of the radioactivity moved to the intestine, which corresponds to biliary excretion. Radiometabolite analysis by radiometric HPLC showed that [(11)C]telmisartan was converted to its acylglucuronide, which was mainly detected in bile, but little in plasma and liver. Integration plot analysis revealed that [(11)C]telmisartan was taken up into the liver as rapidly as the hepatic blood flow rate, and the radiometabolite was subsequently excreted into the bile. When rifampicin, a typical Oatp inhibitor, was coadministered with [(11)C]telmisartan in rats, hepatic uptake clearance of [(11)C]telmisartan was significantly decreased, whereas biliary efflux clearance was not changed. Coinjection with unlabeled telmisartan (4 and 10 mg/kg) also decreased hepatic uptake clearance of [(11)C]telmisartan. On the other hand, PET imaging analysis revealed a significant increase of biliary efflux when telmisartan dose was increased to more than 4 mg/kg. These results suggested that the hepatic uptake of [(11)C]telmisartan mainly consists of a saturable process mediated by Oatps in rats, according to noninvasive real-time measurement of tissue radioactivity with the use of PET. The present study with rats is expected to provide the feasibility of PET imaging study to quantitatively estimate OATP1B3 function in humans.

  4. Kinetic quantitation of cerebral PET-FDG studies without concurrent blood sampling: statistical recovery of the arterial input function.

    PubMed

    O'Sullivan, F; Kirrane, J; Muzi, M; O'Sullivan, J N; Spence, A M; Mankoff, D A; Krohn, K A

    2010-03-01

    Kinetic quantitation of dynamic positron emission tomography (PET) studies via compartmental modeling usually requires the time-course of the radio-tracer concentration in the arterial blood as an arterial input function (AIF). For human and animal imaging applications, significant practical difficulties are associated with direct arterial sampling and as a result there is substantial interest in alternative methods that require no blood sampling at the time of the study. A fixed population template input function derived from prior experience with directly sampled arterial curves is one possibility. Image-based extraction, including requisite adjustment for spillover and recovery, is another approach. The present work considers a hybrid statistical approach based on a penalty formulation in which the information derived from a priori studies is combined in a Bayesian manner with information contained in the sampled image data in order to obtain an input function estimate. The absolute scaling of the input is achieved by an empirical calibration equation involving the injected dose together with the subject's weight, height and gender. The technique is illustrated in the context of (18)F -Fluorodeoxyglucose (FDG) PET studies in humans. A collection of 79 arterially sampled FDG blood curves are used as a basis for a priori characterization of input function variability, including scaling characteristics. Data from a series of 12 dynamic cerebral FDG PET studies in normal subjects are used to evaluate the performance of the penalty-based AIF estimation technique. The focus of evaluations is on quantitation of FDG kinetics over a set of 10 regional brain structures. As well as the new method, a fixed population template AIF and a direct AIF estimate based on segmentation are also considered. Kinetics analyses resulting from these three AIFs are compared with those resulting from radially sampled AIFs. The proposed penalty-based AIF extraction method is found to

  5. An Investigation into Associations with Attachment, Companion Pet Attachment, Empathy, and Prosocial Behaviors in 18-20 Year Old College Students: A Mixed Methods Study

    ERIC Educational Resources Information Center

    Anderson, Christian

    2010-01-01

    This study examines empathy, parental attachment, companion pet attachment and social behaviors in a sample of 120 students between the ages of 18-20 enrolled at Front Range Community College in Westminster CO during the fall semester 2008. The study is based on the research questions posed by Thompson and Gullone (2008) but pays particular…

  6. Acute marijuana effects on rCBF and cognition: a PET study.

    PubMed

    O'Leary, D S; Block, R I; Flaum, M; Schultz, S K; Boles Ponto, L L; Watkins, G L; Hurtig, R R; Andreasen, N C; Hichwa, R D

    2000-11-27

    The effects of smoking marijuana on cognition and brain function were assessed with PET using H2(15)O. Regional cerebral blood flow (rCBF) was measured in five recreational users before and after smoking a marijuana cigarette, as they repeatedly performed an auditory attention task. Blood flow increased following smoking in a number of paralimbic brain regions (e.g. orbital frontal lobes, insula, temporal poles) and in anterior cingulate and cerebellum. Large reductions in rCBF were observed in temporal lobe regions that are sensitive to auditory attention effects. Brain regions showing increased rCBF may mediate the intoxicating and mood-related effects of smoking marijuana, whereas reduction of task-related rCBF in temporal lobe cortices may account for the impaired cognitive functions associated with acute intoxication.

  7. Role of PET and SPECT in the Study of Amyotrophic Lateral Sclerosis

    PubMed Central

    Cuccurullo, Vincenzo; Pagani, Marco; Valentini, Maria Consuelo; Mansi, Luigi

    2014-01-01

    Amyotrophic lateral sclerosis has been defined as a “heterogeneous group of neurodegenerative syndromes characterized by progressive muscle paralysis caused by the degeneration of motor neurons allocated in primary motor cortex, brainstem, and spinal cord.” A comprehensive diagnostic workup for ALS usually includes several electrodiagnostic, clinical laboratory and genetic tests. Neuroimaging exams, such as computed tomography, magnetic resonance imaging and spinal cord myelogram, may also be required. Nuclear medicine, with PET and SPECT, may also play a role in the evaluation of patients with ALS, and provide additional information to the clinicians. This paper aims to offer to the reader a comprehensive review of the different radiotracers for the assessment of the metabolism of glucose (FDG), the measurement of cerebral blood flow (CBF), or the evaluation of neurotransmitters, astrocytes, and microglia by means of newer and not yet clinically diffuse radiopharmaceuticals. PMID:24818133

  8. Study of the neutron field in the vicinity of an unshielded PET cyclotron.

    PubMed

    Méndez, R; Iñiguez, M P; Martí-Climent, J M; Peñuelas, I; Vega-Carrillo, H R; Barquero, R

    2005-11-01

    The neutron field in the proximity of an unshielded PET cyclotron was investigated during 18F radioisotope production with an 18 MeV proton beam. Thermoluminescent detector (TLD) models TLD600 and TLD700 as well as Bonner moderating spheres were irradiated at different positions inside the vault room where the cyclotron is located to determine the thermal neutron flux, neutron spectrum and dose equivalent. Furthermore, from a combination of measurements and Monte Carlo simulations the neutron source intensity at the target was estimated. The resulting intensity is in good agreement with the IAEA recommendations. Neutron doses derived from the measured spectra were found to vary between 7 and 320 mSv per 1 microA h of proton-integrated current. Finally, gamma doses were determined from TLD700 readings and amounted to around 10% of the neutron doses.

  9. Cerebral organization in bilinguals: a PET study of Chinese-English verb generation.

    PubMed

    Klein, D; Milner, B; Zatorre, R J; Zhao, V; Nikelski, J

    1999-09-01

    Positron emission tomography (PET) was used to investigate cerebral organization in seven subjects who had Mandarin Chinese as their native language (L1), and learned English (L2) later in life. When activation from word repetition was subtracted from verb generation in L1 and L2, CBF increases were observed for both languages in left inferior frontal, dorsolateral frontal, temporal and parietal cortices, and right cerebellum. Direct comparison of the difference between verb generation and word repetition in L1 and L2 revealed no significant differences. Within-subject analysis of verb generation minus word repetition yielded CBF increases in left frontal cortex for all individuals for L1 and L2, and a comparison of differences yielded no spatial separation in frontal peaks. We argue for shared neural substrates even for such contrasting languages as Mandarin and English.

  10. Preparation and characterization of solution cast films of PET, reorganized PET and their MWNT nanocomposites

    NASA Astrophysics Data System (ADS)

    Singh, Arvind R.; Deshpande, Vineeta D.

    2013-06-01

    The samples of polyethylene terephthalate (PET), reorganized PET (r-PET) and their nanocomposites with 0.05 wt % and 0.1 wt % multi walled carbon nanotubes (MWNT) were prepared by standard solution casting method using trifluoroacetic acid (TFA) as a solvent. Reorganization of PET was obtained by precipitation method using TFA as a solvent and acetone as an antisolvent. Structural and morphological properties of the films were investigated by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Differential Scanning Calorimetry (DSC) was used to study the thermal properties of the films. Bulk resistivity of the prepared samples was studied using LCR meter. The results show better dispersion of MWNT in r-PET than in PET. Better dispersion is attributed to the morphological changes in r-PET. The films obtained were conductive and transparent even after addition of MWNT signifying their use as a flexible solar substrate.

  11. Distinct cerebral lesions in sporadic and 'D90A' SOD1 ALS: studies with [11C]flumazenil PET.

    PubMed

    Turner, M R; Hammers, A; Al-Chalabi, A; Shaw, C E; Andersen, P M; Brooks, D J; Leigh, P N

    2005-06-01

    Five to ten percent of amyotrophic lateral sclerosis (ALS) cases are associated with mutations of the superoxide dismutase-1 (SOD1) gene, and the 'D90A' mutation is associated with a unique phenotype and markedly slower disease progression (mean survival time 14 years). Relative sparing of inhibitory cortical neuronal circuits might be one mechanism contributing to the slower progression in patients homozygous for the D90A mutation (homD90A). The GABA(A) receptor PET ligand [11C]flumazenil has demonstrated motor and extra-motor cortical changes in sporadic ALS. In this study, we used [11C]flumazenil PET to explore differences in the pattern of cortical involvement between sporadic and genetically homogeneous ALS groups. Twenty-four sporadic ALS (sALS) and 10 homD90A patients underwent [11C]flumazenil PET of the brain. In addition, two subjects homozygous for the D90A mutation, but without symptoms or signs ('pre-symptomatic', psD90A), also underwent imaging. Results for each group were compared with those for 24 healthy controls of similar age. Decreases in the binding of [11C]flumazenil in the sALS group were found within premotor regions, motor cortex and posterior motor association areas. In the homD90A group of ALS patients, however, decreases were concentrated in the left fronto-temporal junction and anterior cingulate gyrus. In the two psD90A subjects, a small focus of reduced [11C]flumazenil binding at the left fronto-temporal junction was seen, similar to the pattern seen in the clinically affected patients. Within the sALS group, there was no statistically significant association between decreases in cortical [11C]flumazenil binding and revised ALS functional rating scale (ALSFRS-R score), whereas the upper motor neuron (UMN) score correlated with widespread and marked cortical decreases over the dominant hemisphere. In the homD90A group, there was a stronger statistical association between reduced cortical [11C]flumazenil binding and the ALSFRS-R, rather

  12. Synthesis and PET studies of [11C-cyano]letrozole (Femara®), an aromatase inhibitor drug

    PubMed Central

    Kil, Kun-Eek; Biegon, Anat; Ding, Yu-Shin; Fischer, Andre; Ferrieri, Richard A.; Kim, Sung Won; Pareto, Deborah; Schueller, Michael J.; Fowler, Joanna S.

    2011-01-01

    Introduction Aromatase, a member of the cytochrome P450 family, converts androgens such as androstenedione and testosterone to estrone and estradiol respectively. Letrozole (1-[bis-(4-cyanophenyl)methyl]-1H-1,2,4-triazole, Femara®) is a high affinity aromatase inhibitor (Ki=11.5 nM) which has FDA approval for breast cancer treatment. Here we report the synthesis of carbon-11 labeled letrozole and its assessment as a radiotracer for brain aromatase in the baboon. Methods Letrozole and its precursor (4-[(4-bromophenyl)-1H-1,2,4-triazol-1-ylmethyl]benzonitrile, 3) were prepared in two-step syntheses from 4-cyanobenzyl bromide and 4-bromobenzyl bromide, respectively. The [11C]cyano group was introduced via the tetrakis(triphenylphosphine)palladium(0) catalyzed coupling of [11C]cyanide with the bromo-precursor (3). PET studies in the baboon brain were carried out to assess regional distribution and kinetics, reproducibility of repeated measures and saturability. The free fraction of letrozole in the plasma, log D, and the [11C-cyano]letrozole fraction in the arterial plasma were also measured. Results [11C-cyano]Letrozole was synthesized in 60 min with a radiochemical yield of 79–80%, with a radiochemical purity greater than 98% and a specific activity of 4.16±2.21 Ci/μmol at the end of bombardment (n=4). PET studies in the baboon revealed initial rapid and high uptake and initial rapid clearance followed by slow clearance of carbon-11 from the brain with no difference between brain regions. The brain kinetics was not affected by co-injection of unlabeled letrozole (0.1 mg/kg). The free fraction of letrozole in plasma was 48.9% and log D was 1.84. Conclusion [11C-cyano]Letrozole is readily synthesized via a palladium catalyzed coupling reaction with [11C]cyanide. Although it is unsuitable as a PET radiotracer for brain aromatase as revealed by the absence of regional specificity and saturability in brain regions, such as amygdala, which are known to contain

  13. PET studies of binding competition between endogenous dopamine and the D1 radiotracer [11C]NNC 756.

    PubMed

    Abi-Dargham, A; Simpson, N; Kegeles, L; Parsey, R; Hwang, D R; Anjilvel, S; Zea-Ponce, Y; Lombardo, I; Van Heertum, R; Mann, J J; Foged, C; Halldin, C; Laruelle, M

    1999-05-01

    NNC 756 ((+)-8-chloro-5-(2,3-dihydrobenzofuran-7-yl)-7-hydroxy-3-methyl-2,3,4,5- tetrahydro-1H-3-benzazepine) is a new high affinity dopamine (DA) D1 receptor antagonist. Labeled with C-11, it has been used as a PET radiotracer to visualize D1 receptors both in striatal and extrastriatal areas, such as the prefrontal cortex. The goal of this study was to evaluate several methods for derivation of D1 receptor binding potential (BP) with [11C]NNC 756 in baboons, and to use these methods to assess the vulnerability of [11C]NNC 756 binding to competition by endogenous DA. A three-compartment model provided a good fit to PET data acquired following a single bolus injection. BP values obtained with this analysis were in good agreement with values derived from in vitro studies. BP values measured following injection of the potent DA releaser amphetamine (1 mg/kg, n=2) were similar to values measured under control conditions. Kinetic parameters derived from single bolus experiments were used to design a bolus plus continuous infusion administration protocol aimed at achieving a state of sustained binding equilibrium. Injection of amphetamine during sustained equilibrium did not affect [11C]NNC 756 binding. Similar results were observed with another D1 radiotracer, [11C]SCH 23390. Doses of amphetamine used in this study are known to reduce by 20-40% the binding potential of several D2 receptors radiotracers. Therefore, the absence of displacement of [11C]NNC 756 by an endogenous DA surge may indicate important differences between D1 and D2 receptors in vivo, such as differences in proportion of high affinity states not occupied by DA at baseline. These findings may also imply that a simple binding competition model is inadequate to account for the effects of manipulation of endogenous DA levels on the in vivo binding of radiolabeled antagonists.

  14. A case study of voltage-gated potassium channel antibody-related limbic encephalitis with PET/MRI findings

    PubMed Central

    Day, Brian K.; Eisenman, Lawrence; Black, Joseph; Maccotta, Luigi; Hogan, R. Edward

    2015-01-01

    Preclinical and clinical studies have demonstrated the significance of inflammation and autoantibodies in epilepsy, and the use of immunotherapies in certain situations has become an established practice. Temporal lobe epilepsy can follow paraneoplastic or nonparaneoplastic limbic encephalitis associated with antibodies directed against brain antigens. Here, we focus on a patient with worsening confusion and temporal lobe seizures despite treatment with antiepileptic medications. Serial brain MRIs did not conclusively reveal structural abnormalities, so the patient underwent brain PET/MRI to simultaneously evaluate brain structure and function, revealing bitemporal abnormalities. The patient was diagnosed with voltage-gated potassium channel antibody-related limbic encephalitis based on clinical presentation, imaging findings, and antibody testing. Treatment included the addition of a second antiepileptic agent and oral steroids. His seizures and cognitive deficits improved and stabilized. PMID:26106579

  15. Automated production of [¹⁸F]VAT suitable for clinical PET study of vesicular acetylcholine transporter.

    PubMed

    Yue, Xuyi; Bognar, Christopher; Zhang, Xiang; Gaehle, Gregory G; Moerlein, Stephen M; Perlmutter, Joel S; Tu, Zhude

    2016-01-01

    Automated production of a promising radiopharmaceutical (-)-(1-(8-(2-[(18)F]fluoroethoxy)-3-hydroxy-1,2,3,4-tetrahydronaphthalen-2-yl)-piperidin-4-yl)(4-fluorophenyl)methanone ([(18)F]VAT) for the vesicular acetylcholine transporter(VAChT) was achieved using a two-step procedure in a current Good Manufacturing Practices fashion. The production of [(18)F]VAT was accomplished in approximately 140 min, with radiochemical yield of ~15.0% (decay corrected), specific activity>111 GBq/µmol, radiochemical purity>99% and mass of VAT ~3.4 μg/batch (n>10). The radiopharmaceutical product meets all quality control criteria for human use, and is suitable for clinical PET studies of VAChT. PMID:26408913

  16. Archaeometric study of ceramic figurines from the Maya settlement of La Blanca (Petén, Guatemala)

    NASA Astrophysics Data System (ADS)

    Horcajada, P.; Roldán, C.; Vidal, C.; Rodenas, I.; Carballo, J.; Murcia, S.; Juanes, D.

    2014-04-01

    In this article, analytical results will be presented and discussed regarding a selected set of figurines from the ancient Maya settlement of La Blanca in Petén, Guatemala. The objective is to characterize the ceramic material by two analytical complementary techniques: X-ray diffraction (XRD) and total reflection X-ray fluorescence (TXRF). The data obtained by means of both XRD and TXRF were compared and analyzed by multivariate statistical techniques in order to obtain sample groups according to their chemical composition. The results of this archaeometric study have been compared to those that have been obtained through macroscopic characterization by means of the traditional classification system know as Type-Variety. Discordances have been found between the clusters obtained by the Type-Variety classification system and the multivariate classification procedures performed on analytical data.

  17. SU-E-I-96: A Study About the Influence of ROI Variation On Tumor Segmentation in PET

    SciTech Connect

    Li, L; Tan, S; Lu, W; D'Souza, W

    2014-06-01

    Purpose: To study the influence of different regions of interest (ROI) on tumor segmentation in PET. Methods: The experiments were conducted on a cylindrical phantom. Six spheres with different volumes (0.5ml, 1ml, 6ml, 12ml, 16ml and 20 ml) were placed inside a cylindrical container to mimic tumors of different sizes. The spheres were filled with 11C solution as sources and the cylindrical container was filled with 18F-FDG solution as the background. The phantom was continuously scanned in a Biograph-40 True Point/True View PET/CT scanner, and 42 images were reconstructed with source-to-background ratio (SBR) ranging from 16:1 to 1.8:1. We took a large and a small ROI for each sphere, both of which contain the whole sphere and does not contain any other spheres. Six other ROIs of different sizes were then taken between the large and the small ROI. For each ROI, all images were segmented by eitht thresholding methods and eight advanced methods, respectively. The segmentation results were evaluated by dice similarity index (DSI), classification error (CE) and volume error (VE). The robustness of different methods to ROI variation was quantified using the interrun variation and a generalized Cohen's kappa. Results: With the change of ROI, the segmentation results of all tested methods changed more or less. Compared with all advanced methods, thresholding methods were less affected by the ROI change. In addition, most of the thresholding methods got more accurate segmentation results for all sphere sizes. Conclusion: The results showed that the segmentation performance of all tested methods was affected by the change of ROI. Thresholding methods were more robust to this change and they can segment the PET image more accurately. This work was supported in part by National Natural Science Foundation of China (NNSFC), under Grant Nos. 60971112 and 61375018, and Fundamental Research Funds for the Central Universities, under Grant No. 2012QN086. Wei Lu was supported in

  18. Is perivetricular hyperintensity region caused by decreased cerebral blood flow?; assessment by {sup 15}O-PET study

    SciTech Connect

    Kaminaga, T.; Hayashida, K.; Ishida, Y.

    1994-05-01

    The clinical significance of the regional cerebral blood flow (rCBF) and oxygen metabolism has not been established in patients who had periventricular hyperintensity (PVH) by magnetic resonance imaging (MRI). The aim of this study is to correlate the results of rCBF and oxygen metabolism by positron emission tomography (PET) with PVH by MRI. The subjects were 27 patients; 16 patient (group I) (male; 7, female; 9, age; 56.8{plus_minus}18.6) with PVH and age matched 11 patients (group II) (male; 6, female; 5, age; 55.3{plus_minus}13.6) without PVH. {sup 15}O-PET study was carried out by Headtome IV and rCBF, cerebral metabolic rate of oxygen (CMRO{sub 2}), oxygen extraction fraction (OEF) of PVH and cerebellum was calculated. T1- and T2-weighted images were obtained in all patients. Angiography was performed over 11 patients. The mean rCBF of group I in PVH (28.5{plus_minus}7.5 ml/100g/min) was significantly (p<0.01) lower than that of group II (38.6{plus_minus}5.7). The mean rCBF of group I and group II in cerebellum were 49.5{plus_minus}9.9 ml/100g/min and 50.2{plus_minus}8.9 respectively. There was no significant difference on CMRO{sub 2} and OEF between group I and group II. In MRI examination, PVH was detected in all group I patients and multiple high intensities were also detected in 7 patients of group I and 4 patients of group II on T2-weighted images. No significant stenosis (more than 75%) was detected in 11 patients by angiography. These data strongly indicate that PVH might be caused by decreased cerebral blood flow.

  19. An analysis of whole body tracer kinetics in dynamic PET studies with application to image-based blood input function extraction.

    PubMed

    Huang, Jian; O'Sullivan, Finbarr

    2014-05-01

    In a positron emission tomography (PET) study, the local uptake of the tracer is dependent on vascular delivery and retention. For dynamic studies the measured uptake time-course information can be best interpreted when knowledge of the time-course of tracer in the blood is available. This is certainly true for the most established tracers such as 18F-Fluorodeoxyglucose (FDG) and 15O-Water (H2O). Since direct sampling of blood as part of PET studies is increasingly impractical, there is ongoing interest in image-extraction of blood time-course information. But analysis of PET-measured blood pool signals is complicated because they will typically involve a combination of arterial, venous and tissue information. Thus, a careful appreciation of these components is needed to interpret the available data. To facilitate this process, we propose a novel Markov chain model for representation of the circulation of a tracer atom in the body. The model represents both arterial and venous time-course patterns. Under reasonable conditions equilibration of tracer activity in arterial and venous blood is achieved by the end of the PET study-consistent with empirical measurement. Statistical inference for Markov model parameters is a challenge. A penalized nonlinear least squares process, incorporating a generalized cross-validation score, is proposed. Random effects analysis is used to adaptively specify the structure of the penalty function based on historical samples of directly measured blood data. A collection of arterially sampled data from PET studies with FDG and H2O is used to illustrate the methodology. These data analyses are highly supportive of the overall modeling approach. An adaptation of the model to the problem of extraction of arterial blood signals from imaging data is also developed and promising preliminary results for cerebral and thoracic imaging studies with FDG and H2O are obtained.

  20. An Analysis of Whole Body Tracer Kinetics in Dynamic PET Studies With Application to Image-Based Blood Input Function Extraction

    PubMed Central

    Huang, Jian; O’Sullivan, Finbarr

    2014-01-01

    In a positron emission tomography (PET) study, the local uptake of the tracer is dependent on vascular delivery and retention. For dynamic studies the measured uptake time-course information can be best interpreted when knowledge of the time-course of tracer in the blood is available. This is certainly true for the most established tracers such as 18F-Fluorodeoxyglucose (FDG) and 15O-Water (H2O). Since direct sampling of blood as part of PET studies is increasingly impractical, there is ongoing interest in image-extraction of blood time-course information. But analysis of PET-measured blood pool signals is complicated because they will typically involve a combination of arterial, venous and tissue information. Thus, a careful appreciation of these components is needed to interpret the available data. To facilitate this process, we propose a novel Markov chain model for representation of the circulation of a tracer atom in the body. The model represents both arterial and venous time-course patterns. Under reasonable conditions equilibration of tracer activity in arterial and venous blood is achieved by the end of the PET study—consistent with empirical measurement. Statistical inference for Markov model parameters is a challenge. A penalized nonlinear least squares process, incorporating a generalized cross-validation score, is proposed. Random effects analysis is used to adaptively specify the structure of the penalty function based on historical samples of directly measured blood data. A collection of arterially sampled data from PET studies with FDG and H2O is used to illustrate the methodology. These data analyses are highly supportive of the overall modeling approach. An adaptation of the model to the problem of extraction of arterial blood signals from imaging data is also developed and promising preliminary results for cerebral and thoracic imaging studies with FDG and H2O are obtained. PMID:24770914

  1. A 15O-H2O PET study of meditation and the resting state of normal consciousness.

    PubMed

    Lou, H C; Kjaer, T W; Friberg, L; Wildschiodtz, G; Holm, S; Nowak, M

    1999-01-01

    The aim of the present study was to examine whether the neural structures subserving meditation can be reproducibly measured, and, if so, whether they are different from those supporting the resting state of normal consciousness. Cerebral blood flow distribution was investigated with the 15O-H20 PET technique in nine young adults, who were highly experienced yoga teachers, during the relaxation meditation (Yoga Nidra), and during the resting state of normal consciousness. In addition, global CBF was measured in two of the subjects. Spectral EEG analysis was performed throughout the investigations. In meditation, differential activity was seen, with the noticeable exception of V1, in the posterior sensory and associative cortices known to participate in imagery tasks. In the resting state of normal consciousness (compared with meditation as a baseline), differential activity was found in dorso-lateral and orbital frontal cortex, anterior cingulate gyri, left temporal gyri, left inferior parietal lobule, striatal and thalamic regions, pons and cerebellar vermis and hemispheres, structures thought to support an executive attentional network. The mean global flow remained unchanged for both subjects throughout the investigation (39+/-5 and 38+/-4 ml/100 g/min, uncorrected for partial volume effects). It is concluded that the (H2)15O PET method may measure CBF distribution in the meditative state as well as during the resting state of normal consciousness, and that characteristic patterns of neural activity support each state. These findings enhance our understanding of the neural basis of different aspects of consciousness. PMID:9950067

  2. Elevation of dopamine induced by cigarette smoking: novel insights from a [11C]-+-PHNO PET study in humans.

    PubMed

    Le Foll, Bernard; Guranda, Mihail; Wilson, Alan A; Houle, Sylvain; Rusjan, Pablo M; Wing, Victoria C; Zawertailo, Laurie; Busto, Usoa; Selby, Peter; Brody, Arthur L; George, Tony P; Boileau, Isabelle

    2014-01-01

    Positron emission tomography (PET) has convincingly provided in vivo evidence that psychoactive drugs increase dopamine (DA) levels in human brain, a feature thought critical to their reinforcing properties. Some controversy still exists concerning the role of DA in reinforcing smoking behavior and no study has explored whether smoking increases DA concentrations at the D3 receptor, speculated to have a role in nicotine's addictive potential. Here, we used PET and [(11)C]-(+)-PHNO ([(11)C]-(+)-4-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b][1,4]oxazin-9-ol) to test the hypothesis that smoking increases DA release (decreases [(11)C]-(+)-PHNO binding) in D2-rich striatum and D3-rich extra-striatal regions and is related to craving, withdrawal and smoking behavior. Ten participants underwent [(11)C]-(+)-PHNO scans after overnight abstinence and after smoking a cigarette. Motivation to smoke (smoking topography), mood, and craving were recorded. Smoking significantly decreased self-reported craving, withdrawal, and [(11)C]-(+)-PHNO binding in D2 and D3-rich areas (-12.0 and -15.3%, respectively). We found that motivation to smoke (puff rate) predicted magnitude of DA release in limbic striatum, and the latter was correlated with decreased craving and withdrawal symptoms. This is the first report suggesting that, in humans, DA release is increased in D3-rich areas in response to smoking. Results also support the preferential involvement of the limbic striatum in motivation to smoke, anticipation of pleasure from cigarettes and relief of withdrawal symptoms. We propose that due to the robust effect of smoking on [(11)C]-(+)-PHNO binding, this radiotracer represents an ideal translational tool to investigate novel therapeutic strategies targeting DA transmission.

  3. Nature or nurture? Determining the heritability of human striatal dopamine function: an [18F]-DOPA PET study.

    PubMed

    Stokes, Paul R A; Shotbolt, Paul; Mehta, Mitul A; Turkheimer, Eric; Benecke, Aaf; Copeland, Caroline; Turkheimer, Federico E; Lingford-Hughes, Anne R; Howes, Oliver D

    2013-02-01

    Striatal dopamine function is important for normal personality, cognitive processes and behavior, and abnormalities are linked to a number of neuropsychiatric disorders. However, no studies have examined the relative influence of genetic inheritance and environmental factors in determining striatal dopamine function. Using [18F]-DOPA positron emission tomography (PET), we sought to determine the heritability of presynaptic striatal dopamine function by comparing variability in uptake values in same sex monozygotic (MZ) twins to dizygotic (DZ) twins. Nine MZ and 10 DZ twin pairs underwent high-resolution [18F]-DOPA PET to assess presynaptic striatal dopamine function. Uptake values for the overall striatum and functional striatal subdivisions were determined by a Patlak analysis using a cerebellar reference region. Heritability, shared environmental effects and non-shared individual-specific effects were estimated using a region of interest (ROI) analysis and a confirmatory parametric analysis. Overall striatal heritability estimates from the ROI and parametric analyses were 0.44 and 0.33, respectively. We found a distinction between striatal heritability in the functional subdivisions, with the greatest heritability estimates occurring in the sensorimotor striatum and the greatest effect of individual-specific environmental factors in the limbic striatum. Our results indicate that variation in overall presynaptic striatal dopamine function is determined by a combination of genetic factors and individual-specific environmental factors, with familial environmental effects having no effect. These findings underline the importance of individual-specific environmental factors for striatal dopaminergic function, particularly in the limbic striatum, with implications for understanding neuropsychiatric disorders such as schizophrenia and addictions.

  4. Target dependency of brain mechanism involved in dispositional inference: a PET study.

    PubMed

    Sugiura, Motoaki; Gotoh, Ryoi; Okada, Ken; Yamaguchi, Keiichiroh; Itoh, Masatoshi; Fukuda, Hiroshi; Kawashima, Ryuta

    2004-04-01

    The cognitive mechanism for inference of personal dispositions, such as personality traits and abilities, is postulated to be dependent on the amount of episodic memory concerning target persons. To examine whether there is such target dependency in the brain mechanism during dispositional inference, we measured brain activity of normal volunteers while they were performing seven dispositional inference tasks, each for a target person in different categories, using positron emission tomography (PET). Effect of the target-person category on activation was significant in the posterodorsal, polar, and ventral subdivisions of medial prefrontal cortex, right orbitoinsular junction, left temporal pole and superior temporal sulcus, cerebellum, and thalamus, suggesting the existence of target dependency in activation during dispositional inference. The amount of episodic memory concerning a target person measured using the self-evaluative questionnaire was positively correlated with the activation in the polar subdivision of the medial prefrontal cortex, and negatively with that in a region in the left superior temporal sulcus. Together with the available knowledge on the functional roles of these regions and the proposed cognitive model in social psychology, our results suggest that these two regions play roles supplementary to each other in dispositional inference; a region in the superior temporal sulcus is involved in the processing of relevant episodic exemplar and the polar subdivision of the medial prefrontal cortex in the processing of summarized value information about the target person. PMID:15050563

  5. Viewing another person's body as a target object: a behavioural and PET study of pointing.

    PubMed

    Cleret de Langavant, Laurent; Trinkler, Iris; Remy, Philippe; Thirioux, Bérangère; McIntyre, Joseph; Berthoz, Alain; Dupoux, Emmanuel; Bachoud-Lévi, Anne-Catherine

    2012-07-01

    Humans usually point at objects to communicate with other persons, although they generally avoid pointing at the other's body. Moreover, patients with heterotopagnosia after left parietal damage cannot point at another person's body parts, although they can point at objects and at their own body parts and although they can grasp the others' body parts. Strikingly, their performance gradually improves for figurative human body targets. Altogether, this suggests that the body of another real person holds a specific status in communicative pointing. Here, we test in healthy individuals whether performance for communicative pointing is influenced by the communicative capacity of the target. In Experiment 1, pointing at another real person's body parts was compared to pointing at objects, and in Experiment 2, the person was replaced by a manikin. While reaction times for pointing at objects were shorter compared to pointing at other person's body parts, they were similar for objects and manikin body parts. By adapting Experiment 1 to PET-scan imaging (Experiment 3), we showed that, compared to pointing at objects, the brain network for pointing at other person's body parts involves the left posterior intraparietal sulcus, lesion of which could cause heterotopagnosia. Taken together, our results indicate that the specificity of pointing at another person's body goes beyond the visuo-spatial features of the human body and might rather rely on its communicative capacity. PMID:22579967

  6. Increased activation of the human cerebellum during pitch discrimination: a positron emission tomography (PET) study.

    PubMed

    Petacchi, Augusto; Kaernbach, Christian; Ratnam, Rama; Bower, James M

    2011-12-01

    Recent years have seen a growing debate concerning the function of the cerebellum. Here we used a pitch discrimination task and PET to test for cerebellar involvement in the active control of sensory data acquisition. Specifically, we predicted greater cerebellar activity during active pitch discrimination compared to passive listening, with the greatest activity when pitch discrimination was most difficult. Ten healthy subjects were trained to discriminate deviant tones presented with a slightly higher pitch than a standard tone, using a Go/No Go paradigm. To ensure that discrimination performance was matched across subjects, individual psychometric curves were assessed beforehand using a two-step psychoacoustic procedure. Subjects were scanned while resting in the absence of any sounds, while passively listening to standard tones, and while detecting deviant tones slightly higher in pitch among these standard tones at four different performance levels. Consistent with our predictions, 1) passive listening alone elicited cerebellar activity (lobule IX), 2) cerebellar activity increased during pitch discrimination as compared to passive listening (crus I and II, lobules VI, VIIB, and VIIIB), and 3) this increase was correlated with the difficulty of the discrimination task (lobules V, VI, and IX). These results complement recent findings showing pitch discrimination deficits in cerebellar patients (Parsons et al., 2009) and further support a role for the cerebellum in sensory data acquisition. The data are discussed in the light of anatomical and physiological evidence functionally connecting auditory system and cerebellum.

  7. Reconsideration of Hemodynamic Cerebral Ischemia Using Recent PET/SPECT Studies.

    PubMed

    Nakagawara, Jyoji

    2016-01-01

    Hemodynamic cerebral ischemia has been conceptually confirmed by positron emission tomography (PET) imaging, and misery perfusion could be compensated with both vascular and metabolic reserve; however, these compensatory reserve capacities do not always respond in the same manner from short-term to long-term compromise of hemodynamic cerebral ischemia.In patients with acute misery perfusion, CMRO2 is immediately compensated by a marked increase of OEF combined with a limited increase of CBV. In patients with chronic misery perfusion, a moderate increase of OEF is compatible with a moderate increase of CBV, which could correlate with a moderate decrease of vascular reserve (VR). In moyamoya disease with long-standing misery perfusion, hemodynamic cerebral ischemia is initially compensated with a great deal of vasodilation, and can then be followed with an increased OEF in response to the degree of progression.The stage of hemodynamic cerebral ischemia has been defined by an increase of OEF, but could be reconsidered from different patterns of the engagement of compensatory reserve capacities, and misery perfusion could be classified into three subtypes, such as acute, chronic, and long-standing misery perfusion. PMID:27637635

  8. Viewing another person's body as a target object: a behavioural and PET study of pointing.

    PubMed

    Cleret de Langavant, Laurent; Trinkler, Iris; Remy, Philippe; Thirioux, Bérangère; McIntyre, Joseph; Berthoz, Alain; Dupoux, Emmanuel; Bachoud-Lévi, Anne-Catherine

    2012-07-01

    Humans usually point at objects to communicate with other persons, although they generally avoid pointing at the other's body. Moreover, patients with heterotopagnosia after left parietal damage cannot point at another person's body parts, although they can point at objects and at their own body parts and although they can grasp the others' body parts. Strikingly, their performance gradually improves for figurative human body targets. Altogether, this suggests that the body of another real person holds a specific status in communicative pointing. Here, we test in healthy individuals whether performance for communicative pointing is influenced by the communicative capacity of the target. In Experiment 1, pointing at another real person's body parts was compared to pointing at objects, and in Experiment 2, the person was replaced by a manikin. While reaction times for pointing at objects were shorter compared to pointing at other person's body parts, they were similar for objects and manikin body parts. By adapting Experiment 1 to PET-scan imaging (Experiment 3), we showed that, compared to pointing at objects, the brain network for pointing at other person's body parts involves the left posterior intraparietal sulcus, lesion of which could cause heterotopagnosia. Taken together, our results indicate that the specificity of pointing at another person's body goes beyond the visuo-spatial features of the human body and might rather rely on its communicative capacity.

