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Sanson F, Pandey AK, Papagiannouli I, Harms F, Dovillaire G, Baynard E, Demailly J, Guilbaud O, Lucas B, Neveu O, Pittman M, Ros D, Richardson M, Johnson E, Li W, Balcou P, Kazamias S. Highly multimodal structure of high topological charge extreme ultraviolet vortex beams. Opt Lett 2020; 45:4790-4793. [PMID: 32870858 DOI: 10.1364/ol.397206] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 07/28/2020] [Indexed: 06/11/2023]
Abstract
Optical beams carrying orbital angular momentum are a very active field of research for their prospective applications, especially at short wavelengths. We consider here such beams produced through high-harmonic generation (HHG) in a rare gas and analyze the characterization of their high-charge vortex structure by an extreme ultraviolet Hartmann wavefront sensor. We show that such HHG beams are generally composed of a set of numerous vortex modes. The sensitivity of the intensity and phase of the HHG beam to the infrared laser aberrations is investigated using a deformable mirror.
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Mayoral M, Niñerola-Baizán A, Marti-Fuster B, Donaire A, Perissinotti A, Rumià J, Bargalló N, Sala-Llonch R, Pavia J, Ros D, Carreño M, Pons F, Setoain X. Epileptogenic Zone Localization With 18FDG PET Using a New Dynamic Parametric Analysis. Front Neurol 2019; 10:380. [PMID: 31057476 PMCID: PMC6478660 DOI: 10.3389/fneur.2019.00380] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/28/2019] [Indexed: 11/13/2022] Open
Abstract
Introduction: [18F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is part of the regular preoperative work-up in medically refractory epilepsy. As a complement to visual evaluation of PET, statistical parametric maps can help in the detection of the epileptogenic zone (EZ). However, software packages currently available are time-consuming and little intuitive for physicians. We develop a user-friendly software (referred as PET-analysis) for EZ localization in PET studies that allows dynamic real-time statistical parametric analysis. To evaluate its performance, the outcome of PET-analysis was compared with the results obtained by visual assessment and Statistical Parametric Mapping (SPM). Methods: Thirty patients with medically refractory epilepsy who underwent presurgical 18F-FDG PET with good post-operative outcomes were included. The 18F-FDG PET studies were evaluated by visual assessment, with SPM8 and PET-analysis. In SPM, parametric T-maps were thresholded at corrected p < 0.05 and cluster size k = 50 and at uncorrected p < 0.001 and k = 100 (the most used parameters in the literature). Since PET-analysis rapidly processes different threshold combinations, T-maps were thresholded with multiple p-value and different clusters sizes. The presurgical EZ identified by visual assessment, SPM and PET-analysis was compared to the confirmed EZ according to post-surgical follow-up. Results: PET-analysis obtained 66.7% (20/30) of correctly localizing studies, comparable to the 70.0% (21/30) achieved by visual assessment and significantly higher (p < 0.05) than that obtained with the SPM threshold p < 0.001/k = 100, of 36.7% (11/30). Only one study was positive, albeit non-localizing, with the SPM threshold corrected p < 0.05/k = 50. Concordance was substantial for PET-analysis (κ = 0.643) and visual interpretation (κ = 0.622), being fair for SPM (κ = 0.242). Conclusion: Compared to SPM with the fixed standard parameters, PET-analysis may be superior in EZ localization with its easy and rapid processing of different threshold combinations. The results of this initial proof-of-concept study validate the clinical use of PET-analysis as a robust objective complementary tool to visual assessment for EZ localization.
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Affiliation(s)
- Maria Mayoral
- Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain
| | - Aida Niñerola-Baizán
- Biomedical Imaging Group, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,Biophysics and Bioengineering Unit, Biomedicine Department, School of Medicine, University of Barcelona, Barcelona, Spain
| | - Berta Marti-Fuster
- Biomedical Imaging Group, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,Biophysics and Bioengineering Unit, Biomedicine Department, School of Medicine, University of Barcelona, Barcelona, Spain
| | - Antonio Donaire
- Neurology Department, Hospital Clínic, Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
| | | | - Jordi Rumià
- Neurosurgery Department, Hospital Clínic, Barcelona, Spain
| | - Núria Bargalló
- August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain.,Radiology Department, Hospital Clínic, Barcelona, Spain
| | - Roser Sala-Llonch
- Biophysics and Bioengineering Unit, Biomedicine Department, School of Medicine, University of Barcelona, Barcelona, Spain
| | - Javier Pavia
- Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.,Biomedical Imaging Group, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
| | - Domènec Ros
- Biomedical Imaging Group, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,Biophysics and Bioengineering Unit, Biomedicine Department, School of Medicine, University of Barcelona, Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
| | - Mar Carreño
- Neurology Department, Hospital Clínic, Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
| | - Francesca Pons
- Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
| | - Xavier Setoain
- Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain.,Biomedical Imaging Group, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,August Pi i Sunyer Biomedical Research Institute (IDIBAPS), Barcelona, Spain
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Perissinotti A, Niñerola-Baizán A, Rubí S, Carreño M, Marti-Fuster B, Aparicio J, Mayoral M, Donaire A, Sanchez-Izquierdo N, Bargalló N, Rumiá J, Boget T, Pons F, Lomeña F, Ros D, Pavía J, Setoain X. PISCOM: a new procedure for epilepsy combining ictal SPECT and interictal PET. Eur J Nucl Med Mol Imaging 2018; 45:2358-2367. [PMID: 30069576 PMCID: PMC6208811 DOI: 10.1007/s00259-018-4080-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/25/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE We present a modified version of the SISCOM procedure that uses interictal PET instead of interictal SPECT for seizure onset zone localization. We called this new nuclear imaging processing technique PISCOM (PET interictal subtracted ictal SPECT coregistered with MRI). METHODS We retrospectively studied 23 patients (age range 4-61 years) with medically refractory epilepsy who had undergone MRI, ictal SPECT, interictal SPECT and interictal FDG PET and who had been seizure-free for at least 2 years after surgical treatment. FDG PET images were reprocessed (rFDG PET) to assimilate SPECT features for image subtraction. Interictal SPECT and rFDG PET were compared using statistical parametric mapping (SPM). PISCOM and SISCOM images were evaluated visually and using an automated volume of interest-based analysis. The results of the two studies were compared with each other and with the known surgical resection site. RESULTS SPM showed no significant differences in cortical activity between SPECT and rFDG PET images. PISCOM and SISCOM showed equivalent results in 17 of 23 patients (74%). The seizure onset zone was successfully identified in 19 patients (83%) by PISCOM and in 17 (74%) by SISCOM: in 15 patients (65%) the two techniques showed concordant successful results. The volume of interest-based analysis showed no significant differences between PISCOM and SISCOM in identifying the extension of the seizure onset zone. However, PISCOM showed a lower amount of indeterminate activity due to propagation, background or artefacts. CONCLUSION Preliminary findings of this initial proof-of-concept study suggest that perfusion and glucose metabolism in the cerebral cortex can be correlated and that PISCOM may be a valid technique for identification of the seizure onset zone. However, further studies are needed to validate these results.
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Affiliation(s)
- Andrés Perissinotti
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain
| | - Aida Niñerola-Baizán
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,University of Barcelona, Barcelona, Spain
| | - Sebastià Rubí
- Nuclear Medicine Department, Hospital Universitari Son Espases, Palma, Spain.,Institut d'Investigació Sanitària Illes Balears (IdISBa), Palma, Spain
| | - Mar Carreño
- Department of Neurology, Hospital Clínic, Barcelona, Spain
| | - Berta Marti-Fuster
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,University of Barcelona, Barcelona, Spain
| | - Javier Aparicio
- Department of Neurology, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Maria Mayoral
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain
| | | | | | - Nuria Bargalló
- Department of Radiology, Hospital Clínic, Barcelona, Spain
| | - Jordi Rumiá
- Department of Neurosurgery, Hospital Clínic, Barcelona, Spain
| | - Teresa Boget
- Department of Psychiatry and Psychology, Hospital Clínic, Barcelona, Spain
| | - Francesca Pons
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain.,University of Barcelona, Barcelona, Spain
| | - Francisco Lomeña
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain
| | - Domènec Ros
- Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.,University of Barcelona, Barcelona, Spain
| | - Javier Pavía
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Xavier Setoain
- Department of Nuclear Medicine, Hospital Clínic, C/Villarroel 170, 08036, Barcelona, Spain. .,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain. .,University of Barcelona, Barcelona, Spain.
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Sanson F, Pandey AK, Harms F, Dovillaire G, Baynard E, Demailly J, Guilbaud O, Lucas B, Neveu O, Pittman M, Ros D, Richardson M, Johnson E, Li W, Balcou P, Kazamias S. Hartmann wavefront sensor characterization of a high charge vortex beam in the extreme ultraviolet spectral range. Opt Lett 2018; 43:2780-2783. [PMID: 29905687 DOI: 10.1364/ol.43.002780] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate for the first time, to the best of our knowledge, the ability of extreme ultraviolet (XUV) Hartmann wavefront sensors to characterize high charge vortex beams produced by high-order harmonic generation up to the order of 25. We also show that phase matched absorption limited high harmonic generation is able to maintain the high charge vortex structure of the XUV beam even in a rather long (1 cm) generation medium.