  9. Improved attenuation correction for freely moving animal brain PET studies using a virtual scanner geometry

    NASA Astrophysics Data System (ADS)

    Angelis, Georgios I.; Ryder, William J.; Kyme, Andre Z.; Fulton, Roger R.; Meikle, Steven R.

    2014-03-01

    Attenuation correction in positron emission tomography brain imaging of freely moving animals can be very challenging since the body of the animal is often within the field of view and introduces a non negligible atten- uating factor that can degrade the quantitative accuracy of the reconstructed images. An attractive approach that avoids the need for a transmission scan involves the generation of the convex hull of the animal's head based on the reconstructed emission images. However, this approach ignores the potential attenuation introduced by the animal's body. In this work, we propose a virtual scanner geometry, which moves in synchrony with the animal's head and discriminates between those events that traverse only the animal's head (and therefore can be accurately compensated for attenuation) and those that might have also traversed the animal's body. For each pose a new virtual scanner geometry was defined and therefore a new system matrix was calculated leading to a time-varying system matrix. This new approach was evaluated on phantom data acquired on the microPET Focus 220 scanner using a custom-made rat phantom. Results showed that when the animal's body is within the FOV and not accounted for during attenuation correction it can lead to bias of up to 10%. On the contrary, at- tenuation correction was more accurate when the virtual scanner was employed leading to improved quantitative estimates (bias <2%), without the need to account for the animal's body.

  10. Reproducibility of quantitative measures of binding potential in rat striatum: A test re-test study using DTBZ dynamic PET studies

    SciTech Connect

    Avendaño-Estrada, A. Lara-Camacho, V. M. Ávila-García, M. C. Ávila- Rodríguez, M. A.

    2014-11-07

    There is great interest in the study of dopamine (DA) pathways due to the increasing number of patients with illnesses related to the dopaminergic system and molecular imaging based in Positron Emission Tomography (PET) has been proven helpful for this task. Among the different radiopharmaceuticals available to study DA interaction, [{sup 11}C]Dihydrotetrabenazine (DTBZ) has a high affinity for the vesicular monoamine transporter type 2 (VMAT2) and its binding potential (BP) is a marker of DA terminal integrity. This paper reports on the intersubject reproducibility of BP measurements in rat striatum with [11C]DTBZ using the Logańs method.

  11. Trends in PET imaging

    SciTech Connect

    Moses, William W.

    2000-11-01

    Positron Emission Tomography (PET) imaging is a well established method for obtaining information on the status of certain organs within the human body or in animals. This paper presents an overview of recent trends PET instrumentation. Significant effort is being expended to develop new PET detector modules, especially those capable of measuring depth of interaction. This is aided by recent advances in scintillator and pixellated photodetector technology. The other significant area of effort is development of special purpose PET cameras (such as for imaging breast cancer or small animals) or cameras that have the ability to image in more than one modality (such as PET / SPECT or PET / X-Ray CT).

  12. SU-E-J-82: Intra-Fraction Proton Beam-Range Verification with PET Imaging: Feasibility Studies with Monte Carlo Simulations and Statistical Modeling

    SciTech Connect

    Lou, K; Mirkovic, D; Sun, X; Zhu, X; Poenisch, F; Grosshans, D; Shao, Y; Clark, J

    2014-06-01

    Purpose: To study the feasibility of intra-fraction proton beam-range verification with PET imaging. Methods: Two phantoms homogeneous cylindrical PMMA phantoms (290 mm axial length, 38 mm and 200 mm diameter respectively) were studied using PET imaging: a small phantom using a mouse-sized PET (61 mm diameter field of view (FOV)) and a larger phantom using a human brain-sized PET (300 mm FOV). Monte Carlo (MC) simulations (MCNPX and GATE) were used to simulate 179.2 MeV proton pencil beams irradiating the two phantoms and be imaged by the two PET systems. A total of 50 simulations were conducted to generate 50 positron activity distributions and correspondingly 50 measured activity-ranges. The accuracy and precision of these activity-ranges were calculated under different conditions (including count statistics and other factors, such as crystal cross-section). Separate from the MC simulations, an activity distribution measured from a simulated PET image was modeled as a noiseless positron activity distribution corrupted by Poisson counting noise. The results from these two approaches were compared to assess the impact of count statistics on the accuracy and precision of activity-range calculations. Results: MC Simulations show that the accuracy and precision of an activity-range are dominated by the number (N) of coincidence events of the reconstructed image. They are improved in a manner that is inversely proportional to 1/sqrt(N), which can be understood from the statistical modeling. MC simulations also indicate that the coincidence events acquired within the first 60 seconds with 10{sup 9} protons (small phantom) and 10{sup 10} protons (large phantom) are sufficient to achieve both sub-millimeter accuracy and precision. Conclusion: Under the current MC simulation conditions, the initial study indicates that the accuracy and precision of beam-range verification are dominated by count statistics, and intra-fraction PET image-based beam-range verification is

  13. [Regional distribution of the muscarinic cholinergic receptor in the human brain studied with 11C-benztropine and PET using an anatomical standardization technique].

    PubMed

    Ono, S; Kawashima, R; Ito, H; Koyama, M; Goto, R; Inoue, K; Sato, K; Fujiwara, T; Meguro, K; Yanai, K; Sasaki, H; Ido, T; Ito, M; Fukuda, H

    1996-07-01

    We measured regional distribution of the muscarinic cholinergic receptor in the normal human brain with 11C-benztropine (BZT) and positron emission tomography (PET) using an anatomical standardization technique. Seven normal volunteers who gave informed consents were involved in this study. Immediately after intravenous injection of 11C-BZT into the subjects, we started dynamic PET scanning and serial frequent arterial blood sampling. Analyses of plasma metabolites were also performed at selected time points and plasma time activity curves (TAC) of unmetabolized ligand were generated. From these PET and TAC data, we obtained Patlak plot slope calculation images. Using the HBA (human brain atlas) system, the Patlak plot slope calculation image of each subject was transformed into the shape of the standard brain. Mean and standard deviation (SD) calculation images were generated from those anatomically standardized images. On these mean and SD images, we placed regions of interest which were previously outlined on a MR image of the standard brain. From those data, we found the highest receptor distribution in the striatum and occipital cortex, as well as high distribution in the frontal, parietal, and temporal cortices, which were consistent with previous reports. These results suggested that anatomical standardization of PET receptor images with 11C-BZT will be useful for delineating the physiological or pathological alterations of the muscarinic cholinergic receptor in the human brain.

  14. Extension and validation of an analytical model for in vivo PET verification of proton therapy—a phantom and clinical study

    NASA Astrophysics Data System (ADS)

    Attanasi, F.; Knopf, A.; Parodi, K.; Paganetti, H.; Bortfeld, T.; Rosso, V.; Del Guerra, A.

    2011-08-01

    The interest in positron emission tomography (PET) as a tool for treatment verification in proton therapy has become widespread in recent years, and several research groups worldwide are currently investigating the clinical implementation. After the first off-line investigation with a PET/CT scanner at MGH (Boston, USA), attention is now focused on an in-room PET application immediately after treatment in order to also detect shorter-lived isotopes, such as O15 and N13, minimizing isotope washout and avoiding patient repositioning errors. Clinical trials are being conducted by means of commercially available PET systems, and other tests are planned using application-dedicated tomographs. Parallel to the experimental investigation and new hardware development, great interest has been shown in the development of fast procedures to provide feedback regarding the delivered dose from reconstructed PET images. Since the thresholds of inelastic nuclear reactions leading to tissue β+-activation fall within the energy range of 15-20 MeV, the distal activity fall-off is correlated, but not directly matched, to the distal fall-off of the dose distribution. Moreover, the physical interactions leading to β+-activation and energy deposition are of a different nature. All these facts make it essential to further develop accurate and fast methodologies capable of predicting, on the basis of the planned dose distribution, expected PET images to be compared with actual PET measurements, thus providing clinical feedback on the correctness of the dose delivery and of the irradiation field position. The aim of this study has been to validate an analytical model and to implement and evaluate it in a fast and flexible framework able to locally predict such activity distributions directly taking the reference planning CT and planned dose as inputs. The results achieved in this study for phantoms and clinical cases highlighted the potential of the implemented method to predict expected

  15. Extension and validation of an analytical model for in vivo PET verification of proton therapy--a phantom and clinical study.

    PubMed

    Attanasi, F; Knopf, A; Parodi, K; Paganetti, H; Bortfeld, T; Rosso, V; Del Guerra, A

    2011-08-21

    The interest in positron emission tomography (PET) as a tool for treatment verification in proton therapy has become widespread in recent years, and several research groups worldwide are currently investigating the clinical implementation. After the first off-line investigation with a PET/CT scanner at MGH (Boston, USA), attention is now focused on an in-room PET application immediately after treatment in order to also detect shorter-lived isotopes, such as O15 and N13, minimizing isotope washout and avoiding patient repositioning errors. Clinical trials are being conducted by means of commercially available PET systems, and other tests are planned using application-dedicated tomographs. Parallel to the experimental investigation and new hardware development, great interest has been shown in the development of fast procedures to provide feedback regarding the delivered dose from reconstructed PET images. Since the thresholds of inelastic nuclear reactions leading to tissue β+ -activation fall within the energy range of 15-20 MeV, the distal activity fall-off is correlated, but not directly matched, to the distal fall-off of the dose distribution. Moreover, the physical interactions leading to β+ -activation and energy deposition are of a different nature. All these facts make it essential to further develop accurate and fast methodologies capable of predicting, on the basis of the planned dose distribution, expected PET images to be compared with actual PET measurements, thus providing clinical feedback on the correctness of the dose delivery and of the irradiation field position. The aim of this study has been to validate an analytical model and to implement and evaluate it in a fast and flexible framework able to locally predict such activity distributions directly taking the reference planning CT and planned dose as inputs. The results achieved in this study for phantoms and clinical cases highlighted the potential of the implemented method to predict expected

  16. Stereotactic Comparison Study of (18)F-Alfatide and (18)F-FDG PET Imaging in an LLC Tumor-Bearing C57BL/6 Mouse Model.

    PubMed

    Wei, Yu-Chun; Gao, Yongsheng; Zhang, Jianbo; Fu, Zheng; Zheng, Jinsong; Liu, Ning; Hu, Xudong; Hou, Wenhong; Yu, Jinming; Yuan, Shuanghu

    2016-01-01

    This study aimed to stereotactically compare the PET imaging performance of (18)F-Alfatide ((18)F-ALF-NOTA-PRGD2, denoted as (18)F-Alfatide) and (18)F-fluorodeoxyglucose (FDG) and immunohistochemistry (IHC) staining in Lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mouse model. (18)F-FDG standard uptake values (SUVs) were higher than (18)F-Alfatide SUVs in tumors, most of the normal tissues and organs except for the bladder. Tumor-to-brain, tumor-to-lung, and tumor-to-heart ratios of (18)F-Alfatide PET were significantly higher than those of (18)F-FDG PET (P < 0.001). The spatial heterogeneity of the tumors was detected, and the tracer accumulation enhanced from the outer layer to the inner layer consistently using the two tracers. The parameters of the tumors were significantly correlated with each other between (18)F-FDG SUV and GLUT-1 (R = 0.895, P < 0.001), (18)F-Alfatide SUV and αvβ3 (R = 0.595, P = 0.019), (18)F-FDG SUV and (18)F-Alfatide SUV (R = 0.917, P < 0.001), and GLUT-1 and αvβ3 (R = 0.637, P = 0.011). Therefore, (18)F-Alfatide PET may be an effective tracer for tumor detection, spatial heterogeneity imaging and an alternative supplement to (18)F-FDG PET, particularly for patients with enhanced characteristics in the brain, chest tumors or diabetes, meriting further study. PMID:27350554

  17. Selective Nodal Irradiation on Basis of {sup 18}FDG-PET Scans in Limited-Disease Small-Cell Lung Cancer: A Prospective Study

    SciTech Connect

    Loon, Judith van; De Ruysscher, Dirk; Wanders, Rinus; Boersma, Liesbeth; Simons, Jean; Oellers, Michel; Dingemans, Anne-Marie C.; Hochstenbag, Monique; Bootsma, Gerben; Geraedts, Wiel; Pitz, Cordula; Teule, Jaap; Rhami, Ali; Thimister, Willy; Snoep, Gabriel; Dehing-Oberije, Cary; Lambin, Philippe

    2010-06-01

    Purpose: To evaluate the results of selective nodal irradiation on basis of {sup 18}F-deoxyglucose positron emission tomography (PET) scans in patients with limited-disease small-cell lung cancer (LD-SCLC) on isolated nodal failure. Methods and Materials: A prospective study was performed of 60 patients with LD-SCLC. Radiotherapy was given to a dose of 45 Gy in twice-daily fractions of 1.5 Gy, concurrent with carboplatin and etoposide chemotherapy. Only the primary tumor and the mediastinal lymph nodes involved on the pretreatment PET scan were irradiated. A chest computed tomography (CT) scan was performed 3 months after radiotherapy completion and every 6 months thereafter. Results: A difference was seen in the involved nodal stations between the pretreatment {sup 18}F-deoxyglucose PET scans and computed tomography scans in 30% of patients (95% confidence interval, 20-43%). Of the 60 patients, 39 (65%; 95% confidence interval [CI], 52-76%) developed a recurrence; 2 patients (3%, 95% CI, 1-11%) experienced isolated regional failure. The median actuarial overall survival was 19 months (95% CI, 17-21). The median actuarial progression-free survival was 14 months (95% CI, 12-16). 12% (95% CI, 6-22%) of patients experienced acute Grade 3 (Common Terminology Criteria for Adverse Events, version 3.0) esophagitis. Conclusion: PET-based selective nodal irradiation for LD-SCLC resulted in a low rate of isolated nodal failures (3%), with a low percentage of acute esophagitis. These findings are in contrast to those from our prospective study of CT-based selective nodal irradiation, which resulted in an unexpectedly high percentage of isolated nodal failures (11%). Because of the low rate of isolated nodal failures and toxicity, we believe that our data support the use of PET-based SNI for LD-SCLC.

  18. Stereotactic Comparison Study of 18F-Alfatide and 18F-FDG PET Imaging in an LLC Tumor-Bearing C57BL/6 Mouse Model

    PubMed Central

    Wei, Yu-Chun; Gao, Yongsheng; Zhang, Jianbo; Fu, Zheng; Zheng, Jinsong; Liu, Ning; Hu, Xudong; Hou, Wenhong; Yu, Jinming; Yuan, Shuanghu

    2016-01-01

    This study aimed to stereotactically compare the PET imaging performance of 18F-Alfatide (18F-ALF-NOTA-PRGD2, denoted as 18F-Alfatide) and 18F-fluorodeoxyglucose (FDG) and immunohistochemistry (IHC) staining in Lewis lung carcinoma (LLC) tumor-bearing C57BL/6 mouse model. 18F-FDG standard uptake values (SUVs) were higher than 18F-Alfatide SUVs in tumors, most of the normal tissues and organs except for the bladder. Tumor-to-brain, tumor-to-lung, and tumor-to-heart ratios of 18F-Alfatide PET were significantly higher than those of 18F-FDG PET (P < 0.001). The spatial heterogeneity of the tumors was detected, and the tracer accumulation enhanced from the outer layer to the inner layer consistently using the two tracers. The parameters of the tumors were significantly correlated with each other between 18F-FDG SUV and GLUT-1 (R = 0.895, P < 0.001), 18F-Alfatide SUV and αvβ3 (R = 0.595, P = 0.019), 18F-FDG SUV and 18F-Alfatide SUV (R = 0.917, P < 0.001), and GLUT-1 and αvβ3 (R = 0.637, P = 0.011). Therefore, 18F-Alfatide PET may be an effective tracer for tumor detection, spatial heterogeneity imaging and an alternative supplement to 18F-FDG PET, particularly for patients with enhanced characteristics in the brain, chest tumors or diabetes, meriting further study. PMID:27350554

  19. Low dopamine activity in Lesch Nyhan Disease. An 18-fluorodopa PET study

    SciTech Connect

    Ernst, M.; Zametkin, A.; Matochik, J.

    1996-05-01

    Lesch-Nyhan Disease (LND) is a rare devastating X-linked recessive disorder characterized by the virtual absence of hypoxanthine guanine phosphoribosyl transferase (HPRT), a major enzyme of the salvage pathway of purine metabolism. The clinical presentation includes hyperuricemia choreoathetosis, dystonia, aggression and self-injurious behavior. The genetic and biochemical abnormalities are fully identified. However, the neuropathophysiological process by which the lack of HPRT produces the neuropsychiatric syndrome of LND in unclear. Presynaptic uptake of 18-Fluorodopa (FD) in basal ganglia, substantia nigra, and frontal and occipital cortices was measured by PET in 12 patients with LND, 10 to 20 years old, and 15 health controls, 12 to 23 years old. Radioactive counts (mCi/cc), recorded between 90 and 130 minutes after tracer injection, were measured in regions of interest by a rater blind to subjects` identities. Results were expressed as ratios of FD uptake in specific to non-specific (occipital cortex) brain areas. Presynaptic dopamine activity was significantly lower by 69% in putamen (p<0.0001), 61% in caudate (p<0.0001), 56% in frontal cortex (p=0.003) and 43% in substantiat nigra (p<0.016) in LND patients than in control subjects. Absolute FD measures in occipital regions did not differ between the two groups. Activity of FD in the basal ganglia was stable over time in the LND group and tended to increase in the control group (r=0.50, n=15, p=0.060). In the LND group, aggressive behavior was worse as FD activity was higher (r=0.60, n=12, p=0.40). LND is associated with a striking reduction of presynaptic dopamine activity that is not region-specific. The temporal stability of FD measures and of the severity of LND symptomatology is consistent with a developmental rather than degenerative process.

  20. Dorsal premotor cortex and conditional movement selection: A PET functional mapping study.

    PubMed

    Grafton, S T; Fagg, A H; Arbib, M A

    1998-02-01

    Positron emission tomography (PET) brain mapping was used to investigate whether or not human dorsal premotor cortex is involved in selecting motor acts based on arbitrary visual stimuli. Normal subjects performed four movement selection tasks. A manipulandum with three graspable stations was used. An imperative visual cue (LEDs illuminated in random order) indicated which station to grasp next with no instructional delay period. In a power task, a large aperture power grip was used for all trials, irrespective of the LED color. In a precision task, a pincer grasp of thumb and index finger was used. In a conditional task, the type of grasp (power or precision) was randomly determined by LED color. Comparison of the conditional selection task versus the average of the power and precision tasks revealed increased blood flow in left dorsal premotor cortex and superior parietal lobule. The average rate of producing the different grasp types and transport to the manipulandum stations was equivalent across this comparison, minimizing the contribution of movement attributes such as planning the individual movements (as distinct from planning associated with use of instructional stimuli), kinematics, or direction of target or limb movement. A comparison of all three movement tasks versus a rest task identified movement related activity involving a large area of central, precentral and postcentral cortex. In the region of the precentral sulcus movement related activity was located immediately caudal to the area activated during selection. The results establish a role for human dorsal premotor cortex and superior parietal cortex in selecting stimulus guided movements and suggest functional segregation within dorsal premotor cortex.

  1. Batch-reactor microfluidic device: first human use of a microfluidically produced PET radiotracer.

    PubMed

    Lebedev, Artem; Miraghaie, Reza; Kotta, Kishore; Ball, Carroll E; Zhang, Jianzhong; Buchsbaum, Monte S; Kolb, Hartmuth C; Elizarov, Arkadij

    2013-01-01

    The very first microfluidic device used for the production of (18)F-labeled tracers for clinical research is reported along with the first human Positron Emission Tomography scan obtained with a microfluidically produced radiotracer. The system integrates all operations necessary for the transformation of [(18)F]fluoride in irradiated cyclotron target water to a dose of radiopharmaceutical suitable for use in clinical research. The key microfluidic technologies developed for the device are a fluoride concentration system and a microfluidic batch reactor assembly. Concentration of fluoride was achieved by means of absorption of the fluoride anion on a micro ion-exchange column (5 μL of resin) followed by release of the radioactivity with 45 μL of the release solution (95 ± 3% overall efficiency). The reactor assembly includes an injection-molded reactor chip and a transparent machined lid press-fitted together. The resulting 50 μL cavity has a unique shape designed to minimize losses of liquid during reactor filling and liquid evaporation. The cavity has 8 ports for gases and liquids, each equipped with a 2-way on-chip mechanical valve rated for pressure up to 20.68 bar (300 psi). The temperature is controlled by a thermoelectric heater capable of heating the reactor up to 180 °C from RT in 150 s. A camera captures live video of the processes in the reactor. HPLC-based purification and reformulation units are also integrated in the device. The system is based on "split-box architecture", with reagents loaded from outside of the radiation shielding. It can be installed either in a standard hot cell, or as a self-shielded unit. Along with a high level of integration and automation, split-box architecture allowed for multiple production runs without the user being exposed to radiation fields. The system was used to support clinical trials of [(18)F]fallypride, a neuroimaging radiopharmaceutical under IND Application #109,880.

  2. Estimating neurotransmitter kinetics with ntPET: a simulation study of temporal precision and effects of biased data.

    PubMed

    Normandin, Marc D; Morris, Evan D

    2008-02-01

    We recently introduced neurotransmitter PET (ntPET), an analysis technique that estimates the kinetics of stimulus-induced neurotransmitter (NT) release. Here, we evaluate two formulations of ntPET. The arterial (ART) approach measures the tracer input function (TIF) directly. The reference (REF) approach derives the TIF from reference region data. Arterial sampling is considered the gold standard in PET modeling but reference region approaches are preferred for reduced cost and complexity. If simulated PET data with unbiased TIFs were analyzed using ART or REF, temporal precision was better than 3 min provided NT concentration peaked less than 30 min into the scanning session. The consequences of biased TIFs or stimulus-induced changes in tracer delivery were also evaluated. ART TIFs were biased by the presence of uncorrected radiometabolites in the plasma whereas REF TIFs were biased by specific binding in the reference region. Simulated changes in tracer delivery emulated ethanol-induced blood flow alterations observed previously with PET. ART performance deteriorated significantly if metabolites amounted to 50% of plasma radioactivity by 60 min. The accuracy and precision of REF were preserved even if the reference region contained 40% of the receptor density of the target region. Both methods were insensitive to blood flow alterations (proportional changes in K(1) and k(2)). Our results suggest that PET data contain information--heretofore not extracted--about the timing of NT release. The REF formulation of ntPET proved to be robust to many plausible model violations and under most circumstances is an appropriate alternative to ART.

  3. Reproducibility of 18F-FDG PET uptake measurements in head and neck squamous cell carcinoma on both PET/CT and PET/MR

    PubMed Central

    Fischer, B M; Aznar, M C; Hansen, A E; Vogelius, I R; Löfgren, J; Andersen, F L; Loft, A; Kjaer, A; Højgaard, L; Specht, L

    2015-01-01

    Objective: To investigate reproducibility of fluorine-18 fludeoxyglucose (18F-FDG) uptake on 18F-FDG positron emission tomography (PET)/CT and 18F-FDG PET/MR scans in patients with head and neck squamous cell carcinoma (HNSCC). Methods: 30 patients with HNSCC were included in this prospective study. The patients were scanned twice before radiotherapy treatment with both PET/CT and PET/MR. Patients were scanned on the same scanners, 3 days apart and according to the same protocol. Metabolic tumour activity was measured by the maximum and peak standardized uptake value (SUVmax and SUVpeak, respectively), and total lesion glycolysis from the metabolic tumour volume defined from ≥50% SUVmax. Bland–Altman analysis with limits of agreement, coefficient of variation (CV) from the two modalities were performed in order to test the reproducibility. Furthermore, CVs from SUVmax and SUVpeak were compared. The area under the curve from cumulative SUV–volume histograms were measured and tested for reproducibility of the distribution of 18F-FDG uptake. Results: 24 patients had two pre-treatment PET/CT scans and 21 patients had two pre-treatment PET/MR scans available for further analyses. Mean difference for SUVmax, peak and mean was approximately 4% for PET/CT and 3% for PET/MR, with 95% limits of agreement less than ±20%. CV was small (5–7%) for both modalities. There was no significant difference in CVs between PET/CT and PET/MR (p = 0.31). SUVmax was not more reproducible than SUVpeak (p = 0.09). Conclusion: 18F-FDG uptake in PET/CT and PET/MR is highly reproducible and we found no difference in reproducibility between PET/CT and PET/MR. Advances in knowledge: This is the first report to test reproducibility of PET/CT and PET/MR. PMID:25634069

  4. ROC (Receiver Operating Characteristics) study of maximum likelihood estimator human brain image reconstructions in PET (Positron Emission Tomography) clinical practice

    SciTech Connect

    Llacer, J.; Veklerov, E.; Nolan, D. ); Grafton, S.T.; Mazziotta, J.C.; Hawkins, R.A.; Hoh, C.K.; Hoffman, E.J. )

    1990-10-01

    This paper will report on the progress to date in carrying out Receiver Operating Characteristics (ROC) studies comparing Maximum Likelihood Estimator (MLE) and Filtered Backprojection (FBP) reconstructions of normal and abnormal human brain PET data in a clinical setting. A previous statistical study of reconstructions of the Hoffman brain phantom with real data indicated that the pixel-to-pixel standard deviation in feasible MLE images is approximately proportional to the square root of the number of counts in a region, as opposed to a standard deviation which is high and largely independent of the number of counts in FBP. A preliminary ROC study carried out with 10 non-medical observers performing a relatively simple detectability task indicates that, for the majority of observers, lower standard deviation translates itself into a statistically significant detectability advantage in MLE reconstructions. The initial results of ongoing tests with four experienced neurologists/nuclear medicine physicians are presented. Normal cases of {sup 18}F -- fluorodeoxyglucose (FDG) cerebral metabolism studies and abnormal cases in which a variety of lesions have been introduced into normal data sets have been evaluated. We report on the results of reading the reconstructions of 90 data sets, each corresponding to a single brain slice. It has become apparent that the design of the study based on reading single brain slices is too insensitive and we propose a variation based on reading three consecutive slices at a time, rating only the center slice. 9 refs., 2 figs., 1 tab.

  5. FDG-PET/CT in pediatric solid tumors.

    PubMed

    Franzius, C

    2010-08-01

    Positron emission tomography/computed tomography (PET/CT) has become an important imaging modality in the non-invasive evaluation and monitoring of children with known or suspected malignant diseases. In sarcoma patients, [18F]FDG (FDG) PET and FDG PET/CT is useful in staging, therapy monitoring, and detection of relapse. However, FDG PET has been proven to be less sensitive than chest CT in the detection of pulmonary metastases derived from sarcoma. This disadvantage has been overcome using a PET/CT scanner. In neuroblastoma patients, PET using FDG is indicated in MIBG-negative cases. Furthermore, there are specific PET tracers for tumors of the sympathetic nervous system, such as [11C]Hydroxyephedrine (HED) and [18F]-labeled dihydrophenylalanine (F-DOPA), which can be used for PET/CT imaging for detection of disease, staging and monitoring therapy. However, there are only few studies using specific PET tracers in neuroblastoma patients. In other pediatric malignancies including germ cell tumors and hepatoblastoma PET and PET/CT may be helpful in individual cases, but the literature in these entities is limited so far. Although publications on the additional value of the combined PET/CT compared to both stand-alone modalities are still limited in pediatrics, it can already be anticipated that the combination of morphological and functional information obtained by integrated PET/CT will improve the accuracy of staging and will change patient management in a significant number of pediatric patients.

  6. Imaging dopaminergic dysfunction as a surrogate marker of neuropathology in a small-animal model of HIV.

    PubMed

    Lee, Dianne E; Reid, William C; Ibrahim, Wael G; Peterson, Kristin L; Lentz, Margaret R; Maric, Dragan; Choyke, Peter L; Jagoda, Elaine M; Hammoud, Dima A

    2014-01-01

    The dopaminergic system is especially vulnerable to the effects of human immunodeficiency virus (HIV) infection, rendering dopaminergic deficits early surrogate markers of HIV-associated neuropathology. We quantified dopamine D2/3 receptors in young HIV-1 transgenic (Tg) (n  =  6) and age-matched control rats (n  =  7) and adult Tg (n  =  5) and age-matched control rats (n  =  5) using [18F]fallypride positron emission tomography (PET). Regional uptake was quantified as binding potential (BPND) using the two-tissue reference model with the cerebellum as the reference. Time-activity curves were generated for the ventral striatum, dorsal striatum, thalamus, and cerebellum. Whereas BPND values were significantly lower in the ventral striatum (p < .001) and dorsal striatum (p  =  .001) in the adult Tg rats compared to controls rats, they were significantly lower only in the dorsal striatum (p < .05) in the young rats. Tg rats had smaller striatal volumes on magnetic resonance imaging. We also found lower expression levels of tyrosine hydroxylase on immunohistochemistry in the Tg animals. Our findings suggest that progressive striatal D2/3 receptor deficits occur in Tg rats as they age and can be detected using small-animal PET imaging. The effectiveness of various approaches in preventing or halting this dopaminergic loss in the Tg rat can thus be measured preclinically using [18F]fallypride PET as a molecular imaging biomarker of HIV-associated neuropathology. PMID:25248756

  7. Birds Kept as Pets

    MedlinePlus

    ... restricts the importation of pet birds from certain countries and enforces a 30-day quarantine for all imported birds except those that come from Canada. People interested in importing pet birds should visit the USDA non-US Origin Pet Bird Importation website . Choosing a bird Match ...

  8. Temporal lobe deficits in murderers: EEG findings undetected by PET.

    PubMed

    Gatzke-Kopp, L M; Raine, A; Buchsbaum, M; LaCasse, L

    2001-01-01

    This study evaluates electroencephalography (EEG) and positron emission tomography (PET) in the same subjects. Fourteen murderers were assessed by using both PET (while they were performing the continuous performance task) and EEG during a resting state. EEG revealed significant increases in slow-wave activity in the temporal, but not frontal, lobe in murderers, in contrast to prior PET findings that showed reduced prefrontal, but not temporal, glucose metabolism. Results suggest that resting EEG shows empirical utility distinct from PET activation findings.

  9. Pet Care Teaching Unit: 1st-3rd Grades.

    ERIC Educational Resources Information Center

    Peninsula Humane Society, San Mateo, CA.

    Activities in this unit are designed to familiarize primary grade students with the responsibilities involved in pet ownership. Teaching plans are provided for a total of 12 lessons involving social studies, language arts, math, and health sciences. Activities adaptable for readers and non-readers focus on pet overpopulation, care of pets when…

  10. The Psychological Effect of Pet-Ownership on Reading Achievement.

    ERIC Educational Resources Information Center

    Hamtil, Rosemary

    A study examined the possible influence that pets may have on children's reading achievement. Subjects, 61 students from three third-grade classes in an urban school, completed a questionnaire about pet ownership. Responses were compiled and score values established to recognize the length of time the child had owned the pet and how much…

  11. Extra-nigral pathologies are common in Parkinson disease with freezing of gait: an in vivo PET study

    PubMed Central

    Bohnen, Nicolaas I.; Frey, Kirk A.; Studenski, Stephanie; Kotagal, Vikas; Koeppe, Robert A; Constantine, Gregory M.; Scott, Peter J.H.; Albin, Roger L.; Müller, Martijn L.T.M

    2014-01-01

    BACKGROUND Cholinergic denervation has been associated with falls and slower gait speed and β-amyloid deposition with greater severity of axial motor impairments in Parkinson disease (PD). However, little is known about the association between the presence of extra-nigral pathologies and freezing of gait (FoG). METHODS Patients with PD (n=143; age 65.5±7.4 years, Hoehn and Yahr stage 2.4±0.6, Montreal Cognitive Assessment score 25.9±2.6) underwent [11C]methyl-4-pi-peridinyl propionate acetylcholinesterase and [11C]dihydrotetrabenazine dopaminergic PET imaging, and clinical, including FoG, assessment in the dopaminergic “off” state. A subset of subjects (n=61) underwent [11C]Pittsburgh compound-B β-amyloid PET imaging. Normative data were used to dichotomize abnormal β-amyloid uptake or cholinergic deficits. RESULTS FoG was present in 20 patients (14.0%). Freezers had longer duration of disease (P=0.009), more severe motor disease (P<0.0001) and lower striatal dopaminergic activity (P=0.013) compared to non-freezers. FoG was more common in patients with diminished neocortical cholinergic innervation (23.9%, χ2=5.56, P=0.018) but not in the thalamic cholinergic denervation group (17.4%, χ2=0.26, P=0.61). Subgroup analysis showed higher frequency of FoG with increased neocortical β-amyloid deposition (30.4%, Fisher Exact test: P = 0.032). FoG frequency was lowest with absence of both pathology (4.8%), intermediate in subjects with single extra-nigral pathology (14.3%) and highest with combined neocortical cholinopathy and amyloidopathy (41.7%; Cochran-Armitage trend test Z=2.63, P=0.015). Within the group of freezers, 90% had at least one of the two extra-nigral pathologies studied. CONCLUSIONS Extra-nigral pathologies, in particular the combined presence of cortical cholinopathy and amyloidopathy, are common in PD with FoG and may contribute to its pathophysiology. PMID:24909584

  12. A Prospective Randomized Trial to Study the Impact of Pretreatment FDG-PET for Cervical Cancer Patients With MRI-Detected Positive Pelvic but Negative Para-Aortic Lymphadenopathy

    SciTech Connect

    Tsai, C.-S.; Lai, C.-H.; Chang, T.-C.; Yen, T.-C.; Ng, K.-K.; Hsueh Swei; Lee, Steve P.; Hong, J.-H.

    2010-02-01

    Purpose: This prospective randomized study was undertaken to determine the possible impact of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) on extrapelvic metastasis detection, radiation field design, and survival outcome for cervical cancer patients with enlarged pelvic nodes on MRI image. Methods and Materials: Inclusion criteria were patients with newly diagnosed Stage I-IVA cervical cancer and with positive pelvic but negative para-aortic lymph nodes (PALN) as detected by magnetic resonance image and good performance status for concurrent chemoradiotherapy. Eligible patients were randomized to receive either pretreatment FDG-PET (study group) or not (control group). Whole pelvis was the standard irradiation field for the control group and those with no extrapelvic findings on PET. The radiation fields for the rest of the study group were extended to include the PALN region or were modified according to the extrapelvic PET finding. Results: From January 2002 to April 2006, 129 patients were included, and 66 of them were randomized to receive FDG-PET. PET detected seven extrapelvic metastases (11%, 6 PALN and 1 omental node), and four of them remained disease-free after treatment modification. For patients who underwent PET compared with those who did not, there were no differences in the 4-year rates of overall survival (79% vs. 85%, p = 0.65), disease-free survival (75% vs. 77%, p = 0.64), and distant metastasis-free survival (82% vs. 78%, p = 0.83). Conclusions: Pretreatment FDG-PET in conjunction with magnetic resonance imaging can improve the detection of extrapelvic metastasis, mainly PALN, and help select patients for extended-field radiotherapy. However, the addition of FDG-PET may not translate into survival benefit, even though PALN relapses are reduced.

  13. Monte Carlo patient study on the comparison of prompt gamma and PET imaging for range verification in proton therapy.

    PubMed

    Moteabbed, M; España, S; Paganetti, H

    2011-02-21

    The purpose of this work was to compare the clinical adaptation of prompt gamma (PG) imaging and positron emission tomography (PET) as independent tools for non-invasive proton beam range verification and treatment validation. The PG range correlation and its differences with PET have been modeled for the first time in a highly heterogeneous tissue environment, using different field sizes and configurations. Four patients with different tumor locations (head and neck, prostate, spine and abdomen) were chosen to compare the site-specific behaviors of the PG and PET images, using both passive scattered and pencil beam fields. Accurate reconstruction of dose, PG and PET distributions was achieved by using the planning computed tomography (CT) image in a validated GEANT4-based Monte Carlo code capable of modeling the treatment nozzle and patient anatomy in detail. The physical and biological washout phenomenon and decay half-lives for PET activity for the most abundant isotopes such as (11)C, (15)O, (13)N, (30)P and (38)K were taken into account in the data analysis. The attenuation of the gamma signal after traversing the patient geometry and respective detection efficiencies were estimated for both methods to ensure proper comparison. The projected dose, PG and PET profiles along many lines in the beam direction were analyzed to investigate the correlation consistency across the beam width. For all subjects, the PG method showed on average approximately 10 times higher gamma production rates than the PET method before, and 60 to 80 times higher production after including the washout correction and acquisition time delay. This rate strongly depended on tissue density and elemental composition. For broad passive scattered fields, it was demonstrated that large differences exist between PG and PET signal falloff positions and the correlation with the dose distribution for different lines in the beam direction. These variations also depended on the treatment site and the

  14. Acquiring a Pet Dog Significantly Reduces Stress of Primary Carers for Children with Autism Spectrum Disorder: A Prospective Case Control Study

    ERIC Educational Resources Information Center

    Wright, H. F.; Hall, S.; Hames, A.; Hardiman, J.; Mills, R.; Mills, D. S.

    2015-01-01

    This study describes the impact of pet dogs on stress of primary carers of children with Autism Spectrum Disorder (ASD). Stress levels of 38 primary carers acquiring a dog and 24 controls not acquiring a dog were sampled at: Pre-intervention (17 weeks before acquiring a dog), post-intervention (3-10 weeks after acquisition) and follow-up…

  15. Incidental 11C-choline PET/CT brain uptake due to meningioma in a patient studied for prostate cancer: correlation with MRI and imaging fusion.

    PubMed

    Bertagna, Francesco; Bosio, Giovanni; Pinelli, Lorenzo; Treglia, Giorgio; Giubbini, Raffaele

    2013-11-01

    We report a case of a 75-year-old male patient treated with radiotherapy in 1999 for prostate cancer. Due to a rise in prostate-specific antigen, he underwent (11)C-choline PET/CT. The study was negative for secondary lesions but revealed an incidental pathologic focal brain uptake. A subsequent magnetic resonance examination confirmed the presence of a brain lesion typical for meningioma.

  16. Reliving lifelong episodic autobiographical memories via the hippocampus: a correlative resting PET study in healthy middle-aged subjects.

    PubMed

    Piolino, Pascale; Desgranges, Béatrice; Hubert, Valérie; Bernard, Frédéric A; Matuszewski, Vanessa; Chételat, Gaël; Baron, Jean-Claude; Eustache, Francis

    2008-01-01

    We aimed at identifying the cerebral structures whose synaptic function subserves the recollection of lifetime's episodic autobiographical memory (AM) via autonoetic consciousness. Twelve healthy middle-aged subjects (mean age: 59 years +/- 2.5) underwent a specially designed cognitive test to assess the ability to relive richly detailed episodic autobiographical memories from five time periods using the Remember/Know procedure. We computed an index of episodicity (number of Remember responses justified by the recall of specific events and details) and an index of retrieval spontaneity, and additionally an index of semanticized memories (number of Know responses). The regional cerebral blood flow (rCBF) was measured in the resting state, with H(2)O(15) as part of an activation PET study. The indexes were correlated with blood flow using volumes of interest in frontotemporal regions, including hippocampus and voxel-wise analyses in SPM. With both analyses, significant correlations were mainly found between the index of episodicity and rCBF in the medial temporal lobe, including hippocampus, across the five time periods (unlike the index of semanticized memories) and between the spontaneity index and rCBF in the prefrontal areas. These results highlight, in healthy subjects, the distinct role of these two structures in AM retrieval and support the view that the hippocampus is needed for reexperiencing detailed episodic memories no matter how old they are. PMID:18240320

  17. Apathy and impaired emotional facial recognition networks overlap in Parkinson's disease: a PET study with conjunction analyses.

    PubMed

    Robert, Gabriel; Le Jeune, Florence; Dondaine, Thibault; Drapier, Sophie; Péron, Julie; Lozachmeur, Clément; Sauleau, Paul; Houvenaghel, Jean-François; Travers, David; Millet, Bruno; Vérin, Marc; Drapier, Dominique

    2014-10-01

    Apathy is a disabling non-motor symptom that is frequently observed in Parkinson's disease (PD). Its description and physiopathology suggest that it is partially mediated by emotional impairment, but this research issue has never been addressed at a clinical and metabolic level. We therefore conducted a metabolic study using (18)fluorodeoxyglucose positron emission tomography ((18)FDG PET) in 36 PD patients without depression and dementia. Apathy was assessed on the Apathy Evaluation Scale (AES), and emotional facial recognition (EFR) performances (ie, percentage of correct responses) were calculated for each patient. Confounding factors such as age, antiparkinsonian and antidepressant medication, global cognitive functions and depressive symptoms were controlled for. We found a significant negative correlation between AES scores and performances on the EFR task. The apathy network was characterised by increased metabolism within the left posterior cingulate (PC) cortex (Brodmann area (BA) 31). The impaired EFR network was characterised by decreased metabolism within the bilateral PC gyrus (BA 31), right superior frontal gyrus (BAs 10, 9 and 6) and left superior frontal gyrus (BA 10 and 11). By applying conjunction analyses to both networks, we identified the right premotor cortex (BA 6), right orbitofrontal cortex (BA 10), left middle frontal gyrus (BA 8) and left posterior cingulate gyrus (BA 31) as the structures supporting the association between apathy and impaired EFR. These results confirm that apathy in PD is partially mediated by impaired EFR, opening up new prospects for alleviating apathy in PD, such as emotional rehabilitation. PMID:24403280

  18. Effects of Electroacupuncture at Head Points on the Function of Cerebral Motor Areas in Stroke Patients: A PET Study

    PubMed Central

    Fang, Zuo; Ning, Jia; Xiong, Chang; Shulin, Yao

    2012-01-01

    Positron emission tomography (PET) is used to observe the cerebral function widely and is a good method to explore the mechanism of acupuncture treatment on the central nervous system. By using this method, we observed the cerebral function of 6 patients suffering from ischemic stroke after receiving EA treatment at Baihui(GV20) and right Qubin(GB7). The results were: (1) the glucose metabolism changed significantly on primary motor area (M1), premotor cortex (PMC), and superior parietal louble (LPs) bilaterally, as well as the Supplementary Motor Area (SMA) on the unaffected hemisphere right after the first EA treatment. (2) The glucose metabolism on bilateral M1 and LPs changed significantly after three weeks of daily EA treatments. (3) The glucose metabolism on other areas such as insula, putamen, and cerebellum changed significantly. It demonstrated that EA at Qubin and Baihui couldactivate the cerebral structures related to motor function on the bilateral hemispheres.We concluded that EA was very helpful for the cerebral motor plasticity after the ischemic stroke. Also based on this study we assumed that the brain plasticity should be a network and that acupuncture participated in some sections of this course. PMID:22956979

  19. 3D inpatient dose reconstruction from the PET-CT imaging of {sup 90}Y microspheres for metastatic cancer to the liver: Feasibility study

    SciTech Connect

    Fourkal, E.; Veltchev, I.; Lin, M.; Meyer, J.; Koren, S.; Doss, M.; Yu, J. Q.

    2013-08-15

    Purpose: The introduction of radioembolization with microspheres represents a significant step forward in the treatment of patients with metastatic disease to the liver. This technique uses semiempirical formulae based on body surface area or liver and target volumes to calculate the required total activity for a given patient. However, this treatment modality lacks extremely important information, which is the three-dimensional (3D) dose delivered by microspheres to different organs after their administration. The absence of this information dramatically limits the clinical efficacy of this modality, specifically the predictive power of the treatment. Therefore, the aim of this study is to develop a 3D dose calculation technique that is based on the PET imaging of the infused microspheres.Methods: The Fluka Monte Carlo code was used to calculate the voxel dose kernel for {sup 90}Y source with voxel size equal to that of the PET scan. The measured PET activity distribution was converted to total activity distribution for the subsequent convolution with the voxel dose kernel to obtain the 3D dose distribution. In addition, dose-volume histograms were generated to analyze the dose to the tumor and critical structures.Results: The 3D inpatient dose distribution can be reconstructed from the PET data of a patient scanned after the infusion of microspheres. A total of seven patients have been analyzed so far using the proposed reconstruction method. Four patients underwent treatment with SIR-Spheres for liver metastases from colorectal cancer and three patients were treated with Therasphere for hepatocellular cancer. A total of 14 target tumors were contoured on post-treatment PET-CT scans for dosimetric evaluation. Mean prescription activity was 1.7 GBq (range: 0.58–3.8 GBq). The resulting mean maximum measured dose to targets was 167 Gy (range: 71–311 Gy). Mean minimum dose to 70% of target (D70) was 68 Gy (range: 25–155 Gy). Mean minimum dose to 90% of target

  20. Recent developments in PET detector technology

    PubMed Central

    Lewellen, Tom K

    2010-01-01

    Positron emission tomography (PET) is a tool for metabolic imaging that has been utilized since the earliest days of nuclear medicine. A key component of such imaging systems is the detector modules—an area of research and development with a long, rich history. Development of detectors for PET has often seen the migration of technologies, originally developed for high energy physics experiments, into prototype PET detectors. Of the many areas explored, some detector designs go on to be incorporated into prototype scanner systems and a few of these may go on to be seen in commercial scanners. There has been a steady, often very diverse development of prototype detectors, and the pace has accelerated with the increased use of PET in clinical studies (currently driven by PET/CT scanners) and the rapid proliferation of pre-clinical PET scanners for academic and commercial research applications. Most of these efforts are focused on scintillator-based detectors, although various alternatives continue to be considered. For example, wire chambers have been investigated many times over the years and more recently various solid-state devices have appeared in PET detector designs for very high spatial resolution applications. But even with scintillators, there have been a wide variety of designs and solutions investigated as developers search for solutions that offer very high spatial resolution, fast timing, high sensitivity and are yet cost effective. In this review, we will explore some of the recent developments in the quest for better PET detector technology. PMID:18695301

  1. Deformation field correction for spatial normalization of PET images

    PubMed Central

    Bilgel, Murat; Carass, Aaron; Resnick, Susan M.; Wong, Dean F.; Prince, Jerry L.

    2015-01-01

    Spatial normalization of positron emission tomography (PET) images is essential for population studies, yet the current state of the art in PET-to-PET registration is limited to the application of conventional deformable registration methods that were developed for structural images. A method is presented for the spatial normalization of PET images that improves their anatomical alignment over the state of the art. The approach works by correcting the deformable registration result using a model that is learned from training data having both PET and structural images. In particular, viewing the structural registration of training data as ground truth, correction factors are learned by using a generalized ridge regression at each voxel given the PET intensities and voxel locations in a population-based PET template. The trained model can then be used to obtain more accurate registration of PET images to the PET template without the use of a structural image. A cross validation evaluation on 79 subjects shows that the proposed method yields more accurate alignment of the PET images compared to deformable PET-to-PET registration as revealed by 1) a visual examination of the deformed images, 2) a smaller error in the deformation fields, and 3) a greater overlap of the deformed anatomical labels with ground truth segmentations. PMID:26142272

  2. Acquiring a Pet Dog Significantly Reduces Stress of Primary Carers for Children with Autism Spectrum Disorder: A Prospective Case Control Study.

    PubMed

    Wright, H F; Hall, S; Hames, A; Hardiman, J; Mills, R; Mills, D S

    2015-08-01

    This study describes the impact of pet dogs on stress of primary carers of children with Autism Spectrum Disorder (ASD). Stress levels of 38 primary carers acquiring a dog and 24 controls not acquiring a dog were sampled at: Pre-intervention (17 weeks before acquiring a dog), post-intervention (3-10 weeks after acquisition) and follow-up (25-40 weeks after acquisition), using the Parenting Stress Index. Analysis revealed significant improvements in the intervention compared to the control group for Total Stress, Parental Distress and Difficult Child. A significant number of parents in the intervention group moved from clinically high to normal levels of Parental Distress. The results highlight the potential of pet dogs to reduce stress in primary carers of children with an ASD. PMID:25832799

  3. Drug pharmacokinetics and pharmacodynamics: PET and microdial studies of SR 46349B, a selective 5HT2 antagonist

    SciTech Connect

    Tan, P.; Dewey, S.L.; Gatley, S.J.

    1994-05-01

    The brain serotonin system is an important molecular target in drug development. SR 46349B is a propenone oxime ether derivative with a high affinity and selectivity for the serotonin 5HT2 receptor (Kd=1.2 nM). We have labeled SR 46349B with carbon-11 via N-methylation of a nor-precursor (supplied by Sanofi Recherche) with C-11 methyl iodide. Purification by HPLC gave [11C]SR 46349B in 98% radiochemical purity with a specific activity of 1.5 Ci/{mu}mol. Serial PET studies were carried out in a baboon for a 60 minute study period with a two hour time interval between studies. The first study was at baseline and the second after pretreatment with altanserin (0.5 mg/kg iv, 30 min prior to [11C]SR 46349B). Carbon-11 peaked at ca. 20 minutes in the frontal, parietal, temporal and occipital cortices where it plateaued for the rest of the study. Cerebellum, thalamus and striatum peaked at ca. 10 minutes and cleared to 62%, 72% and 80% of peak by 60 min. At 60 minutes, the frontal cortex to cerebellum ratio was 1.5. Treatment with altanserin reduced the frontal cortex to cerebellum ratio to 1.0. HPLC of mouse brain homogenate after [11C]SR 46349B showed >94% of the C-11 was parent compound. Microdialysis in freely moving rats after injection of SR 46349B (n=6; 10 mg/kg, ip) showed an average peak increase in extracellular dopamine of 375% which is higher than the 150% effect of altanserin. Spontaneous movements were markedly reduced. The pharmacokinetics of [11C] SR 46349B in cortical areas is consistent with the long term effects of SR 46349B on 5HT2 receptors and the elevations in extracellular dopamine without increased locomotor activity are consistent with serotonin mediated disinhibition of striatal dopamine release via blockade of serotonin receptors.

  4. Microglia activation in multiple sclerosis black holes predicts outcome in progressive patients: an in vivo [(11)C](R)-PK11195-PET pilot study.

    PubMed

    Giannetti, Paolo; Politis, Marios; Su, Paul; Turkheimer, Federico; Malik, Omar; Keihaninejad, Shiva; Wu, Kit; Reynolds, Richard; Nicholas, Richard; Piccini, Paola

    2014-05-01

    The pathophysiological correlates and the contribution to persisting disability of hypointense T1-weighted MRI lesions, black holes (BH), in multiple sclerosis (MS) are still unclear. In order to study the in vivo functional correlates of this MRI finding, we used 11C-PK11195 PET (PK-PET) to investigate changes in microglial activity. Ten relapsing and 9 progressive MS subjects had a PK-PET scan and a MRI scan alongside a full clinical assessment, including the expanded disability status scale (EDSS) for evaluation of disability. We studied the PK binding potential of the specifically bound radioligand relative to the non-displaceable radioligand in tissue (BPND) in T1 BHs. Out of a total of 1242 BHs identified, 947 were PK enhancing. The PKBPND was correlated with the EDSS (r=0.818; p<0.05) only in the progressive group. In the relapsing patients there was an inverse correlation between PKBPND and BH total lesion volume in whole brain (r=-0.781; p<0.05). When progressive patients were grouped according to the disability outcome at 2years from the PK-PET scan, the total PKBPND in BHs was found to be a significant outcome predictor of disability (p<0.01). Our findings show that relapsing and progressive patients have heterogeneous patterns of PKBPND in T1 BHs and indicate that BHs are not just "holes" representing loss of axons and myelin, but display inflammatory activity in the form of activated microglia. The significant association between PKBPND, neurological impairment and outcome in progressive subjects supports a role for activated microglia in disability progression.

  5. In vivo markers of inflammatory response in recent-onset schizophrenia: a combined study using [(11)C]DPA-713 PET and analysis of CSF and plasma.

    PubMed

    Coughlin, J M; Wang, Y; Ambinder, E B; Ward, R E; Minn, I; Vranesic, M; Kim, P K; Ford, C N; Higgs, C; Hayes, L N; Schretlen, D J; Dannals, R F; Kassiou, M; Sawa, A; Pomper, M G

    2016-01-01

    Several lines of evidence suggest aberrant immune response in schizophrenia, including elevated levels of cytokines. These cytokines are thought to be produced by activated microglia, the innate immune cells of the central nervous system. However, increase in translocator protein 18 kDa (TSPO), a marker of activated glia, has not been found in patients with chronic schizophrenia using second-generation radiotracers and positron emission tomography (PET)-based neuroimaging. In this study we focused on patients with recent onset of schizophrenia (within 5 years of diagnosis). Quantified levels of TSPO in the cortical and subcortical brain regions using the PET-based radiotracer [(11)C]DPA-713 were compared between the patients and healthy controls. Markers of inflammation, including interleukin 6 (IL-6), were assessed in the plasma and cerebrospinal fluid (CSF) in these participants. We observed no significant change in the binding of [(11)C]DPA-713 to TSPO in 12 patients with recent onset of schizophrenia compared with 14 controls. Nevertheless, the patients with recent onset of schizophrenia showed a significant increase in IL-6 in both plasma (P<0.001) and CSF (P=0.02). The CSF levels of IL-6 were significantly correlated with the levels of IL-6 in plasma within the total study population (P<0.001) and in patients with recent onset of schizophrenia alone (P=0.03). Our results suggest that increased levels of IL-6 may occur in the absence of changed TSPO PET signal in the brains of medicated patients with recent onset of schizophrenia. Future development of PET-based radiotracers targeting alternative markers of glial activation and immune response may be needed to capture the inflammatory signature present in the brains of patients with early-stage disease. PMID:27070405

  6. In vivo markers of inflammatory response in recent-onset schizophrenia: a combined study using [11C]DPA-713 PET and analysis of CSF and plasma

    PubMed Central

    Coughlin, J M; Wang, Y; Ambinder, E B; Ward, R E; Minn, I; Vranesic, M; Kim, P K; Ford, C N; Higgs, C; Hayes, L N; Schretlen, D J; Dannals, R F; Kassiou, M; Sawa, A; Pomper, M G

    2016-01-01

    Several lines of evidence suggest aberrant immune response in schizophrenia, including elevated levels of cytokines. These cytokines are thought to be produced by activated microglia, the innate immune cells of the central nervous system. However, increase in translocator protein 18 kDa (TSPO), a marker of activated glia, has not been found in patients with chronic schizophrenia using second-generation radiotracers and positron emission tomography (PET)-based neuroimaging. In this study we focused on patients with recent onset of schizophrenia (within 5 years of diagnosis). Quantified levels of TSPO in the cortical and subcortical brain regions using the PET-based radiotracer [11C]DPA-713 were compared between the patients and healthy controls. Markers of inflammation, including interleukin 6 (IL-6), were assessed in the plasma and cerebrospinal fluid (CSF) in these participants. We observed no significant change in the binding of [11C]DPA-713 to TSPO in 12 patients with recent onset of schizophrenia compared with 14 controls. Nevertheless, the patients with recent onset of schizophrenia showed a significant increase in IL-6 in both plasma (P<0.001) and CSF (P=0.02). The CSF levels of IL-6 were significantly correlated with the levels of IL-6 in plasma within the total study population (P<0.001) and in patients with recent onset of schizophrenia alone (P=0.03). Our results suggest that increased levels of IL-6 may occur in the absence of changed TSPO PET signal in the brains of medicated patients with recent onset of schizophrenia. Future development of PET-based radiotracers targeting alternative markers of glial activation and immune response may be needed to capture the inflammatory signature present in the brains of patients with early-stage disease. PMID:27070405

  7. Increase of 20-HETE synthase after brain ischemia in rats revealed by PET study with 11C-labeled 20-HETE synthase-specific inhibitor

    PubMed Central

    Kawasaki, Toshiyuki; Marumo, Toshiyuki; Shirakami, Keiko; Mori, Tomoko; Doi, Hisashi; Suzuki, Masaaki; Watanabe, Yasuyoshi; Chaki, Shigeyuki; Nakazato, Atsuro; Ago, Yukio; Hashimoto, Hitoshi; Matsuda, Toshio; Baba, Akemichi; Onoe, Hirotaka

    2012-01-01

    20-Hydroxyeicosatetraenoic acid (20-HETE), an arachidonic acid metabolite known to be produced after cerebral ischemia, has been implicated in ischemic and reperfusion injury by mediating vasoconstriction. To develop a positron emission tomography (PET) probe for 20-HETE synthase imaging, which might be useful for monitoring vasoconstrictive processes in patients with brain ischemia, we synthesized a 11C-labeled specific 20-HETE synthase inhibitor, N′(4-dimethylaminohexyloxy)phenyl imidazole ([11C]TROA). Autoradiographic study showed that [11C]TROA has high-specific binding in the kidney and liver consistent with the previously reported distribution of 20-HETE synthase. Using transient middle cerebral artery occlusion in rats, PET study showed significant increases in the binding of [11C]TROA in the ipsilateral hemisphere of rat brains after 7 and 10 days, which was blocked by co-injection of excess amounts of TROA (10 mg/kg). The increased [11C]TROA binding on the ipsilateral side returned to basal levels within 14 days. In addition, quantitative real-time PCR revealed that increased expression of 20-HETE synthase was only shown on the ipsilateral side on day 7. These results indicate that [11C]TROA might be a useful PET probe for imaging of 20-HETE synthase in patients with cerebral ischemia. PMID:22669478

  8. Respiratory motion compensation for simultaneous PET/MR based on a 3D-2D registration of strongly undersampled radial MR data: a simulation study

    NASA Astrophysics Data System (ADS)

    Rank, Christopher M.; Heußer, Thorsten; Flach, Barbara; Brehm, Marcus; Kachelrieß, Marc

    2015-03-01

    We propose a new method for PET/MR respiratory motion compensation, which is based on a 3D-2D registration of strongly undersampled MR data and a) runs in parallel with the PET acquisition, b) can be interlaced with clinical MR sequences, and c) requires less than one minute of the total MR acquisition time per bed position. In our simulation study, we applied a 3D encoded radial stack-of-stars sampling scheme with 160 radial spokes per slice and an acquisition time of 38 s. Gated 4D MR images were reconstructed using a 4D iterative reconstruction algorithm. Based on these images, motion vector fields were estimated using our newly-developed 3D-2D registration framework. A 4D PET volume of a patient with eight hot lesions in the lungs and upper abdomen was simulated and MoCo 4D PET images were reconstructed based on the motion vector fields derived from MR. For evaluation, average SUVmean values of the artificial lesions were determined for a 3D, a gated 4D, a MoCo 4D and a reference (with ten-fold measurement time) gated 4D reconstruction. Compared to the reference, 3D reconstructions yielded an underestimation of SUVmean values due to motion blurring. In contrast, gated 4D reconstructions showed the highest variation of SUVmean due to low statistics. MoCo 4D reconstructions were only slightly affected by these two sources of uncertainty resulting in a significant visual and quantitative improvement in terms of SUVmean values. Whereas temporal resolution was comparable to the gated 4D images, signal-to-noise ratio and contrast-to-noise ratio were close to the 3D reconstructions.

  9. Tariquidar-induced P-glycoprotein inhibition at the rat blood-brain barrier studied with (R)-11C-verapamil and PET

    PubMed Central

    Bankstahl, Jens P.; Kuntner, Claudia; Abrahim, Aiman; Karch, Rudolf; Stanek, Johann; Wanek, Thomas; Wadsak, Wolfgang; Kletter, Kurt; Müller, Markus; Löscher, Wolfgang; Langer, Oliver

    2013-01-01

    The multidrug efflux transporter P-glycoprotein (P-gp) is expressed in high concentrations at the blood-brain barrier (BBB) and believed to be implicated in resistance to central nervous system drugs. We used small-animal positron emission tomography (PET) and (R)-11C-verapamil together with tariquidar, a new-generation P-gp modulator, to study the functional activity of P-gp at the BBB of rats. To enable a comparison with human PET data we performed kinetic modeling to estimate the rate constants of radiotracer transport across the rat BBB. Methods A group of 7 Wistar Unilever rats underwent paired (R)-11C-verapamil PET scans at an interval of 3 h, one baseline scan and one scan after i.v. injection of tariquidar (15 mg/kg, n=5) or vehicle (n=2). Results Following tariquidar administration, the distribution volume DV of (R)-11C-verapamil was 12-fold higher as compared to baseline (3.68±0.81 versus 0.30±0.08; p=0.0007, paired t-test), whereas the DVs were essentially the same when only vehicle was administered. The increase in DV could mainly be attributed to an increased influx rate constant K1 of (R)-11C-verapamil into the brain, which was about 8-fold higher after tariquidar. A dose-response assessment with tariquidar provided an estimated half-maximum effect dose (ED50) of 8.4±9.5 mg/kg. Conclusion Our data demonstrate that (R)-11C-verapamil PET combined with tariquidar administration is a promising approach to measure P-gp function at the BBB. PMID:18632828

  10. PET neuroimaging studies of [18F]CABS13 in a double transgenic mouse model of Alzheimer’s disease and non-human primates

    PubMed Central

    Liang, Steven H.; Holland, Jason P.; Stephenson, Nickeisha A.; Kassenbrock, Alina; Rotstein, Benjamin H.; Daignault, Cory P.; Lewis, Rebecca; Collier, Lee; Hooker, Jacob M.; Vasdev, Neil

    2016-01-01

    Fluorine-18 labeled 2-fluoro-8-hydroxyquinoline ([18F]CABS13) is a promising positron emission tomography (PET) radiopharmaceutical based on a metal chelator developed to probe the “metal hypothesis of Alzheimer’s disease”. Herein, a practical radiosynthesis of [18F]CABS13 was achieved by radiofluorination followed by deprotection of an O-benzyloxymethyl group. Automated production and formulation of [18F]CABS13 resulted in 19 ± 5% uncorrected radiochemical yield, relative to starting [18F]fluoride, with ≥95% chemical and radiochemical purities, and high specific activity (>2.5 Ci/μmol) within 80 minutes. Temporal PET neuroimaging studies were carried out in female transgenic B6C3- Tg(APPswe,PSEN1dE9)85Dbo/J (APP/PS1) and age-matched wild-type (WT) B6C3F1/J control mice at 3, 7 and 10 months of age. [18F]CABS13 showed an overall higher uptake and retention of radioactivity in the central nervous system of APP/PS1 mice versus WT mice with increasing age. However, PET/magnetic resonance imaging in normal non-human primates revealed that the tracer had low uptake in the brain and rapid formation of a hydrophilic radiometabolite. Identification of more metabolically stable 18F-hydroxyquinolines that can be readily accessed by the radiochemical strategy presented herein is underway. PMID:25776827

  11. Improved PET Imaging of uPAR Expression Using new 64Cu-labeled Cross-Bridged Peptide Ligands: Comparative in vitro and in vivo Studies

    PubMed Central

    Persson, Morten; Hosseini, Masood; Madsen, Jacob; Jørgensen, Thomas J. D.; Jensen, Knud J; Kjaer, Andreas; Ploug, Michael

    2013-01-01

    The correlation between uPAR expression, cancer cell invasion and metastases is now well-established and has prompted the development of a number of uPAR PET imaging agents, which could potentially identify cancer patients with invasive and metastatic lesions. In the present study, we synthesized and characterized two new cross-bridged 64Cu-labeled peptide conjugates for PET imaging of uPAR and performed a head-to-head comparison with the corresponding and more conventionally used DOTA conjugate. Based on in-source laser-induced reduction of chelated Cu(II) to Cu(I), we now demonstrate the following ranking with respect to the chemical inertness of their complexed Cu ions: DOTA-AE105 << CB-TE2A-AE105 < CB-TE2A-PA-AE105, which is correlated to their corresponding demetallation rate. No penalty in the uPAR receptor binding affinity of the targeting peptide was encountered by conjugation to either of the macrobicyclic chelators (IC50 ~ 5-10 nM) and high yields and radiochemical purities (>95%) were achieved in all cases by incubation at 95ºC. In vivo, they display identical tumor uptake after 1h, but differ significantly after 22 hrs, where the DOTA-AE105 uptake remains surprisingly high. Importantly, the more stable of the new uPAR PET tracers, 64Cu-CB-TE2A-PA-AE105, exhibits a significantly reduced liver uptake compared to 64Cu-DOTA-AE105 as well as 64Cu-CB-TE2A-AE105, (p<0.0001), emphasizing that our new in vitro stability measurements by mass spectrometry predicts in vivo stability in mice. Specificity of the best performing ligand, 64Cu-CB-TE2A-PA-AE105 was finally confirmed in vivo using a non-binding 64Cu-labeled peptide as control (64Cu-CB-TE2A-PA-AE105mut). This control PET-tracer revealed significantly reduced tumor uptake (p<0.0001), but identical hepatic uptake compared to its active counterpart (64Cu-CB-TE2A-PA-AE105) after 1h. In conclusion, our new approach using in-source laser-induced reduction of Cu(II)-chelated PET-ligands provides useful

  12. Investigation of the coincidence resolving time performance of a PET scanner based on liquid xenon: a Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Gomez-Cadenas, J. J.; Benlloch-Rodríguez, J. M.; Ferrario, P.; Monrabal, F.; Rodríguez, J.; Toledo, J. F.

    2016-09-01

    The measurement of the time of flight of the two 511 keV gammas recorded in coincidence in a PET scanner provides an effective way of reducing the random background and therefore increases the scanner sensitivity, provided that the coincidence resolving time (CRT) of the gammas is sufficiently good. The best commercial PET-TOF system today (based in LYSO crystals and digital SiPMs), is the VEREOS of Philips, boasting a CRT of 316 ps (FWHM). In this paper we present a Monte Carlo investigation of the CRT performance of a PET scanner exploiting the scintillating properties of liquid xenon. We find that an excellent CRT of 70 ps (depending on the PDE of the sensor) can be obtained if the scanner is instrumented with silicon photomultipliers (SiPMs) sensitive to the ultraviolet light emitted by xenon. Alternatively, a CRT of 160 ps can be obtained instrumenting the scanner with (much cheaper) blue-sensitive SiPMs coated with a suitable wavelength shifter. These results show the excellent time of flight capabilities of a PET device based in liquid xenon.

  13. An assessment of the impact of the pet trade on five CITES-Appendix II case studies - Boa constrictor imperator

    USGS Publications Warehouse

    Montgomery, Chad E.; Boback, Scott M.; Reed, Robert N.; Frazier, Julius A.

    2015-01-01

    Boa constrictor is a wide ranging snake species that is common in the pet trade and is currently listed in CITES Appendix II. Hog Island boas, or Cayos Cochinos boas, are a dwarf, insular race of Boa constrictor imperator endemic to the Cayos Cochinos Archipelago, Honduras. Cayos Cochinos boas are prized in the international pet trade for their light pink dorsal coloration, as well as for being much smaller and more docile than mainland boas (Porras, 1999; Russo, 2007). The boa population in the Cayos Cochinos was heavily exploited for the pet trade from 1979 to 1993, and researchers reported finding no boas on the islands during a five day herpetological survey trip in the early 1990s (Wilson and CruzDiaz, 1993), leading to the speculation that the population had been extirpated (e.g., Russo, 2007). The Cayos Cochinos Archipelago Natural Marine Monument has been managed by the Honduran Coral Reef Foundation since 1994 and prohibits removal of boas from the area. Poaching for the pet trade continues today, although at a lower level. Due to the endemic nature of this island morph of B. c. imperator it is imperative that we understand the dynamics of the populations and the ongoing threats that could negatively impact their long-term survival.

  14. Different partial volume correction methods lead to different conclusions: An (18)F-FDG-PET study of aging.

    PubMed

    Greve, Douglas N; Salat, David H; Bowen, Spencer L; Izquierdo-Garcia, David; Schultz, Aaron P; Catana, Ciprian; Becker, J Alex; Svarer, Claus; Knudsen, Gitte M; Sperling, Reisa A; Johnson, Keith A

    2016-05-15

    A cross-sectional group study of the effects of aging on brain metabolism as measured with (18)F-FDG-PET was performed using several different partial volume correction (PVC) methods: no correction (NoPVC), Meltzer (MZ), Müller-Gärtner (MG), and the symmetric geometric transfer matrix (SGTM) using 99 subjects aged 65-87years from the Harvard Aging Brain study. Sensitivity to parameter selection was tested for MZ and MG. The various methods and parameter settings resulted in an extremely wide range of conclusions as to the effects of age on metabolism, from almost no changes to virtually all of cortical regions showing a decrease with age. Simulations showed that NoPVC had significant bias that made the age effect on metabolism appear to be much larger and more significant than it is. MZ was found to be the same as NoPVC for liberal brain masks; for conservative brain masks, MZ showed few areas correlated with age. MG and SGTM were found to be similar; however, MG was sensitive to a thresholding parameter that can result in data loss. CSF uptake was surprisingly high at about 15% of that in gray matter. The exclusion of CSF from SGTM and MG models, which is almost universally done, caused a substantial loss in the power to detect age-related changes. This diversity of results reflects the literature on the metabolism of aging and suggests that extreme care should be taken when applying PVC or interpreting results that have been corrected for partial volume effects. Using the SGTM, significant age-related changes of about 7% per decade were found in frontal and cingulate cortices as well as primary visual and insular cortices. PMID:26915497

  15. 11C-Acetate PET/CT Imaging in Localized Prostate Cancer: A study with MRI and Histopathologic Correlation

    PubMed Central

    Mena, Esther; Turkbey, Baris; Mani, Haresh; Adler, Stephen; Valera, Vladimir A.; Bernardo, Marcelino; Shah, Vijay; Pohida, Thomas; McKinney, Yolanda; Kwarteng, Gideon; Daar, Dagane; Lindenberg, Maria L.; Eclarinal, Philip; Wade, Revia; Linehan, W. Marston; Merino, Maria J.; Pinto, Peter A.; Choyke, Peter L.; Kurdziel, Karen A.