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5
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Niñerola-Baizán A, Gallego J, Cot A, Aguiar P, Lomeña F, Pavía J, Ros D. Optimization of the reconstruction parameters in [ 123I]FP-CIT SPECT. Phys Med Biol 2018; 63:085009. [PMID: 29553048 DOI: 10.1088/1361-6560/aab799] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this work was to obtain a set of parameters to be applied in [123I]FP-CIT SPECT reconstruction in order to minimize the error between standardized and true values of the specific uptake ratio (SUR) in dopaminergic neurotransmission SPECT studies. To this end, Monte Carlo simulation was used to generate a database of 1380 projection data-sets from 23 subjects, including normal cases and a variety of pathologies. Studies were reconstructed using filtered back projection (FBP) with attenuation correction and ordered subset expectation maximization (OSEM) with correction for different degradations (attenuation, scatter and PSF). Reconstruction parameters to be optimized were the cut-off frequency of a 2D Butterworth pre-filter in FBP, and the number of iterations and the full width at Half maximum of a 3D Gaussian post-filter in OSEM. Reconstructed images were quantified using regions of interest (ROIs) derived from Magnetic Resonance scans and from the Automated Anatomical Labeling map. Results were standardized by applying a simple linear regression line obtained from the entire patient dataset. Our findings show that we can obtain a set of optimal parameters for each reconstruction strategy. The accuracy of the standardized SUR increases when the reconstruction method includes more corrections. The use of generic ROIs instead of subject-specific ROIs adds significant inaccuracies. Thus, after reconstruction with OSEM and correction for all degradations, subject-specific ROIs led to errors between standardized and true SUR values in the range [-0.5, +0.5] in 87% and 92% of the cases for caudate and putamen, respectively. These percentages dropped to 75% and 88% when the generic ROIs were used.
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Affiliation(s)
- Aida Niñerola-Baizán
- Department of Biomedicine, Universitat de Barcelona, Barcelona, Spain. Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
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López-Vilanova N, Pavía J, Duch MA, Catafau A, Ros D, Bullich S. Impact of Region-of-Interest Delineation Methods, Reconstruction Algorithms, and Intra- and Inter-Operator Variability on Internal Dosimetry Estimates Using PET. Mol Imaging Biol 2016; 19:305-314. [PMID: 27632424 DOI: 10.1007/s11307-016-1003-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Human dosimetry studies play a central role in radioligand development for positron emission tomography (PET). Drawing regions of interest (ROIs) on the PET images is used to measure the dose in each organ. In the study aspects related to ROI delineation methods were evaluated for two radioligands of different biodistribution (intestinal vs urinary). PROCEDURES PET images were simulated from a human voxel-based phantom. Several ROI delineation methods were tested: antero-posterior projections (AP), 3D sub-samples of the organs (S), and a 3D volume covering the whole-organ (W). Inter- and intra-operator variability ROI drawing was evaluated by using human data. RESULTS The effective dose estimates using S and W methods were comparable to the true values. AP methods overestimated (49 %) the dose for the radioligand with intestinal biodistribution. Moreover, the AP method showed the highest inter-operator variability: 11 ± 1 %. CONCLUSIONS The sub-sampled organ method showed the best balance between quantitative accuracy and inter- and intra-operator variability.
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Affiliation(s)
- N López-Vilanova
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain. .,Institut de Tècniques Energètiques (INTE), Universitat Politècnica de Catalunya (UPC), Barcelona, Spain.
| | - J Pavía
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.,Nuclear Medicine Department, Hospital Clínic i Provincial de Barcelona, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - M A Duch
- Institut de Tècniques Energètiques (INTE), Universitat Politècnica de Catalunya (UPC), Barcelona, Spain
| | - A Catafau
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Barcelona Imaging Group (BIG), Barcelona, Spain
| | - D Ros
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Unitat de Biofísica i Bioenginyeria, Universitat de Barcelona, Barcelona, Spain
| | - S Bullich
- Molecular Imaging Centre (CRC-CIM), Barcelona Biomedical Research Park, Barcelona, Spain
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Sampedro F, Vilaplana E, de Leon MJ, Alcolea D, Pegueroles J, Montal V, Carmona-Iragui M, Sala I, Sánchez-Saudinos MB, Antón-Aguirre S, Morenas-Rodríguez E, Camacho V, Falcón C, Pavía J, Ros D, Clarimón J, Blesa R, Lleó A, Fortea J. APOE-by-sex interactions on brain structure and metabolism in healthy elderly controls. Oncotarget 2016; 6:26663-74. [PMID: 26397226 PMCID: PMC4694943 DOI: 10.18632/oncotarget.5185] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 08/28/2015] [Indexed: 11/25/2022] Open
Abstract
Background The APOE effect on Alzheimer Disease (AD) risk is stronger in women than in men but its mechanisms have not been established. We assessed the APOE-by-sex interaction on core CSF biomarkers, brain metabolism and structure in healthy elderly control individuals (HC). Methods Cross-sectional study. HC from the Alzheimer’s Disease Neuroimaging Initiative with available CSF (n = 274) and/or 3T-MRI (n = 168) and/or a FDG-PET analyses (n = 328) were selected. CSF amyloid-β1–42 (Aβ1–42), total-tau (t-tau) and phospho-tau (p-tau181p) levels were measured by Luminex assays. We analyzed the APOE-by-sex interaction on the CSF biomarkers in an analysis of covariance (ANCOVA). FDG uptake was analyzed by SPM8 and cortical thickness (CTh) was measured by FreeSurfer. FDG and CTh difference maps were derived from interaction and group analyses. Results APOE4 carriers had lower CSF Aβ1–42 and higher CSF p-tau181p values than non-carriers, but there was no APOE-by-sex interaction on CSF biomarkers. The APOE-by-sex interaction on brain metabolism and brain structure was significant. Sex stratification showed that female APOE4 carriers presented widespread brain hypometabolism and cortical thinning compared to female non-carriers whereas male APOE4 carriers showed only a small cluster of hypometabolism and regions of cortical thickening compared to male non-carriers. Conclusions The impact of APOE4 on brain metabolism and structure is modified by sex. Female APOE4 carriers show greater hypometabolism and atrophy than male carriers. This APOE-by-sex interaction should be considered in clinical trials in preclinical AD where APOE4 status is a selection criterion.
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Affiliation(s)
- Frederic Sampedro
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain.,Nuclear Medicine Department, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Eduard Vilaplana
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Mony J de Leon
- New York University School of Medicine, New York, NY, USA
| | - Daniel Alcolea
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Jordi Pegueroles
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Victor Montal
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - María Carmona-Iragui
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Isabel Sala
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - María-Belén Sánchez-Saudinos
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Sofía Antón-Aguirre
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Estrella Morenas-Rodríguez
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Valle Camacho
- Nuclear Medicine Department, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Carles Falcón
- Unitat de Biofísica i Bioenginyeria, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona - IDIBAPS, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine - CIBER-BBN, Barcelona, Spain
| | - Javier Pavía
- Nuclear Medicine Department. Hospital Clínic de Barcelona, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine - CIBER-BBN, Barcelona, Spain
| | - Domènec Ros
- Unitat de Biofísica i Bioenginyeria, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona - IDIBAPS, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine - CIBER-BBN, Barcelona, Spain
| | - Jordi Clarimón
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Rafael Blesa
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Alberto Lleó
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
| | - Juan Fortea
- Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau - Biomedical Research Institute Sant Pau - Universitat Autònoma de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain
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Guilbaud O, Cojocaru GV, Li L, Delmas O, Ungureanu RG, Banici RA, Kazamias S, Cassou K, Neveu O, Demailly J, Baynard E, Pittman M, Le Marec A, Klisnick A, Zeitoun P, Ursescu D, Ros D. Gain dynamics in quickly ionized plasma for seeded operated soft x-ray lasers. Opt Lett 2015; 40:4775-4778. [PMID: 26469617 DOI: 10.1364/ol.40.004775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Harmonic seeded operation of a neon-like titanium plasma-based soft x-ray laser is described. The plasma amplifier is pumped with a variation of the grazing incidence technique involving a fast and localized ionization step. We discuss its effect on gain dynamics by measuring the amplifying factor as a function of the delay between pump pulse and harmonic seed. Two different regimes are pointed out, following the pumping scheme used. For one of them, a delay in the gain generation compared with the pumping laser pulse is observed.