    2012-01-01

    This work characterizes the uptake of 11C-Acetate in prostate cancer (PCa), benign prostate hyperplasia (BPH) and normal prostate tissue in comparison with multi-parametric MRI, whole mount histopathology and clinical markers, to evaluate its potential utility for delineating intra-prostatic tumors in a population of patients with localized PCa. METHODS 39 men with presumed localized PCa underwent dynamic/static abdomen-pelvic 11C-Acetate PET/CT for 30-minutes and 3T multi-parametric (MP) MRI prior to prostatectomy. PET/CT images were registered to MRI using pelvic bones for initial rotation-translation, followed by manual adjustments to account for prostate motion and deformation from the MRI endorectal coil. Whole-mount pathology specimens were sectioned using an MRI-based patient specific mold resulting in improved registration between the MRI, PET and pathology. 11C-Acetate PET standardized uptake values were compared with MP-MRI and pathology. RESULTS 11C-Acetate uptake was rapid but reversible, peaking at 3–5 minutes post-injection and reaching a relative plateau at ~10 minutes. The average SUVmax(10–12min) of tumors was significantly higher than that of normal prostate tissue (4.4±2.05, range 1.8–9.2 vs. 2.1±0.94, range 0.7–3.4; p<0.001); however it was not significantly different from benign prostatic hyperplasia (4.8±2.01; range 1.8–8.8). A sector-based comparison with histopathology, including all tumors > 0.5 cm, revealed a sensitivity and specificity of 61.6 % and 80.0 % for 11C-Acetate PET/CT, and 82.3% and 95.1% for MRI, respectively. Considering only tumors >0.9 cm the 11C-Acetate accuracy was comparable to that of MRI. In a small cohort (n=9), 11C-Acetate uptake was independent of fatty acid synthase expression based on immunohistochemistry. CONCLUSION 11C-Acetate PET/CT demonstrates higher uptake in tumor foci than normal prostate tissue; however 11C-Acetate uptake in tumors is similar to BPH nodules. While 11C-Acetate PET/CT is not

  16. A feasibility study of a PET/MRI insert detector using strip-line and waveform sampling data acquisition

    NASA Astrophysics Data System (ADS)

    Kim, H.; Chen, C.-T.; Eclov, N.; Ronzhin, A.; Murat, P.; Ramberg, E.; Los, S.; Wyrwicz, A. M.; Li, L.; Kao, C.-M.

    2015-06-01

    We are developing a time-of-flight Positron Emission Tomography (PET) detector by using silicon photo-multipliers (SiPM) on a strip-line and high speed waveform sampling data acquisition. In this design, multiple SiPMs are connected on a single strip-line and signal waveforms on the strip-line are sampled at two ends of the strip to reduce readout channels while fully exploiting the fast time response of SiPMs. In addition to the deposited energy and time information, the position of the hit SiPM along the strip-line is determined by the arrival time difference of the waveform. Due to the insensitivity of the SiPMs to magnetic fields and the compact front-end electronics, the detector approach is highly attractive for developing a PET insert system for a magnetic resonance imaging (MRI) scanner to provide simultaneous PET/MR imaging. To investigate the feasibility, experimental tests using prototype detector modules have been conducted inside a 9.4 T small animal MRI scanner (Bruker BioSpec 94/30 imaging spectrometer). On the prototype strip-line board, 16 SiPMs (5.2 mm pitch) are installed on two strip-lines and coupled to 2×8 LYSO scintillators (5.0×5.0×10.0 mm3 with 5.2 mm pitch). The outputs of the strip-line boards are connected to a Domino-Ring-Sampler (DRS4) evaluation board for waveform sampling. Preliminary experimental results show that the effect of interference on the MRI image due to the PET detector is negligible and that PET detector performance is comparable with the results measured outside the MRI scanner.

  17. Rapid dual-tracer PTSM+ATSM PET imaging of tumour blood flow and hypoxia: a simulation study.

    PubMed

    Rust, T C; Kadrmas, D J

    2006-01-01

    Blood flow and hypoxia are interrelated aspects of physiology that affect cancer treatment and response. Cu-PTSM and Cu-ATSM are related PET tracers for blood flow and hypoxia, and the ability to rapidly image both tracers in a single scan would bring several advantages over conventional single-tracer techniques. Using dynamic imaging with staggered injections, overlapping signals for multiple PET tracers may be recovered utilizing information from kinetics and radioactive decay. In this work, rapid dual-tracer PTSM+ATSM PET was simulated and tested as a function of injection delay, order and relative dose for several copper isotopes, and the results were compared relative to separate single-tracer data. Time-activity curves representing a broad range of tumour blood flow and hypoxia levels were simulated, and parallel dual-tracer compartment modelling was used to recover the signals for each tracer. The main results were tested further using a torso phantom simulation of PET tumour imaging. Using scans as short as 30 minutes, the dual-tracer method provided measures of blood flow and hypoxia similar to single-tracer imaging. The best performance was obtained by injecting PTSM first and using a somewhat higher dose for ATSM. Comparable results for different copper isotopes suggest that tracer kinetics with staggered injections play a more important role than radioactive decay in the signal separation process. Rapid PTSM+ATSM PET has excellent potential for characterizing both tumour blood flow and hypoxia in a single, fast scan, provided that technological hurdles related to algorithm development and routine use can be overcome.

  18. A feasibility study of a PET/MRI insert detector using strip-line and waveform sampling data acquisition

    PubMed Central

    Kim, H.; Chen, C.-T.; Eclov, N.; Ronzhin, A.; Murat, P.; Ramberg, E.; Los, S.; Wyrwicz, Alice M.; Li, Limin; Kao, C.-M.

    2014-01-01

    We are developing a time-of-flight Positron Emission Tomography (PET) detector by using silicon photo-multipliers (SiPM) on a strip-line and high speed waveform sampling data acquisition. In this design, multiple SiPMs are connected on a single strip-line and signal waveforms on the strip-line are sampled at two ends of the strip to reduce readout channels while fully exploiting the fast time response of SiPMs. In addition to the deposited energy and time information, the position of the hit SiPM along the strip-line is determined by the arrival time difference of the waveform. Due to the insensitivity of the SiPMs to magnetic fields and the compact front-end electronics, the detector approach is highly attractive for developing a PET insert system for a magnetic resonance imaging (MRI) scanner to provide simultaneous PET/MR imaging. To investigate the feasibility, experimental tests using prototype detector modules have been conducted inside a 9.4 Tesla small animal MRI scanner (Bruker BioSpec 94/30 imaging spectrometer). On the prototype strip-line board, 16 SiPMs (5.2 mm pitch) are installed on two strip-lines and coupled to 2 × 8 LYSO scintillators (5.0 × 5.0 × 10.0 mm3 with 5.2 mm pitch). The outputs of the strip-line boards are connected to a Domino-Ring-Sampler (DRS4) evaluation board for waveform sampling. Preliminary experimental results show that the effect of interference on the MRI image due to the PET detector is negligible and that PET detector performance is comparable with the results measured outside the MRI scanner. PMID:25937685

  19. Dopamine response to psychosocial stress in chronic cannabis users: a PET study with [11C]-+-PHNO.

    PubMed

    Mizrahi, Romina; Suridjan, Ivonne; Kenk, Miran; George, Tony P; Wilson, Alan; Houle, Sylvain; Rusjan, Pablo

    2013-03-01

    A number of addictions have been linked with decreased striatal dopamine (DA) receptor availability and DA release. Stress has a key role in cannabis craving, as well as in modulation of dopaminergic signaling. The present study aimed to assess DA release in response to a laboratory stress task with [(11)C]-(+)-PHNO positron emission tomography in cannabis users (CU). Thirteen healthy CU and 12 healthy volunteers (HV) were scanned during a sensorimotor control task (SMCT) and under a stress condition using the validated Montreal imaging stress task (MIST). The simplified reference tissue model (SRTM) was used to obtain binding potential (BP(ND)) in striatal subdivisions: limbic striatum (LST), associative striatum (AST), and sensorimotor striatum (SMST). Stress-induced DA release (indexed as a percentage of reduction in [(11)C]-(+)-PHNO BP (ND)) between CU and HV was tested with analysis of variance. SMCT BP(ND) was significantly higher in CU compared with HV in the AST (F=10.38, p=0.003), LST (F=4.95, p=0.036), SMST (F=4.33, p=0.048), and whole striatum (F=9.02, p=0.006). Percentage of displacement (change in BP(ND) between SMCT and MIST PET scans) was not significantly different across groups in any brain region, except in the GP (-5.03±14.6 in CU, compared with 6.15±12.1 in HV; F=4.39, p=0.049). Duration of cannabis use was significantly associated with stress-induced [(11)C]-(+)-PHNO displacement by endogenous DA in the LST (r=0.566, p=0.044), with no effect in any other brain region. In conclusion, despite an increase in striatal BP(ND) observed during the control task, chronic cannabis use is not associated with alterations in stress-induced DA release. PMID:23212454

  20. APOE and BCHE as modulators of cerebral amyloid deposition: a florbetapir PET genome-wide association study

    PubMed Central

    Ramanan, Vijay K.; Risacher, Shannon L.; Nho, Kwangsik; Kim, Sungeun; Swaminathan, Shanker; Shen, Li; Foroud, Tatiana M.; Hakonarson, Hakon; Huentelman, Matthew J.; Aisen, Paul S.; Petersen, Ronald C.; Green, Robert C.; Jack, Clifford R.; Koeppe, Robert A.; Jagust, William J.; Weiner, Michael W.; Saykin, Andrew J.

    2013-01-01

    Deposition of amyloid-β (Aβ) in the cerebral cortex is thought to be a pivotal event in Alzheimer’s disease (AD) pathogenesis with a significant genetic contribution. Molecular imaging can provide an early noninvasive phenotype but small samples have prohibited genome-wide association studies (GWAS) of cortical Aβ load until now. We employed florbetapir (18F) positron emission tomography (PET) imaging to assess brain Aβ levels in vivo for 555 participants from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). More than six million common genetic variants were tested for association to quantitative global cortical Aβ load controlling for age, gender, and diagnosis. Independent genome-wide significant associations were identified on chromosome 19 within APOE (rs429358, p = 5.5 × 10−14) and on chromosome 3 upstream of BCHE (rs509208, p = 2.7 × 10−8) in a region previously associated with serum butyrylcholinesterase activity. Together, these loci explained 15% of the variance in cortical Aβ levels in this sample (APOE 10.7%, BCHE 4.3%). Suggestive associations were identified within ITGA6, near EFNA5, EDIL3, ITGA1, PIK3R1, NFIB, and ARID1B, and between NUAK1 and C12orf75. These results confirm the association of APOE with Aβ deposition and represent the largest known effect of BCHE on an AD-related phenotype. Butyrylcholinesterase has been found in senile plaques and this new association of genetic variation at the BCHE locus with Aβ burden in humans may have implications for potential disease-modifying effects of butyrylcholinesterase-modulating agents in the AD spectrum. PMID:23419831

  1. Laboratory and cyclotron requirements for PET research

    SciTech Connect

    Schlyer, D.J.

    1993-06-01

    This report describes four types of PET facilities: Clinical PET with no radionuclide production; clinical PET with a small accelerator; clinical PET with research support; and research PET facilities. General facility considerations are also discussed.

  2. Determination of dietary starch in animal feeds and pet food by an enzymatic-colorimetric method: collaborative study.

    PubMed

    Hall, Mary Beth

    2015-01-01

    Starch, glycogen, maltooligosaccharides, and other α-1,4- and α-1,6-linked glucose carbohydrates, exclusive of resistant starch, are collectively termed "dietary starch". This nutritionally important fraction is increasingly measured for use in diet formulation for animals as it can have positive or negative effects on animal performance and health by affecting energy supply, glycemic index, and formation of fermentation products by gut microbes. AOAC Method 920.40 that was used for measuring dietary starch in animal feeds was invalidated due to discontinued production of a required enzyme. As a replacement, an enzymatic-colorimetric starch assay developed in 1997 that had advantages in ease of sample handling and accuracy compared to other methods was considered. The assay was further modified to improve utilization of laboratory resources and reduce time required for the assay. The assay is quasi-empirical: glucose is the analyte detected, but its release is determined by run conditions and specification of enzymes. The modified assay was tested in an AOAC collaborative study to evaluate its accuracy and reliability for determination of dietary starch in animal feedstuffs and pet foods. In the assay, samples are incubated in screw cap tubes with thermostable α-amylase in pH 5.0 sodium acetate buffer for 1 h at 100°C with periodic mixing to gelatinize and partially hydrolyze α-glucan. Amyloglucosidase is added, and the reaction mixture is incubated at 50°C for 2 h and mixed once. After subsequent addition of water, mixing, clarification, and dilution as needed, free + enzymatically released glucose are measured. Values from a separate determination of free glucose are subtracted to give values for enzymatically released glucose. Dietary starch equals enzymatically released glucose multiplied by 162/180 (or 0.9) divided by the weight of the as received sample. Fifteen laboratories that represented feed company, regulatory, research, and commercial feed

  3. The MiniPET: a didactic PET system

    NASA Astrophysics Data System (ADS)

    Pedro, R.; Silva, J.; Gurriana, L.; Silva, J. M.; Maio, A.; Soares Augusto, J.

    2013-03-01

    The MiniPET project aims to design and build a small PET system. It consists of two 4 × 4 matrices of 16 LYSO scintillator crystals and two PMTs with 16 channels resulting in a low cost system with the essential functionality of a clinical PET instrument. It is designed to illustrate the physics of the PET technique and to provide a didactic platform for the training of students and nuclear imaging professionals as well as for scientific outreach. The PET modules can be configured to test for the coincidence of 511 keV gamma rays. The model has a flexible mechanical setup [1] and can simulate 14 diferent ring geometries, from a configuration with as few as 18 detectors per ring (ring radius phi=51 mm), up to a geometry with 70 detectors per ring (phi=200 mm). A second version of the electronic system [2] allowed measurement and recording of the energy deposited in 4 detector channels by photons from a 137Cs radioactive source and by photons resulting of the annihilation of positrons from a 22Na radioactive source. These energy spectra are used for detector performance studies, as well as angular dependency studies. In this paper, the mechanical setup, the front-end high-speed analog electronics, the digital acquisition and control electronics implemented in a FPGA, as well as the data-transfer interface between the FPGA board and a host PC are described. Recent preliminary results obtained with the 4 active channels in the prototype are also presented.

  4. Novel system using microliter order sample volume for measuring arterial radioactivity concentrations in whole blood and plasma for mouse PET dynamic study

    NASA Astrophysics Data System (ADS)

    Kimura, Yuichi; Seki, Chie; Hashizume, Nobuya; Yamada, Takashi; Wakizaka, Hidekatsu; Nishimoto, Takahiro; Hatano, Kentaro; Kitamura, Keishi; Toyama, Hiroshi; Kanno, Iwao

    2013-11-01

    This study aimed to develop a new system, named CD-Well, for mouse PET dynamic study. CD-Well allows the determination of time-activity curves (TACs) for arterial whole blood and plasma using 2-3 µL of blood per sample; the minute sample size is ideal for studies in small animals. The system has the following merits: (1) measures volume and radioactivity of whole blood and plasma separately; (2) allows measurements at 10 s intervals to capture initial rapid changes in the TAC; and (3) is compact and easy to handle, minimizes blood loss from sampling, and delay and dispersion of the TAC. CD-Well has 36 U-shaped channels. A drop of blood is sampled into the opening of the channel and stored there. After serial sampling is completed, CD-Well is centrifuged and scanned using a flatbed scanner to define the regions of plasma and blood cells. The length measured is converted to volume because the channels have a precise and uniform cross section. Then, CD-Well is exposed to an imaging plate to measure radioactivity. Finally, radioactivity concentrations are computed. We evaluated the performance of CD-Well in in vitro measurement and in vivo 18F-fluorodeoxyglucose and [11C]2-carbomethoxy-3β-(4-fluorophenyl) tropane studies. In in vitro evaluation, per cent differences (mean±SE) from manual measurement were 4.4±3.6% for whole blood and 4.0±3.5% for plasma across the typical range of radioactivity measured in mouse dynamic study. In in vivo studies, reasonable TACs were obtained. The peaks were captured well, and the time courses coincided well with the TAC derived from PET imaging of the heart chamber. The total blood loss was less than 200 µL, which had no physiological effect on the mice. CD-Well demonstrates satisfactory performance, and is useful for mouse PET dynamic study.

  5. A comparison of the psychological burden of PET/MRI and PET/CT scans and association to initial state anxiety and previous imaging experiences

    PubMed Central

    Neriman, D; Hoath, J; Millner, L; Endozo, R; Azzopardi, G; O'Meara, C; Bomanji, J; Groves, A M

    2015-01-01

    Objective: To investigate the level of psychological burden experienced by patients undergoing positron emission tomography (PET)/MRI scanning compared with PET/CT. Methods: 100 adult patients referred for PET/CT and underwent PET/MRI scanning were eligible. Initial state, psychological burden of PET/CT and PET/MRI, scan satisfaction and preference were assessed using a purpose-designed questionnaire, comprising 61 five-point Likert scale questions and a three-point tick box question indicating preference between PET/CT and PET/MRI. State anxiety was assessed using the state portion of the State Trait Anxiety Inventory. Wilcoxon signed-rank tests compared psychological burden experienced by participants following PET/CT and PET/MRI scan. Results: A greater level of psychological burden was experienced by patients during PET/MRI than PET/CT p ≤ 0.001, consistent with patients' preference for PET/CT over PET/MRI (p = 0.013). There was a significant relationship between PET/CT psychological burden and initial state (r = 0.386, p ≤ 0.001). No significant relationship was identified between Initial state and psychological burden of PET MRI (r = −0.089; p = 217). There was a significant relationship between psychological burden of PET/CT and PET/MRI (r = 0.354; p = 0.001). Conclusion: Patients' experience increased psychological burden during PET/MRI compared with PET/CT. Previous scanning experiences and patients' interactions prior to and during PET/MRI improved patient satisfaction. Interventions could be implemented to improve imaging outcome. Advances in knowledge: This study provides evidence for the increased psychological burden of PET/MRI compared with PET/CT, and that people prefer the PET/CT procedure. We have shown that the patients who expressed a preference for PET/MRI demonstrated significantly lower psychological burden for that procedure than those that preferred PET/CT, which indicates that the benefit of reduced

  6. Subanesthetic doses of ketamine transiently decrease serotonin transporter activity: a PET study in conscious monkeys.

    PubMed

    Yamamoto, Shigeyuki; Ohba, Hiroyuki; Nishiyama, Shingo; Harada, Norihiro; Kakiuchi, Takeharu; Tsukada, Hideo; Domino, Edward F

    2013-12-01

    Subanesthetic doses of ketamine, an N-methyl-D-aspartic acid (NMDA) antagonist, have a rapid antidepressant effect which lasts for up to 2 weeks. However, the neurobiological mechanism regarding this effect remains unclear. In the present study, the effects of subanesthetic doses of ketamine on serotonergic systems in conscious monkey brain were investigated. Five young monkeys underwent four positron emission tomography measurements with [(11)C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)benzonitrile ([(11)C]DASB) for the serotonin transporter (SERT), during and after intravenous infusion of vehicle or ketamine hydrochloride in a dose of 0.5 or 1.5 mg/kg for 40 min, and 24 h post infusion. Global reduction of [(11)C]DASB binding to SERT was observed during ketamine infusion in a dose-dependent manner, but not 24 h later. The effect of ketamine on the serotonin 1A receptor (5-HT1A-R) and dopamine transporter (DAT) was also investigated in the same subjects studied with [(11)C]DASB. No significant changes were observed in either 5-HT1A-R or DAT binding after ketamine infusion. Microdialysis analysis indicated that ketamine infusion transiently increased serotonin levels in the extracellular fluid of the prefrontal cortex. The present study demonstrates that subanesthetic ketamine selectively enhanced serotonergic transmission by inhibition of SERT activity. This action coexists with the rapid antidepressant effect of subanesthetic doses of ketamine. Further studies are needed to investigate whether the transient combination of SERT and NMDA reception inhibition enhances each other's antidepressant actions. PMID:23880871

  7. Postapplication Fipronil Exposure Following Use on Pets.

    PubMed

    Cochran, R C; Yu, Liu; Krieger, R I; Ross, J H

    2015-01-01

    Fipronil is a pyrazole acaricide and insecticide that may be used for insect, tick, lice, and mite control on pets. Residents' short-term and long-term postapplication exposures to fipronil, including secondary environmental exposures, were estimated using data from chemical-specific studies. Estimations of acute (24-h) absorbed doses for residents were based on U.S. Environmental Protection Agency (U.S. EPA) 2012 standard operating procedures (SOPs) for postapplication exposure. Chronic exposures were not estimated for residential use, as continuous, long-term application activities were unlikely to occur. Estimated acute postapplication absorbed doses were as high as 0.56 μg/kg-d for toddlers (1-2 yr) in households with treated pets based on current U.S. EPA SOPs. Acute toddler exposures estimated here were fivefold larger in comparison to adults. Secondary exposure from the household environment in which a treated pet lives that is not from contacting the pet, but from contacting the house interior to which pet residues were transferred, was estimated based on monitoring socks worn by pet owners. These secondary exposures were more than an order of magnitude lower than those estimated from contacting the pet and thus may be considered negligible.

  8. Brain hypometabolism of glucose in anorexia nervosa: a PET scan study.

    PubMed

    Delvenne, V; Lotstra, F; Goldman, S; Biver, F; De Maertelaer, V; Appelboom-Fondu, J; Schoutens, A; Bidaut, L M; Luxen, A; Mendelwicz, J

    1995-02-01

    Cerebral glucose metabolism was studied in 20 underweight anorectic girls and in 10 age- and sex-matched healthy volunteers using positron emission tomography with (18-F)-fluorodeoxy-glucose. Both groups were scanned during rest, with eye closed and with low ambient noise. Compared to controls, the underweight anorectic group showed a global hypometabolism (p = .002) and an absolute (p < .001) as well as relative (p < .01) hypometabolism of glucose in cortical regions, with the most significant differences found in the frontal and the parietal cortices. Within the underweight anorectic and the control groups, no correlations were found between absolute or relative rCMRGlu and BMI, anxiety scores, or Hamilton scores of depression. Different factors might explain this reduction of glucose metabolism in anorexia nervosa. It might be the consequence of neurophysiological or morphological aspects of anorexia nervosa and/or the result of some associated symptoms such as anxiety or depressed feelings. Supported by cognitive studies, we can also hypothesize a primary corticocerebral dysfunctioning in anorexia nervosa. PMID:7727624

  9. Variability in paralimbic dopamine signaling correlates with subjective responses to d-amphetamine.

    PubMed

    Smith, Christopher T; Dang, Linh C; Cowan, Ronald L; Kessler, Robert M; Zald, David H

    2016-09-01

    Subjective responses to psychostimulants vary, the basis of which is poorly understood, especially in relation to possible cortical contributions. Here, we tested for relationships between participants' positive subjective responses to oral d-amphetamine (dAMPH) versus placebo and variability in striatal and extrastriatal dopamine (DA) receptor availability and release, measured via positron emission tomography (PET) with the radiotracer (18)F-fallypride. Analyses focused on 35 healthy adult participants showing positive subjective effects to dAMPH measured via the Drug Effects Questionnaire (DEQ) Feel, Like, High, and Want More subscales (Responders), and were repeated after inclusion of 11 subjects who lacked subjective responses. Associations between peak DEQ subscale ratings and both baseline (18)F-fallypride binding potential (BPnd; an index of D2/D3 receptor availability) and the percentage change in BPnd post dAMPH (%ΔBPnd; a measure of DA release) were assessed. Baseline BPnd in ventromedial prefrontal cortex (vmPFC) predicted the peak level of High reported following dAMPH. Furthermore, %ΔBPnd in vmPFC positively correlated with DEQ Want More ratings. DEQ Want More was also positively correlated with %ΔBPnd in right ventral striatum and left insula. This work indicates that characteristics of DA functioning in vmPFC, a cortical area implicated in subjective valuation, are associated with both subjective high and incentive (wanting) responses. The observation that insula %ΔBPnd was associated with drug wanting converges with evidence suggesting its role in drug craving. These findings highlight the importance of variability in DA signaling in specific paralimbic cortical regions in dAMPH's subjective response, which may confer risk for abusing psychostimulants. PMID:27174408

  10. Comparative anatomo-functional imaging of two neuroreceptors and glucose metabolism: a PET study performed in the living baboon

    SciTech Connect

    Larson, S.M.; Di Chiro, G.

    1985-07-01

    Regional specialization of two types of neuroreceptor--opiate and dopamine--was mapped by positron emission tomography (PET) in the subcortical gray matter of the living baboon and analyzed in comparison with glucose metabolism. The three radiopharmaceuticals used--(/sup 18/F)3-acetylcyclofoxy, (/sup 11/C)3-N-methylspiperone, and (/sup 18/F)2-fluoro-2-deoxyglucose--traced opiate- and dopamine-receptor distribution and regional glucose metabolism, respectively. A combination of high spatial resolution (6-7 mm) and the intrinsic sensitivity of the PET method made possible the detection of nanomolar concentrations of neuroreceptors and micromolar concentrations of metabolized glucose, with different and distinctive anatomo-functional distributions in thalami and basal ganglia.

  11. Profits from precious pets.

    PubMed

    Pennisi, E

    2000-06-01

    In 1998, an anonymous millionaire, hoping to clone his pet dog Missy, awarded a Texas A&M University animal scientist $2.3 million to develop the necessary techniques. Now several companies are cashing in on the boom in frozen-tissue storage of pets for future cloning.

  12. My Pet Rock

    ERIC Educational Resources Information Center

    Lark, Adam; Kramp, Robyne; Nurnberger-Haag, Julie

    2008-01-01

    Many teachers and students have experienced the classic pet rock experiment in conjunction with a geology unit. A teacher has students bring in a "pet" rock found outside of school, and the students run geologic tests on the rock. The tests include determining relative hardness using Mohs scale, checking for magnetization, and assessing luster.…

  13. A study of structure formation on PET, PBT, and PS surfaces by excimer laser ablation

    NASA Astrophysics Data System (ADS)

    Kim, Jongdae

    Usually polymer surface treatment is performed to modify surface layers by inserting some functional group and/or by inducing roughness on surfaces to improve their wettability, printability, and adhesion to other polymers or metals. In this work, different polymer surfaces were treated using an excimer laser (LPX 240i, Lambda Physik). Polystyrene, polyethylene terephtalate, and polybutylene terephtalate were chosen as model materials for this study. Films were made by cast film processing and stretched with biaxial stretching machine. With excimer laser treatment on polymer surfaces, it was found that we could produce 1--2 micron size structures depending on material properties and film processing conditions. Materials with lower UV absorption coefficient produced double digit micron size structures, while those with higher UV absorption coefficients produced single digit micron size structures. In all these cases the structures formed only on stretched films. In addition to those microstructure developments, the determination of ablation threshold fluence was of interest mainly for understanding fundamentals of ablation behavior and technical applications. In this study, ablation thresholds were measured by various methods including ablation depth, ablation weight, and ablation sound level measurements. Among these methods, we confirmed that the measurement by ablation sound level gives the most reliable results, because this method is based on single pulse ablation. To understand the ablation phenomenon, and how microstructures can be developed during ablation, different material processing and excimer laser conditions were chosen for experimentation. During our experiments, we observed incubation phenomenon during laser ablation and showed that this incubation was significant for materials with low UV absorption coefficients. Based on UV absorption value change after excimer laser irradiation, we proposed a mechanism to explain the ablation of PS films. From

  14. Neural substrates of human facial expression of pleasant emotion induced by comic films: a PET Study.

    PubMed

    Iwase, Masao; Ouchi, Yasuomi; Okada, Hiroyuki; Yokoyama, Chihiro; Nobezawa, Shuji; Yoshikawa, Etsuji; Tsukada, Hideo; Takeda, Masaki; Yamashita, Ko; Takeda, Masatoshi; Yamaguti, Kouzi; Kuratsune, Hirohiko; Shimizu, Akira; Watanabe, Yasuyoshi

    2002-10-01

    Laughter or smile is one of the emotional expressions of pleasantness with characteristic contraction of the facial muscles, of which the neural substrate remains to be explored. This currently described study is the first to investigate the generation of human facial expression of pleasant emotion using positron emission tomography and H(2)(15)O. Regional cerebral blood flow (rCBF) during laughter/smile induced by visual comics and the magnitude of laughter/smile indicated significant correlation in the bilateral supplementary motor area (SMA) and left putamen (P < 0.05, corrected), but no correlation in the primary motor area (M1). In the voluntary facial movement, significant correlation between rCBF and the magnitude of EMG was found in the face area of bilateral M1 and the SMA (P < 0.001, uncorrected). Laughter/smile, as opposed to voluntary movement, activated the visual association areas, left anterior temporal cortex, left uncus, and orbitofrontal and medial prefrontal cortices (P < 0.05, corrected), whereas voluntary facial movement generated by mimicking a laughing/smiling face activated the face area of the left M1 and bilateral SMA, compared with laughter/smile (P < 0.05, corrected). We demonstrated distinct neural substrates of emotional and volitional facial expression and defined cognitive and experiential processes of a pleasant emotion, laughter/smile.

  15. Preliminary Study of Pet Owner Adherence in Behaviour, Cardiology, Urology, and Oncology Fields

    PubMed Central

    Talamonti, Zita; Cassis, Chiara; Brambilla, Paola G.; Scarpa, Paola; Stefanello, Damiano; Cannas, Simona; Minero, Michela; Palestrini, Clara

    2015-01-01

    Successful veterinary treatment of animals requires owner adherence with a prescribed treatment plan. The aim of our study was to evaluate and compare the level of adherence of the owners of patients presented for behavioural, cardiological, urological, and oncological problems. At the end of the first examination, each owner completed a questionnaire. Then, the owners were called four times to fill out another questionnaire over the phone. With regard to the first questionnaire, statistically significant data concern behavioral medicine and cardiology. In the first area the owner's worry decreases during the follow-up and the number of owners who would give away the animal increases. In cardiology, owners who think that the pathology harms their animal's quality of life decreased significantly over time. With regard to the 9 additional follow-up questions, in behavioural medicine and urology the owner's discomfort resulting from the animal's pathology significantly decreases over time. Assessment of adherence appears to be an optimal instrument in identifying the positive factors and the difficulties encountered by owners during the application of a treatment protocol. PMID:26185708

  16. PET studies on the memory processing of word pairs in bilingual Finnish-English subjects.

    PubMed

    Halsband, U; Krause, B J; Sipilä, H; Teräs, M; Laihinen, A

    2002-04-15

    This study examined the fundamental question whether verbal memory processing in two unrelated languages is mediated by a common neural system or by distinct cortical areas. Ten right-handed, male Finnish--English adult late bilinguals who had acquired the second language after the age of 10 were scanned whilst either encoding/retrieving word pairs in their mother tongue (Finnish) or in a foreign language (English). Within each language, subjects had to encode and retrieve four sets of 12 visually presented paired word associates which were not semantically related. Two sets consisted of highly imageable words (e.g. monkey-table; koira-lasi) and the other two sets of abstract word pairs (e.g. freedom-moral; uhka-suure). Presentation of pseudowords served as a reference condition. An emission scan was recorded after each intravenous administration of O-15 water. Encoding was associated with prefrontal and hippocampal activation. During memory retrieval, precuneus showed a consistent activation in both languages and for both highly imageable and abstract words. Although the brain mechanisms of the two languages share common components, differential activations were found in Broca's area and in the cerebellum as well as in the angular/supramarginal gyri according to the language used.

  17. A study on occupational exposure in a PET/CT facility.

    PubMed

    Vargas Castrillón, S; Cutanda Henríquez, F

    2011-09-01

    Staff occupational exposure for (18)F-FDG studies has been assessed. For this purpose, different detectors, all traceable to PTB standards, have been used. Measurements were carried out in different working areas in the facility for different procedures and 400 MBq per patient standard injected activity. A radiological map of the patient lying on the couch was obtained; the largest dose rate result was obtained in contact with the patient's abdomen. The maximum dose to the most exposed staff member for this position is 3.6 mSv y(-1), under some conservative assumptions. A typical value would be 0.9 ± 0.3 mSv y(-1) close to the abdomen, taking into account staff rotations. These results have been obtained from a sample of 50 patients and average values have been statistically tested. Particularly, a negligible probability of reaching 20 mSv in a year (assuming no incidents or contamination) was obtained (P < 0.01). Annual dose received by personnel lies well within the recommended limits (International Commission on Radiological Protection), these measurements help to optimise working procedures in the facility. PMID:21733867

  18. Imaging corn plants with PhytoPET, a modular PET system for plant biology

    SciTech Connect

    Lee, S.; Kross, B.; McKisson, J.; McKisson, J. E.; Weisenberger, A. G.; Xi, W.; Zorn, C.; Bonito, G.; Howell, C. R.; Reid, C. D.; Crowell, A.; Cumberbatch, L. C.; Topp, C.; Smith, M. F.

    2013-11-01

    PhytoPET is a modular positron emission tomography (PET) system designed specifically for plant imaging. The PhytoPET design allows flexible arrangements of PET detectors based on individual standalone detector modules built from single Hamamatsu H8500 position sensitive photomultiplier tubes and pixelated LYSO arrays. We have used the PhytoPET system to perform preliminary corn plant imaging studies at the Duke University Biology Department Phytotron. Initial evaluation of the PhytoPET system to image the biodistribution of the positron emitting tracer {sup 11}C in corn plants is presented. {sup 11}CO{sub 2} is loaded into corn seedlings by a leaf-labeling cuvette and translocation of {sup 11}C-sugars is imaged by a flexible arrangement of PhytoPET modules on each side. The PhytoPET system successfully images {sup 11}C within corn plants and allows for the dynamic measurement of {sup 11}C-sugar translocation from the leaf to the roots.

  19. Preliminary study on the effects of ageing cold oxygen plasma treated PET/PP with respect to protein adsorption.

    PubMed

    Chen, Rui; Bayon, Yves; Hunt, John A

    2012-08-01

    Surfaces of polyethylene terephthalate (PET) and polypropylene (PP) have been modified by oxygen plasma. The surface hydrophilicity and changes in topography during up to 90 days storage in water and in dry air in a desiccator were analysed by dynamic contact angle test and atomic force microscopy (AFM). Clear ageing effects on the plasma treated surface were observed as increases in contact angle and changes in roughness as functions of increasing storage time. However, the effect of oxygen plasma treatment to increase the hydrophilicity of surface was still evident on the treated surfaces even after 90 days storage either in dry air or in water. In protein adsorption experiments, human serum albumin (HSA) and fibrinogen (Fg) were adsorbed on untreated and oxygen plasma treated PET and PP surfaces. The quantified ATR-FTIR results showed that both HSA and Fg adsorption on PET and PP surfaces decreased after oxygen plasma treatment, with the effect most evident for HSA. Although for both proteins adsorption increased with ageing, the amount of adsorbed proteins was still lower than untreated surface at 30 days. This suggests the shelf life of oxygen plasma treated samples could be as long as 30 days. PMID:22521680

  20. Dosimetry and stability studies of the boron neutron capture therapy agent F-BPA-Fr using PET and MRI

    NASA Astrophysics Data System (ADS)

    Dyke, Jonathan Paul

    The treatment of deep seated brain tumors such as glioblastoma Multiforme has been unsuccessful for many patients. Surgical debulking, chemotherapy and standard radiotherapy have met with limited success. Boron neutron capture therapy offers a binary mode brachytherapy based on the following capture reaction that may provide an innovative alternative to standard forms of treatment:10B + n /to/ 11B /to 7Li + 4He + 2.31 MeVBoron is chemically attached to a tumor binding compound creating a non-toxic neutron absorber. A dose of epithermal neutrons provides the catalyst to produce the lithium and alpha particles which destroy any tissue within a length of one cell diameter from the boron compound. This dissertation uses 19F-MRI and 18F-PET to provide answers to the localization and biodistribution questions that arise in such a treatment modality. Practical patient dosimetry and actual treatment planning using the PET data is also examined. Finally, theoretical work done in the areas of compartmental modelling dealing with pharmacokinetic uptake of the PET radiotracer and dose analysis in microdosimetry is also presented.

  1. Endogenous opioidergic dysregulation of pain in fibromyalgia: a PET and fMRI study.

    PubMed

    Schrepf, Andrew; Harper, Daniel E; Harte, Steven E; Wang, Heng; Ichesco, Eric; Hampson, Johnson P; Zubieta, Jon-Kar; Clauw, Daniel J; Harris, Richard E

    2016-10-01

    Endogenous opioid system dysfunction potentially contributes to chronic pain in fibromyalgia (FM), but it is unknown if this dysfunction is related to established neurobiological markers of hyperalgesia. We previously reported that µ-opioid receptor (MOR) availability was reduced in patients with FM as compared with healthy controls in several pain-processing brain regions. In the present study, we compared pain-evoked functional magnetic resonance imaging with endogenous MOR binding and clinical pain ratings in female opioid-naive patients with FM (n = 18) using whole-brain analyses and regions of interest from our previous research. Within antinociceptive brain regions, including the dorsolateral prefrontal cortex (r = 0.81, P < 0.001) and multiple regions of the anterior cingulate cortex (all r > 0.67; all P < 0.02), reduced MOR availability was associated with decreased pain-evoked neural activity. Additionally, reduced MOR availability was associated with lower brain activation in the nucleus accumbens (r = 0.47, P = 0.050). In many of these regions, pain-evoked activity and MOR binding potential were also associated with lower clinical affective pain ratings. These findings are the first to link endogenous opioid system tone to regional pain-evoked brain activity in a clinical pain population. Our data suggest that dysregulation of the endogenous opioid system in FM could lead to less excitation in antinociceptive brain regions by incoming noxious stimulation, resulting in the hyperalgesia and allodynia commonly observed in this population. We propose a conceptual model of affective pain dysregulation in FM.

  2. Comparison of [11C]cocaine binding at tracer and pharmacological doses of baboon brain: A PET study

    SciTech Connect

    Volkow, N.D.; Fowler, J.S.; Logan, J.

    1994-05-01

    In vitro studies have shown that cocaine (C) binds to both high and low affinity sites on the dopamine transporter (DAT). We have previously characterized the binding of tracer doses of [{sup 11}C]cocaine (C*)to a high affinity site on the DAT. To assess if in vivo C also binds to low affinity sites we used PET to compare binding of tracer doses (17.8{plus_minus}12.2 {mu}g C) of C* to pharmacological doses (8 mg of C coadministered with C*). Sixteen paired studies were done to assess test/retest variability, specific versus non specific binding and to characterize binding profile. Dynamic scans were started immediately after injection of C* (5-8 mCi) for 50 min on the CTI-931 (6 x 6 x 6.5 mm FWHM). Time activity curves for tissue concentration and for unchanged tracer in plasma were used to calculate the transport constant between plasma and tissue (K1) and to obtain the distribution volume (DV). The ratio of the DV in striatum (ST) to that in cerebellum (CB) (which corresponds to Bmax/Kd-1) was used as model parameter. Peak brain uptake of C* was significantly higher for tracer than for pharmacological doses (0.041 versus 0.033 % dose/cc), as were the values for K1 (1.07{plus_minus}0.21 versus 0.68{plus_minus}0.26 (t=3.0 p<0.01)). Repeated measures were reproducible for tracer ({plus_minus}2%) and pharmacological doses of C* ({plus_minus}4%). Tracer dose C* showed highest binding and slowest clearance in ST which was reduced by C (0.5-2.0 mg/kg iv, -25 to -30%) and by drugs that inhibit DAT (2mg/kg nomifensine - 21%, 0.5 mg/kg methylphenidate -12%) and was increased by serotonin transporter inhibitors (5HT-Ti) (2 mg/kg citalopram +11%, 0.5 mg/kg fluoxetine +6%) and not changed by NE transporter inhibitors (0.5 mg/kg desipramine or 2 mg/kg tomoxetine). The increase with (5HT-Ti) may reflect neurotransmitter interactions or changes in bioavailability. At pharmacological doses C* showed homogeneous distribution and was not changed by C nor by any of the above drugs.

  3. Relations between hypometabolism in the posterior association neocortex and hippocampal atrophy in Alzheimer's disease: a PET/MRI correlative study

    PubMed Central

    Meguro, K; LeMestric, C; Landeau, B; Desgranges, B; Eustache, F; Baron, J

    2001-01-01

    OBJECTIVES—Hippocampal atrophy and hypometabolism in the posterior association neocortex are two well known features of Alzheimer's disease. A correlation between these two features was reported twice previously, suggesting intriguing relations. This question has been reassessed, this time controlling for severity of dementia as well as assessing each side of the brain separately and using a voxel based image analysis in addition to the previously employed regions of interest (ROIs).
PATIENTS AND METHODS—Eleven patients were studied with probable Alzheimer's disease and mild to moderate dementia in whom both volume MRI and PET assessed cerebral glucose consumption (CMRGlc) were available. Hypothesis driven correlations between hippocampal width (an index of atrophy) and CMRGlc were performed for two posterior association regions, the superior temporal and the inferior parietal (angular gyrus) cortices, using ROIs set separately for each hemisphere. To confirm significant correlations from the ROIs approach, if any, and to assess their specificity for the posterior association neocortex, CMRGlc image voxel based analysis of correlations with hippocampal width was then carried out.
RESULTS—There was a significant correlation, in the positive—neurobiologically expected—direction, between right hippocampal width and right angular gyrus metabolism (p< 0.01, Spearman), which remained significant with Kendall partial correlation controlling for dementia severity (estimated by mini mental state scores). Statistical non-parametric mapping (SnPM) confirmed this correlation (p< 0.025), and showed a single additional correlation in the right middle temporal gyrus (p< 0.005), which is also part of the posterior association cortex.
CONCLUSION—The findings with both ROIs and voxel based mapping replicate earlier reports of a relation between hippocampal atrophy and ipsilateral association cortex hypometabolism in Alzheimer's disease, and for the first time

  4. Synthesis of (R)- and (S)-[C-11]L-365,260 for PET studies of brain cholecystokinin (CCK) receptors

    SciTech Connect

    Haradahira, T.; Suzuki, K.; Inoue, O.

    1994-05-01

    Cholecystokinin (CCK) is a recognized peptide hormone in the gut and proposed as a neurotransmitter or neuromodulator in the central nervous system. Two distinct CCK receptors termed CCK-A and CCK-B have been characterized. CCK-A receptor is primarily distributed in the peripheral tissues including pancreas and gallbladder and also known to be distributed in a few brain regions. CCK-B receptor is widely distributed in the brain and has been proposed to be involved in anxiety, satiety and nociception. To investigate the functional roles of the CCK receptors in the brain by positron emission tomography, we have synthesized an enantiomeric pair of C-11 labeled non-peptide antagonists against the CCK receptors. L-365,260 [3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepine-3-yl)-N`-(3-methylpheny lurea)] is a potent CCK-B selective non-peptide antagonist (CCK-A/CCK-B ratio of IC50, 140), whereas its (S)-enantiomer is selective toward CCK-A receptor (CCK-A/CCK-B ratio of IC50, 0.02). We have synthesized the (R)- and (S)-enantiomers of [C-11]-365,260 by N-methylation (50{degrees}C for 5 min) of the racemic desmethyl precursor with [C-11]iodomethane using sodium hydride as a base and subsequent optical resolution with HPLC (column: ChiraSpher, 250 x 10 mm, Merck; eluent: n-hexane / 1,4-dioxane / 2-propanol / triethylamine = 70 / 25 / 5 / 0.1). Radiochemical yields (decay corrected) and optical purities were 34%, 99% for R-enantiomer and 36%, 99% for S-enantiomer, respectively. The total synthesis time was 40 min and specific activity was about 37 GBq/{mu}mol. In PET studies on rhesus monkey (R)-enantiomer showed a high uptake of radioactivity in the cerebral cortex, region known to have a high concentration of CCK-B receptor.

  5. Normal Myocardial Flow Reserve in HIV-Infected Patients on Stable Antiretroviral Therapy: A Cross-Sectional Study Using Rubidium-82 PET/CT.

    PubMed

    Knudsen, Andreas; Christensen, Thomas E; Ghotbi, Adam Ali; Hasbak, Philip; Lebech, Anne-Mette; Kjær, Andreas; Ripa, Rasmus Sejersten

    2015-10-01

    Studies have found HIV-infected patients to be at increased risk of myocardial infarction, which may be caused by coronary microvascular dysfunction. For the first time among HIV-infected patients, we assessed the myocardial flow reserve (MFR) by Rubidium-82 (82Rb) positron emission tomography (PET), which can quantify the coronary microvascular function. MFR has proved highly predictive of future coronary artery disease and cardiovascular events in the general population.In a prospective cross-sectional study, HIV-infected patients all receiving antiretroviral therapy (ART) with full viral suppression and HIV-uninfected controls were scanned using 82Rb PET/computed tomography at rest and adenosine-induced stress, thereby obtaining the MFR (stress flow/rest flow), stratified into low ≤1.5, borderline >1.5 to 2.0, or normal >2.0.Fifty-six HIV-infected patients and 25 controls were included. The HIV-infected patients had a mean age of 53 years (range 37-68 years) with 23% active smokers. The controls had a mean age of 52 years (range 36-68 years) and 26% active smokers. In the HIV-infected group 73% had a normal MFR, 17% borderline, and 10% low values of MFR. Among controls these values were 71%, 19%, and 10%, respectively (P = 0.99). However, the HIV-infected group had lower values of stress myocardial blood flow (MBF) (2.63 ± 0.09 mL/g/min vs 2.99 ± 0.14 mL/g/min; P = 0.03). We found no evidence of decreased MFR as assessed by 82Rb PET among HIV-infected patients on stable ART with full viral suppression compared with HIV-uninfected controls. We did notice a decreased MBF during stress. PMID:26512605

  6. Sea otter health: challenging a pet hypothesis

    USGS Publications Warehouse

    Lafferty, Kevin D.

    2015-01-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission.

  7. Sea otter health: Challenging a pet hypothesis

    PubMed Central

    Lafferty, Kevin D.

    2015-01-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission. PMID:26155464

  8. Sea otter health: Challenging a pet hypothesis.

    PubMed

    Lafferty, Kevin D

    2015-12-01

    A recent series of studies on tagged sea otters (Enhydra lutris nereis) challenges the hypothesis that sea otters are sentinels of a dirty ocean, in particular, that pet cats are the main source of exposure to Toxoplasma gondii in central California. Counter to expectations, sea otters from unpopulated stretches of coastline are less healthy and more exposed to parasites than city-associated otters. Ironically, now it seems that spillover from wildlife, not pets, dominates spatial patterns of disease transmission. PMID:26155464

  9. Impact of [{sup 18}F]Fluorodeoxyglucose PET-CT Staging on Treatment Planning in Radiotherapy Incorporating Elective Nodal Irradiation for Non-Small-Cell Lung Cancer: A Prospective Study;Non-small-cell lung cancer; PET; Radiotherapy; Elective nodal irradiation

    SciTech Connect

    Kolodziejczyk, Milena; Kepka, Lucyna; Dziuk, Miroslaw; Zawadzka, Anna; Szalus, Norbert; Gizewska, Agnieszka; Bujko, Krzysztof

    2011-07-15

    Purpose: To evaluate prospectively how positron emission tomography (PET) information changes treatment plans for non-small-cell lung cancer (NSCLC) patients receiving or not receiving elective nodal irradiation (ENI). Methods and Materials: One hundred consecutive patients referred for curative radiotherapy were included in the study. Treatment plans were carried out with CT data sets only. For stage III patients, mediastinal ENI was planned. Then, patients underwent PET-CT for diagnostic/planning purposes. PET/CT was fused with the CT data for final planning. New targets were delineated. For stage III patients with minimal N disease (N0-N1, single N2), the ENI was omitted in the new plans. Patients were treated according to the PET-based volumes and plans. The gross tumor volume (GTV)/planning tumor volume (PTV) and doses for critical structures were compared for both data sets. The doses for areas of potential geographical misses derived with the CT data set alone were compared in patients with and without initially planned ENI. Results: In the 75 patients for whom the decision about curative radiotherapy was maintained after PET/CT, there would have been 20 cases (27%) with potential geographical misses by using the CT data set alone. Among them, 13 patients would receive ENI; of those patients, only 2 patients had the PET-based PTV covered by 90% isodose by using the plans based on CT alone, and the mean of the minimum dose within the missed GTV was 55% of the prescribed dose, while for 7 patients without ENI, it was 10% (p = 0.006). The lung, heart, and esophageal doses were significantly lower for plans with ENI omission than for plans with ENI use based on CT alone. Conclusions: PET/CT should be incorporated in the planning of radiotherapy for NSCLC, even in the setting of ENI. However, if PET/CT is unavailable, ENI may to some extent compensate for an inadequate dose coverage resulting from diagnostic uncertainties.

  10. {sup 18}F-FLT uptake kinetics in head and neck squamous cell carcinoma: A PET imaging study

    SciTech Connect

    Liu, Dan Fenwick, John D.; Chalkidou, Anastasia; Landau, David B.; Marsden, Paul K.

    2014-04-15

    Purpose: To analyze the kinetics of 3{sup ′}-deoxy-3{sup ′}-[F-18]-fluorothymidine (18F-FLT) uptake by head and neck squamous cell carcinomas and involved nodes imaged using positron emission tomography (PET). Methods: Two- and three-tissue compartment models were fitted to 12 tumor time-activity-curves (TACs) obtained for 6 structures (tumors or involved nodes) imaged in ten dynamic PET studies of 1 h duration, carried out for five patients. The ability of the models to describe the data was assessed using a runs test, the Akaike information criterion (AIC) and leave-one-out cross-validation. To generate parametric maps the models were also fitted to TACs of individual voxels. Correlations between maps of different parameters were characterized using Pearson'sr coefficient; in particular the phosphorylation rate-constants k{sub 3-2tiss} and k{sub 5} of the two- and three-tissue models were studied alongside the flux parameters K{sub FLT-2tiss} and K{sub FLT} of these models, and standardized uptake values (SUV). A methodology based on expectation-maximization clustering and the Bayesian information criterion (“EM-BIC clustering”) was used to distil the information from noisy parametric images. Results: Fits of two-tissue models 2C3K and 2C4K and three-tissue models 3C5K and 3C6K comprising three, four, five, and six rate-constants, respectively, pass the runs test for 4, 8, 10, and 11 of 12 tumor TACs. The three-tissue models have lower AIC and cross-validation scores for nine of the 12 tumors. Overall the 3C6K model has the lowest AIC and cross-validation scores and its fitted parameter values are of the same orders of magnitude as literature estimates. Maps ofK{sub FLT} and K{sub FLT-2tiss} are strongly correlated (r = 0.85) and also correlate closely with SUV maps (r = 0.72 for K{sub FLT-2tiss}, 0.64 for K{sub FLT}). Phosphorylation rate-constant maps are moderately correlated with flux maps (r = 0.48 for k{sub 3-2tiss} vs K{sub FLT-2tiss} and r = 0

  11. Water Quality Evaluation of PET Bottled Water by Mineral Balance in the Northeast Asian Region: A Case Study of South Korea

    PubMed Central

    Houri, Daisuke; Koo, Chung Mo

    2015-01-01

    Background The past few years have seen a demand for drinking water in contemporary society with a focus on safety and taste. Mineral water is now marketed as a popular commercial product and, partly due to health concerns, the production. Methods For the study, a comparison was carried out of water samples from 9 types of polyethylene terephthalate (PET) bottled water sold in South Korea as well as from tap water in the cities of Seoul and Chuncheon. These were compared with samples of Japanese PET bottled water in order to determine shared commonalities and identify individual characteristics. To evaluate water quality objectively, we quantified the elements contained in the water samples. Samples were assessed not with the usual sensory evaluation but with the evaluation approach advocated by Hashimoto et al. which employs the Water Index of Taste and the Water Index of Health. The levels of water quality obtained were compared with the “Prerequisites for Tasty Water” and the “Standards for Tasty Water” devised for city water. Results The PET Bottled water varieties analyzed in this study—Seoksu, Icis, Bong Pyong, Soon Soo 100, Dong Won Saem Mul, GI JANG SOO and DIAMOND—showed the Water Index of Taste ≥ 2.0 and the Water Index of Health ≥ 5.2, which we classified as tasty/healthy water. SamDaSoo and NamiNeral can be classified as tasty water due to their values of the Water Index of Taste ≥ 2.0 and the Water Index of Health < 5.2. Conclusion The South Korean PET bottled water studied here fulfills the “Water Index of Taste,” “Water Index of Health,” “Standard for Tasty Water” and “Prerequisites for Tasty Water” that Japanese people value for city water. We can conclude that bottled water which meets water quality requirements will be considered good-tasting by a majority of people. PMID:26538797

  12. Agonist and antagonist bind differently to 5-HT1A receptors during Alzheimer's disease: A post-mortem study with PET radiopharmaceuticals.

    PubMed

    Vidal, Benjamin; Sebti, Johan; Verdurand, Mathieu; Fieux, Sylvain; Billard, Thierry; Streichenberger, Nathalie; Troakes, Claire; Newman-Tancredi, Adrian; Zimmer, Luc

    2016-10-01

    PET imaging studies using 5-HT1A receptor radiotracers show a decreased density of this receptor in hippocampi of patients with Alzheimer's disease (AD) at advanced stages. However, current 5-HT1A receptor radiopharmaceuticals used in neuroimaging are antagonists, thought to bind to 5-HT1A receptors in different functional states (i.e., both the one which displays high affinity for agonists and is thought to mediate receptor activation, as well as the state which has low affinity for agonists). Comparing the PET imaging obtained using an agonist radiotracer, which binds selectively to functional receptors, with the PET imaging obtained using an antagonist radiotracer would therefore provide original information on 5-HT1A receptor impairment during AD. Quantitative autoradiography using [(18)F]F13640 and [(18)F]MPPF, a 5-HT1A agonist and antagonist, respectively, was measured in hippocampi of patients with AD (n = 25, at different Braak stages) and control subjects (n = 9). The neuronal density was measured in the same tissues by NeuN immunohistochemistry. The specific binding of both radiotracers was determined by addition of WAY-100635, a selective 5-HT1A receptor antagonist. The autoradiography distribution of both 5-HT1A PET radiotracers varied across hippocampus regions. The highest binding density was in the pyramidal layer of CA1. Incubation with Gpp(NH)p, a non-hydrolysable analogue of GTP, reduced significantly [(18)F]F13640 binding in hippocampal regions, confirming its preferential interaction with G-coupled receptors, and slightly increased [(18)F]MPPF binding. In the CA1 subfield, [(18)F]F13640 binding was significantly decreased at Braak stages I/II (-19%), Braak stages III/IV (-23%), and Braak stages V/VI (-36%) versus control. In contrast, [(18)F]MPPF binding was statistically reduced only at the most advanced Braak stages V/VI compared to control (-33%). Since [(18)F]F13640 and [(18)F]MPPF can be used in vivo in humans, this

  13. Evaluation of brain SERT occupancy by resveratrol against MDMA-induced neurobiological and behavioral changes in rats: A 4-[¹⁸F]-ADAM/small-animal PET study.

    PubMed

    Shih, Jui-Hu; Ma, Kuo-Hsing; Chen, Chien-Fu F; Cheng, Cheng-Yi; Pao, Li-Heng; Weng, Shao-Ju; Huang, Yuahn-Sieh; Shiue, Chyng-Yann; Yeh, Ming-Kung; Li, I-Hsun

    2016-01-01

    The misuse of 3,4-methylenedioxymethamphetamine (MDMA) has drawn a growing concern worldwide for its psychophysiological impacts on humans. MDMA abusers are often accompanied by long-term serotonergic neurotoxicity, which is associated with reduced density of cerebral serotonin transporters (SERT) and depressive disorders. Resveratrol (RSV) is a natural polyphenolic phytoalexin that has been known for its antidepressant and neuroprotective effects. However, biological targets of RSV as well as its neuroprotective effects against MDMA remained largely unknown. In this study, we examined binding potency of RSV and MDMA to SERT using small-animal positron emission tomography (PET) with the SERT radioligand, N,N-dimethyl-2-(2-amino-4-[(18)F]fluorophenylthio)benzylamine (4-[(18)F]-ADAM) and investigated the protection of RSV against the acute and long-term adverse effects of MDMA. We found that RSV exhibit binding potentials to SERT in vivo in a dose-dependent manner with variation among brain regions. When the MDMA-treated rats (10mg/kg, s.c.) were co-injected with RSV (20mg/kg, i.p.) twice daily for 4 consecutive days, MDMA-induced acute elevation in plasma corticosterone was significantly reduced. Further, 4-[(18)F]-ADAM PET imaging revealed that RSV protected against the MDMA-induced decrease in SERT availability in the midbrain and the thalamus 2 weeks following the co-treatment. The PET data were comparable to the observation from the forced swim test that RSV sufficiently ameliorated the depressive-like behaviors of the MDMA-treated rats. Together, these findings suggest that RSV is a potential antidepressant and may confer protection against neurobiological and behavioral changes induced by MDMA. PMID:26612383

  14. Intravenous ethanol increases dopamine release in the ventral striatum in humans: PET study using bolus-plus-infusion administration of [11C]raclopride

    PubMed Central

    Aalto, Sargo; Ingman, Kimmo; Alakurtti, Kati; Kaasinen, Valtteri; Virkkala, Jussi; Någren, Kjell; Rinne, Juha O; Scheinin, Harry

    2015-01-01

    Ethanol increases the interstitial dopamine (DA) concentration in the nucleus accumbens (NAcc) of experimental animals, but positron emission tomography (PET) studies using the single-bolus protocol of the [11C]-raclopride competition paradigm have yielded conflicting results in humans. To resolve disparate previous findings, we utilized the bolus-plus-infusion (B/I) method, allowing both baseline and intervention quantification of [11C]raclopride binding during a single 105-minute PET scan, to investigate possible ethanol-induced DA release in nine healthy male subjects. A 25-minute intravenous ethanol (7.6%) infusion, resulting in a 1.3 g/L mean blood ethanol concentration, was administered using masked timing during the PET scan. Automated region-of-interest analysis testing the difference between baseline (40–50 minutes) and intervention (60–85 minutes) revealed an average 12.6% decrease in [11C]raclopride binding in the ventral striatum (VST, P=0.003) including the NAcc. In addition, a shorter time interval from the start of ethanol infusion to the first subjective effect was associated with a greater binding potential decrease bilaterally in the VST (r=0.92, P=0.004), and the feeling of pleasure was associated with a decrease in binding potential values in both the caudate nucleus (r=−0.87, P=0.003) and putamen (r=−0.74; P=0.02). These results confirm that ethanol induces rapid DA release in the limbic striatum, which can be reliably estimated using the B/I method in one imaging session. PMID:25492110

  15. Development of an LC-MS/MS method for studying migration characteristics of acetaldehyde in polyethylene terephthalate (PET)-packed mineral water.

    PubMed

    Baumjohann, Nina; Harms, Diedrich

    2015-01-01

    During storage, acetaldehyde migration from polyethylene terephthalate (PET) bottles can affect the quality of mineral water even in the low µg l(-1) range negatively, as it features a fruity or plastic-like off-flavour. For a sensitive and fast analysis of acetaldehyde in mineral water, a new analysis method of 2,4-dinitrophenylhydrazine (DNPH) derivatisation followed by HPLC-electrospray tandem mass spectrometry (ESI-MS/MS) was developed. Acetaldehyde was directly derivatised in the mineral water sample avoiding extraction and/or pre-concentration steps and then analysed by reversed-phase HPLC-ESI-MS/MS using multiple reaction monitoring mode (MRM). Along with method development, the optimum molar excess of DNPH in contrast to acetaldehyde was studied for the mineral water matrix, because no specific and robust data were yet available for this critical parameter. Best results were obtained by using a calibration via the derivatisation reaction. Without any analyte enrichment or extraction, an LOD of 0.5 µg l(-1) and an LOQ of 1.9 µg l(-1) were achieved. Using the developed method, mineral water samples packed in PET bottles from Germany were analysed and the correlation between the acetaldehyde concentration and other characteristics of the samples was evaluated illustrating the applicability of the method. Besides a relationship between bottle size and CO2 content of the mineral water and acetaldehyde migration, a correlation with acetaldehyde migration and the material composition of the bottle, e.g. recycled PET, was noted. Investigating the light influence on the acetaldehyde migration with a newly developed, reproducible light exposure setup, a significant increase of the acetaldehyde concentration in carbonated mineral water samples was observed. PMID:26258902

  16. Dynamic neurotransmitter interactions measured with PET

    SciTech Connect

    Schiffer, W.K.; Dewey, S.L.

    2001-04-02

    Positron emission tomography (PET) has become a valuable interdisciplinary tool for understanding physiological, biochemical and pharmacological functions at a molecular level in living humans, whether in a healthy or diseased state. The utility of tracing chemical activity through the body transcends the fields of cardiology, oncology, neurology and psychiatry. In this, PET techniques span radiochemistry and radiopharmaceutical development to instrumentation, image analysis, anatomy and modeling. PET has made substantial contributions in each of these fields by providing a,venue for mapping dynamic functions of healthy and unhealthy human anatomy. As diverse as the disciplines it bridges, PET has provided insight into an equally significant variety of psychiatric disorders. Using the unique quantitative ability of PET, researchers are now better able to non-invasively characterize normally occurring neurotransmitter interactions in the brain. With the knowledge that these interactions provide the fundamental basis for brain response, many investigators have recently focused their efforts on an examination of the communication between these chemicals in both healthy volunteers and individuals suffering from diseases classically defined as neurotransmitter specific in nature. In addition, PET can measure the biochemical dynamics of acute and sustained drug abuse. Thus, PET studies of neurotransmitter interactions enable investigators to describe a multitude of specific functional interactions in the human brain. This information can then be applied to understanding side effects that occur in response to acute and chronic drug therapy, and to designing new drugs that target multiple systems as opposed to single receptor types. Knowledge derived from PET studies can be applied to drug discovery, research and development (for review, see (Fowler et al., 1999) and (Burns et al., 1999)). Here, we will cover the most substantial contributions of PET to understanding

  17. A survey of attitudes toward responsible pet ownership.

    PubMed

    Selby, L A; Rhoades, J D; Hewett, J E; Irvin, J A

    1979-01-01

    The concerns of medical and community officials about responsible pet ownership have increased. Before a practical solution can be found for irresponsible ownership and community health problems associated with pet populations, the public's attitudes on issues related to responsible pet ownership must be determined. Such issues include attitudes on dog and cat overpopulation, potential public health problems associated with pet populations, and methods of controlling pet populations and stray animals. Responses to a questionnaire were used to evaluate the attitudes of 910 pet owners and nonowners toward factors comprising responsible pet ownership. The median age of the respondents was 33 years; 414 (45 percent) were men, and 496 (55 percent) were women. At the time of the study, 18 percent owned a cat and a dog, 35 percent owned only a dog, 11 percent showed only a cat, and 36 percent were nonowners. Not only the sex of the respondent but also the category of pet ownership affected opinions on overpopulation of dogs and cats, nuisance and pollution problems associated with these animals, and methods of controlling pet populations in the community. For example, owners agreed strongly on family planning for pets, but a majority of male owners stated that they would not have their dogs neutered.

  18. A survey of attitudes toward responsible pet ownership.

    PubMed Central

    Selby, L A; Rhoades, J D; Hewett, J E; Irvin, J A

    1979-01-01

    The concerns of medical and community officials about responsible pet ownership have increased. Before a practical solution can be found for irresponsible ownership and community health problems associated with pet populations, the public's attitudes on issues related to responsible pet ownership must be determined. Such issues include attitudes on dog and cat overpopulation, potential public health problems associated with pet populations, and methods of controlling pet populations and stray animals. Responses to a questionnaire were used to evaluate the attitudes of 910 pet owners and nonowners toward factors comprising responsible pet ownership. The median age of the respondents was 33 years; 414 (45 percent) were men, and 496 (55 percent) were women. At the time of the study, 18 percent owned a cat and a dog, 35 percent owned only a dog, 11 percent showed only a cat, and 36 percent were nonowners. Not only the sex of the respondent but also the category of pet ownership affected opinions on overpopulation of dogs and cats, nuisance and pollution problems associated with these animals, and methods of controlling pet populations in the community. For example, owners agreed strongly on family planning for pets, but a majority of male owners stated that they would not have their dogs neutered. PMID:572978

  19. Is non-attenuation-corrected PET inferior to body attenuation-corrected PET or PET/CT in lung cancer?

    NASA Astrophysics Data System (ADS)

    Maintas, Dimitris; Houzard, Claire; Ksyar, Rachid; Mognetti, Thomas; Maintas, Catherine; Scheiber, Christian; Itti, Roland

    2006-12-01

    It is considered that one of the great strengths of PET imaging is the ability to correct for body attenuation. This enables better lesion uptake quantification and quality of PET images. The aim of this work is to compare the sensitivity of non-attenuation-corrected (NAC) PET images, the gamma photons (GPAC) and CT attenuation-corrected (CTAC) images in detecting and staging of lung cancer. We have studied 66 patients undergoing PET/CT examinations for detecting and staging NSC lung cancer. The patients were injected with 18-FDG; 5 MBq/kg under fasting conditions and examination was started 60 min later. Transmission data were acquired by a spiral CT X-ray tube and by gamma photons emitting Cs-137l source and were used for the patient body attenuation correction without correction for respiratory motion. In 55 of 66 patients we performed both attenuation correction procedures and in 11 patients only CT attenuation correction. In seven patients with solitary nodules PET was negative and in 59 patients with lung cancer PET/CT was positive for pulmonary or other localization. In the group of 55 patients we found 165 areas of focal increased 18-FDG uptake in NAC, 165 in CTAC and 164 in GPAC PET images.In the patients with only CTAC we found 58 areas of increased 18-FDG uptake on NAC and 58 areas lesions on CTAC. In the patients with positive PET we found 223 areas of focal increased uptake in NAC and 223 areas in CTAC images. The sensitivity of NAC was equal to the sensitivity of CTAC and GPAC images. The visualization of peripheral lesions was better in NAC images and the lesions were better localized in attenuation-corrected images. In three lesions of the thorax the localization was better in GPAC and fused images than in CTAC images.

  20. Distribution of Intravenously Administered Acetylcholinesterase Inhibitor and Acetylcholinesterase Activity in the Adrenal Gland: 11C-Donepezil PET Study in the Normal Rat

    PubMed Central

    Watabe, Tadashi; Naka, Sadahiro; Ikeda, Hayato; Horitsugi, Genki; Kanai, Yasukazu; Isohashi, Kayako; Ishibashi, Mana; Kato, Hiroki; Shimosegawa, Eku; Watabe, Hiroshi; Hatazawa, Jun

    2014-01-01

    Purpose Acetylcholinesterase (AChE) inhibitors have been used for patients with Alzheimer's disease. However, its pharmacokinetics in non-target organs other than the brain has not been clarified yet. The purpose of this study was to evaluate the relationship between the whole-body distribution of intravenously administered 11C-Donepezil (DNP) and the AChE activity in the normal rat, with special focus on the adrenal glands. Methods The distribution of 11C-DNP was investigated by PET/CT in 6 normal male Wistar rats (8 weeks old, body weight  = 220±8.9 g). A 30-min dynamic scan was started simultaneously with an intravenous bolus injection of 11C-DNP (45.0±10.7 MBq). The whole-body distribution of the 11C-DNP PET was evaluated based on the Vt (total distribution volume) by Logan-plot analysis. A fluorometric assay was performed to quantify the AChE activity in homogenized tissue solutions of the major organs. Results The PET analysis using Vt showed that the adrenal glands had the 2nd highest level of 11C-DNP in the body (following the liver) (13.33±1.08 and 19.43±1.29 ml/cm3, respectively), indicating that the distribution of 11C-DNP was the highest in the adrenal glands, except for that in the excretory organs. The AChE activity was the third highest in the adrenal glands (following the small intestine and the stomach) (24.9±1.6, 83.1±3.0, and 38.5±8.1 mU/mg, respectively), indicating high activity of AChE in the adrenal glands. Conclusions We demonstrated the whole-body distribution of 11C-DNP by PET and the AChE activity in the major organs by fluorometric assay in the normal rat. High accumulation of 11C-DNP was observed in the adrenal glands, which suggested the risk of enhanced cholinergic synaptic transmission by the use of AChE inhibitors. PMID:25225806

  1. Evaluation of radiation dose and image quality of CT scan for whole-body pediatric PET/CT: A phantom study

    SciTech Connect

    Yang, Ching-Ching; Liu, Shu-Hsin; Mok, Greta S. P.; Wu, Tung-Hsin

    2014-09-15

    Purpose: This study aimed to tailor the CT imaging protocols for pediatric patients undergoing whole-body PET/CT examinations with appropriate attention to radiation exposure while maintaining adequate image quality for anatomic delineation of PET findings and attenuation correction of PET emission data. Methods: The measurements were made by using three anthropomorphic phantoms representative of 1-, 5-, and 10-year-old children with tube voltages of 80, 100, and 120 kVp, tube currents of 10, 40, 80, and 120 mA, and exposure time of 0.5 s at 1.75:1 pitch. Radiation dose estimates were derived from the dose-length product and were used to calculate risk estimates for radiation-induced cancer. The influence of image noise on image contrast and attenuation map for CT scans were evaluated based on Pearson's correlation coefficient and covariance, respectively. Multiple linear regression methods were used to investigate the effects of patient age, tube voltage, and tube current on radiation-induced cancer risk and image noise for CT scans. Results: The effective dose obtained using three anthropomorphic phantoms and 12 combinations of kVp and mA ranged from 0.09 to 4.08 mSv. Based on our results, CT scans acquired with 80 kVp/60 mA, 80 kVp/80 mA, and 100 kVp/60 mA could be performed on 1-, 5-, and 10-year-old children, respectively, to minimize cancer risk due to CT scans while maintaining the accuracy of attenuation map and CT image contrast. The effective doses of the proposed protocols for 1-, 5- and 10-year-old children were 0.65, 0.86, and 1.065 mSv, respectively. Conclusions: Low-dose pediatric CT protocols were proposed to balance the tradeoff between radiation-induced cancer risk and image quality for patients ranging in age from 1 to 10 years old undergoing whole-body PET/CT examinations.

  2. PET and SPECT imaging in veterinary medicine.

    PubMed

    LeBlanc, Amy K; Peremans, Kathelijne

    2014-01-01

    Veterinarians have gained increasing access to positron emission tomography (PET and PET/CT) imaging facilities, allowing them to use this powerful molecular imaging technique for clinical and research applications. SPECT is currently being used more in Europe than in the United States and has been shown to be useful in veterinary oncology and in the evaluation of orthopedic diseases. SPECT brain perfusion and receptor imaging is used to investigate behavioral disorders in animals that have interesting similarities to human psychiatric disorders. This article provides an overview of the potential applications of PET and SPECT. The use of commercially available and investigational PET radiopharmaceuticals in the management of veterinary disease has been discussed. To date, most of the work in this field has utilized the commercially available PET tracer, (18)F-fluorodeoxyglucose for oncologic imaging. Normal biodistribution studies in several companion animal species (cats, dogs, and birds) have been published to assist in lesion detection and interpretation for veterinary radiologists and clinicians. Studies evaluating other (18)F-labeled tracers for research applications are underway at several institutions and companion animal models of human diseases are being increasingly recognized for their value in biomarker and therapy development. Although PET and SPECT technologies are in their infancy for clinical veterinary medicine, increasing access to and interest in these applications and other molecular imaging techniques has led to a greater knowledge and collective body of expertise for veterinarians worldwide. Initiation and fostering of physician-veterinarian collaborations are key components to the forward movement of this field.

  3. Cardiac PET Perfusion: Prognosis, Risk Stratification, Clinical Management

    PubMed Central

    Dorbala, Sharmila; Di Carli, Marcelo F.