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Gallego J, Niñerola-Baizán A, Cot A, Aguiar P, Crespo C, Falcón C, Lomeña F, Sempau J, Pavía J, Ros D. Validation of semi-quantitative methods for DAT SPECT: influence of anatomical variability and partial volume effect. Phys Med Biol 2015; 60:5925-38. [PMID: 26184983 DOI: 10.1088/0031-9155/60/15/5925] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this work was to evaluate the influence of anatomical variability between subjects and of the partial volume effect (PVE) on the standardized Specific Uptake Ratio (SUR) in [(123)I]FP-bib SPECT studies. To this end, magnetic resonance (MR) images of 23 subjects with differences in the striatal volume of up to 44% were segmented and used to generate a database of 138 Monte Carlo simulated SPECT studies. Data included normal uptakes and pathological cases. Studies were reconstructed by filtered back projection (FBP) and the ordered-subset expectation-maximization algorithm. Quantification was carried out by applying a reference method based on regions of interest (ROIs) derived from the MR images and ROIs derived from the Automated Anatomical Labelling map. Our results showed that, regardless of anatomical variability, the relationship between calculated and true SUR values for caudate and putamen could be described by a multiple linear model which took into account the spill-over phenomenon caused by PVE (R² ≥ 0.963 for caudate and ≥0.980 for putamen) and also by a simple linear model (R(2) ≥ 0.952 for caudate and ≥0.973 for putamen). Calculated values were standardized by inverting both linear systems. Differences between standardized and true values showed that, although the multiple linear model was the best approach in terms of variability (X² ≥ 11.79 for caudate and ≤7.36 for putamen), standardization based on a simple linear model was also suitable (X² ≥ 12.44 for caudate and ≤12.57 for putamen).
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Affiliation(s)
- J Gallego
- Unitat de Biofísica i Bioenginyeria, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona-IDIBAPS, Barcelona, Spain. Institut de Tècniques Energètiques, Universitat Politècnica de Catalunya, Barcelona, Spain
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Pino F, Roé N, Aguiar P, Falcon C, Ros D, Pavía J. Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems. Med Phys 2015; 42:703-14. [PMID: 25652484 DOI: 10.1118/1.4905157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera. METHODS Three methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4-2008 image-quality phantom. RESULTS A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12. CONCLUSIONS Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters.
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Affiliation(s)
- Francisco Pino
- Unitat de Biofísica, Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain and Servei de Física Mèdica i Protecció Radiològica, Institut Català d'Oncologia, L'Hospitalet de Llobregat 08907, Spain
| | - Nuria Roé
- Unitat de Biofísica, Facultat de Medicina, Universitat de Barcelona, Barcelona 08036, Spain
| | - Pablo Aguiar
- Fundación Ramón Domínguez, Complexo Hospitalario Universitario de Santiago de Compostela 15706, Spain and Grupo de Imagen Molecular, Instituto de Investigacións Sanitarias de Santiago de Compostela (IDIS), Galicia 15782, Spain
| | - Carles Falcon
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona 08036, Spain
| | - Domènec Ros
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain and CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona 08036, Spain
| | - Javier Pavía
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 080836, Spain; CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona 08036, Spain; and Servei de Medicina Nuclear, Hospital Clínic, Barcelona 08036, Spain
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Niñerola-Baizán A, Rojas S, Roé-Vellvé N, Lomeña F, Ros D, Pavía J. Dopamine transporter imaging in the aged rat: a [¹²³I]FP-CIT SPECT study. Nucl Med Biol 2015; 42:395-8. [PMID: 25624150 DOI: 10.1016/j.nucmedbio.2014.12.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 12/23/2014] [Accepted: 12/30/2014] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Rodent models are extensively used to assess the biochemical and physiological changes associated with aging. They play a major role in the development of therapies for age-related pathologies such as Parkinson's disease. To validate the usefulness of these animal models in aging or age-related disease research, the consistency of cerebral aging processes across species must be evaluated. The dopaminergic system seems particularly susceptible to the aging process. One of the results of this susceptibility is a decline in striatal dopamine transporter (DAT) availability. METHODS We sought to ascertain whether similar age changes could be detected in-vivo in rats, using molecular imaging techniques such as single photon emission computed tomography (SPECT) with [(123)I]FP-CIT. RESULTS A significant decrease of 17.21% in the striatal specific uptake ratio was observed in the aged rats with respect to the young control group. CONCLUSIONS Our findings suggest that age-related degeneration in the nigrostriatal track is similar in humans and rats, which supports the use of this animal in models to evaluate the effect of aging on the dopaminergic system. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE Our findings indicate that age-related degeneration in the nigrostriatal track is similar in humans and rats and that these changes can be monitored in vivo using small animal SPECT with [(123)I]FP-CIT, which could facilitate the translational research in rat models of age related disorders of dopaminergic system.
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Affiliation(s)
- Aida Niñerola-Baizán
- Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona
| | - Santiago Rojas
- Institut d'Alta Tecnologia, PRBB, CRC Corporació Sanitària; Fundació Pasqual Maragall
| | - Núria Roé-Vellvé
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona; Unidad de Imagen, CIMES, Fundación General de la Universidad de Málaga
| | - Francisco Lomeña
- Servei de Medicina Nuclear, Hospital Clínic de Barcelona; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM); Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)
| | - Domènec Ros
- Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS)
| | - Javier Pavía
- Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN); Servei de Medicina Nuclear, Hospital Clínic de Barcelona; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS).
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12
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Popota FD, Aguiar P, España S, Lois C, Udias JM, Ros D, Pavia J, Gispert JD. Monte Carlo simulations versus experimental measurements in a small animal PET system. A comparison in the NEMA NU 4-2008 framework. Phys Med Biol 2015; 60:151-62. [PMID: 25479341 DOI: 10.1088/0031-9155/60/1/151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this work a comparison between experimental and simulated data using GATE and PeneloPET Monte Carlo simulation packages is presented. All simulated setups, as well as the experimental measurements, followed exactly the guidelines of the NEMA NU 4-2008 standards using the microPET R4 scanner. The comparison was focused on spatial resolution, sensitivity, scatter fraction and counting rates performance. Both GATE and PeneloPET showed reasonable agreement for the spatial resolution when compared to experimental measurements, although they lead to slight underestimations for the points close to the edge. High accuracy was obtained between experiments and simulations of the system's sensitivity and scatter fraction for an energy window of 350-650 keV, as well as for the counting rate simulations. The latter was the most complicated test to perform since each code demands different specifications for the characterization of the system's dead time. Although simulated and experimental results were in excellent agreement for both simulation codes, PeneloPET demanded more information about the behavior of the real data acquisition system. To our knowledge, this constitutes the first validation of these Monte Carlo codes for the full NEMA NU 4-2008 standards for small animal PET imaging systems.
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Affiliation(s)
- F D Popota
- Unitat de Biofisica i Bioenginyeria, Universitat de Barcelona, Barcelona, Spain. Universidad de Pompeu Fabra, Barcelona, Spain
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13
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El Bitar Z, Pino F, Candela C, Ros D, Pavía J, Rannou FR, Ruibal A, Aguiar P. The performance of a hybrid analytical-Monte Carlo system response matrix in pinhole SPECT reconstruction. Phys Med Biol 2014; 59:7573-85. [DOI: 10.1088/0031-9155/59/24/7573] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Roé-Vellvé N, Pino F, Falcon C, Cot A, Gispert JD, Marin C, Pavía J, Ros D. Quantification of rat brain SPECT with (123)I-ioflupane: evaluation of different reconstruction methods and image degradation compensations using Monte Carlo simulation. Phys Med Biol 2014; 59:4567-82. [PMID: 25069105 DOI: 10.1088/0031-9155/59/16/4567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SPECT studies with (123)I-ioflupane facilitate the diagnosis of Parkinson's disease (PD). The effect on quantification of image degradations has been extensively evaluated in human studies but their impact on studies of experimental PD models is still unclear. The aim of this work was to assess the effect of compensating for the degrading phenomena on the quantification of small animal SPECT studies using (123)I-ioflupane. This assessment enabled us to evaluate the feasibility of quantitatively detecting small pathological changes using different reconstruction methods and levels of compensation for the image degrading phenomena. Monte Carlo simulated studies of a rat phantom were reconstructed and quantified. Compensations for point spread function (PSF), scattering, attenuation and partial volume effect were progressively included in the quantification protocol. A linear relationship was found between calculated and simulated specific uptake ratio (SUR) in all cases. In order to significantly distinguish disease stages, noise-reduction during the reconstruction process was the most relevant factor, followed by PSF compensation. The smallest detectable SUR interval was determined by biological variability rather than by image degradations or coregistration errors. The quantification methods that gave the best results allowed us to distinguish PD stages with SUR values that are as close as 0.5 using groups of six rats to represent each stage.