    2014-01-01

    Myocardial perfusion imaging (MPI) with positron emission tomography (PET) has expanded significantly over the past decade. With the wider availability of PET scanners and the routine use of quantitative blood flow imaging, the clinical use of PET MPI is expected to increase further. PET MPI is a powerful tool to identify risk, to quantify risk, and to guide therapy in patients with known or suspected coronary artery disease (CAD). A large body of evidence supports the prognostic value of PET MPI and ejection fraction in intermediate to high risk subjects, in women, in obese individuals and in post coronary artery bypass grafting (CABG) individuals. A normal perfusion study indicates low risk (< 1% annualized rate of cardiac events of cardiac death and non-fatal myocardial infarction), while an abnormal study indicates high risk. With accurate risk stratification, high quality images, and quantitation PET MPI may transform the management of patients with known or suspected CAD. PMID:25234079

  4. Does Pet Arrival Trigger Prosocial Behaviors in Individuals with Autism?

    PubMed Central

    Grandgeorge, Marine; Tordjman, Sylvie; Lazartigues, Alain; Lemonnier, Eric; Deleau, Michel; Hausberger, Martine

    2012-01-01

    Alteration of social interactions especially prosocial behaviors – an important aspect of development – is one of the characteristics of autistic disorders. Numerous strategies or therapies are used to improve communication skills or at least to reduce social impairments. Animal-assisted therapies are used widely but their relevant benefits have never been scientifically evaluated. In the present study, we evaluated the association between the presence or the arrival of pets in families with an individual with autism and the changes in his or her prosocial behaviors. Of 260 individuals with autism - on the basis of presence or absence of pets - two groups of 12 individuals and two groups of 8 individuals were assigned to: study 1 (pet arrival after age of 5 versus no pet) and study 2 (pet versus no pet), respectively. Evaluation of social impairment was assessed at two time periods using the 36-items ADI-R algorithm and a parental questionnaire about their child-pet relationships. The results showed that 2 of the 36 items changed positively between the age of 4 to 5 (t0) and time of assessment (t1) in the pet arrival group (study 1): “offering to share” and “offering comfort”. Interestingly, these two items reflect prosocial behaviors. There seemed to be no significant changes in any item for the three other groups. The interactions between individuals with autism and their pets were more – qualitatively and quantitatively - reported in the situation of pet arrival than pet presence since birth. These findings open further lines of research on the impact of pet’s presence or arrival in families with an individual with autism. Given the potential ability of individuals with autism to develop prosocial behaviors, related studies are needed to better understand the mechanisms involved in the development of such child-pet relationship. PMID:22870246

  5. A study on the effects of an extended CT field of view (FOV) on the standardized uptake value (SUV) in a PET/CT scan using 18F-fluoro-2deoxy-D-glucose

    NASA Astrophysics Data System (ADS)

    Park, Soon-Ki; Nam, Ki-Pyo; Jung, Woo-Young; Kim, Kyeong-Sik; Shin, Sang-Ki; Cho, Shee-Man; Kim, Ho-Sung; Dong, Kyung-Rae; Park, Yong-Soon; Chung, Woon-Kwan; Cho, Jae-Hwan; Yeo, Hwa-Yeon

    2012-12-01

    This study examined the effect of an extended CT field of view (FOV) on the standardized uptake value (SUV) of positron emission tomography — computed tomography (PET/CT) when the image extended beyond the CT FOV. CT images were reconstructed at different FOV sizes (500 mm and 700 mm). Two sets of CT images were reconstructed from the CT projection data by using the two FOV sizes. Twenty patients were examined in this study. The PET images were reconstructed from attenuation maps with a 500 mm CT FOV and a 700 mm extended CT FOV images. The regions of interest (ROIs) were drawn on the PET images. In addition, in the twenty patients, the PET images reconstructed by using a 500-mm CT FOV and 700-mm extended CT FOV were compared with the standardized uptake value (SUVmax). When attenuation maps with the 700-mm extended CT FOV were used, the SUVmax analyses of the liver (p = 0.000), lung (p = 0.007) and mediastinum (p = 0.001) produced statistically significant result. A 700 mm extended CT FOV help recover the true activity distribution in the PET emission data and affected the SUV measurements of the liver, lung and mediastinum.

  6. Overview of the Results of the Organics PET Study of the Cometary Samples from Comet Wild 2 by the Stardust Mission

    NASA Technical Reports Server (NTRS)

    Sandford, S. A.; Aleon, J.; Alexander, C. M. O'D.; Araki, T.; Bajt, S.; Baratta, G. A.; Borg, J.; Bradley J. P.; Brownlee, D. E.; Brucato, J. R.; Burchell, M. J.; Busemann, H.; Butterworth, A.; Clemett, S. J.; Cody, G.; Colangeli, L.; Cooper, G.

    2007-01-01

    STARDUST is the first mission designed to bring samples back to Earth from a known comet. The captured samples were successfully returned to Earth on 15 Jan 2006, after which they were subjected to a preliminary examination by a number of teams of scientists from around the world. This abstract describes the efforts of the Organics Preliminary Examination Team (PET). More detailed discussions of specific analyses of the samples can be found in other papers presented at this meeting by individual members of the Organics PET (see the author list above for team members). The studied Wild 2 gas and dust samples were collected by impact onto aerogel tiles and Al foils when the spacecraft flew through the coma of 81P/Wild 2 on 2 Jan 2004 at a relative velocity of approx.6.1 kilometers per second. After recovery of the Sample Return Capsule (SRC) on 15 Jan 2006, the aerogel collector trays were removed in a clean room at JSC. After documentation of the collection, selected aerogel tiles and aluminum foils were removed and aerogel and cometary samples extracted for study.

  7. Severity of negative symptoms in schizophrenia correlated to hyperactivity of the left globus pallidus and the right claustrum. A PET study.

    PubMed

    Galeno, Roxana; Molina, Mario; Guirao, Manuel; Isoardi, Roberto

    2004-01-01

    Schizophrenia has been characterized as a complex disease, in which various cerebral regions may be affected. The purpose of this study was to compare the cerebral regions that are involved in mild and severe negative symptoms, and to determine whether the degree of severity can be related to specific dysfunctional areas of the brain. The PANS Scale was used to form two groups of patients with prevalence of negative symptoms: Mildly Affected (MA), and Severely Affected (SA). Brain PETs were obtained in resting conditions, and SPM (Statistical Parametric Mapping) was used to perform statistical comparisons. The MA-group showed increased activity in: posterior cingulate gyrus, middle frontal gyrus, precentral gyrus, middle occipital gyrus, cuneus and post-central gyrus; decreased activity in inferior frontal gyrus, orbitofrontal and fusiform gyrus. The SA-group showed increased activity in: globus pallidus, insular cortex, cuneus, claustrum, post-central gyrus and pre-central gyrus; decreased activity in fusiform gyrus and superior temporal gyri. These results permit correlation of negative symptomatology with abnormalities in the cortico-striato-pallido-thalamic neural circuit. Severity of negative symptoms is clearly correlated to abnormal left external pallidal activation, evidencing the relevance of this nucleus for cognitive, planning and social capabilities. Specific therapeutic strategies might be derived from pallidal neurotransmitter systems studies. Key words: schizophrenia, negative symptoms, severity, PET, globus pallidus, claustrum.

  8. Healthy Pets and People

    MedlinePlus

    ... Pregnant women should avoid adopting or handling stray cats, especially kittens. They particularly should not clean litter ... may be sick. Many pets, such as dogs, cats, reptiles, rodents, and birds, carry germs that can ...

  9. Pets and Parasites

    MedlinePlus

    ... make me sick? Household pets such as dogs, cats, birds and reptiles can carry diseases or parasites ... might be used as litter boxes by neighborhood cats. Keep your children out of the dirt in ...

  10. Heart PET scan

    MedlinePlus

    ... large tunnel-shaped scanner. Electrodes for an electrocardiogram ( ECG ) will be placed on your chest. The PET ... often used when other tests, such as echocardiogram (ECG) and cardiac stress tests do not provide enough ...

  11. Household Hazards to Pets

    MedlinePlus

    ... health by becoming aware of the most common health hazards found in many pet-owning households. Hazards in the Kitchen Foods Many foods are perfectly safe for humans, but could be harmful or potentially deadly to ...

  12. Brain PET scan

    MedlinePlus

    ... tests, such as magnetic resonance imaging ( MRI ) and computed tomography ( CT ) scans only reveal the structure of the ... a PET/CT. Alternative Names ... PT, Rijntjes M, Weiller C. Neuroimaging: Functional neuroimaging. In: Daroff RB, Fenichel GM, Jankovic ...

  13. Attenuation correction for small animal PET tomographs

    NASA Astrophysics Data System (ADS)

    Chow, Patrick L.; Rannou, Fernando R.; Chatziioannou, Arion F.

    2005-04-01

    Attenuation correction is one of the important corrections required for quantitative positron emission tomography (PET). This work will compare the quantitative accuracy of attenuation correction using a simple global scale factor with traditional transmission-based methods acquired either with a small animal PET or a small animal x-ray computed tomography (CT) scanner. Two phantoms (one mouse-sized and one rat-sized) and two animal subjects (one mouse and one rat) were scanned in CTI Concorde Microsystem's microPET® Focus™ for emission and transmission data and in ImTek's MicroCAT™ II for transmission data. PET emission image values were calibrated against a scintillation well counter. Results indicate that the scale factor method of attenuation correction places the average measured activity concentration about the expected value, without correcting for the cupping artefact from attenuation. Noise analysis in the phantom studies with the PET-based method shows that noise in the transmission data increases the noise in the corrected emission data. The CT-based method was accurate and delivered low-noise images suitable for both PET data correction and PET tracer localization.

  14. Evaluation of a BGO-Based PET System for Single-Cell Tracking Performance by Simulation and Phantom Studies.

    PubMed

    Ouyang, Yu; Kim, Tae Jin; Pratx, Guillem

    2016-01-01

    A recent method based on positron emission was reported for tracking moving point sources using the Inveon PET system. However, the effect of scanner background noise was not further explored. Here, we evaluate tracking with the Genisys4, a bismuth germanate-based PET system, which has no significant intrinsic background and may be better suited to tracking lower and/or faster activity sources. Position-dependent sensitivity of the Genisys4 was simulated in Geant4 Application for Tomographic Emission (GATE) using a static (18)F point source. Trajectories of helically moving point sources with varying activity and rotation speed were reconstructed from list-mode data as described previously. Simulations showed that the Inveon's ability to track sources within 2 mm of localization error is limited to objects with a velocity-to-activity ratio < 0.13 mm/decay, compared to < 0.29 mm/decay for the Genisys4. Tracking with the Genisys4 was then validated using a physical phantom of helically moving [(18)F] fluorodeoxyglucose-in-oil droplets (< 0.24 mm diameter, 139-296 Bq), yielding < 1 mm localization error under the tested conditions, with good agreement between simulated sensitivity and measured activity (Pearson correlation R = .64, P < .05 in a representative example). We have investigated the tracking performance with the Genisys4, and results suggest the feasibility of tracking low activity, point source-like objects with this system. PMID:27175009

  15. Positron follow-up in liquid water: II. Spatial and energetic study for the most important radioisotopes used in PET.

    PubMed

    Champion, C; Le Loirec, C

    2007-11-21

    With the increasing development of positron emission tomography (PET), beta(+)-emitters are more and more regularly used in nuclear medicine. Therefore, today it is of prime importance to have a reliable description of their behavior in living matter in order to quantify the full spectra of the molecular damages potentially radio-induced and then to access a cellular dosimetry. In this work, we present a detailed inter-comparison of the main isotopes commonly used in PET: (18)F, (11)C, (13)N, (15)O, (68)Ga and (82)Rb. We have used an event-by-event Monte Carlo code recently developed for positron tracking in water (Champion and Le Loirec 2006 Phys. Med. Biol. 51 1707-23) which consists in simulating step-by-step, interaction after interaction, the history of each ionizing particle created during the irradiation of the biological matter. This simulation has been finally adapted for describing the decays of medically important positron emitters. Quantitative information about positron penetrations, Positronium formation, annihilation event distributions, energy deposit patterns and dose profiles is then accessible and compared to published measurements and/or calculations.

  16. HIGHER IN VIVO SEROTONIN-1A BINDING IN POSTTRAUMATIC STRESS DISORDER: A PET STUDY WITH [11C]WAY-100635

    PubMed Central

    Sullivan, Gregory M.; Ogden, R. Todd; Huang, Yung-yu; Oquendo, Maria A.; Mann, J. John; Parsey, Ramin V.

    2013-01-01

    Background Brain serotonin-1A receptors (5-HT1A) are implicated in anxiety. We compared regional brain 5-HT1A binding in medication-free participants with posttraumatic stress disorder (PTSD) and healthy volunteers using fully quantitative positron emission tomography (PET) methods. Methods Twenty patients with DSM-IV PTSD (13 with comorbid major depressive disorder, [MDD]) and 49 healthy volunteers underwent PET imaging with 5-HT1A antagonist radioligand [C-11]WAY100635. Arterial blood sampling provided a metabolite-corrected input function and the concentration of free ligand in plasma (fP) for estimation of regional binding potential, BPF ( = Bavailable /KD). Linear mixed modeling compared BPF between groups across regions of interest (ROIs). Results The PTSD group had higher 5-HT1A BPF across brain ROIs (P = .0006). Post hoc comparisons showed higher 5-HT1A BPF in PTSD in all cortical ROIs (26–33%), amygdala (34%), and brainstem raphe nuclei (43%), but not hippocampus. The subgroup of seven PTSD patients without comorbid MDD had higher 5-HT1A BPF compared with healthy volunteers (P = .03). Conclusions This is the first report of higher brainstem and forebrain 5-HT1A binding in vivo in PTSD. The finding is independent of MDD. PTSD and MDD have in common an upregulation of 5-HT1A binding including midbrain autoreceptors that would favor less firing and serotonin release. This abnormality may represent a common biomarker of these stress-associated brain disorders. PMID:23408467

  17. PET/CT artifacts.

    PubMed

    Blodgett, Todd M; Mehta, Ajeet S; Mehta, Amar S; Laymon, Charles M; Carney, Jonathan; Townsend, David W

    2011-01-01

    There are several artifacts encountered in positron emission tomography/computed tomographic (PET/CT) imaging, including attenuation correction (AC) artifacts associated with using CT for AC. Several artifacts can mimic a 2-deoxy-2-[18F] fluoro-d-glucose (FDG) avid malignant lesions and therefore recognition of these artifacts is clinically relevant. Our goal was to identify and characterize these artifacts and also discuss some protocol variables that may affect image quality in PET/CT.

  18. Microfluidics for synthesis of peptide-based PET tracers.

    PubMed

    Liu, Yang; Tian, Mei; Zhang, Hong

    2013-01-01

    Positron emission tomography (PET) is a powerful noninvasive tool for acquisition of the physiological parameters in human and animals with the help of PET tracers. Among all the PET tracers, radiolabeled peptides have been widely explored for cancer-related receptor imaging due to their high affinity and specificity to receptors. But radiochemistry procedures for production of peptide-based PET tracers are usually complex, which makes large-scale clinical studies relatively challenging. New radiolabeling technologies which could simplify synthesis and purification procedures, are extremely needed. Over the last decade, microfluidics and lab-on-a-chip (LOC) technology have boomed as powerful tools in the field of organic chemistry, which potentially provide significant help to the PET chemistry. In this minireview, microfluidic radiolabeling technology is described and its application for synthesis of peptide-based PET tracers is summarized and discussed.

  19. The preclinical study of predicting radiosensitivity in human nasopharyngeal carcinoma xenografts by 18F-ML-10 animal- PET/CT imaging

    PubMed Central

    Wang, Siyang; Zheng, Yujia; Wang, Mingwei; Gu, Bingxin; Zhang, Jianping; Zhang, Yongping; Zhang, Yingjian

    2016-01-01

    Previous studies have reported that the radiosensitivity is associated with apoptosis. Hereby, we aimed to investigate the value of 18F-ML-10 PET/CT, which selectively targeted cells undergoing apoptosis, in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts. We used CNE1 (highly differentiated) and CNE2 (poorly differentiated) NPC cell lines to construct tumor models, which had very different radiosensitivities. After irradiation, the volumes of CNE2 tumors decreased significantly while those of CNE1 tumors increased. In 18F-ML-10 imaging, the values of tumor/muscle (T/M) between CNE1 and CNE2 mice were statistically different at both 24 h and 48 h after irradiation. Besides, ΔT/M1-0 and ΔT/M2-0 of CNE2 mice were higher than those of CNE1 mice, demonstrating obvious discrepancy. Furthermore, we observed obvious changes of radioactive distribution in CNE2 group. On the contrary, T/M of 18F-FDG in irradiation group revealed no obvious change in both CNE1 and CNE2 groups. In conclusion, 18F-ML-10 animal PET/CT showed its potential to predict radiosensitivity in NPC. PMID:26942701

  20. Unique Distribution of Aromatase in the Human Brain: In Vivo Studies With PET and [N-Methyl-11C]Vorozole

    SciTech Connect

    Biegon, A.; Biegon, A.; Kim, S.W.; Alexoff, D.; Millard, J.; Carter, P.; Hubbard, B.; King, P.; Logan, J.; Muench, L.; Pareto, D.; Schlyer, D.; Shea, C.; Telang, F.; Wang, G.-J.; Xu, Y.; Fowler, J.

    2010-10-01

    Aromatase catalyzes the last step in estrogen biosynthesis. Brain aromatase is involved in diverse neurophysiological and behavioral functions including sexual behavior, aggression, cognition, and neuroprotection. Using positron emission tomography (PET) with the radiolabeled aromatase inhibitor [N-methyl-{sup 11}C]vorozole, we characterized the tracer distribution and kinetics in the living human brain. Six young, healthy subjects, three men and three women, were administered the radiotracer alone on two separate occasions. Women were scanned in distinct phases of the menstrual cycle. Specificity was confirmed by pretreatment with a pharmacological (2.5 mg) dose of the aromatase inhibitor letrozole. PET data were acquired over a 90-min period and regions of interest placed over selected brain regions. Brain and plasma time activity curves, corrected for metabolites, were used to derive kinetic parameters. Distribution volume (V{sub T}) values in both men and women followed the following rank order: thalamus > amygdala = preoptic area > medulla (inferior olive) > accumbens, pons, occipital and temporal cortex, putamen, cerebellum, and white matter. Pretreatment with letrozole reduced VT in all regions, though the size of the reduction was region-dependent, ranging from {approx}70% blocking in thalamus andpreoptic area to {approx}10% in cerebellum. The high levels of aromatase in thalamus and medulla (inferior olive) appear to be unique to humans. These studies set the stage for the noninvasive assessment of aromatase involvement in various physiological and pathological processes affecting the human brain.

  1. Cryptosporidiosis outbreak in visitors of a UK industry-compliant petting farm caused by a rare Cryptosporidium parvum subtype: a case-control study.

    PubMed

    Utsi, L; Smith, S J; Chalmers, R M; Padfield, S

    2016-04-01

    A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51-19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01-0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections. PMID:26424385

  2. Evaluation of the ECAT EXACT HR{sup +} 3D PET scanner in {sup 15}O-water brain activation studies

    SciTech Connect

    Moreno-Cantu, J.J.; Thompson, C.J.; Zatorre, R.J.

    1996-12-31

    We evaluated the performance of the ECAT EXACT HR{sup +} 3D whole body PET scanner when employed to measure brain function using {sup 15}O-water-bolus activation protocols in single data acquisition sessions. Using vibrotactile and auditory stimuli as independent activation tasks, we studied the scanner`s performance under different imaging conditions in four healthy volunteers. Cerebral blood flow images were acquired from each volunteer using {sup 15}O-water-bolus injections of activity varying from 5 to 20mCi. Performance characteristics. The scanner`s dead time grew linearly with injected dose from 10% to 25%. Random events varied from 30% to 50% of the detected events. Scattered events were efficiently corrected at all doses. Noise-effective-count curves plateau at about 15mCi. One-session 12-injection bolus PET activation protocol. Using an acquisition protocol that accounts for the scanner`s performance and the practical aspects of imaging volunteers and patients in one session, we assessed the correlation between the statistical significance of activation foci and the dose per injection used The one-session protocol employs 12 bolus injections per subject. We present evidence suggesting that 15-20mCi is the optimal dose per injection to be used routinely in one-time scanning sessions.

  3. Cryptosporidiosis outbreak in visitors of a UK industry-compliant petting farm caused by a rare Cryptosporidium parvum subtype: a case-control study.

    PubMed

    Utsi, L; Smith, S J; Chalmers, R M; Padfield, S

    2016-04-01

    A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51-19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01-0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections.

  4. Unique distribution of aromatase in the human brain: in vivo studies with PET and [N-methyl-11C]vorozole.

    PubMed

    Biegon, Anat; Kim, Sung Won; Alexoff, David L; Jayne, Millard; Carter, Pauline; Hubbard, Barbara; King, Payton; Logan, Jean; Muench, Lisa; Pareto, Deborah; Schlyer, David; Shea, Colleen; Telang, Frank; Wang, Gene-Jack; Xu, Youwen; Fowler, Joanna S

    2010-11-01

    Aromatase catalyzes the last step in estrogen biosynthesis. Brain aromatase is involved in diverse neurophysiological and behavioral functions including sexual behavior, aggression, cognition, and neuroprotection. Using positron emission tomography (PET) with the radiolabeled aromatase inhibitor [N-methyl-(11)C]vorozole, we characterized the tracer distribution and kinetics in the living human brain. Six young, healthy subjects, three men and three women, were administered the radiotracer alone on two separate occasions. Women were scanned in distinct phases of the menstrual cycle. Specificity was confirmed by pretreatment with a pharmacological (2.5 mg) dose of the aromatase inhibitor letrozole. PET data were acquired over a 90-min period and regions of interest placed over selected brain regions. Brain and plasma time activity curves, corrected for metabolites, were used to derive kinetic parameters. Distribution volume (V(T)) values in both men and women followed the following rank order: thalamus > amygdala = preoptic area > medulla (inferior olive) > accumbens, pons, occipital and temporal cortex, putamen, cerebellum, and white matter. Pretreatment with letrozole reduced V(T) in all regions, though the size of the reduction was region-dependent, ranging from ∼70% blocking in thalamus andpreoptic area to ∼10% in cerebellum. The high levels of aromatase in thalamus and medulla (inferior olive) appear to be unique to humans. These studies set the stage for the noninvasive assessment of aromatase involvement in various physiological and pathological processes affecting the human brain.

  5. Unique distribution of aromatase in the human brain: in vivo studies with PET and [N-methyl-11C]vorozole

    PubMed Central

    Biegon, Anat; Kim, Sung Won; Alexoff, David L.; Jayne, Millard; Carter, Pauline; Hubbard, Barbara; King, Payton; Logan, Jean; Muench, Lisa; Pareto, Deborah; Schlyer, David; Shea, Colleen; Telang, Frank; Wang, Gene-Jack; Xu, Youwen; Fowler, Joanna S.

    2010-01-01

    Aromatase catalyzes the last step in estrogen biosynthesis. Brain aromatase is involved in diverse neurophysiological and behavioral functions including sexual behavior, aggression, cognition and neuroprotection. Using positron emission tomography (PET) with the radiolabeled aromatase inhibitor [N-methyl-11C]vorozole, we characterized the tracer distribution and kinetics in the living human brain. Six young, healthy subjects, 3 men and 3 women, were administered the radiotracer alone on two separate occasions. Women were scanned in distinct phases of the menstrual cycle. Specificity was confirmed by pretreatment with a pharmacological (2.5mg) dose of the aromatase inhibitor letrozole. PET data were acquired over a 90 min period and regions of interest placed over selected brain regions. Brain and plasma time activity curves, corrected for metabolites, were used to derive kinetic parameters. Distribution volume (VT) values in both men and women followed the rank order: thalamus>amygdala=preoptic area>medulla(inferior olive) > accumbens, pons, occipital and temporal cortex, putamen, cerebellum and white matter. Pretreatment with letrozole reduced VT in all regions, though the size of the reduction was region dependent; ranging from ~70% blocking in thalamus and preoptic area to ~10% in cerebellum. The high levels of aromatase in thalamus and medulla (inferior olive) appear to be unique to humans. These studies set the stage for the non-invasive assessment of aromatase involvement in various physiological and pathological processes affecting the human brain. PMID:20842717

  6. Brown Adipose Reporting Criteria in Imaging STudies (BARCIST 1.0): Recommendations for Standardized FDG-PET/CT Experiments in Humans.

    PubMed

    Chen, Kong Y; Cypess, Aaron M; Laughlin, Maren R; Haft, Carol R; Hu, Houchun Harry; Bredella, Miriam A; Enerbäck, Sven; Kinahan, Paul E; Lichtenbelt, Wouter van Marken; Lin, Frank I; Sunderland, John J; Virtanen, Kirsi A; Wahl, Richard L

    2016-08-01

    Human brown adipose tissue (BAT) presence, metabolic activity, and estimated mass are typically measured by imaging [18F]fluorodeoxyglucose (FDG) uptake in response to cold exposure in regions of the body expected to contain BAT, using positron emission tomography combined with X-ray computed tomography (FDG-PET/CT). Efforts to describe the epidemiology and biology of human BAT are hampered by diverse experimental practices, making it difficult to directly compare results among laboratories. An expert panel was assembled by the National Institute of Diabetes and Digestive and Kidney Diseases on November 4, 2014 to discuss minimal requirements for conducting FDG-PET/CT experiments of human BAT, data analysis, and publication of results. This resulted in Brown Adipose Reporting Criteria in Imaging STudies (BARCIST 1.0). Since there are no fully validated best practices at this time, panel recommendations are meant to enhance comparability across experiments, but not to constrain experimental design or the questions that can be asked. PMID:27508870

  7. Pilot PET Study to Assess the Functional Interplay Between ABCB1 and ABCG2 at the Human Blood–Brain Barrier

    PubMed Central

    Bauer, M; Römermann, K; Karch, R; Wulkersdorfer, B; Stanek, J; Philippe, C; Maier‐Salamon, A; Haslacher, H; Jungbauer, C; Wadsak, W; Jäger, W; Löscher, W; Hacker, M; Zeitlinger, M

    2016-01-01

    ABCB1 and ABCG2 work together at the blood–brain barrier (BBB) to limit brain distribution of dual ABCB1/ABCG2 substrates. In this pilot study we used positron emission tomography (PET) to assess brain distribution of two model ABCB1/ABCG2 substrates ([11C]elacridar and [11C]tariquidar) in healthy subjects without (c.421CC) or with (c.421CA) the ABCG2 single‐nucleotide polymorphism (SNP) c.421C>A. Subjects underwent PET scans under conditions when ABCB1 and ABCG2 were functional and during ABCB1 inhibition with high‐dose tariquidar. In contrast to the ABCB1‐selective substrate (R)‐[11C]verapamil, [11C]elacridar and [11C]tariquidar showed only moderate increases in brain distribution during ABCB1 inhibition. This provides evidence for a functional interplay between ABCB1 and ABCG2 at the human BBB and suggests that both ABCB1 and ABCG2 need to be inhibited to achieve substantial increases in brain distribution of dual ABCB1/ABCG2 substrates. During ABCB1 inhibition c.421CA subjects had significantly higher increases in [11C]tariquidar brain distribution than c.421CC subjects, pointing to impaired cerebral ABCG2 function. PMID:26940368

  8. Proceedings of the cardiac PET summit meeting 12 may 2014: Cardiac PET and SPECT instrumentation.

    PubMed

    Garcia, Ernest V

    2015-06-01

    Advances in PET and SPECT and imaging hardware and software are vastly improving the noninvasive evaluation of myocardial perfusion and function. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, and precise attenuation correction (AC). These developments have also resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional PET or SPECT studies. Hybrid PET/CT cameras utilize transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium and myocardial anatomy but at a higher cost than PET scanners that use (68)Ge radioactive line sources. As cardiac PET systems continue to improve, dedicated cardiac SPECT systems are also undergoing a profound change in their design. The scintillation camera general purpose design is being replaced with systems with multiple detectors focused on the heart yielding 5 to 10 times the sensitivity of conventional SPECT. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. This article reviews these concepts and compares the attributes of PET and SPECT instrumentation. PMID:25824018

  9. Proceedings of the cardiac PET summit meeting 12 may 2014: Cardiac PET and SPECT instrumentation.

    PubMed

    Garcia, Ernest V

    2015-06-01

    Advances in PET and SPECT and imaging hardware and software are vastly improving the noninvasive evaluation of myocardial perfusion and function. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, and precise attenuation correction (AC). These developments have also resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional PET or SPECT studies. Hybrid PET/CT cameras utilize transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium and myocardial anatomy but at a higher cost than PET scanners that use (68)Ge radioactive line sources. As cardiac PET systems continue to improve, dedicated cardiac SPECT systems are also undergoing a profound change in their design. The scintillation camera general purpose design is being replaced with systems with multiple detectors focused on the heart yielding 5 to 10 times the sensitivity of conventional SPECT. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. This article reviews these concepts and compares the attributes of PET and SPECT instrumentation.

  10. Friends with benefits: on the positive consequences of pet ownership.

    PubMed

    McConnell, Allen R; Brown, Christina M; Shoda, Tonya M; Stayton, Laura E; Martin, Colleen E

    2011-12-01

    Social support is critical for psychological and physical well-being, reflecting the centrality of belongingness in our lives. Human interactions often provide people with considerable social support, but can pets also fulfill one's social needs? Although there is correlational evidence that pets may help individuals facing significant life stressors, little is known about the well-being benefits of pets for everyday people. Study 1 found in a community sample that pet owners fared better on several well-being (e.g., greater self-esteem, more exercise) and individual-difference (e.g., greater conscientiousness, less fearful attachment) measures. Study 2 assessed a different community sample and found that owners enjoyed better well-being when their pets fulfilled social needs better, and the support that pets provided complemented rather than competed with human sources. Finally, Study 3 brought pet owners into the laboratory and experimentally demonstrated the ability of pets to stave off negativity caused by social rejection. In summary, pets can serve as important sources of social support, providing many positive psychological and physical benefits for their owners. PMID:21728449

  11. Friends with benefits: on the positive consequences of pet ownership.

    PubMed

    McConnell, Allen R; Brown, Christina M; Shoda, Tonya M; Stayton, Laura E; Martin, Colleen E

    2011-12-01

    Social support is critical for psychological and physical well-being, reflecting the centrality of belongingness in our lives. Human interactions often provide people with considerable social support, but can pets also fulfill one's social needs? Although there is correlational evidence that pets may help individuals facing significant life stressors, little is known about the well-being benefits of pets for everyday people. Study 1 found in a community sample that pet owners fared better on several well-being (e.g., greater self-esteem, more exercise) and individual-difference (e.g., greater conscientiousness, less fearful attachment) measures. Study 2 assessed a different community sample and found that owners enjoyed better well-being when their pets fulfilled social needs better, and the support that pets provided complemented rather than competed with human sources. Finally, Study 3 brought pet owners into the laboratory and experimentally demonstrated the ability of pets to stave off negativity caused by social rejection. In summary, pets can serve as important sources of social support, providing many positive psychological and physical benefits for their owners.

  12. Critters in the cube farm: perceived psychological and organizational effects of pets in the workplace.

    PubMed

    Wells, M; Perrine, R

    2001-01-01

    This article reports the findings of an exploratory study examining the perceived functions and psychological and organizational effects of pets in the workplace. Participants were 193 employees from 31 companies allowing pets in the workplace who completed anonymous questionnaires. Results indicated that participants perceived pets in the workplace to reduce stress and to positively affect employee health and the organization. Participants who brought their pets to work perceived greater benefits than participants who did not bring their pets to work and participants who did not own pets. PMID:11199259

  13. Novel system using microliter order sample volume for measuring arterial radioactivity concentrations in whole blood and plasma for mouse PET dynamic study.

    PubMed

    Kimura, Yuichi; Seki, Chie; Hashizume, Nobuya; Yamada, Takashi; Wakizaka, Hidekatsu; Nishimoto, Takahiro; Hatano, Kentaro; Kitamura, Keishi; Toyama, Hiroshi; Kanno, Iwao

    2013-11-21

    This study aimed to develop a new system, named CD-Well, for mouse PET dynamic study. CD-Well allows the determination of time-activity curves (TACs) for arterial whole blood and plasma using 2-3 µL of blood per sample; the minute sample size is ideal for studies in small animals. The system has the following merits: (1) measures volume and radioactivity of whole blood and plasma separately; (2) allows measurements at 10 s intervals to capture initial rapid changes in the TAC; and (3) is compact and easy to handle, minimizes blood loss from sampling, and delay and dispersion of the TAC. CD-Well has 36 U-shaped channels. A drop of blood is sampled into the opening of the channel and stored there. After serial sampling is completed, CD-Well is centrifuged and scanned using a flatbed scanner to define the regions of plasma and blood cells. The length measured is converted to volume because the channels have a precise and uniform cross section. Then, CD-Well is exposed to an imaging plate to measure radioactivity. Finally, radioactivity concentrations are computed. We evaluated the performance of CD-Well in in vitro measurement and in vivo (18)F-fluorodeoxyglucose and [(11)C]2-carbomethoxy-3β-(4-fluorophenyl) tropane studies. In in vitro evaluation, per cent differences (mean±SE) from manual measurement were 4.4±3.6% for whole blood and 4.0±3.5% for plasma across the typical range of radioactivity measured in mouse dynamic study. In in vivo studies, reasonable TACs were obtained. The peaks were captured well, and the time courses coincided well with the TAC derived from PET imaging of the heart chamber. The total blood loss was less than 200 µL, which had no physiological effect on the mice. CD-Well demonstrates satisfactory performance, and is useful for mouse PET dynamic study.

  14. Study of the production yields of 18F, 11C, 13N and 15O positron emitters from plasma-laser proton sources at ELI-Beamlines for labeling of PET radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Margarone, Daniele; Pagano, Benedetta; Baldari, Sergio; Korn, Georg

    2016-03-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of microfluidics labeling approaches. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources such that expected at the ELI-Beamlines facility. 18F, 11C, 13N and 15O production yields were calculated through the TALYS software, by taking into account the broad proton spectra expected. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of 18F-, 11C- and 13N-labeled radiopharmaceuticals exploiting fast and efficient microfluidic labeling systems.

  15. Demography of the pet dog and cat population on the island of Ireland and human factors influencing pet ownership.

    PubMed

    Downes, Martin; Canty, Mary J; More, Simon J

    2009-11-01

    Published data on aspects of domestic pet demographics are available in many countries. Several of these studies have linked household demographics, such as the presence of children in the household, to pet ownership. There is very little published information about the demography of domestic pets on the island of Ireland (the Republic of Ireland, Northern Ireland). This study was conducted to describe the demography of the pet dog and cat populations on the island of Ireland and to identify human factors influencing pet ownership. A questionnaire was designed and administered to households to collect data about the demographics of households and their dogs and cats. The questions related to location, building structure, social class, nationality and family structure of the household, and the sex, age and source of each pet dog and/or cat. The survey was administered by a commercial company, using computer-assisted telephone interview techniques to 1250 households selected using random digit dialling and quota controls. In this study, a pet dog was defined as a dog that was been fed by a household and considered a pet by the participant of the study. A pet cat was defined as a cat that was both fed by the household and allowed into the house. The results show that 35.6% of households in Ireland have one or more pet dogs and 10.4% of households have one or more pet cats. In total, 47.3% of pet dogs and 76.1% of pet cats were neutered. Females of both species are more likely to be neutered than males. Factors associated with dog ownership included location, house type, household social class, household composition, the presence of school children in the house, and the presence of a cat in the house. Factors associated with pet cat ownership included the type of house structure, the presence of a dog in the house and the gender and age of the participant. Cats tend to stray into households. This study was the first to provide detailed information about the

  16. [Microeconomics of introduction of a PET system based on the revised Japanese National Insurance reimbursement system].