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Affiliation(s)
- N Roé-Vellvé
- Unitat de Biofísica i Bioenginyeria, Universitat de Barcelona, Casanova 143, 08036 Barcelona, Spain. Unidad de Imagen, CIMES, Fundación General de la Universidad de Málaga, Marqués de Beccaria 3, 29010, Málaga, Spain
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15
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Tudela R, Soria G, Pérez-De-Puig I, Ros D, Pavía J, Planas AM. Infarct volume prediction using apparent diffusion coefficient maps during middle cerebral artery occlusion and soon after reperfusion in the rat. Brain Res 2014; 1583:169-78. [PMID: 25128601 DOI: 10.1016/j.brainres.2014.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/30/2014] [Accepted: 08/06/2014] [Indexed: 11/19/2022]
Abstract
Middle cerebral artery occlusion (MCAO) in rodents causes brain infarctions of variable sizes that depend on multiple factors, particularly in models of ischemia/reperfusion. This is a major problem for infarct volume comparisons between different experimental groups since unavoidable variability can induce biases in the results and imposes the use of large number of subjects. MRI can help to minimize these difficulties by ensuring that the severity of ischemia is comparable between groups. Furthermore, several studies showed that infarct volumes can be predicted with MRI data obtained soon after ischemia onset. However, such predictive studies require multiparametric MRI acquisitions that cannot be routinely performed, and data processing using complex algorithms that are often not available. The aim here was to provide a simplified method for infarct volume prediction using apparent diffusion coefficient (ADC) data in a model of transient MCAO in rats. ADC images were obtained before, during MCAO and after 60 min of reperfusion. Probability histograms were generated using ADC data obtained either during MCAO, after reperfusion, or both combined. The results were compared to real infarct volumes, i.e.T2 maps obtained at day 7. Assessment of the performance of the estimations showed better results combining ADC data obtained during occlusion and at reperfusion. Therefore, ADC data alone can provide sufficient information for a reasonable prediction of infarct volume if the MRI information is obtained both during the occlusion and soon after reperfusion. This approach can be used to check whether drug administration after MRI acquisition can change infarct volume prediction.
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Affiliation(s)
- Raúl Tudela
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.
| | - Guadalupe Soria
- Experimental MRI 7T Unit, IDIBAPS, Barcelona, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain
| | - Isabel Pérez-De-Puig
- Department of Brain Ischemia and Neurodegeneration, Institut d'Investigacions Biomèdiques de Barcelona (IIBB)-Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain; IDIBAPS, Barcelona, Spain
| | - Domènec Ros
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain; Biophysics and Bioengineering Laboratory, University of Barcelona, Barcelona, Spain
| | - Javier Pavía
- CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain; Nuclear Medicine Department, Hospital Clínic, Barcelona, Spain
| | - Anna M Planas
- Department of Brain Ischemia and Neurodegeneration, Institut d'Investigacions Biomèdiques de Barcelona (IIBB)-Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain; IDIBAPS, Barcelona, Spain
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16
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Niñerola-Baizán A, Rojas S, Bonastre M, Tudela R, Lomeña F, Pavía J, Marin C, Ros D. In vivo evaluation of the dopaminergic neurotransmission system using [123I]FP-CIT SPECT in 6-OHDA lesioned rats. Contrast Media Mol Imaging 2014; 10:67-73. [PMID: 24888455 DOI: 10.1002/cmmi.1608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 03/24/2014] [Accepted: 04/10/2014] [Indexed: 02/04/2023]
Abstract
The 6-hydroxydopamine (6-OHDA) rodent model of Parkinson's disease (PD) has been used to evaluate the nigrostriatal pathway. The aim of this work was to explore the relationship between the degree of 6-OHDA-induced dopaminergic degeneration and [(123)I]FP-CIT binding using single photon emission computed tomography (SPECT). Fourteen rats received a 6-OHDA injection (4 or 8 µg) into the left medial forebrain bundle. After 3 weeks, magnetic resonance imaging and scans with a small-animal SPECT system were performed. Finally, the nigrostriatal lesion was assessed by immunohistochemical analysis. Immunohistochemical analysis confirmed two levels of dopaminergic degeneration. Lesions induced by 6-OHDA diminished the ipsilateral [(123)I]FP-CIT binding by 61 and 76%, respectively. The decrease in tracer uptake between control and lesioned animals was statistically significant, as was the difference between the two 6-OHDA lesioned groups. Results concluded that [(123)I]FP-CIT SPECT is a useful technique to discriminate the degree of dopaminergic degeneration in a rat model of PD.
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Affiliation(s)
- Aida Niñerola-Baizán
- Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Bioingeniería, Biomateriales y Nanomedicina, Barcelona, Spain
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Wilson LA, Tallents GJ, Pasley J, Whittaker DS, Rose SJ, Guilbaud O, Cassou K, Kazamias S, Daboussi S, Pittman M, Delmas O, Demailly J, Neveu O, Ros D. Energy transport in short-pulse-laser-heated targets measured using extreme ultraviolet laser backlighting. Phys Rev E 2012; 86:026406. [PMID: 23005868 DOI: 10.1103/physreve.86.026406] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 06/26/2012] [Indexed: 11/07/2022]
Abstract
The accurate characterization of thermal electron transport and the determination of heating by suprathermal electrons in laser driven solid targets are both issues of great importance to the current experiments being performed at the National Ignition Facility, which aims to achieve thermonuclear fusion ignition using lasers. Ionization, induced by electronic heat conduction, can cause the opacity of a material to drop significantly once bound-free photoionization is no longer energetically possible. We show that this drop in opacity enables measurements of the transmission of extreme ultraviolet (EUV) laser pulses at 13.9 nm to act as a signature of the heating of thin (50 nm) iron layers with a 50-nm thick parylene-N (CH) overlay irradiated by 35-fs pulses at irradiance 3×10(16) Wcm(-2). Comparing EUV transmission measurements at different times after irradiation to fluid code simulations shows that the target is instantaneously heated by hot electrons (with approximately 10% of the laser energy), followed by thermal conduction with a flux limiter of ≈0.05.
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Affiliation(s)
- L A Wilson
- York Plasma Institute, The Department of Physics, The University of York, York, UK.
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Lopez-Vilanova N, Pavía J, Ros D, Bullich S. EP-1411 IMPACT OF REGION-OF-INTEREST DELINEATION METHODS ON INTERNAL DOSIMETRY ESTIMATES USING PET. Radiother Oncol 2012. [DOI: 10.1016/s0167-8140(12)71744-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Habib J, Guilbaud O, Zielbauer B, Zimmer D, Pittman M, Kazamias S, Montet C, kuehl T, Ros D. Low energy prepulse for 10 Hz operation of a soft-x-ray laser. Opt Express 2012; 20:10128-10137. [PMID: 22535105 DOI: 10.1364/oe.20.010128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The influence on Nickel-like Molybdenum soft-x-ray laser performance and stability of a low energy laser prepulse arriving prior to the main laser pumping pulses is experimentally investigated. A promising regime for 10 Hz operation has been observed. A four times increase in soft-x-ray laser operation time with a same target surface is demonstrated. This soft-x-ray laser operation mode corresponds to an optimum delay between the prepulse and the main pulses and to a prepulse energy greater than 20 mJ. We also show that this regime is not associated with a weaker degradation of the target or any reduced ablation rate. Therefore the role of preplasma density gradient in this effect is discussed.
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Affiliation(s)
- J Habib
- LASERIX, Univ. Paris-Sud, bat 210 campus d’Orsay, 91405 Orsay, France.
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20
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Horga G, Parellada E, Lomeña F, Fernández-Egea E, Mané A, Font M, Falcón C, Konova AB, Pavia J, Ros D, Bernardo M. Differential brain glucose metabolic patterns in antipsychotic-naïve first-episode schizophrenia with and without auditory verbal hallucinations. J Psychiatry Neurosci 2011; 36:312-21. [PMID: 21266125 PMCID: PMC3163647 DOI: 10.1503/jpn.100085] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Auditory verbal hallucinations (AVHs) are a core symptom of schizophrenia. Previous reports on neural activity patterns associated with AVHs are inconsistent, arguably owing to the lack of an adequate control group (i.e., patients with similar characteristics but without AVHs) and neglect of the potential confounding effects of medication. METHODS The current study was conducted in a homogeneous group of patients with schizophrenia to assess whether the presence or absence of AVHs was associated with differential regional cerebral glucose metabolic patterns. We investigated differences between patients with commenting AVHs and patients without AVHs among a group of dextral antipsychotic-naive inpatients with acute first-episode schizophrenia examined with [(18)F]fluoro-deoxyglucose positron emission tomography (FDG-PET) at rest. Univariate and multivariate approaches were used to establish between-group differences. RESULTS We included 9 patients with AVHs and 7 patients without AVHs in this study. Patients experiencing AVHs during FDG uptake had significantly higher metabolic rates in the left superior and middle temporal cortices, bilateral superior medial frontal cortex and left caudate nucleus (cluster level p < 0.005, family wise error-corrected, and bootstrap ratio > 3.3, respectively). Additionally, the multivariate method identified hippocampal-parahippocampal, cerebellar and parietal relative hypoactivity during AVHs in both hemispheres (bootstrap ratio < -3.3). LIMITATIONS The FDG-PET imaging technique does not provide information regarding the temporal course of neural activity. The limited sample size may have increased the risk of false-negative findings. CONCLUSION Our results indicate that AVHs in patients with schizophrenia may be mediated by an alteration of neural pathways responsible for normal language function. Our findings also point to the potential role of the dominant caudate nucleus and the parahippocampal gyri in the pathophysiology of AVHs. We discuss the relevance of phenomenology-based grouping in the study of AVHs.
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Affiliation(s)
- Guillermo Horga
- Clinic Schizophrenia Program, Psychiatry Department, Hospital Clinic of Barcelona, Barcelona, Spain.
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Iranzo A, Valldeoriola F, Lomeña F, Molinuevo JL, Serradell M, Salamero M, Cot A, Ros D, Pavía J, Santamaria J, Tolosa E. Serial dopamine transporter imaging of nigrostriatal function in patients with idiopathic rapid-eye-movement sleep behaviour disorder: a prospective study. Lancet Neurol 2011; 10:797-805. [PMID: 21802993 DOI: 10.1016/s1474-4422(11)70152-1] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Serial dopamine transporter (DAT) imaging in patients with Parkinson's disease (PD) and other synucleinopathies shows progressive nigrostriatal dopaminergic dysfunction. Because idiopathic rapid-eye-movement (REM) sleep behaviour disorder (IRBD) can precede the classic symptoms of PD and other synucleinopathies, we postulated that serial DAT imaging in patients with IRBD could be used to detect decline in striatal tracer uptake, indicating progressive nigrostriatal cell degeneration. METHODS In a prospective study, 20 patients with IRBD (mean age 70·55 years [SD 6·02]) underwent serial DAT imaging with (123)I-2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane ((123)I-FP-CIT) SPECT at baseline and again after 1·5 years and 3 years; 20 age-matched and sex-matched control participants (69·50 years [6·77]) underwent imaging at baseline and 3 years. The striatum to occipital cortex uptake ratios were calculated for the putamen and caudate nucleus in each hemisphere. In patients, the ratio was judged to be reduced when it was less than two SD of the mean ratio in controls at the same timepoint. Differences in (123)I-FP-CIT uptake between patients and controls in each striatal region and rates of decline were assessed by use of multivariate ANOVA (MANOVA). FINDINGS Compared with controls, patients had significantly reduced mean (123)I-FP-CIT binding in all four striatal regions at baseline and after 3 years. Striatal (123)I-FP-CIT uptake was reduced compared with that in controls in ten patients at baseline and in 13 patients after 3 years. In patients, the mean reduction in (123)I-FP-CIT uptake from baseline to 3 years was 19·36% (95% CI 15·14 to 23·59) in the left putamen, 15·57% (10·87 to 20·28) in the right putamen, 10·81% (6·49 to 15·18) in the left caudate nucleus, and 7·14% (2·74 to 11·56) in the right caudate nucleus. After adjustment for the baseline (123)I-FP-CIT uptake ratios, the decline in (123)I-FP-CIT binding at baseline to 3 years was significantly greater in patients than in controls in the left putamen (9·78% difference between groups, 95% CI 3·22 to 16·32), right putamen (5·43%, 1·99 to 12·86), and left caudate nucleus (8·07%, 1·44 to 14·70), but not in the right caudate nucleus (4·16%, -3·00 to 11·34). At the 3-year assessment, three patients were diagnosed with PD. These patients had the lowest (123)I-FP-CIT uptake at baseline and a mean reduction in (123)I-FP-CIT uptake at 3 years of 32·81% in the left putamen, 30·40% in the right putamen, 26·51% in the left caudate nucleus, and 23·75% in the right caudate nucleus. INTERPRETATION In patients with IRBD, serial (123)I-FP-CIT SPECT shows decline in striatal tracer uptake that reflects progressive nigrostriatal dopaminergic dysfunction. Serial (123)I-FP-CIT SPECT can be used to monitor the progression of nigrostriatal deficits in patients with IRBD, and could be useful in studies of potential disease-modifying compounds in these patients. FUNDING Fondo de Investigaciones Sanitarias of Spain.
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Affiliation(s)
- Alex Iranzo
- Neurology Service, Hospital Clinic, Barcelona, Spain.
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Pino F, Roé N, Orero A, Falcón C, Rojas S, Benlloch JM, Ros D, Pavía J. Development of a variable-radius pinhole SPECT system with a portable gamma camera. ACTA ACUST UNITED AC 2011; 30:286-91. [PMID: 21640439 DOI: 10.1016/j.remn.2011.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 03/02/2011] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To develop a small-animal SPECT system using a low cost commercial portable gamma camera equipped with a pinhole collimator, a continuous scintillation crystal and a position-sensitive photomultiplier tube. MATERIAL AND METHODS The gamma camera was attached to a variable radius system, which enabled us to optimize sensitivity and resolution by adjusting the radius of rotation to the size of the object. To investigate the capability of the SPECT system for small animal imaging, the dependence of resolution and calibration parameters on radius was assessed and acquisitions of small phantoms and mice were carried out. RESULTS Resolution values, ranging from 1.0mm for a radius of 21.4mm and 1.4mm for a radius of 37.2mm were obtained, thereby justifying the interest of a variable radius SPECT system. CONCLUSIONS The image quality of phantoms and animals were satisfactory, thus confirming the usefulness of the system for small animal SPECT imaging.
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Affiliation(s)
- F Pino
- Unitat de Biofísica, Facultat de Medicina, Universitat de Barcelona, Spain.
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Aguiar P, Rafecas M, Ortuño JE, Kontaxakis G, Santos A, Pavía J, Ros D. Geometrical and Monte Carlo projectors in 3D PET reconstruction. Med Phys 2011; 37:5691-702. [PMID: 21158281 DOI: 10.1118/1.3501884] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE In the present work, the authors compare geometrical and Monte Carlo projectors in detail. The geometrical projectors considered were the conventional geometrical Siddon ray-tracer (S-RT) and the orthogonal distance-based ray-tracer (OD-RT), based on computing the orthogonal distance from the center of image voxel to the line-of-response. A comparison of these geometrical projectors was performed using different point spread function (PSF) models. The Monte Carlo-based method under consideration involves an extensive model of the system response matrix based on Monte Carlo simulations and is computed off-line and stored on disk. METHODS Comparisons were performed using simulated and experimental data of the commercial small animal PET scanner rPET. RESULTS The results demonstrate that the orthogonal distance-based ray-tracer and Siddon ray-tracer using PSF image-space convolutions yield better images in terms of contrast and spatial resolution than those obtained after using the conventional method and the multiray-based S-RT. Furthermore, the Monte Carlo-based method yields slight improvements in terms of contrast and spatial resolution with respect to these geometrical projectors. CONCLUSIONS The orthogonal distance-based ray-tracer and Siddon ray-tracer using PSF image-space convolutions represent satisfactory alternatives to factorizing the system matrix or to the conventional on-the-fly ray-tracing methods for list-mode reconstruction, where an extensive modeling based on Monte Carlo simulations is unfeasible.
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Affiliation(s)
- Pablo Aguiar
- Fundación IDICHUS/IDIS, Complexo Hospitalario Universitario de Santiago de Compostela, Departamento de Física de Partículas, Universidade de Santiago de Compostela, Spain.
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Ros D, Juvells I, Vallmitjana S, De F. Moneo J. A Simplified Method for the Automatic Alignment of Images Affected by Random Noise. ACTA ACUST UNITED AC 2010. [DOI: 10.1080/713821420] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- D. Ros
- a Departamento Física Médica, Facultad Medicina, Universidad Barcelona, Casanova 143, 08036 Barcelona, Spain
| | - I. Juvells
- b Departamento Optica, Facultad Física, Universidad Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - S. Vallmitjana
- b Departamento Optica, Facultad Física, Universidad Barcelona, Diagonal 645, 08028 Barcelona, Spain
| | - J.R. De F. Moneo
- b Departamento Optica, Facultad Física, Universidad Barcelona, Diagonal 645, 08028 Barcelona, Spain
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Affiliation(s)
- J.R. De F. Moneo
- a Facultad de Fśica, Universidad de Barcelona, Cátedra de Optica, España
| | - I. Juvells
- a Facultad de Fśica, Universidad de Barcelona, Cátedra de Optica, España
| | - S. Vallmitjana
- a Facultad de Fśica, Universidad de Barcelona, Cátedra de Optica, España
| | - D. Ros
- b Facultad de Medicina, Universidad de Barcelona, Cátedra de Física Médica, España
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Guilbaud O, Tissandier F, Goddet JP, Ribière M, Sebban S, Gautier J, Joyeux D, Ros D, Cassou K, Kazamias S, Klisnick A, Habib J, Zeitoun P, Benredjem D, Mocek T, Nedjl J, de Rossi S, Maynard G, Cros B, Boudaa A, Calisti A. Fourier-limited seeded soft x-ray laser pulse. Opt Lett 2010; 35:1326-1328. [PMID: 20436557 DOI: 10.1364/ol.35.001326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We present what we believe to be the first measurement of the spectral properties of a soft x-ray laser seeded by a high-order harmonic beam. Using an interferometric method, the spectral profile of a seeded Ni-like krypton soft x-ray laser (32.8 nm) generated by optical field ionization has been experimentally determined, and the shortest possible pulse duration has been deduced. The source exhibits a Voigt spectral profile with an FWHM of 3.1+/-0.3 mA, leading to a Fourier-transform pulse duration of 4.7 ps. This value is comparable with the upper limit of the soft x-ray pulse duration determined by experimentally investigating the gain dynamics, from which we conclude that the source has reached the Fourier limit. The measured bandwidth is in good agreement with the predictions of a radiative transfer code, including gain line narrowing and saturation rebroadening.
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Affiliation(s)
- O Guilbaud
- LIXAM, CNRS, Univ Paris-Sud, bat 350 campus d'Orsay, 91405 Orsay, France.
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Bullich S, Cot A, Gallego J, Gunn R, Suárez M, Pavía J, Ros D, Laruelle M, Catafau A. Impact of scatter correction on D2 receptor occupancy measurements using 123I-IBZM SPECT: Comparison to 11C-Raclopride PET. Neuroimage 2010; 50:1511-8. [DOI: 10.1016/j.neuroimage.2010.01.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 12/28/2009] [Accepted: 01/07/2010] [Indexed: 10/20/2022] Open
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Bullich S, Ros D, Pavía J, Cot A, López N, Catafau AM. Neurotransmission SPECT and MR registration combining mutual and gradient information. Med Phys 2009; 36:4903-10. [DOI: 10.1118/1.3232002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Oliva E, Zeitoun P, Sebban S, Fajardo M, Velarde P, Cassou K, Ros D. Optimization of soft x-ray amplifier by tailoring plasma hydrodynamics. Opt Lett 2009; 34:2640-2642. [PMID: 19724517 DOI: 10.1364/ol.34.002640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Plasma-based seeded soft x-ray lasers have the potential to generate a high-energy, highly coherent, short pulse beam. Owing to their high density, plasmas created by interaction of an intense laser with a solid target should store the highest amount of energy among all plasma amplifiers. However, to date output energy from seeded solid amplifiers remains as low as 60 nJ. We demonstrated that careful tailoring of the plasma shape is crucial for extracting energy stored in the plasma. With 1-mm-wide plasma, energy as high as 20 microJ in sub-ps pulses is achievable. With such tailored plasma, gain and pumping efficiency have been increased by nearly a factor of 10 as compared to the narrower plasma amplifiers studied here.
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Affiliation(s)
- E Oliva
- Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, 28006 Madrid, Spain.
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Pareto D, Aguiar P, Pavia J, Gispert J, Cot A, Falcon C, Benabarre A, Lomena F, Vieta E, Ros D. Assessment of SPM in Perfusion Brain SPECT Studies. A Numerical Simulation Study Using Bootstrap Resampling Methods. IEEE Trans Biomed Eng 2008; 55:1849-53. [DOI: 10.1109/tbme.2008.919718] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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31
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Crespo C, Gallego J, Cot A, Falcón C, Bullich S, Pareto D, Aguiar P, Sempau J, Lomeña F, Calviño F, Pavía J, Ros D. Quantification of dopaminergic neurotransmission SPECT studies with 123I-labelled radioligands. A comparison between different imaging systems and data acquisition protocols using Monte Carlo simulation. Eur J Nucl Med Mol Imaging 2008; 35:1334-42. [DOI: 10.1007/s00259-007-0711-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Accepted: 12/26/2007] [Indexed: 11/29/2022]
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Aguiar P, Pareto D, Gispert JD, Crespo C, Falcón C, Cot A, Lomeña F, Pavía J, Ros D. Effect of anatomical variability, reconstruction algorithms and scattered photons on the SPM output of brain PET studies. Neuroimage 2007; 39:1121-8. [PMID: 18042402 DOI: 10.1016/j.neuroimage.2007.09.055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Revised: 09/09/2007] [Accepted: 09/22/2007] [Indexed: 10/22/2022] Open
Abstract
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.
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Affiliation(s)
- P Aguiar
- Unitat Biofísica, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona--IDIBAPS, Spain
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Lindau F, Lundh O, Persson A, Cassou K, Kazamias S, Ros D, Plé F, Jamelot G, Klisnick A, de Rossi S, Joyeux D, Zielbauer B, Ursescu D, Kühl T, Wahlström CG. Quantitative study of 10 Hz operation of a soft x-ray laser-energy stability and target considerations. Opt Express 2007; 15:9486-9493. [PMID: 19547296 DOI: 10.1364/oe.15.009486] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A soft x-ray laser from Ni-like Mo, pumped in grazing incidence (GRIP), is analyzed with regard to high repetition rate operation. Reliable lasing is obtained, but with significant energy fluctuations attributed mainly to beam pointing jitter from the pump laser. Two modes of operation are compared: continuously moving target and stationary target. With a moving target the soft X-ray output is constant on average, whereas the repeated use of the same target position leads to a pulse energy which increases for several tens of shots. This effect might be caused by improved guiding of the pump laser in the formed groove and the removal, through laser ablation, of the oxide layer on the target surface.
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Cassou K, Kazamias S, Ros D, Plé F, Jamelot G, Klisnick A, Lundh O, Lindau F, Persson A, Wahlström CG, de Rossi S, Joyeux D, Zielbauer B, Ursescu D, Kühl T. Optimization toward a high-average-brightness soft-x-ray laser pumped at grazing incidence. Opt Lett 2007; 32:139-41. [PMID: 17186043 DOI: 10.1364/ol.32.000139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We report the near-field imaging characterization of a 10 Hz Ni-like 18.9 nm molybdenum soft-x-ray laser pumped in a grazing incidence pumping (GRIP) geometry with a table-top laser driver. We investigate the effect of varying the GRIP angle on the spatial behavior of the soft-x-ray laser source. After multiparameter optimization, we were able to find conditions to generate routinely a high-repetition-rate soft-x-ray laser with an energy level of up to 3 microJ/pulse and to 6x10(17) photons/s/mm2/mrad2/(0.1% bandwidth) average brightness and 1x10(28) photons/s/mm2/mrad2/(0.1% bandwidth) peak brightness.
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Affiliation(s)
- K Cassou
- LIXAM, UMR 8624, Université Paris Sud, Orsay, France.
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Panikov NS, Sizova MV, Ros D, Christodoulatos C, Balas W, Nicolich S. Biodegradation kinetics of the nitramine explosive CL-20 in soil and microbial cultures. Biodegradation 2006; 18:317-32. [PMID: 17091356 DOI: 10.1007/s10532-006-9066-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2006] [Accepted: 06/14/2006] [Indexed: 10/23/2022]
Abstract
The cyclic nitramine explosive CL-20 (C(6)H(6)N(12)O(12), 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12 -hexaazaisowurtzitane) is a relatively new energetic compound which could be a persistent organic pollutant. To follow its biodegradation dynamics, CL-20 was added to soil alone or together with organic co-substrates and N-source and incubated under oxic and anoxic conditions. Without co-substrates, the CL-20 degradation was detectable only under anoxic conditions. The highest degradation rate was found under aerobic conditions and with the addition of co-substrates, succinate and pyruvate being more efficient than acetate, glucose, starch or yeast extract. When added to intact soil, CL-20 degradation was not affected by the N content, but in soil serially diluted with N-free succinate-mineral medium, the process became N-limited. About 40% of randomly selected bacterial colonies grown on succinate agar medium were able to decompose CL-20. Based on 16S rDNA gene sequence and cell morphology, they were affiliated to Pseudomonas, Rhodococcus, Ochrobactrum, Mycobacterium and Ralstonia. In the pure culture of Pseudomonas sp. MS-P grown on the succinate-mineral N(+) medium, the degradation kinetics were first order with the same apparent kinetic constant throughout growth and decline phases of the batch culture. The observed kinetics agreed with the model that supposes co-metabolic transformation of CL-20 uncoupled from cell growth, which can be carried out by several constitutive cellular enzymes with wide substrate specificity.
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Affiliation(s)
- N S Panikov
- Department of Chemistry and Chemical Biology, Castle Point on Hudson, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
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Bullich S, Ros D, Pavia J, Suarez M, Cot A, Perich J, Catafau A. Neurotransmission SPECT and MR registration combining mutual and gradient information. Neuroimage 2006. [DOI: 10.1016/j.neuroimage.2006.04.080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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37
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Cot A, Falcón C, Crespo C, Sempau J, Pareto D, Bullich S, Lomeña F, Calviño F, Pavía J, Ros D. Absolute quantification in dopaminergic neurotransmission SPECT using a Monte Carlo-based scatter correction and fully 3-dimensional reconstruction. J Nucl Med 2005; 46:1497-504. [PMID: 16157533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023] Open
Abstract
UNLABELLED Dopamine transporter (DAT) ligands have been developed for in vivo imaging of the dopaminergic system in SPECT. Although the visual analysis of SPECT images is, in general, suitable for clinical assessment, the accurate quantification of the striatal uptake might increase the sensitivity of the technique and help in the early diagnosis, follow-up, and eventual treatment response of Parkinson's disease (PD). This work is focused on assessment of the quantification of specific uptake of (99m)Tc-DAT ligands when compensation for all degrading phenomena is performed. METHODS The SimSET Monte Carlo (MC) code was used to generate a set of SPECT projections of a numeric striatal phantom with different specific uptake ratios (SURs). An absolute quantification method (AQM), which performs a MC-based scatter compensation and a fully 3-dimensional (3D) reconstruction, was implemented. The scatter estimate was included in the reconstruction algorithm. RESULTS The use of attenuation, point-spread-function (PSF), and scatter corrections resulted in an improvement in the value of the SUR of 37% on average with respect to the reconstruction without corrections. The magnitude of each improvement corresponded to 7% for the attenuation correction, 12% for the PSF correction using a 2-dimensional reconstruction algorithm and a further 11% for the PSF correction using a 3D reconstruction algorithm, and 7% for the scatter correction. CONCLUSION Our findings indicate that the PSF correction plays a major role in the quantification of striatal uptake in comparison with the attenuation correction and the scatter correction. The implemented method also provides an absolute quantification procedure based on MC methods that do not depend on empiric approximations. The relative quantification results using the proposed AQM accounted for 96%-97% of the nominal SUR, whereas the limit achieved using only primary photons attained 98%-99%. The volumetric activity values obtained using the AQM converged toward the nominal values.
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Affiliation(s)
- Albert Cot
- Unitat de Biofísica i Bioenginyeria, Departament Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona, Spain
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Cot A, Sempau J, Pareto D, Bullich S, Pavía J, Calviño F, Ros D. Study of the point spread function (PSF) for123I SPECT imaging using Monte Carlo simulation. Phys Med Biol 2004; 49:3125-36. [PMID: 15357186 DOI: 10.1088/0031-9155/49/14/007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The iterative reconstruction algorithms employed in brain single-photon emission computed tomography (SPECT) allow some quantitative parameters of the image to be improved. These algorithms require accurate modelling of the so-called point spread function (PSF). Nowadays, most in vivo neurotransmitter SPECT studies employ pharmaceuticals radiolabelled with 123I. In addition to an intense line at 159 keV, the decay scheme of this radioisotope includes some higher energy gammas which may have a non-negligible contribution to the PSF. The aim of this work is to study this contribution for two low-energy high-resolution collimator configurations, namely, the parallel and the fan beam. The transport of radiation through the material system is simulated with the Monte Carlo code PENELOPE. We have developed a main program that deals with the intricacies associated with tracking photon trajectories through the geometry of the collimator and detection systems. The simulated PSFs are partly validated with a set of experimental measurements that use the 511 keV annihilation photons emitted by a 18F source. Sensitivity and spatial resolution have been studied, showing that a significant fraction of the detection events in the energy window centred at 159 keV (up to approximately 49% for the parallel collimator) are originated by higher energy gamma rays, which contribute to the spatial profile of the PSF mostly outside the 'geometrical' region dominated by the low-energy photons. Therefore, these high-energy counts are to be considered as noise, a fact that should be taken into account when modelling PSFs for reconstruction algorithms. We also show that the fan beam collimator gives higher signal-to-noise ratios than the parallel collimator for all the source positions analysed.
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Affiliation(s)
- A Cot
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain
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Pareto D, Cot A, Pavía J, Falcón C, Juvells I, Lomeña F, Ros D. Iterative reconstruction with correction of the spatially variant fan-beam collimator response in neurotransmission SPET imaging. Eur J Nucl Med Mol Imaging 2003; 30:1322-9. [PMID: 12845485 DOI: 10.1007/s00259-003-1229-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2002] [Accepted: 04/24/2003] [Indexed: 10/26/2022]
Abstract
The dopamine transporter (DAT) has been shown to be a sensitive indicator of nigrostriatal dopamine function. Although visual inspection is often sufficient to assess DAT imaging, quantification could improve the diagnostic accuracy of single-photon emission tomography (SPET) studies of the dopaminergic system. The aim of this study was to assess the accuracy of quantification of the striatal/background uptake ratio when correction for attenuation, scatter and spatially variant fan-beam collimator response is performed in technetium-99m and iodine-123 SPET imaging. A numerical striatal phantom was implemented, and simulated projections of low-energy photons were obtained by using the SimSET Monte Carlo code. High-energy contamination in 123I studies was modelled from experimental measurements with 99mTc and 123I. The ordered subsets expectation maximisation (OSEM) algorithm was employed in reconstruction. Mean improvements of 8% and 16% were obtained in the calculated striatal/background uptake ratio in the putamen and the caudate, respectively, when the spatially variant point spread function was included in the transition matrix. Ideal scatter correction resulted in improvements in the putamen and caudate of 9% for 99mTc agents and 19% for 123I agents. Improvements averaged 31% in the putamen and 43% in the caudate when correction for attenuation, scatter and spatially variant collimator response was included in the reconstruction.
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Affiliation(s)
- Deborah Pareto
- Unitat de Biofísica i Bioenginyeria, Departament de Ciències Fisiològiques I, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain
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Bullich S, Ros D, Cot A, Falcón C, Muxí A, Pavia J. Dynamic model of the left ventricle for use in simulation of myocardial perfusion SPECT and gated SPECT. Med Phys 2003; 30:1968-75. [PMID: 12945962 DOI: 10.1118/1.1589497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Simulation is a useful tool in cardiac SPECT to assess quantification algorithms. However, simple equation-based models are limited in their ability to simulate realistic heart motion and perfusion. We present a numerical dynamic model of the left ventricle, which allows us to simulate normal and anomalous cardiac cycles, as well as perfusion defects. Bicubic splines were fitted to a number of control points to represent endocardial and epicardial surfaces of the left ventricle. A transformation from each point on the surface to a template of activity was made to represent the myocardial perfusion. Geometry-based and patient-based simulations were performed to illustrate this model. Geometry-based simulations modeled (1) a normal patient, (2) a well-perfused patient with abnormal regional function, (3) an ischaemic patient with abnormal regional function, and (4) a patient study including tracer kinetics. Patient-based simulation consisted of a left ventricle including a realistic shape and motion obtained from a magnetic resonance study. We conclude that this model has the potential to study the influence of several physical parameters and the left ventricle contraction in myocardial perfusion SPECT and gated-SPECT studies.
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Affiliation(s)
- S Bullich
- Unitat de Biofísica i Bienginyeria, Facultat de Medicina, Universitat de Barcelona, Casanova 143, 08036 Barcelona, Spain
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Sebban S, Mocek T, Ros D, Upcraft L, Balcou P, Haroutunian R, Grillon G, Rus B, Klisnick A, Carillon A, Jamelot G, Valentin C, Rousse A, Rousseau JP, Notebaert L, Pittman M, Hulin D. Demonstration of a Ni-like Kr optical-field-ionization collisional soft x-ray laser at 32.8 nm. Phys Rev Lett 2002; 89:253901. [PMID: 12484885 DOI: 10.1103/physrevlett.89.253901] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Indexed: 05/24/2023]
Abstract
We report the first experimental demonstration of a Ni-like optical-field ionization collisional soft x-ray laser. The amplifying medium is generated by focusing a circularly polarized 760 mJ, 30 fs, 10-Hz Ti:sapphire laser beam in a few mm cell filled with krypton. We have measured a gain coefficient of 78 cm(-1) on the 3d(9)4d 1S0-3d(9)4p(1)P1 transition at 32.8 nm, which is here amplified for the first time. This radiation source represents the shortest wavelength optical-field ionization collisional soft x-ray laser ever produced. The influence of the gas pressure and the pumping energy on the lasing output are also presented.
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Affiliation(s)
- S Sebban
- Laboratoire d'Optique Appliquée, CNRS UMR 7639, F-91761 Palaiseau cedex, France
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Sebban S, Haroutunian R, Balcou P, Grillon G, Rousse A, Kazamias S, Marin T, Rousseau JP, Notebaert L, Pittman M, Chambaret JP, Antonetti A, Hulin D, Ros D, Klisnick A, Carillon A, Jaeglé P, Jamelot G, Wyart JF. Saturated amplification of a collisionally pumped optical-field-ionization soft X-ray laser at 41.8 nm. Phys Rev Lett 2001; 86:3004-3007. [PMID: 11290093 DOI: 10.1103/physrevlett.86.3004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2000] [Indexed: 05/23/2023]
Abstract
We report the first saturated amplification of an optical-field-ionization soft x-ray laser. The amplifying medium is generated by focusing a circularly polarized 330-mJ, 35-fs, 10-Hz Ti:sapphire laser system in a few-mm cell filled with xenon. A gain of 67 cm(-1) on the 4d(9)5p-4d(9)5d transition at 41.8 nm in Pd-like xenon and a gain-length product of 15 have been inferred at saturation. This source delivers about 5 x 10(9) photons per pulse. The influence of the pumping energy and the laser polarization on the lasing output are also presented.
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Affiliation(s)
- S Sebban
- Laboratoire d' Optique Appliquée, ENSTA/Ecole Polytechnique, CNRS UMR 7639, Palaiseau, France
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Abstract
Fan-beam collimators offer a good balance between resolution and noise. The collimator response may be included in iterative reconstruction algorithms in order to improve single-photon emission tomography (SPET) resolution. To this end, accurate determination of the focal region and characterisation of the collimator response as a function of the source co-ordinates must be performed. In this paper, a method to characterise fanbeam collimators is evaluated. First, we calculated the real focal region and the accuracy of the collimator convergence. Then, we confirmed the hypothesis that Gaussian distributions adequately fit the collimator responses, although no individualised treatment was performed for the tails of detector response which are associated with scattering and septal penetration. Finally, analytical functions were used to model the resolution and sensitivity. The parameter values in these functions were obtained from experimental measures by non-linear regression fitting. Our findings show differences of 1.43% between nominal and real focal length and standard deviations of 2.5 mm in the x-direction and 7.1 mm in the y-direction for the focal convergence. The correlation coefficients between experimental and predicted values were 0.994 for resolution and 0.991 for sensitivity. As a consequence, the proposed method can be used to characterise the collimator response.
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Affiliation(s)
- D Pareto
- Laboratori de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Spain
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44
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Abstract
Five functions of merit were used for the registration of 99Tcm-HMPAO brain SPET studies. The correlation coefficient (COR), the stochastic sign change (SSC), the standard deviation of ratios (SDR), the sum of the absolute differences (SAD) and a new function based on a local correlation coefficient (LOC) were tested in the registration of photic neuroactivation (ACT), epilepsy (EPL) and Wada (WAD) SPET studies. The comparison included simulated and real studies. The translation error in registration was 0.1 +/- 0.1 pixels (mean +/- S.D.) for all functions of merit for the complete set of simulated studies (10 runs for each ACT, EPL and WAD). For rotation, LOC yielded the best results with a mean error of 0.3 +/- 0.2 degree and a maximum error of 0.6 degree. Slightly higher errors were found with SAD (0.4 +/- 0.2 degree, maximum 1.0 degree) and COR (0.5 +/- 1.0 degree, maximum 1.0 degree). The highest errors were found with SDR (0.8 +/- 1.0 degree, maximum 4.8 degrees) and SSC (0.8 +/- 1.1 degrees, maximum 4.7 degrees). The results obtained from five real studies of ACT, of EPL and of WAD were in agreement with the findings from the simulated studies, thus confirming the robustness of LOC, SAD and COR for the registration of 99Tcm-HMPAO brain SPET studies.
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Affiliation(s)
- D Ros
- Laboratori de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Spain
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45
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Abstract
One of the problems in the routine use of the maximum-likelihood estimator method-expectation maximization (MLE-EM) algorithm is to decide when the iterative process should be stopped. We studied a cross-validation stopping rule to assess its usefulness in SPECT. We tested this stopping rule criterion in the MLE-EM algorithm without acceleration as well as in two accelerating algorithms, the successive substitutions algorithm (SSA) and the additive algorithm (AA). Different values of an acceleration factor were tested in SSA and AA. Our results from numerical and physical phantoms show that the stopping rule based on the cross-validation ratio (CVR) takes into account the similarity of the reconstructed image to the ideal image, noise and the contrast of the image. CVR yields reconstructed images with balanced values of the figures of merit (FOM) employed to assess the image quality. The CVR criterion can be used in the original MLE-EM algorithm as well as in SSA and AA. The reconstructed images obtained with SSA and AA showed FOM values that were very similar. These results were justified by considering AA to be an approximate form of SSA. The range of validity for the acceleration factor in SSA and AA was found to be [1, 2]. In this range, an inverse function connects the acceleration factor to the number of iterations needed to attain prefixed values of FOMs.
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Affiliation(s)
- C Falcón
- Laboratori de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Spain
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46
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Abstract
Simplified methods based on a single blood sample have been proposed to estimate the clearance of 131I-hippuran (HIP) and 99Tcm-mercaptoacetyltriglycine (MAG). The blood sample is usually drawn at that time which yields a minimum error between the estimated clearance and that obtained by the standard nine-sample method. In this paper, we establish the regression equations to obtain the HIP and MAG clearances using one sample withdrawn during a fixed time interval. As HIP has long been the agent of choice, we have also established regression equations to estimate the clearance of HIP using one sample after MAG administration. Our results suggest that it is possible to obtain plasma samples 30-50 min post-injection which result in an error of the estimate only slightly higher than the minimum.
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Affiliation(s)
- C Piera
- Servicio de Medicina Nuclear, Hospital Clínic i Provincial, Barcelona, Spain
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47
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Catafau AM, Parellada E, Lomeña F, Bernardo M, Pavía J, Ros D, Setoain J. Baseline, visual deprivation and visual stimulation 99TCm-HMPAO-related changes in visual cortex can be detected with a single-head SPET system. Nucl Med Commun 1996; 17:480-4. [PMID: 8822745 DOI: 10.1097/00006231-199606000-00005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To determine the sensitivity of 99TCm-hexamethylpropylene amine oxime (99TCm-HMPAO) and a single-head SPET (single photon emission tomography) system in the detection of perfusion changes in the visual cortex due to different visual conditions, six normal healthy volunteers were studied under conditions of visual deprivation (blindfolded), visual stimulation (stroboscopic light) and baseline (dim light and eyes open). Visual cortex/whole-brain activity ratios, and the percentage of activity change between the different visual conditions were calculated after three-dimensional realignment of the images. The activity in the visual cortex was higher during visual stimulation than during the visual deprivation (P = 0.002, 17.6 +/- 8.6% increase) and baseline conditions (P = 0.009, 8.8 +/- 5.6% increase). Furthermore, the activity in the visual cortex was lower during the visual deprivation than in the baseline condition (P = 0.001, 8.1 +/- 2.9% decrease). 99TCm-HMPAO SPET, even with a single-head system, is capable of detecting changes in rCBF in the striate cortex, not only between conditions of visual stimulation and deprivation, but also between these two conditions and the baseline state.
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Affiliation(s)
- A M Catafau
- Department of Nuclear Medicine, Faculty of Medicine, University of Barcelonia, Spain
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48
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Abstract
Algebraic reconstruction techniques (ARTs) have been intensively studied in image reconstruction. However, reconstructed images often exhibit a characteristic noise when applied to emission tomography. In this work, we study the influence of the ART relaxation parameter and identify values of that parameter which yield smooth images and good convergence. The study includes both simulated and real single photon emission computed tomographic (SPECT) data. In the simulated studies, scattering, attenuation, noise and detector response were included. Relaxation factors ranging between 0.01 and 0.35 were considered. Total counts in projections were between 2.5 x 10(5) and 10(6) in one slice. The goodness of the reconstructions was assessed by using the correlation coefficient between the pattern and the actual reconstruction (CC), the background coefficient of variation (CV), the contrast (CON) and the signal-to-noise ratio (SNR). The results show that values for the relaxation factor and number of interations close to 0.1 and 8, respectively, yield reconstructed images in which CC, CV, CON and SNR have well balanced values and CC, CV and SNR are very close to the extremal. An increase in either the number of iterations or in the relaxation factor results in a rise of CON but the other three FOMs deteriorate. The results from the real phantom, which are in agreement with those of the simulated studies, validate the simulation method and demonstrate the influence of the relaxation parameter.
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Affiliation(s)
- D Ros
- Laboratori de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Spain
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49
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Moragas M, Pavía J, Ginés A, Ros D, Solá M, Huguet M, Pons F, Setoain J. Tc-99m galactosyl-neoglycoalbumin hepatic scintigraphy in fulminant hepatic failure. Clin Nucl Med 1995; 20:329-33. [PMID: 7788990 DOI: 10.1097/00003072-199504000-00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tc-99m galactosyl-neoglycoalbumin (NGA) is a new liver imaging agent that specifically binds to a hepatocyte specific membrane receptor, the hepatic binding protein. Scintigraphy with Tc-99m NGA is a noninvasive method that provides functional images of the liver. This report deals with one case of fulminant hepatic failure in which hepatic scintigraphy with Tc-99m NGA predicted hepatic recovery before clinical and biochemical parameters, being a prognostic index in this patient.
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Affiliation(s)
- M Moragas
- Nuclear Medicine Service, Hospital Clinic i Provincial, Barcelona, Spain
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50
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Pavia J, Ros D, Catafau AM, Lomeña FJ, Huguet M, Setoain J. Three-dimensional realignment of activation brain single-photon emission tomographic studies. Eur J Nucl Med 1994; 21:1298-302. [PMID: 7875167 DOI: 10.1007/bf02426693] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Two methods for 3D realignment of activation brain single-photon emission tomographic (SPET) studies are analyzed. The first is based on principal axes transformation (PAT). The second uses the results of the first method as initial values to start a least-squares iterative process (LS) to search for the maximum value of the correlation function. Both methods were tested with simulated and real studies. The results of the PAT method showed a maximum translation error of 0.3 +/- 0.1 pixels and a rotational error of 1.2 +/- 0.7 degrees in a total of 100 runs. For the LS method these errors were 0.2 +/- 0.1 and 0.6 +/- 0.3. The realignment for 34 real studies was assessed by three expert observers. The alignment was found to be satisfactory in all cases for the LS method, and in 18 cases (53%) for the PAT method. From the results we conclude that a combination of both methods allows the accurate realignment of SPET neuroactivation studies.
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Affiliation(s)
- J Pavia
- Nuclear Medicine Department, Hospital Clinic i Provincial of Barcelona, University of Barcelona, Spain
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