    PubMed

    Abe, Katsumi; Kosuda, Shigeru; Kusano, Shoichi; Nagata, Masayoshi

    2003-11-01

    It is crucial to evaluate an annual balance before-hand when an institution installs a PET system because the revised Japanese national insurance reimbursement system set the cost of a FDG PET study as 75,000 yen. A break-even point was calculated in an 8-hour or a 24-hour operation of a PET system, based on the total costs reported. The break-even points were as follows: 13.4, 17.7, 22.1 studies per day for the 1 cyclotron-1 PET camera, 1 cyclotron-2 PET cameras, 1 cyclotron-3 PET cameras system, respectively, in an ordinary PET system operation of 8 hours. The break-even points were 19.9, 25.5, 31.2 studies per day for the 1 cyclotron-1 PET camera, 1 cyclotron-2 PET cameras, 1 cyclotron-3 PET cameras system, respectively, in a full PET system operation of 24 hours. The results indicate no profit would accrue in an ordinary PET system operation of 8 hours. The annual profit and break-even point for the total cost including the initial investment would be respectively 530 million yen and 2.8 years in a 24-hour operation with 1 cyclotron-3 PET cameras system. PMID:14733110

  17. Tauopathy PET and amyloid PET in the diagnosis of chronic traumatic encephalopathies: studies of a retired NFL player and of a man with FTD and a severe head injury.

    PubMed

    Mitsis, E M; Riggio, S; Kostakoglu, L; Dickstein, D L; Machac, J; Delman, B; Goldstein, M; Jennings, D; D'Antonio, E; Martin, J; Naidich, T P; Aloysi, A; Fernandez, C; Seibyl, J; DeKosky, S T; Elder, G A; Marek, K; Gordon, W; Hof, P R; Sano, M; Gandy, S

    2014-09-16

    Single, severe traumatic brain injury (TBI) which elevates CNS amyloid, increases the risk of Alzheimer's disease (AD); while repetitive concussive and subconcussive events as observed in athletes and military personnel, may increase the risk of chronic traumatic encephalopathy (CTE). We describe two clinical cases, one with a history of multiple concussions during a career in the National Football League (NFL) and the second with frontotemporal dementia and a single, severe TBI. Both patients presented with cognitive decline and underwent [(18)F]-Florbetapir positron emission tomography (PET) imaging for amyloid plaques; the retired NFL player also underwent [(18)F]-T807 PET imaging, a new ligand binding to tau, the main constituent of neurofibrillary tangles (NFT). Case 1, the former NFL player, was 71 years old when he presented with memory impairment and a clinical profile highly similar to AD. [(18)F]-Florbetapir PET imaging was negative, essentially excluding AD as a diagnosis. CTE was suspected clinically, and [(18)F]-T807 PET imaging revealed striatal and nigral [(18)F]-T807 retention consistent with the presence of tauopathy. Case 2 was a 56-year-old man with personality changes and cognitive decline who had sustained a fall complicated by a subdural hematoma. At 1 year post injury, [(18)F]-Florbetapir PET imaging was negative for an AD pattern of amyloid accumulation in this subject. Focal [(18)F]-Florbetapir retention was noted at the site of impact. In case 1, amyloid imaging provided improved diagnostic accuracy where standard clinical and laboratory criteria were inadequate. In that same case, tau imaging with [(18)F]-T807 revealed a subcortical tauopathy that we interpret as a novel form of CTE with a distribution of tauopathy that mimics, to some extent, that of progressive supranuclear palsy (PSP), despite a clinical presentation of amnesia without any movement disorder complaints or signs. A key distinguishing feature is that our patient presented

  18. Tauopathy PET and amyloid PET in the diagnosis of chronic traumatic encephalopathies: studies of a retired NFL player and of a man with FTD and a severe head injury

    PubMed Central

    Mitsis, E M; Riggio, S; Kostakoglu, L; Dickstein, D L; Machac, J; Delman, B; Goldstein, M; Jennings, D; D'Antonio, E; Martin, J; Naidich, T P; Aloysi, A; Fernandez, C; Seibyl, J; DeKosky, S T; Elder, G A; Marek, K; Gordon, W; Hof, P R; Sano, M; Gandy, S

    2014-01-01

    Single, severe traumatic brain injury (TBI) which elevates CNS amyloid, increases the risk of Alzheimer's disease (AD); while repetitive concussive and subconcussive events as observed in athletes and military personnel, may increase the risk of chronic traumatic encephalopathy (CTE). We describe two clinical cases, one with a history of multiple concussions during a career in the National Football League (NFL) and the second with frontotemporal dementia and a single, severe TBI. Both patients presented with cognitive decline and underwent [18F]-Florbetapir positron emission tomography (PET) imaging for amyloid plaques; the retired NFL player also underwent [18F]-T807 PET imaging, a new ligand binding to tau, the main constituent of neurofibrillary tangles (NFT). Case 1, the former NFL player, was 71 years old when he presented with memory impairment and a clinical profile highly similar to AD. [18F]-Florbetapir PET imaging was negative, essentially excluding AD as a diagnosis. CTE was suspected clinically, and [18F]-T807 PET imaging revealed striatal and nigral [18F]-T807 retention consistent with the presence of tauopathy. Case 2 was a 56-year-old man with personality changes and cognitive decline who had sustained a fall complicated by a subdural hematoma. At 1 year post injury, [18F]-Florbetapir PET imaging was negative for an AD pattern of amyloid accumulation in this subject. Focal [18F]-Florbetapir retention was noted at the site of impact. In case 1, amyloid imaging provided improved diagnostic accuracy where standard clinical and laboratory criteria were inadequate. In that same case, tau imaging with [18F]-T807 revealed a subcortical tauopathy that we interpret as a novel form of CTE with a distribution of tauopathy that mimics, to some extent, that of progressive supranuclear palsy (PSP), despite a clinical presentation of amnesia without any movement disorder complaints or signs. A key distinguishing feature is that our patient presented with

  19. SU-D-201-07: Exploring the Utility of 4D FDG-PET/CT Scans in Design of Radiation Therapy Planning Compared with 3D PET/CT: A Prospective Study

    SciTech Connect

    Ma, C; Yin, Y

    2015-06-15

    Purpose: A method using four-dimensional(4D) PET/CT in design of radiation treatment planning was proposed and the target volume and radiation dose distribution changes relative to standard three-dimensional (3D) PET/CT were examined. Methods: A target deformable registration method was used by which the whole patient’s respiration process was considered and the effect of respiration motion was minimized when designing radiotherapy planning. The gross tumor volume of a non-small-cell lung cancer was contoured on the 4D FDG-PET/CT and 3D PET/CT scans by use of two different techniques: manual contouring by an experienced radiation oncologist using a predetermined protocol; another technique using a constant threshold of standardized uptake value (SUV) greater than 2.5. The target volume and radiotherapy dose distribution between VOL3D and VOL4D were analyzed. Results: For all phases, the average automatic and manually GTV volume was 18.61 cm3 (range, 16.39–22.03 cm3) and 31.29 cm3 (range, 30.11–35.55 cm3), respectively. The automatic and manually volume of merged IGTV were 27.82 cm3 and 49.37 cm3, respectively. For the manual contour, compared to 3D plan the mean dose for the left, right, and total lung of 4D plan have an average decrease 21.55%, 15.17% and 15.86%, respectively. The maximum dose of spinal cord has an average decrease 2.35%. For the automatic contour, the mean dose for the left, right, and total lung have an average decrease 23.48%, 16.84% and 17.44%, respectively. The maximum dose of spinal cord has an average decrease 1.68%. Conclusion: In comparison to 3D PET/CT, 4D PET/CT may better define the extent of moving tumors and reduce the contouring tumor volume thereby optimize radiation treatment planning for lung tumors.

  20. Distinct regional anatomic and functional correlates of neurodegenerative apraxia of speech and aphasia: an MRI and FDG-PET study.

    PubMed

    Whitwell, Jennifer L; Duffy, Joseph R; Strand, Edythe A; Xia, Rong; Mandrekar, Jay; Machulda, Mary M; Senjem, Matthew L; Lowe, Val J; Jack, Clifford R; Josephs, Keith A

    2013-06-01

    Progressive apraxia of speech (AOS) can result from neurodegenerative disease and can occur in isolation or in the presence of agrammatic aphasia. We aimed to determine the neuroanatomical and metabolic correlates of progressive AOS and aphasia. Thirty-six prospectively recruited subjects with progressive AOS or agrammatic aphasia, or both, underwent the Western Aphasia Battery (WAB) and Token Test to assess aphasia, an AOS rating scale (ASRS), 3T MRI and 18-F fluorodeoxyglucose (FDG) PET. Correlations between clinical measures and imaging were assessed. The only region that correlated to ASRS was left superior premotor volume. In contrast, WAB and Token Test correlated with hypometabolism and volume of a network of left hemisphere regions, including pars triangularis, pars opercularis, pars orbitalis, middle frontal gyrus, superior temporal gyrus, precentral gyrus and inferior parietal lobe. Progressive agrammatic aphasia and AOS have non-overlapping regional correlations, suggesting that these are dissociable clinical features that have different neuroanatomical underpinnings. PMID:23542727

  1. Analytical study of the effect of collimation on the performance of PET cameras in 3-D imaging

    SciTech Connect

    Maze, A.; Lecomte, R. )

    1990-04-01

    This paper presents an analytical model developed to evaluate the 3-d imaging performance of cylindrical PET systems with the multi-slice and the volumetric configurations. Point source event rates for singles and for true and scattered coincidences were obtained by numerical integration of the equations for probability of incidence on the detectors. Data were subsequently combined to extract the sensitivity and background (scatters + accidentals) count rates for various source dimensions and activity densities. Event rates before detection were evaluated and an ideal tomograph geometry was assumed in order to investigate the fundamental properties inherent to the two tomograph designs. For small sources placed in a scattering cylinder, results indicate higher scatter and accidental fractions in the volumetric system.

  2. Regional cerebral blood flow during light sleep--a H(2)(15)O-PET study.

    PubMed

    Kjaer, Troels W; Law, Ian; Wiltschiøtz, Gordon; Paulson, Olaf B; Madsen, Peter L

    2002-09-01

    This is the first report on the distribution of regional cerebral blood flow (rCBF) changes during stage-1 sleep or somnolence. Two hypotheses were tested: (A) that rCBF differed between the awake relaxed state and stage-1 sleep, (B) that hypnagogic hallucinations frequently experienced at sleep onset would be accompanied by measurable changes in rCBF using positron emission tomography (PET). Eight subjects were PET-scanned with (15)O-labeled water injection in three conditions: awake, stage-1 sleep with reportable experiences and stage-1 sleep without reportable experiences. Electroencephalography (EEG) was performed continuously during the experiment. Sleep interviews were performed after each scan. The EEG was scored blindly to determine sleep stage. The sleep interviews revealed a substantial increase in how unrealistic and how leaping the thoughts were during stage-1 sleep. During sleep there was a relative flow increase in the occipital lobes and a relative flow decrease in the bilateral cerebellum, the bilateral posterior parietal cortex, the right premotor cortex and the left thalamus. Hypnagogic experiences seemed not to be associated with any relative flow changes. The topography of the occipital activation during stage-1 sleep supports a hypothesis of this state being a state of imagery. The rCBF decreases in premotor cortex, thalamus and cerebellum could be indicative of a general decline in preparedness for goal directed action during stage-1 sleep. Stage-1 sleep seems more similar to other forms of altered awareness, for example, relaxation meditation than to deeper sleep stages. We are of the opinion that stage-1 sleep represents the dreaming state of wakefulness, while rapid eye movement (REM) sleep reflects the dreaming state of the unaware, sleeping brain.

  3. Batch-reactor microfluidic device: first human use of a microfluidically produced PET radiotracer†

    PubMed Central

    Miraghaie, Reza; Kotta, Kishore; Ball, Carroll E.; Zhang, Jianzhong; Buchsbaum, Monte S.; Kolb, Hartmuth C.; Elizarov, Arkadij

    2013-01-01

    The very first microfluidic device used for the production of 18F-labeled tracers for clinical research is reported along with the first human Positron Emission Tomography scan obtained with a microfluidically produced radiotracer. The system integrates all operations necessary for the transformation of [18F]fluoride in irradiated cyclotron target water to a dose of radiopharmaceutical suitable for use in clinical research. The key microfluidic technologies developed for the device are a fluoride concentration system and a microfluidic batch reactor assembly. Concentration of fluoride was achieved by means of absorption of the fluoride anion on a micro ion-exchange column (5 μL of resin) followed by release of the radioactivity with 45 μL of the release solution (95 ± 3% overall efficiency). The reactor assembly includes an injection-molded reactor chip and a transparent machined lid press-fitted together. The resulting 50 μL cavity has a unique shape designed to minimize losses of liquid during reactor filling and liquid evaporation. The cavity has 8 ports for gases and liquids, each equipped with a 2-way on-chip mechanical valve rated for pressure up to 20.68 bar (300 psi). The temperature is controlled by a thermoelectric heater capable of heating the reactor up to 180 °C from RT in 150 s. A camera captures live video of the processes in the reactor. HPLC-based purification and reformulation units are also integrated in the device. The system is based on “split-box architecture”, with reagents loaded from outside of the radiation shielding. It can be installed either in a standard hot cell, or as a self-shielded unit. Along with a high level of integration and automation, split-box architecture allowed for multiple production runs without the user being exposed to radiation fields. The system was used to support clinical trials of [18F]fallypride, a neuroimaging radiopharmaceutical under IND Application #109,880. PMID:23135409

  4. Quantitative meta-analysis of fMRI and PET studies reveals consistent activation in fronto-striatal-parietal regions and cerebellum during antisaccades and prosaccades

    PubMed Central

    Jamadar, Sharna D.; Fielding, Joanne; Egan, Gary F.

    2013-01-01

    The antisaccade task is a classic task of oculomotor control that requires participants to inhibit a saccade to a target and instead make a voluntary saccade to the mirror opposite location. By comparison, the prosaccade task requires participants to make a visually-guided saccade to the target. These tasks have been studied extensively using behavioral oculomotor, electrophysiological, and neuroimaging in both non-human primates and humans. In humans, the antisaccade task is under active investigation as a potential endophenotype or biomarker for multiple psychiatric and neurological disorders. A large and growing body of literature has used functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) to study the neural correlates of the antisaccade and prosaccade tasks. We present a quantitative meta-analysis of all published voxel-wise fMRI and PET studies (18) of the antisaccade task and show that consistent activation for antisaccades and prosaccades is obtained in a fronto-subcortical-parietal network encompassing frontal and supplementary eye fields (SEFs), thalamus, striatum, and intraparietal cortex. This network is strongly linked to oculomotor control and was activated to a greater extent for antisaccade than prosaccade trials. Antisaccade but not prosaccade trials additionally activated dorsolateral and ventrolateral prefrontal cortices. We also found that a number of additional regions not classically linked to oculomotor control were activated to a greater extent for antisaccade vs. prosaccade trials; these regions are often reported in antisaccade studies but rarely commented upon. While the number of studies eligible to be included in this meta-analysis was small, the results of this systematic review reveal that antisaccade and prosaccade trials consistently activate a distributed network of regions both within and outside the classic definition of the oculomotor network. PMID:24137150

  5. Non-Isothermal Crystallization of PET/PLA Blends

    NASA Astrophysics Data System (ADS)

    Chen, Huipeng; Pyda, Marek; Cebe, Peggy

    2011-03-01

    Binary blends of poly(ethylene terephthalate) with poly(lactic acid), PET/PLA, were studied by differential scanning calorimetry. The solution cast blends were miscible in the melt over the entire composition range. We report the non-isothermal crystallization of: a.) PET, with and without presence of PLA crystals, and b.) PLA, with and without presence of PET crystals. PET can crystallize in all blends, regardless of whether PLA is amorphous or crystalline, and crystallinity of PET decreases as PLA content increases. PLA crystallization is strongly affected by the mobility of the PET. When PET is wholly amorphous, PLA can crystallize weakly even in 70/30 blends. When PET is crystalline, PLA cannot crystallize when its own content is below 0.90. The different behaviors may be related to the tendency of each polymer to form constrained chains, i.e., to form rigid amorphous fraction, RAF. PET is capable of forming a large amount of RAF, whereas relatively smaller amount of RAF forms in PLA. Like the crystals, rigid amorphous fraction of one component may inhibit growth of crystals of the other blend partner. Supported by the National Science Foundation, Polymers Program of the Division of Materials Research under DMR-0602473 and the MRI Program under DMR-0520655.

  6. Does the Teacher's Pet Phenomenon Inevitably Cause Classroom Conflict? Comparative Viewpoints of Three Pet-Student Groups

    ERIC Educational Resources Information Center

    Chiu, Shao-I; Lee, Jiezhi; Liang, Tsanglang

    2013-01-01

    Although most studies reveal a relationship between the teacher's pet phenomenon with classroom conflict, it does not necessarily cause classroom conflict. This study confirms the model fit for teacher authority, the existence of the teacher's pet phenomenon and its relationship to classroom conflict and students' self-adjustment, as well as…

  7. [C-11]{beta}CNT: A new monoamine uptake ligand for studying serotonin and dopamine transporter sites in the living brain with PET

    SciTech Connect

    Mulholland, G.K.; Zheng, Q.H.; Zhou, F.C.

    1996-05-01

    There is considerable interest in measuring serotonin (5HT) and dopamine (DA) function in the human brain. Altered levels of 5HT and DA are recognized in drug abuse, neurotoxicities, psychiatric disorders, and neurodegenerative conditions including Alzheimer`s and Parkinson`s disease. Several phenyltropane analogs of cocaine bind tightly to both DA and 5HT uptake proteins. We have made a new agent from this class called {beta}CNT, 2{beta}-carboxymethyl-3{beta}-(2-naphthyl)-tropane, the isosteric O-for-CH{sub 2} analog of a compound reported to have among the highest measured affinities for DA and 5HT transporters and studied its in vivo brain distributions in animals for the first time. Optically pure {beta}CNT was made from cocaine, and labeled at the O-methyl position by esterification of {beta}CNT-acid with [C-11]CH{sub 3}OTfl under conditions similar to Wilson`s. HPLC-purified (99+%) final products (15-50% eob yield from CO{sub 2}, 40 min synth) had specific activities 0.1-1.2 Ci/{mu}mol at the time of injection. Preliminary [C-11]{beta}{beta}CNT rodent distribution showed very high brain uptake (3% ID at 60 min) and localization (striat: fr cort: hypo: cer: blood, 11: 5: 4: 1: 06). {beta}CNT-PET studies in juvenile pigs (5-20 mCi, 20-35 kg) found rapid brain uptake, and prominent retention (85 min) in midbrain, anterior brainstem and striatum, followed by cortex and olfactory bulb. Paroxetine pretreatment (5HT uptake blocker, 2mg/kg), diminished retention in most brain areas; nomifensine (DA/NE uptake blocker, 6 mg/kg) reduced striatum selectively. Direct comparisons of [C-11]{beta}CNT with other PET transporter radioligands {beta}CFT, {beta}CIT, and {beta}CTT (RTI-32) in the same pig found {beta}CNT had highest overall brain uptake among the agents. These initial results suggest {beta}CNT has favorable properties for imaging both 5HT and DA transporters in vivo, and further evaluation of its potential as a human PET agent is warranted.

  8. OSSI-PET: Open-Access Database of Simulated [(11)C]Raclopride Scans for the Inveon Preclinical PET Scanner: Application to the Optimization of Reconstruction Methods for Dynamic Studies.

    PubMed

    Garcia, Marie-Paule; Charil, Arnaud; Callaghan, Paul; Wimberley, Catriona; Busso, Florian; Gregoire, Marie-Claude; Bardies, Manuel; Reilhac, Anthonin

    2016-07-01

    A wide range of medical imaging applications benefits from the availability of realistic ground truth data. In the case of positron emission tomography (PET), ground truth data is crucial to validate processing algorithms and assessing their performances. The design of such ground truth data often relies on Monte-Carlo simulation techniques. Since the creation of a large dataset is not trivial both in terms of computing time and realism, we propose the OSSI-PET database containing 350 simulated [(11)C]Raclopride dynamic scans for rats, created specifically for the Inveon pre-clinical PET scanner. The originality of this database lies on the availability of several groups of scans with controlled biological variations in the striata. Besides, each group consists of a large number of realizations (i.e., noise replicates). We present the construction methodology of this database using rat pharmacokinetic and anatomical models. A first application using the OSSI-PET database is presented. Several commonly used reconstruction techniques were compared in terms of image quality, accuracy and variability of the activity estimates and of the computed kinetic parameters. The results showed that OP-OSEM3D iterative reconstruction method outperformed the other tested methods. Analytical methods such as FBP2D and 3DRP also produced satisfactory results. However, FORE followed by OSEM2D reconstructions should be avoided. Beyond the illustration of the potential of the database, this application will help scientists to understand the different sources of noise and bias that can occur at the different steps in the processing and will be very useful for choosing appropriate reconstruction methods and parameters. PMID:26863655

  9. OSSI-PET: Open-Access Database of Simulated [(11)C]Raclopride Scans for the Inveon Preclinical PET Scanner: Application to the Optimization of Reconstruction Methods for Dynamic Studies.

    PubMed

    Garcia, Marie-Paule; Charil, Arnaud; Callaghan, Paul; Wimberley, Catriona; Busso, Florian; Gregoire, Marie-Claude; Bardies, Manuel; Reilhac, Anthonin

    2016-07-01

    A wide range of medical imaging applications benefits from the availability of realistic ground truth data. In the case of positron emission tomography (PET), ground truth data is crucial to validate processing algorithms and assessing their performances. The design of such ground truth data often relies on Monte-Carlo simulation techniques. Since the creation of a large dataset is not trivial both in terms of computing time and realism, we propose the OSSI-PET database containing 350 simulated [(11)C]Raclopride dynamic scans for rats, created specifically for the Inveon pre-clinical PET scanner. The originality of this database lies on the availability of several groups of scans with controlled biological variations in the striata. Besides, each group consists of a large number of realizations (i.e., noise replicates). We present the construction methodology of this database using rat pharmacokinetic and anatomical models. A first application using the OSSI-PET database is presented. Several commonly used reconstruction techniques were compared in terms of image quality, accuracy and variability of the activity estimates and of the computed kinetic parameters. The results showed that OP-OSEM3D iterative reconstruction method outperformed the other tested methods. Analytical methods such as FBP2D and 3DRP also produced satisfactory results. However, FORE followed by OSEM2D reconstructions should be avoided. Beyond the illustration of the potential of the database, this application will help scientists to understand the different sources of noise and bias that can occur at the different steps in the processing and will be very useful for choosing appropriate reconstruction methods and parameters.

  10. Pet Loss: Implications for Counselors.

    ERIC Educational Resources Information Center

    Sharkin, Bruce S.; Bahrick, Audrey S.

    1990-01-01

    Attempts to increase awareness of counselors about topic of pet loss. Discusses how counselors can be actively involved through practice, consultation, and research to help people deal with emotional impact of pet loss. (Author/NB)

  11. MRI compatibility of position-sensitive photomultiplier depth-of-interaction PET detectors modules for in-line multimodality preclinical studies

    NASA Astrophysics Data System (ADS)

    Vaquero, J. J.; Sánchez, J. J.; Udías, J. M.; Cal-González, J.; Desco, M.

    2013-02-01

    This work addresses the feasibility of a small-animal, in-line PET/MR system based on Position-Sensitive Photo Multiplier Tubes (PS-PMTs). To this end, we measured the effects of static magnetic fields on the PS-PMTs performance in order to explore the minimal tandem separation between the PET and MR subsystems to preserve their respective performances. We concluded that it is possible to achieve minimal degradation of the PET scanner performance (after a system recalibration) if the magnetic field strength influencing the PET detectors is less than 1 mT and if it is oriented perpendicularly to the longitudinal axis of the tube. Therefore, we predict that it will be possible to maintain the PET image quality if it is placed outside the 1 mT line.

  12. Effect of chronic antipsychotic treatment on striatal phosphodiesterase 10A levels: a [11C]MP-10 PET rodent imaging study with ex vivo confirmation

    PubMed Central

    Natesan, S; Ashworth, S; Nielsen, J; Tang, S-P; Salinas, C; Kealey, S; Lauridsen, J B; Stensbøl, T B; Gunn, R N; Rabiner, E A; Kapur, S

    2014-01-01

    A number of phosphodiesterase 10A (PDE10) inhibitors are about to undergo clinical evaluation for their efficacy in treating schizophrenia. As phosphodiesterases are in the same signalling pathway as dopamine D2 receptors, it is possible that prior antipsychotic treatment could influence these enzyme systems in patients. Chronic, in contrast to acute, antipsychotic treatment has been reported to increase brain PDE10A levels in rodents. The aim of this study was to confirm these findings in a manner that can be translated to human imaging studies to understand its consequences. Positron emission tomography (PET) scanning was used to evaluate PDE10A enzyme availability, after chronic haloperidol administration, using a specific PDE10A ligand ([11C]MP-10). The binding of [11C]MP-10 in the striatum and the cerebellum was measured in rodents and a simplified reference tissue model (SRTM) with cerebellum as the reference region was used to determine the binding potential (BPND). In rats treated chronically with haloperidol (2 mg kg−1 per day), there was no significant difference in PDE10A levels compared with the vehicle-treated group (BPND±s.d.: 3.57±0.64 versus 2.86±0.71). Following PET scans, ex vivo analysis of striatal brain tissue for PDE10A mRNA (Pde10a) and PDE10A enzyme activity showed no significant difference. Similarly, the PDE10A protein content determined by western blot analysis was similar between the two groups, contrary to an earlier finding. The results of the study indicate that prior exposure to antipsychotic medication in rodents does not alter PDE10A levels. PMID:24690597

  13. Effect of chronic antipsychotic treatment on striatal phosphodiesterase 10A levels: a [¹¹C]MP-10 PET rodent imaging study with ex vivo confirmation.

    PubMed

    Natesan, S; Ashworth, S; Nielsen, J; Tang, S-P; Salinas, C; Kealey, S; Lauridsen, J B; Stensbøl, T B; Gunn, R N; Rabiner, E A; Kapur, S

    2014-01-01

    A number of phosphodiesterase 10A (PDE10) inhibitors are about to undergo clinical evaluation for their efficacy in treating schizophrenia. As phosphodiesterases are in the same signalling pathway as dopamine D2 receptors, it is possible that prior antipsychotic treatment could influence these enzyme systems in patients. Chronic, in contrast to acute, antipsychotic treatment has been reported to increase brain PDE10A levels in rodents. The aim of this study was to confirm these findings in a manner that can be translated to human imaging studies to understand its consequences. Positron emission tomography (PET) scanning was used to evaluate PDE10A enzyme availability, after chronic haloperidol administration, using a specific PDE10A ligand ([(11)C]MP-10). The binding of [(11)C]MP-10 in the striatum and the cerebellum was measured in rodents and a simplified reference tissue model (SRTM) with cerebellum as the reference region was used to determine the binding potential (BPND). In rats treated chronically with haloperidol (2 mg kg(-1) per day), there was no significant difference in PDE10A levels compared with the vehicle-treated group (BPND±s.d.: 3.57 ± 0.64 versus 2.86 ± 0.71). Following PET scans, ex vivo analysis of striatal brain tissue for PDE10A mRNA (Pde10a) and PDE10A enzyme activity showed no significant difference. Similarly, the PDE10A protein content determined by western blot analysis was similar between the two groups, contrary to an earlier finding. The results of the study indicate that prior exposure to antipsychotic medication in rodents does not alter PDE10A levels. PMID:24690597

  14. Positron Emission Tomography (PET) Evaluation After Initial Chemotherapy and Radiation Therapy Predicts Local Control in Rhabdomyosarcoma

    SciTech Connect

    Dharmarajan, Kavita V.; Wexler, Leonard H.; Gavane, Somali; Fox, Josef J.; Schoder, Heiko; Tom, Ashlyn K.; Price, Alison N.; Meyers, Paul A.; Wolden, Suzanne L.

    2012-11-15

    Purpose: 18-fluorodeoxyglucose positron emission tomography (PET) is already an integral part of staging in rhabdomyosarcoma. We investigated whether primary-site treatment response characterized by serial PET imaging at specific time points can be correlated with local control. Patients and Methods: We retrospectively examined 94 patients with rhabdomyosarcoma who received initial chemotherapy 15 weeks (median) before radiotherapy and underwent baseline, preradiation, and postradiation PET. Baseline PET standardized uptake values (SUVmax) and the presence or absence of abnormal uptake (termed PET-positive or PET-negative) both before and after radiation were examined for the primary site. Local relapse-free survival (LRFS) was calculated according to baseline SUVmax, PET-positive status, and PET-negative status by the Kaplan-Meier method, and comparisons were tested with the log-rank test. Results: The median patient age was 11 years. With 3-year median follow-up, LRFS was improved among postradiation PET-negative vs PET-positive patients: 94% vs 75%, P=.02. By contrast, on baseline PET, LRFS was not significantly different for primary-site SUVmax {<=}7 vs >7 (median), although the findings suggested a trend toward improved LRFS: 96% for SUVmax {<=}7 vs 79% for SUVmax >7, P=.08. Preradiation PET also suggested a statistically insignificant trend toward improved LRFS for PET-negative (97%) vs PET-positive (81%) patients (P=.06). Conclusion: Negative postradiation PET predicted improved LRFS. Notably, 77% of patients with persistent postradiation uptake did not experience local failure, suggesting that these patients could be closely followed up rather than immediately referred for intervention. Negative baseline and preradiation PET findings suggested statistically insignificant trends toward improved LRFS. Additional study may further understanding of relationships between PET findings at these time points and outcome in rhabdomyosarcoma.

  15. Pet ownership, dog types and attachment to pets in 9–10 year old children in Liverpool, UK

    PubMed Central

    2013-01-01

    Background Little is known about ethnic, cultural and socioeconomic differences in childhood ownership and attitudes to pets. The objective of this study was to describe the factors associated with living with different pet types, as well as factors that may influence the intensity of relationship or ‘attachment’ that children have to their pet. Data were collected using a survey of 1021 9–10 year old primary school children in a deprived area of the city of Liverpool, UK. Results Dogs were the most common pet owned, most common ‘favourite’ pet, and species most attached to. Twenty-seven percent of dog-owning children (10% of all children surveyed) reported living with a ‘Bull Breed’ dog (which includes Pit Bulls and Staffordshire Bull Terriers), and the most popular dog breed owned was the Staffordshire Bull Terrier. Multivariable regression modelling identified a number of variables associated with ownership of different pets and the strength of attachment to the child’s favourite pet. Girls were more likely to own most pet types, but were no more or less attached to their favourite pet than boys. Children of white ethnicity were more likely to own dogs, rodents and ‘other’ pets but were no more or less attached to their pets than children of non-white ethnicity. Single and youngest children were no more or less likely to own pets than those with younger brothers and sisters, but they showed greater attachment to their pets. Children that owned dogs lived in more deprived areas than those without dogs, and deprivation increased with number of dogs owned. ‘Pit Bull or cross’ and ‘Bull Breed’ dogs were more likely to be found in more deprived areas than other dog types. Non-whites were also more likely to report owning a ‘Pit Bull or cross’ than Whites. Conclusions Gender, ethnicity and socioeconomic status were associated with pet ownership, and sibling status with level of attachment to the pet. These are important to consider when

  16. An Educational PET Camera Model

    ERIC Educational Resources Information Center

    Johansson, K. E.; Nilsson, Ch.; Tegner, P. E.

    2006-01-01

    Positron emission tomography (PET) cameras are now in widespread use in hospitals. A model of a PET camera has been installed in Stockholm House of Science and is used to explain the principles of PET to school pupils as described here.

  17. The role of metabotropic glutamate receptor 5 in the pathogenesis of mood disorders and addiction: combining preclinical evidence with human Positron Emission Tomography (PET) studies

    PubMed Central

    Terbeck, Sylvia; Akkus, Funda; Chesterman, Laurence P.; Hasler, Gregor

    2015-01-01

    In the present review, we deliver an overview of the involvement of metabotropic glutamate receptor 5 (mGluR5) activity and density in pathological anxiety, mood disorders and addiction. Specifically, we will describe mGluR5 studies in humans that employed Positron Emission Tomography (PET) and combined the findings with preclinical animal research. This combined view of different methodological approaches—from basic neurobiological approaches to human studies—might give a more comprehensive and clinically relevant view of mGluR5 function in mental health than the view on preclinical data alone. We will also review the current research data on mGluR5 along the Research Domain Criteria (RDoC). Firstly, we found evidence of abnormal glutamate activity related to the positive and negative valence systems, which would suggest that antagonistic mGluR5 intervention has prominent anti-addictive, anti-depressive and anxiolytic effects. Secondly, there is evidence that mGluR5 plays an important role in systems for social functioning and the response to social stress. Finally, mGluR5's important role in sleep homeostasis suggests that this glutamate receptor may play an important role in RDoC's arousal and modulatory systems domain. Glutamate was previously mostly investigated in non-human studies, however initial human clinical PET research now also supports the hypothesis that, by mediating brain excitability, neuroplasticity and social cognition, abnormal metabotropic glutamate activity might predispose individuals to a broad range of psychiatric problems. PMID:25852460

  18. Receptor-binding, biodistribution, and metabolism studies of 64Cu-DOTA-cetuximab, a PET-imaging agent for epidermal growth-factor receptor-positive tumors.

    PubMed

    Ping Li, Wen; Meyer, Laura A; Capretto, David A; Sherman, Christopher D; Anderson, Carolyn J

    2008-04-01

    The epidermal growth-factor receptor (EGFR) and its ligands have been recognized as critical factors in the pathophysiology of tumorigenesis. Overexpression of the EGFR plays a significant role in the tumor progression of a wide variety of solid human cancers. Therefore, the EGFR represents an attractive target for the design of novel diagnostic and therapeutic agents for cancer. Cetuximab (C225, Erbitux) was the first monoclonal antibody targeted against the ligand-binding site of EGFR approved by the Food and Drug Administration for the treatment of patients with EGFR-expressing, metastatic colorectal carcinoma, although clinical trials showed variability in the response to this treatment. The aim of this study involved using cetuximab to design a positron emission tomography (PET) agent to image the overexpression of EGFR in tumors. Cetuximab was conjugated with the chelator, DOTA, for radiolabeling with the positron-emitter, 64Cu (T(1/2) = 12.7 hours). 64Cu-DOTA-cetuximab showed high binding affinity to EGFR-positive A431 cells (K(D) of 0.28 nM). Both biodistribution and microPET imaging studies with 64Cu-DOTA-cetuximab demonstrated greater uptake at 24 hours postinjection in EGFR-positive A431 tumors (18.49% +/- 6.50% injected dose per gram [ID/g]), compared to EGFR-negative MDA-MB-435 tumors (2.60% +/- 0.35% ID/g). A431 tumor uptake at 24 hours was blocked with unlabeled cetuximab (10.69% +/- 2.72% ID/g), suggesting that the tumor uptake was receptor mediated. Metabolism experiments in vivo showed that 64Cu-DOTA-cetuximab was relatively stable in the blood of tumor-bearing mice; however, there was significant metabolism in the liver and tumors. 64Cu-DOTA-cetuximab is a potential agent for imaging EGFR-positive tumors in humans.

  19. Role of Attachment in Response to Pet Loss

    ERIC Educational Resources Information Center

    Field, Nigel P.; Orsini, Lisa; Gavish, Roni; Packman, Wendy

    2009-01-01

    This study examined the impact of attachment on grief severity following the death of a pet. Seventy-one participants who had lost a dog or cat within the past year completed a set of measures that included an attachment measure assessing individual differences in attachment anxiety and avoidance, strength of the past attachment to the pet, the…

  20. After the Bell: Developing an Awareness of Pet Stewardship

    ERIC Educational Resources Information Center

    Farenga, Stephen J.; Ness, Daniel; Hutchinson, Michael

    2008-01-01

    Given the commonness of pets in communities throughout the United States, Canada, and Australia, among other countries, pet stewardship should be a natural topic of study for the integration of science, mathematics, and technology. Therefore, the term "stewardship" will be examined by applying observation and research to shape our behaviors and…

  1. A rare case of mature teratoma. Has FDG PET/CT a role to play?

    PubMed

    Mohapatra, Tushar; Arora, Abhishek; Srikant, K; Snehalata; Kumar, Nandish

    2011-04-01

    Authors describe a very rare case of mature teratoma with malignant transformation, preoperatively suggested by FDG PET/CT study. So the role of CT component in elucidating three embryonal components and hypermetabolism evident on PET part suggesting possible malignant transformation makes PET/CT a valuable modality in evaluation of these rare tumors.

  2. Behavioral Intervention for Domestic Pet Mistreatment in a Young Child with Autism

    ERIC Educational Resources Information Center

    Bergstrom, Ryan; Tarbox, Jonathan; Gutshall, Katharine A.

    2011-01-01

    Household pets can have a positive influence on quality of life for individuals who live with them (Bryant, 1990). Little previous research has investigated issues related to interaction between individuals with developmental disabilities and pets. In this study, we used simple behavioral intervention procedures to decrease pet mistreatment by a…

  3. Pets and Human Health in Germany and Australia: National Longitudinal Results

    ERIC Educational Resources Information Center

    Headey, Bruce; Grabka, Markus M.

    2007-01-01

    The German and Australian "longitudinal" surveys analysed here are the first national representative surveys to show that (1) people who continuously own a pet are the healthiest group and (2) people who cease to have a pet or never had one are less healthy. Most previous studies which have claimed that pets confer health benefits were…

  4. Estimation of Hoffman-Lauritzen parameters from nonisothermal crystallization kinetics of PET/MWCNT nanocomposites

    NASA Astrophysics Data System (ADS)

    Gaonkar, Amita; Murudkar, Vrishali; Deshpande, V. D.

    2016-05-01

    Polyethylene terephthalate (PET) and Nucleated PET/ multi-walled carbon nanotubes (MWCNTs) nanocomposites with different MWCNTs loadings were prepared by melt compounding. The influence of the addition of MWCNTs and precipitated PET (p-PET) on the morphology and thermal properties of the nanocomposites was investigated. From Transmission Electronic Microscopy (TEM) and Wide angle X-Ray diffraction (WAXD) study, it can be clearly seen that nanocomposites with low MWCNTs contents (0.1 wt. %) get better MWCNTs dispersion than higher MWCNT loading. Comparing with PET, nucleated PET nanocomposite with 0.1% MWCNT loading shows higher value of Lauritzen-Hoffman parameters U* and Kg evaluated using the differential isoconversional method. Crystallization regime transition temperature range shifts to higher temperature (208°C - 215°C) for nanocomposites. The presence of p-PET in addition of MWCNT, which act as good nucleating agent, enhanced the crystallization of PET through heterogeneous nucleation.

  5. Cocaine cue–induced dopamine release in the human prefrontal cortex

    PubMed Central

    Milella, Michele S.; Fotros, Aryandokht; Gravel, Paul; Casey, Kevin F.; Larcher, Kevin; Verhaeghe, Jeroen A.J.; Cox, Sylvia M.L.; Reader, Andrew J.; Dagher, Alain; Benkelfat, Chawki; Leyton, Marco

    2016-01-01

    Background Accumulating evidence indicates that drug-related cues can induce dopamine (DA) release in the striatum of substance abusers. Whether these same cues provoke DA release in the human prefrontal cortex remains unknown. Methods We used high-resolution positron emission tomography with [18F]fallypride to measure cortical and striatal DA D2/3 receptor availability in the presence versus absence of drug-related cues in volunteers with current cocaine dependence. Results Twelve individuals participated in our study. Among participants reporting a craving response (9 of 12), exposure to the cocaine cues significantly decreased [18F]fallypride binding potential (BPND) values in the medial orbitofrontal cortex and striatum. In all 12 participants, individual differences in the magnitude of craving correlated with BPND changes in the medial orbitofrontal cortex, dorsolateral prefrontal cortex, anterior cingulate, and striatum. Consistent with the presence of autoreceptors on mesostriatal but not mesocortical DA cell bodies, midbrain BPND values were significantly correlated with changes in BPND within the striatum but not the cortex. The lower the midbrain D2 receptor levels, the greater the striatal change in BPND and self-reported craving. Limitations Limitations of this study include its modest sample size, with only 2 female participants. Newer tracers might have greater sensitivity to cortical DA release. Conclusion In people with cocaine use disorders, the presentation of drug-related cues induces DA release within cortical and striatal regions. Both effects are associated with craving, but only the latter is regulated by midbrain autoreceptors. Together, the results suggest that cortical and subcortical DA responses might both influence drug-focused incentive motivational states, but with separate regulatory mechanisms. PMID:26900792

  6. Use of subsequent PET/CT in diffuse large B-cell lymphoma patients in complete remission following primary therapy

    PubMed Central

    Zhang, Xu; Fan, Wei; Xia, Zhong-Jun; Hu, Ying-Ying; Lin, Xiao-Ping; Zhang, Ya-Rui; Li, Zhi-Ming; Liang, Pei-Yan; Li, Yuan-Hua

    2015-01-01

    Interim 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (I-PET/CT) is a powerful tool for monitoring the response to therapy in diffuse large B-cell lymphoma (DLBCL). This retrospective study aimed to determine when and how to use I-PET/CT in DLBCL. A total of 197 patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) were enrolled between October 2005 and July 2011; PET/CT was performed at the time of diagnosis (PET/CT0), after 2 and 4 cycles of chemotherapy (PET/CT2 and PET/CT4, respectively), and at the end of treatment (F-PET/CT). According to the International Harmonization Project for Response Criteria in Lymphoma, 110 patients had negative PET/CT2 scans, and 87 had positive PET/CT2 scans. The PET/CT2-negative patients had significantly higher 3-year progression-free survival rate (75.8% vs. 38.2%) and 3-year overall survival rate (93.5% vs. 55.6%) than PET/CT2-positive patients. All PET/CT2-negative patients remained negative at PET/CT4, but 3 were positive at F-PET/CT. Among the 87 PET/CT2-positive patients, 57 remained positive at F-PET/CT, and 32 progressed during chemotherapy (15 at PET/CT4 and 17 at F-PET/CT). Comparing PET/CT4 with PET/CT0, 7 patients exhibited progression, and 8 achieved partial remission. Comparing F-PET/CT with PET/CT0, 10 patients exhibited progression, and 7 achieved partial remission. In conclusion, our results indicate that I-PET/CT should be performed after 2 rather than 4 cycles of immunochemotherapy in DLBCL patients. There is a limited role for subsequent PET/CT in the detection of relapse in PET/CT2-negative patients, but repeat PET/CT is required if the PET/CT2 findings are positive. PMID:25418196

  7. Microglial activity in people at ultra high risk of psychosis and in schizophrenia; an [11C]PBR28 PET brain imaging study

    PubMed Central

    Veronese, Mattia; Rizzo, Gaia; Bertoldo, Alessandra; Owen, David R; Bloomfield, Michael AP; Bonoldi, Ilaria; Kalk, Nicola; Turkheimer, Federico; McGuire, Philip

    2016-01-01

    Objective To determine whether microglial activity, measured using translocator-protein positron emission tomographic imaging (PET), is increased in unmedicated subjects presenting with sub-clinical symptoms indicating they are at ultra high risk of psychosis, and to determine if it is elevated in schizophrenia after controlling for a translocator specific genetic polymorphism. Method Here we use the second generation radioligand [11C]PBR28 and PET to image microglial activity in the brains of subjects at ultra high risk for psychosis. Subjects were recruited from early intervention centres. We also imaged a cohort of patients with schizophrenia and healthy controls for comparison, in total 56 subjects completed the study. At screening, subjects were genotyped to account for the rs6971 polymorphism in the gene encoding the 18Kd Translocator Protein. The main outcome measure was total grey matter [11C]PBR28 binding ratio, representing microglial activity. Results [11C]PBR28 binding ratio in grey matter was elevated in ultra high risk subjects, compared to matched controls, (p=0.004, F= 10.3, Cohen’s d >1.2), and was positively correlated with symptom severity (r= 0.730, p<0.01). Patients with schizophrenia also demonstrated elevated microglial activity with respect to matched controls (p<0.001, F= 20.8, Cohen’s d >1.7). Conclusion Microglial activity is elevated in schizophrenia and in subjects with sub-clinical symptoms who are at ultra high risk of psychosis, and is related to at risk symptom severity. This indicates that neuroinflammation is linked to the risk of psychosis and related disorders, and the expression of sub-clinical symptoms. Follow up of ultra high risk subjects will determine whether this is specific to the later development of schizophrenia or risk factors in general. PMID:26472628

  8. Acute increases in synaptic GABA detectable in the living human brain: a [¹¹C]Ro15-4513 PET study.

    PubMed

    Stokes, Paul R A; Myers, Jim F; Kalk, Nicola J; Watson, Ben J; Erritzoe, David; Wilson, Sue J; Cunningham, Vincent J; Riano Barros, Daniela; Hammers, Alexander; Turkheimer, Federico E; Nutt, David J; Lingford-Hughes, Anne R

    2014-10-01

    The inhibitory γ-aminobutyric acid (GABA) neurotransmitter system is associated with the regulation of normal cognitive functions and dysregulation has been reported in a number of neuropsychiatric disorders including anxiety disorders, schizophrenia and addictions. Investigating the role of GABA in both health and disease has been constrained by difficulties in measuring acute changes in synaptic GABA using neurochemical imaging. The aim of this study was to investigate whether acute increases in synaptic GABA are detectable in the living human brain using the inverse agonist GABA-benzodiazepine receptor (GABA-BZR) positron emission tomography (PET) tracer, [(11)C]Ro15-4513. We examined the effect of 15 mg oral tiagabine, which increases synaptic GABA by inhibiting the GAT1 GABA uptake transporter, on [(11)C]Ro15-4513 binding in 12 male participants using a paired, double blind, placebo-controlled protocol. Spectral analysis was used to examine synaptic α1 and extrasynaptic α5 GABA-BZR subtype availability in brain regions with high levels of [(11)C]Ro15-4513 binding. We also examined the test-retest reliability of α1 and a5-specific [(11)C]Ro15-4513 binding in a separate cohort of 4 participants using the same spectral analysis protocol. Tiagabine administration produced significant reductions in hippocampal, parahippocampal, amygdala and anterior cingulate synaptic α1 [(11)C]Ro15-4513 binding, and a trend significance reduction in the nucleus accumbens. These reductions were greater than test-retest reliability, indicating that they are not the result of chance observations. Our results suggest that acute increases in endogenous synaptic GABA are detectable in the living human brain using [(11)C]Ro15-4513 PET. These findings have potentially major implications for the investigation of GABA function in brain disorders and in the development of new treatments targeting this neurotransmitter system. PMID:24844747

  9. Words in melody: an H(2)15O PET study of brain activation during singing and speaking.

    PubMed

    Jeffries, K J; Fritz, J B; Braun, A R

    2003-04-15

    We used H(2)15O PET to characterize the interaction of words and melody by comparing brain activity measured while subjects spoke or sang the words to a familiar song. Relative increases in activity during speaking vs singing were observed in the left hemisphere, in classical perisylvian language areas including the posterior superior temporal gyrus, supramarginal gyrus, and frontal operculum, as well as in Rolandic cortices and putamen. Relative increases in activity during singing were observed in the right hemisphere: these were maximal in the right anterior superior temporal gyrus and contiguous portions of the insula; relative increases associated with singing were also detected in the right anterior middle temporal gyrus and superior temporal sulcus, medial and dorsolateral prefrontal cortices, mesial temporal cortices and cerebellum, as well as in Rolandic cortices and nucleus accumbens. These results indicate that the production of words in song is associated with activation of regions within right hemisphere areas that are not mirror-image homologues of left hemisphere perisylvian language areas, and suggest that multiple neural networks may be involved in different aspects of singing. Right hemisphere mechanisms may support the fluency-evoking effects of singing in neurological disorders such as stuttering or aphasia.

  10. Tomographic bioluminescence imaging by use of a combined optical-PET (OPET) system: a computer simulation feasibility study

    NASA Astrophysics Data System (ADS)

    Alexandrakis, George; Rannou, Fernando R.; Chatziioannou, Arion F.

    2005-09-01

    The feasibility and limits in performing tomographic bioluminescence imaging with a combined optical-PET (OPET) system were explored by simulating its image formation process. A micro-MRI based virtual mouse phantom was assigned appropriate tissue optical properties to each of its segmented internal organs at wavelengths spanning the emission spectrum of the firefly luciferase at 37 °C. The TOAST finite-element code was employed to simulate the diffuse transport of photons emitted from bioluminescence sources in the mouse. OPET measurements were simulated for single-point, two-point and distributed bioluminescence sources located in different organs such as the liver, the kidneys and the gut. An expectation maximization code was employed to recover the intensity and location of these simulated sources. It was found that spectrally resolved measurements were necessary in order to perform tomographic bioluminescence imaging. The true location of emission sources could be recovered if the mouse background optical properties were known a priori. The assumption of a homogeneous optical property background proved inadequate for describing photon transport in optically heterogeneous tissues and led to inaccurate source localization in the reconstructed images. The simulation results pointed out specific methodological challenges that need to be addressed before a practical implementation of OPET-based bioluminescence tomography is achieved.

  11. The neural correlates of naming and fluency deficits in Alzheimer’s disease: an FDG-PET study

    PubMed Central

    Melrose, Rebecca J.; Campa, Olivia M.; Harwood, Dylan G.; Osato, Sheryl; Mandelkern, Mark A.; Sultzer, David L.

    2009-01-01

    Summary Objective To examine the neural processes associated with language deficits in Alzheimer’s disease (AD), and in particular to elucidate the correlates of confrontation naming and word retrieval impairments. Methods Sixty patients with probable AD were included. Confrontation naming was assessed using the number of words spontaneously named correctly on the Boston Naming Test. We recorded the number of additional words stated following phonemic cuing. We also assessed phonemic (FAS) and semantic (supermarket items) fluency. We then correlated performance on each measure with resting cortical metabolic activity using FDG-PET images. Results We found that poorer ability to spontaneously name an object was associated with hypometabolism of bilateral inferior temporal lobes. In contrast, when a phonemic cue was provided, successful naming under this condition was associated with higher metabolic activity in bilateral inferior frontal gyrus (IFG), right superior frontal gyrus (SFG), left temporal, and occipital regions. Consistent with these findings, we found that poorer semantic fluency was associated with hypometabolism in regions including both IFG and temporal regions, and poorer phonemic fluency was associated with hypometabolism in only left IFG. Across analyses, measures that required cued retrieval were associated with metabolism in the left IFG, whereas measures taxing semantic knowledge were associated with metabolic rate of left temporal cortex. Conclusions Naming deficits in AD reflect compromise to temporal regions involved in the semantic knowledge network, and frontal regions involved in the controlled retrieval of information from that network. PMID:19296551

  12. The functional neuroanatomy of Tourette's syndrome: an FDG PET study III: functional coupling of regional cerebral metabolic rates.

    PubMed

    Jeffries, K J; Schooler, C; Schoenbach, C; Herscovitch, P; Chase, T N; Braun, A R

    2002-07-01

    Functional coupling of regional cerebral metabolic rates for glucose measured with [18F]-Fluoro-2-deoxy-D-glucose PET was compared in 18 drug-free patients with Tourette's Syndrome (TS) and 16 age- and sex-matched control subjects. Pearson product-moment correlation matrices containing correlations between metabolic rates in regions sampled throughout the brain were generated independently for TS patients and controls and compared. Significant differences between Z-transformed correlation coefficients were used to identify group differences, and revealed that the connectivity of the ventral striatum was most severely affected in TS. Changes in the coupling of other brain areas-primary motor areas, somatosensory association areas, and insula-also appeared to differentiate TS patients and controls. Evaluation of interrelationships between cortico-striato-thalamo-cortical circuits revealed the existence of functional connections between the motor and lateral orbitofrontal circuits in both groups, however, a reversal in the pattern of these interactions differentiated TS patients and controls. In controls, activity in these circuits appeared to be negatively correlated-i.e. increased activity in one is associated with relative inactivity the other. In TS patients, on the other hand, activity in the motor and lateral orbitofrontal circuits appears to be positively coupled. These results lend further credence to the hypothesis that altered limbic-motor interactions represent a pathophysiological hallmark of this disease.

  13. PET Imaging: Basics and New Trends

    NASA Astrophysics Data System (ADS)

    Dahlbom, Magnus

    Positron Emission Tomography or PET is a noninvasive molecular imaging method used both in research to study biology and disease, and clinically as a routine diagnostic imaging tool. In PET imaging, the subject is injected with a tracer labeled with a positron-emitting isotope and is then placed in a scanner to localize the radioactive tracer in the body. The localization of the tracer utilizes the unique decay characteristics of isotopes decaying by positron emission. In the PET scanner, a large number of scintillation detectors use coincidence detection of the annihilation radiation that is emitted as a result of the positron decay. By collecting a large number of these coincidence events, together with tomographic image reconstruction methods, the 3-D distribution of the radioactive tracer in the body can be reconstructed. Depending on the type of tracer used, the distribution will reflect a particular biological process, such as glucose metabolism when fluoro-deoxyglucose is used. PET has evolved from a relatively inefficient single-slice imaging system with relatively poor spatial resolution to an efficient, high-resolution imaging modality which can acquire a whole-body scan in a few minutes. This chapter will describe the basic physics and instrumentation used in PET. The various corrections that are necessary to apply to the acquired data in order to produce quantitative images are also described. Finally, some of the latest trends in instrumentation development are also discussed.

  14. Novel Developments in Instrumentation for PET Imaging

    NASA Astrophysics Data System (ADS)

    Karp, Joel

    2013-04-01

    Advances in medical imaging, in particular positron emission tomography (PET), have been based on technical developments in physics and instrumentation that have common foundations with detection systems used in other fields of physics. New detector materials are used in PET systems that maximize efficiency, timing characteristics and robustness, and which lead to improved image quality and quantitative accuracy for clinical imaging. Time of flight (TOF) techniques are now routinely used in commercial PET scanners that combine physiological imaging with anatomical imaging provided by x-ray computed tomography. Using new solid-state photo-sensors instead of traditional photo-multiplier tubes makes it possible to combine PET with magnetic resonance imaging which is a significant technical challenge, but one that is creating new opportunities for both research and clinical applications. An overview of recent advances in instrumentation, such as TOF and PET/MR will be presented, along with examples of imaging studies to demonstrate the impact on patient care and basic research of diseases.

  15. PET tracer development—a tale of mice and men

    PubMed Central

    Hicks, Rodney J; Dorow, Donna; Roselt, Peter

    2006-01-01

    PET scanning is an emerging technology for the clinical evaluation of many disease processes in man. The vast majority of clinical positron emission tomography (PET) studies are performed using a single tracer, fluorodeoxyglucose. Despite the excellent diagnostic performance of this tracer, it has recognised limitations. New tracers offer the potential to both address these limitations, and to establish new applications for PET. Small animal PET is a logical technique for validating new tracers relevant to human diseases. However, interspecies differences in the handling of chemicals may significantly influence the handling of novel tracers. This requires caution in extrapolating findings in animals to expectations of performance in man. Already there are several examples where biodistribution studies in mice would not have predicted the clinical utility of existing PET tracers. Nevertheless, application of a systematic approach to tracer development is likely to speed transition of new tracers from animals into man. PMID:17114061

  16. PET/CT in paediatric malignancies - An update.

    PubMed

    Padma, Subramanyam; Sundaram, Palaniswamy Shanmuga; Tewari, Anshu

    2016-01-01

    (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging modality in adult oncological practice. Its role in childhood malignancies needs to be discussed as paediatric malignancies differ from adults in tumor subtypes and they have different tumor biology and FDG uptake patterns. This is also compounded by smaller body mass, dosimetric restrictions, and physiological factors that can affect the FDG uptake. It calls for careful planning of the PET study, preparing the child, the parents, and expertise of nuclear physicians in reporting pediatric positron emission tomography/computed tomography (PET/CT) studies. In a broad perspective, FDG-PET/CT has been used in staging, assessment of therapy response, identifying metastases and as a follow-up tool in a wide variety of pediatric malignancies. This review outlines the role of PET/CT in childhood malignancies other than hematological malignancies such as lymphoma and leukemia. PMID:27688605

  17. PET/CT in paediatric malignancies - An update

    PubMed Central

    Padma, Subramanyam; Sundaram, Palaniswamy Shanmuga; Tewari, Anshu

    2016-01-01

    18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging modality in adult oncological practice. Its role in childhood malignancies needs to be discussed as paediatric malignancies differ from adults in tumor subtypes and they have different tumor biology and FDG uptake patterns. This is also compounded by smaller body mass, dosimetric restrictions, and physiological factors that can affect the FDG uptake. It calls for careful planning of the PET study, preparing the child, the parents, and expertise of nuclear physicians in reporting pediatric positron emission tomography/computed tomography (PET/CT) studies. In a broad perspective, FDG-PET/CT has been used in staging, assessment of therapy response, identifying metastases and as a follow-up tool in a wide variety of pediatric malignancies. This review outlines the role of PET/CT in childhood malignancies other than hematological malignancies such as lymphoma and leukemia. PMID:27688605

  18. PET/CT in paediatric malignancies - An update

    PubMed Central

    Padma, Subramanyam; Sundaram, Palaniswamy Shanmuga; Tewari, Anshu

    2016-01-01

    18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging modality in adult oncological practice. Its role in childhood malignancies needs to be discussed as paediatric malignancies differ from adults in tumor subtypes and they have different tumor biology and FDG uptake patterns. This is also compounded by smaller body mass, dosimetric restrictions, and physiological factors that can affect the FDG uptake. It calls for careful planning of the PET study, preparing the child, the parents, and expertise of nuclear physicians in reporting pediatric positron emission tomography/computed tomography (PET/CT) studies. In a broad perspective, FDG-PET/CT has been used in staging, assessment of therapy response, identifying metastases and as a follow-up tool in a wide variety of pediatric malignancies. This review outlines the role of PET/CT in childhood malignancies other than hematological malignancies such as lymphoma and leukemia.

  19. PET Imaging in Huntington’s Disease

    PubMed Central

    Roussakis, Andreas-Antonios; Piccini, Paola

    2015-01-01

    To date, little is known about how neurodegeneration and neuroinflammation propagate in Huntington’s disease (HD). Unfortunately, no treatment is available to cure or reverse the progressive decline of function caused by the disease, thus considering HD a fatal disease. Mutation gene carriers typically remain asymptomatic for many years although alterations in the basal ganglia and cortex occur early on in mutant HD gene–carriers. Positron Emission Tomography (PET) is a functional imaging technique of nuclear medicine which enables in vivo visualization of numerous biological molecules expressed in several human tissues. Brain PET is most powerful to study in vivo neuronal and glial cells function as well as cerebral blood flow in a plethora of neurodegenerative disorders including Parkinson’s disease, Alzheimer’s and HD. In absence of HD–specific biomarkers for monitoring disease progression, previous PET studies in HD were merely focused on the study of dopaminergic terminals, cerebral blood flow and glucose metabolism in manifest and premanifest HD–gene carriers. More recently, research interest has been exploring novel PET targets in HD including the state of phosphodiesterse expression and the role of activated microglia. Hence, a better understanding of the HD pathogenesis mechanisms may lead to the development of targeted therapies. PET imaging follow–up studies with novel selective PET radiotracers such as 11C-IMA–107 and 11C-PBR28 may provide insight on disease progression and identify prognostic biomarkers, elucidate the underlying HD pathology and assess novel pharmaceutical agents and over time. PMID:26683130

  20. Pets and the Elderly.

    ERIC Educational Resources Information Center

    Frazier, Billie H.

    This document contains a brief bibliography of peer-reviewed literature, with abstracts, on pets and the elderly. It is one of 12 bibliographies on aging prepared by the National Agricultural Library for its "Pathfinders" series of publications. Topics covered by the other 11 bibliographies include aging parents, adult children, dementia and…

  1. Diagnostic value of [18F] FDG-PET and PET/CT in urinary bladder cancer: a meta-analysis.

    PubMed

    Zhang, Huojun; Xing, Wei; Kang, Qinqin; Chen, Chao; Wang, Linhui; Lu, Jianping

    2015-05-01

    An early diagnosis of urinary bladder cancer is crucial for early treatment and management. The objective of this systematic review was to assess the overall diagnostic accuracy of 18 F FDG-PET and PET/CT in urinary bladder cancer with meta-analysis. The PubMed and CNKI databases were searched for the eligible studies published up to June 01, 2014. The sensitivity, specificity, and other measures of accuracy of 18 F FDG-PET and PET/CT in the diagnosis of urinary bladder cancer were pooled along with 95 % confidence intervals (CI). Summary receiver operating characteristic (ROC) curves were used to summarize overall test performance. Ten studies met our inclusion criteria. The summary estimates for 18 F FDG-PET and PET/CT in the diagnosis of urinary bladder cancer in meta-analysis were as follows: a pooled sensitivity, 0.82 (95 % confidence interval [CI], 0.75 to 0.88); a pooled specificity, 0.92 (95 % CI, 0.87 to 0.95); positive likelihood ratio, 6.80 (95 % CI, 4.31 to 10.74); negative likelihood ratio, 0.27 (95 % CI, 0.19 to 0.36); and diagnostic odds ratio, 25.18 (95 % CI, 17.58 to 70.4). The results indicate that 18 F FDG-PET and PET/CT are relatively high sensitive and specific for the diagnosis of urinary bladder cancer.

  2. Virtual hybrid bronchoscopy using PET/CT data sets

    NASA Astrophysics Data System (ADS)

    Englmeier, Karl-Hans; Seemann, Marcus D.

    2007-03-01

    The aim of this study was to demonstrate the possibilities, advantages and limitations of virtual bronchoscopy using data sets from positron emission tomography (PET) and computed tomography (CT). Eight consecutive patients with lung cancer underwent PET/CT. PET was performed with F-18-labelled 2-[fluorine-18]-fluoro-2-deoxy-D: -glucose ((18)F-FDG). The tracheobronchial system was segmented with a volume-growing algorithm, using the CT data sets, and visualized with a shaded-surface rendering method. The primary tumours and the lymph node metastases were segmented for virtual CT-bronchoscopy using the CT data set and for virtual PET/CT-bronchoscopy using the PET/CT data set. Virtual CT-bronchoscopy using the low-dose or diagnostic CT facilitates the detection of anatomical/morphological structure changes of the tracheobronchial system. Virtual PET/CT-bronchoscopy was superior to virtual CT-bronchoscopy in the detection of lymph node metastases (P=0.001), because it uses the CT information and the molecular/metabolic information from PET. Virtual PET/CT-bronchoscopy with a transparent colour-coded shaded-surface rendering model is expected to improve the diagnostic accuracy of identification and characterization of malignancies, assessment of tumour staging, differentiation of viable tumour tissue from atelectases and scars, verification of infections, evaluation of therapeutic response and detection of an early stage of recurrence that is not detectable or is misjudged in comparison with virtual CT-bronchoscopy.

  3. Update on time-of-flight PET imaging

    PubMed Central

    Surti, Suleman

    2015-01-01

    Time-of-flight (TOF) PET was initially introduced in the early days of PET. TOF PET scanners developed in the 1980s had limited sensitivity and spatial resolution, operated in 2D mode with septa, and used analytic image reconstruction methods. Current generation of TOF PET scanners have the highest sensitivity and spatial resolution ever achieved in commercial whole-body PET, operate in fully-3D mode, and use iterative reconstruction with full system modeling. Previously, it was shown that TOF provides a gain in image signal-to-noise-ratio (SNR) that is proportional to the square root of the object size divided by the system timing resolution. With oncologic studies being the primary application of PET, more recent work has shown that in modern TOF PET scanners there is an improved trade-off between lesion contrast, image noise, and total imaging time, leading to a combination of improved lesion detectability, reduced scan time or injected dose, and more accurate and precise lesion uptake measurement. The benefit of TOF PET is also higher for heavier patients, which leads to a more uniform clinical performance over all patient sizes. PMID:25525181

  4. Influence of Elevated Temperatures on Pet-Concrete Properties

    NASA Astrophysics Data System (ADS)

    Albano, C.; Camacho, N.; Hernández, M.; Matheus, A.; Gutiérrez, A.

    2008-08-01

    Lightweight aggregate is an important material in reducing the unit weight of concrete complying with special concrete structures of large high-rise buildings. Besides, the use of recycled PET bottles as lightweight aggregate in concrete is an effective contribution for environment preservation. So, the objective of the present work was to study experimentally the flexural strength of the PET -concrete blends and the thermal degradation of the PET in the concrete, when the blends with 10 and 20% in volume of PET were exposed to different temperatures (200, 400, 600 °C). The flexural strength of concrete-PET exposed to a heat source is strongly dependent on the temperature, water/cement ratio, as well as the content and particle size of PET. However, the activation energy is affected by the temperature, location of the PET particles on the slabs and the water/cement ratio. Higher water content originates thermal and hydrolytic degradation on the PET, while on the concrete, a higher vapor pressure which causes an increase in crack formation. The values of the activation energy are higher on the center of the slabs than on the surface, since concrete is a poor heat conductor.

  5. Quantitative evaluation of PET image using event information bootstrap

    NASA Astrophysics Data System (ADS)

    Song, Hankyeol; Kwak, Shin Hye; Kim, Kyeong Min; Kang, Joo Hyun; Chung, Yong Hyun; Woo, Sang-Keun

    2016-04-01

    The purpose of this study was to enhance the effect in the PET image quality according to event bootstrap of small animal PET data. In order to investigate the time difference condition, realigned sinograms were generated from randomly sampled data set using bootstrap. List-mode data was obtained from small animal PET scanner for Ge-68 30 sec, Y-90 20 min and Y-90 60 min. PET image was reconstructed by Ordered Subset Expectation Maximization(OSEM) 2D with the list-mode format. Image analysis was investigated by Signal to Noise Ratio(SNR) of Ge-68 and Y-90 image. Non-parametric resampled PET image SNR percent change for the Ge-68 30 sec, Y-90 60 min, and Y-90 20 min was 1.69 %, 7.03 %, and 4.78 %, respectively. SNR percent change of non-parametric resampled PET image with time difference condition was 1.08 % for the Ge-68 30 sec, 6.74 % for the Y-90 60 min and 10.94 % for the Y-90 29 min. The result indicated that the bootstrap with time difference condition had a potential to improve a noisy Y-90 PET image quality. This method should be expected to reduce Y-90 PET measurement time and to enhance its accuracy.

  6. MR/PET or PET/MRI: does it matter?

    PubMed

    Beyer, Thomas; Moser, Ewald

    2013-02-01

    After the very successful clinical introduction of combined PET/CT imaging a decade ago, a hardware combination of PET and MR is following suit. Today, three different approaches towards integrated PET/MR have been proposed: (1) a triple-modality system with a 3T MRI and a time-of-flight PET/CT installed in adjacent rooms, (2) a tandem system with a 3T MRI and a time-of-flight PET/CT in a co-planar installation with a joint patient handling system, and (3) a fully-integrated system with a whole-body PET system mounted inside a 3T MRI system. This special issue of MAGMA brings together contributions from key experts in the field of PET/MR, PET/CT and CT. The various papers share the author's perspectives on the state-of-the-art PET/MR imaging with any of the three approaches mentioned above. In addition to several reviews discussing advantages and challenges of combining PET and MRI for clinical diagnostics, first clinical data are also presented. We expect this special issue to nurture future improvements in hardware, clinical protocols, and efficient post-processing strategies to further assess the diagnostic value of combined PET/MR imaging. It remains to be seen whether a so-called "killer application" for PET/MRI will surface. In that case PET/MR is likely to excel in pre-clinical and selected research applications for now. This special issue helps the readers to stay on track of this exciting development. PMID:23385880

  7. PET studies with low and high affinity dopamine D2 receptor radioligands: Effects of 4-hydroxybutyrate (4HB)

    SciTech Connect

    Gatley, S.J.; Fowler, J.S.; Dewey, S.

    1994-05-01

    D2 radioligands of varying affinities have been developed as PET and SPECT radiotracers, but no consensus has been reached on the abilities of these tracers to quantify D2 receptor concentrations in vivo. Amongst other differences, competition of the radioligand with endogenous DA is expected to depend on affinity for the D2 receptor, so that changes in DA might confound estimates of Bmax. We examined the uptake and kinetics if C-11 raclopride (RAC; Kd = 1.2 nM) and C-11 N-methylspiperone (NMS); Kd = 75 pM in baboon striatum after pretreatment with 4HB (200 mg/Kg, i/v) which inhibits DA release by nigrostriatal nerve terminals. While 4HB diminished uptake (%ID/g) of NMS, it prolonged tissue retention of RAC, confirming previous observations in rodent models. Logan (for RAC) and Patlak (for NMS) plots gave changes of +24% and -20%, respectively, between control and 4HB treated animals. Since decreased competition with DA should increase uptake of NMS as well as RAC the paradoxical decrease in NMS uptake could be due to a second synaptic effect of DA, such as a decrease in agonist mediated internalization of NMS. Alternatively, it could result from an independent effect of 4HB, perhaps related to this drug`s ability to induce anesthesia and to depress cerebral glucose utilization. Although previous work in the rat suggests that 4HB does not alter brain blood flow, we found O-15 water that baboon striatal blood flow was decreased 22% and 42% at 30 and 60 minutes, respectively, after 4HB. Smaller changes were seen in cerebellar blood flow. Though a 4HB induced decrease in blood flow does not rule out a DA mediated alteration in D2 receptor Bmax or Kd for NMS, or other factor, it is unnecessary to invoke this to account for our results.

  8. Detection of Mycobacterium avium in pet birds

    PubMed Central

    Godoy, Silvia Neri; Sakamoto, Sidnei Miyoshi; de Paula, Cátia Dejuste; Catão-Dias, José Luiz; Matushima, Eliana Reiko

    2009-01-01

    The present study is a report on the presence of Mycobacterium avium in four birds of the psittaciform order kept as pets. Anatomopathological diagnosis showed lesions suggestive of the agent and presence of alcohol-acid resistant bacilli (AARB) shown by the Ziehl-Neelsen staining. The identification of Mycobacterium avium was performed by means of PRA (PCR Restriction Analysis). DNA was directly extracted from tissue of the lesions and blocked in paraffin. The role of this agent in pet bird infection is discussed, as well as its zoonotic potential. PMID:24031356

  9. Pet peeves and happiness: how do happy people complain?

    PubMed

    Kowalski, Robin M; Allison, Brooke; Giumetti, Gary W; Turner, Julia; Whittaker, Elizabeth; Frazee, Laura; Stephens, Justin

    2014-01-01

    The present study was designed to investigate the relationships among mindfulness, happiness, and the expression of pet peeves. Previous research has established a positive correlation between happiness and mindfulness, but, to date, no research has examined how each of these variables is related to complaining in the form of pet peeves. Four hundred ten male and female college students listed the pet peeves they had with a current or former relationship partner. They also completed measures of happiness, positive and negative affect, depression, mindfulness, relationship satisfaction, and satisfaction with life. Pet peeves were negatively correlated with relationship satisfaction, well-being, and mindfulness. Consistent with hypotheses, support was found for the mediating role of mindfulness in the relationship between happiness and pet peeves.

  10. Optimization of PET system design for lesion detection

    SciTech Connect

    Qi, Jinyi

    2000-10-13

    Traditionally, the figures of merit used in designing a PET scanner are spatial resolution, noise equivalent count rate, noise equivalent sensitivity, etc. These measures, however, do not directly reflect the lesion detectability using the PET scanner. Here we propose to optimize PET scanner design directly for lesion detection. The signal-to-noise ratio (SNR) of lesion detection can be easily computed using the theoretical expressions that we have previously derived. Because no time consuming Monte Carlo simulation is needed, the theoretical expressions allow evaluation of a large range of parameters. The PET system parameters can then be chosen to achieve the maximum SNR for lesion detection. The simulation study shown in this paper was focused a single ring PET scanner without depth of interaction measurement. Randoms and scatters were also ignored.

  11. PET/MRI in Oncological Imaging: State of the Art

    PubMed Central

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J.

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging. PMID:26854157

  12. PET/MRI in Oncological Imaging: State of the Art.

    PubMed

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition se