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1.
EJNMMI Phys ; 7(1): 11, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32086646

RESUMO

BACKGROUND: Routine PET exams are increasingly performed with reduced injected activities, leading to the use of different image reconstruction parameters than the NEMA parameters, in order to prevent from any deleterious decrease in signal-to-noise ratio (SNR) and thus, in lesion detectability. This study aimed to provide a global head-to-head comparison between digital (Vereos, Philips®) and analog (Ingenuity TF, Philips®) PET cameras of the trade-off between SNR and contrast through a wide-ranging number of reconstruction iterations, and with a further reconstruction optimization based on the SNR of small lesions. METHODS: Image quality parameters were compared between the two cameras on human and phantom images for a number of OSEM reconstruction iterations ranging from 1 to 10, the number of subsets being fixed at 10, and with the further identification of reconstruction parameters maximizing the SNR of spheres and adenopathies nearing 10 mm in diameter. These reconstructions were additionally obtained with and without time-of-flight (TOF) information (TOF and noTOF images, respectively) for further comparisons. RESULTS: On both human and phantom TOF images, the compromise between SNR and contrast was consistently more advantageous for digital than analog PET, with the difference being particularly pronounced for the lowest numbers of iterations and the smallest spheres. SNR was maximized with 1 and 2 OSEM iterations for the TOF images from digital and analog PET, respectively, whereas 4 OSEM iterations were required for the corresponding noTOF images from both cameras. On the TOF images obtained with this SNR optimization, digital PET exhibited a 37% to 44% higher SNR as compared with analog PET, depending on sphere size. These relative differences were however much lower for the noTOF images optimized for SNR (- 4 to + 18%), as well as for images reconstructed according to NEMA standards (- 4 to + 12%). CONCLUSION: SNR may be dramatically higher for digital PET than for analog PET, especially when optimized for small lesions. This superiority is mostly attributable to enhanced TOF resolution and is significantly underestimated in NEMA-based analyses.

2.
Bioorg Med Chem ; 27(18): 4101-4109, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31371219

RESUMO

The design of conjugates displaying simultaneously high selectivity and high affinity for different subtypes of integrins is a current challenge. The arginine-glycine-aspartic acid amino acid sequence (RGD) is one of the most efficient short peptides targeting these receptors. We report herein the development of linear and cyclic fluoro-C-glycoside"RGD" conjugates, taking advantage of the robustness and hydrophilicity of C-glycosides. As attested by in vitro evaluation, the design of these C-glyco"RGD" with a flexible three-carbon triazolyl linker allows distinct profiles towards αIIbß3 and αvß3 integrins. Molecular-dynamics simulations confirm the suitability of cyclic C-glyco-c(RGDfC) to target αvß3 integrin. These C-glyco"RGD" could become promising biological tools in particular for Positron Emission Tomography imaging.

3.
EJNMMI Res ; 9(1): 61, 2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300962

RESUMO

BACKGROUND: The quality of phantom images was previously shown to be higher on digital (Vereos Philips®) compared to analog PET (Ingenuity Philips®) cameras. This study aimed to determine the extent to which this difference still remains significant on normal brain 18F-FDG PET images. METHODS: Relative noise and contrast as well as border sharpness (a spatial resolution index) of central (striata) and peripheral (occiput) gray-matter structures were compared between 10 sets of normal brain 18F-FDG PET images recorded and reconstructed on digital and analog last-generation PET cameras, together with a subjective visual analysis of image quality provided by experienced physicians. RESULTS: Compared with analog PET, digital PET provided marked improvements in image quality parameters. The median relative noise was decreased (- 22%), while gray/white-matter contrast was increased (+ 27%/+ 41% for central/peripheral gray-matter structures), with these results being consistent with visual analysis. In addition, a clear enhancement in image sharpness was further documented for digital PET owing to the possible use of a 1-mm3 voxel size (+ 24%/+ 21%). CONCLUSIONS: On normal brain 18F-FDG images and compared with a last-generation analog PET, the fully digital PET camera offers marked improvements in image noise and contrast, as well as significant potential for further enhancing spatial resolution.

4.
J Neurol ; 266(7): 1685-1692, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30963253

RESUMO

BACKGROUND: Atypical cerebrospinal fluid (CSF) patterns, involving an increase in the concentration of phosphorylated-tau (P-tau) proteins but normal amyloid-ß concentration, are not uncommon in patients with mild neurocognitive disorders and suspected Alzheimer's disease (AD). In these conditions, however, AD diagnosis may be ruled out in the absence of any amyloid deposition at positron-emission tomography (PET). This pilot cross-sectional study was aimed to determine whether this negativity of amyloid PET can be predicted by CSF profiles in such patients. METHODS: Twenty-five patients (73 [68-80] years, 10 women) with mild neurocognitive disorders, suspected AD and an increase in the CSF concentration of P-tau proteins but normal Aß42 concentration and Aß42/Aß40 ratio were prospectively included and referred to a 18F-florbetaben PET. The latter was considered as definitively negative with the conjunction of both visual (brain amyloid plaque load score) and quantified (standard uptake value ratios) criteria. Predictors of a negative PET were searched among current CSF biomarkers (Aß42, Aß40, T-tau, P-tau, Aß42/Aß40, Aß42/p-tau). RESULTS: Amyloid PET was negative in 15 patients (60%) with a CSF Aß42 concentration being the sole independent predictor of this negativity. The criterion of an Aß42 concentration in the very high range (> 843 pg/mL), observed in 60% (15/25) of the study patients, was associated with a negative amyloid PET in 93% (14/15) of cases. CONCLUSIONS: In mild neurocognitive disorders patients with suspected AD and showing an increase in CSF P-tau protein level, amyloid PETs are commonly negative, when Aß42 concentration is in the very high range. In such case, AD diagnosis based on biomarkers can be ruled out with reasonable certainty, without the need for additional CSF second-line assays or results from amyloid PET.


Assuntos
Doença de Alzheimer/líquido cefalorraquidiano , Doença de Alzheimer/diagnóstico por imagem , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Fragmentos de Peptídeos/líquido cefalorraquidiano , Tomografia por Emissão de Pósitrons/métodos , Proteínas tau/líquido cefalorraquidiano , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Biomarcadores/líquido cefalorraquidiano , Estudos Transversais , Feminino , Humanos , Masculino , Fragmentos de Peptídeos/metabolismo , Fosforilação/fisiologia , Projetos Piloto , Estudos Prospectivos , Proteínas tau/metabolismo
5.
J Alzheimers Dis ; 68(3): 1061-1069, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30883358

RESUMO

BACKGROUND/OBJECTIVE: The aim of this study was to assess, in routine, the rates with which an amyloid deposition was documented by 18F-florbetaben PET in patients with suspected Alzheimer's disease (AD) but with isolated increases in cerebrospinal fluid (CSF) tau-protein concentrations, and the subsequent impact of these PET results on medical management. METHODS: This prospective study included 34 patients with mild neurocognitive disorders (MND) and suspected AD (73±9 years, 16 women) and with abnormal CSF concentrations in total-tau (T-tau) and/or phosphorylated-tau (P-tau) proteins but normal Aß42 concentration and Aß42/Aß40 ratio. These patients were referred to 8F-florbetaben PET from which the PET-related changes in the confidence for AD diagnosis (low, intermediate, or high) and treatments were reported. RESULTS: The PET examinations were positive for amyloid deposition (brain amyloid plaque load, BAPL score >1) in none of the 9 patients with an increase in only T-tau proteins and in 8 among the 25 (32%) with an increase in P-tau proteins (one BAPL score of 2 and seven BAPL scores of 3). Knowledge of the PET results was associated with subsequent changes in diagnostic confidence in 44% of patients (15/34) and in the intention-to-treat with a cholinesterase inhibitor drug in 18% (6/34). CONCLUSION: In patients with suspected AD and isolated increase in CSF tau protein concentrations, an amyloid deposition is documented by 18F-florbetaben PET in as much as one third of cases when the concentration of P-tau is abnormal, and PET results are associated with significant further changes in medical management.

6.
J Nucl Cardiol ; 26(5): 1539-1549, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30815836

RESUMO

PURPOSE: To determine whether the left ventricular ejection fractions (EFs), measured on a high-sensitivity CZT single photon emission computed tomography (SPECT)-camera with a 70% reduction in recording times and a prevention of EF overestimation through an additional count-calibration, are concordant with reference EF from planar radionuclide angiography (2D-RNA). METHODS: An additional 10-minute CZT-SPECT recording was performed in patients referred to 2D-RNA for cardiomyopathy (n = 23) or chemotherapy monitoring (n = 50) with an in vivo red blood cell labeling with 850 MBq [Formula: see text]. The EF, obtained from CZT-SPECT with 100% (SPECT100) or 30% (SPECT30) projection times and with a SPECT-count calibration on the 2D-RNA counts of corresponding cavity volumes, were compared to EF from 2D-RNA. RESULTS: Strong and equivalent relationships were documented between the EF from 2D-RNA and the calibrated EF from SPECT100 (y = 0.89x + 6.62; R2 = 0.87) and SPECT30 (y = 0.87x + 8.40; R2 = 0.85), and the mean EF from SPECT100 (54% ± 15%) and SPECT30 (53% ± 16%) were close to that from 2D-RNA (55% ± 15%). However, upward shifts in these mean values were documented in the absence of count calibration for both SPECT100 (60% ± 18%) and SPECT30 (60% ± 18%). CONCLUSION: Left ventricular EF may be determined on a high-sensitivity CZT-camera, a 70% reduction in injected activities, and an additional count-calibration for further enhancing the concordance with 2D-RNA values.

7.
J Nucl Cardiol ; 26(4): 1313-1322, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29327252

RESUMO

This phantom-based study was aimed to determine whether cardiac CZT-cameras, which provide an enhanced spatial resolution and image contrast compared to Anger cameras, are similarly affected by small cardiac motions. Translations of a left ventricular (LV) insert at half-SPECT acquisitions through six possible orthogonal directions and with 5- or 10-mm amplitude were simulated on the Discovery NM-530c and DSPECT CZT-cameras and on an Anger Symbia T2 camera equipped with an astigmatic (IQ.SPECT) or conventional parallel-hole collimator (Conv.SPECT). SPECT images were initially reconstructed as currently recommended for clinical routine. The heterogeneity in recorded activity from the 17 LV segments gradually increased between baseline and motions simulated at 5- and 10-mm amplitudes with all cameras, although being higher for Anger- than CZT-cameras at each step and resulting in a higher mean number of artifactual abnormal segments (at 10-mm amplitude, Conv.SPECT: 3.7; IQ.SPECT: 1.8, Discovery: 0.7, DSPECT: 0). However, this vulnerability to motion was markedly (1) decreased for Conv.SPECT reconstructed without the recommended Resolution Recovery algorithm and (2) increased for DSPECT reconstructed without the recommended cardiac model. CZT-cameras and especially the DSPECT appear less vulnerable to small cardiac motions than Anger-cameras although these differences are strongly dependent on reconstruction parameters.

8.
J Nucl Med ; 60(6): 824-829, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30389818

RESUMO

This prospective randomized study assessed myocardial perfusion imaging with the high-sensitivity D.SPECT cadmium-zinc-telluride camera in a forward-leaning bikerlike position, which may potentially lower diaphragmatic attenuation and reduce breathing-related cardiac motion, in a manner comparable to the prone position proposed with other SPECT cameras. Methods: Patients referred for a stress-rest 99mTc-sestamibi protocol and positioned in the biker position, with the chest leaning forward on the D.SPECT camera-head at 35° from vertical, had an additional resting D.SPECT recording in the supine position (n = 40) or in the sitting position with the back rearward at 30° from vertical (n = 40). Segments with attenuation artifacts were defined as those with less than 65% uptake but with strictly normal contractility at gated SPECT and no defect reversibility from stress images. Results: The biker position was associated with lower heart-to-detector distances than the supine or sitting positions (both P < 0.001); lower cardiac motion amplitudes, assessed on panograms, than the supine position (P < 0.001); and fewer segments with attenuation artifacts than the supine position (on average, 1.10 ± 1.01 vs. 1.90 ± 1.74, P = 0.010) or the sitting position (0.75 ± 0.93 vs. 1.38 ± 1.60, P = 0.011). Conclusion: Myocardial perfusion images from D.SPECT are enhanced for patients positioned in a forward-leaning bikerlike position comparatively to sitting or supine positions, with a notably lower rate of attenuation artifacts.

9.
J Nucl Cardiol ; 2018 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-30128917

RESUMO

BACKGROUND: Short periods of fasting and/or low-carbohydrate diet have been proven beneficial for decreasing the myocardial uptake of 18F-fluorodeoxyglucose (18F-FDG) and enhancing the detection of inflammatory heart diseases by 18F-FDG positron emission tomography (PET). This study aimed at determining whether this benefit is increased when a low-carbohydrate ketogenic diet is prolonged up to 7 days. METHODS: Wistar rats underwent serial 18F-FDG-PET imaging after an 18-hour fasting period and after 2, 4 and 7 days of a ketogenic diet (3% carbohydrate) and they were compared to rats submitted to the same protocol but with normal diet (44% carbohydrate). The 18F-FDG-PET/ketogenic protocol was also applied in rats with immune myocarditis (injection of porcine cardiac myosin). RESULTS: The 7-day ketogenic diet was associated with (1) a sustained increase in circulating ketone bodies at an equivalent level to that reached after 18-hour fasting, (2) a gradual decrease in 18F-FDG uptake within normal myocardium reaching a lower level compared to fasting at the 7th day (myocardium-to-blood ratios: 1.68 ± 1.02 vs 3.25 ± 1.40, P < .05) and (3) a high 18F-FDG-PET detectability of myocarditis areas. CONCLUSION: One-week extension of a ketogenic diet provides a further decrease in the 18F-FDG uptake of normal myocardium and a high detectability of inflammatory areas.

10.
EJNMMI Res ; 8(1): 51, 2018 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-29904818

RESUMO

BACKGROUND: Tracers triggering αvß3 integrins, such as certain RGD-containing peptides, were found promising in previous pilot studies characterizing high-grade gliomas. However, only limited comparisons have been performed with current PET tracers. This study aimed at comparing the biodistribution of 18F-fluorodeoxyglucose (18F-FDG) with that of 68Ga-NODAGA-RGD, an easily synthesized monomeric RGD compound with rapid kinetics, in two different rodent models of engrafted human glioblastoma. METHODS: Nude rodents bearing human U87-MG glioblastoma tumor xenografts in the flank (34 tumors in mice) or in the brain (5 tumors in rats) were analyzed. Kinetics of 68Ga-NODAGA-RGD and of 18F-FDG were compared with PET imaging in the same animals, along with additional autohistoradiographic analyses and blocking tests for 68Ga-NODAGA-RGD. RESULTS: Both tracers showed a primary renal route of clearance, although with faster clearance for 68Ga-NODAGA-RGD resulting in higher activities in the kidneys and bladder. The tumor activity from 68Ga-NODAGA-RGD, likely corresponding to true integrin binding (i.e., suppressed by co-injection of a saturating excess of unlabeled RGD), was found relatively high, but only at the 2nd hour following injection, corresponding on average to 53% of total tumor activity. Tumor uptake of 68Ga-NODAGA-RGD decreased progressively with time, contrary to that of 18F-FDG, although 68Ga-NODAGA-RGD exhibited 3.4 and 3.7-fold higher tumor-to-normal brain ratios on average compared to 18F-FDG in mice and rat models, respectively. Finally, ex-vivo analyses revealed that the tumor areas with high 68Ga-NODAGA-RGD uptake also exhibited the highest rates of cell proliferation and αv integrin expression, irrespective of cell density. CONCLUSIONS: 68Ga-NODAGA-RGD has a high potential for PET imaging of glioblastomas, especially for areas with high integrin expression and cell proliferation, although PET recording needs to be delayed until the 2nd hour following injection in order to provide sufficiently high integrin specificity.

11.
J Nucl Cardiol ; 25(6): 2016-2023, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-28512723

RESUMO

PURPOSE OF THE REPORT: This study aimed at assessing an original low-dose dual-isotope procedure in which the abnormal stress Tc-99m Sestamibi SPECT is followed by rest Tl-201 SPECT, along with a head-to-head comparison with a single-isotope procedure. METHODS AND RESULTS: One hundred two patients, referred for a low-dose stress-SPECT with Sestamibi (123 ± 20 MBq) on a CZT camera and for whom a rest Sestamibi SPECT was warranted, had an additional Tl-201 rest-SPECT (52 ± 5 MBq) between stress and rest Sestamibi SPECT recordings. Tl-201 images were processed for spill-over and scatter corrections, and uptake differences with stress Sestamibi SPECT were analyzed: (1) for rest acquisitions from Tl-201 (dual-isotope procedure) and from Sestamibi (single-isotope procedure) and (2) in segments for which a diagnosis of ischemia, infarct, or normal perfusion was achieved. Mean effective dose was 8.3 mSv for dual-isotope but would decrease to 5.7 mSv for an expected rate of 37% of patients for whom rest-SPECT is not warranted. After a further background correction of Tl-201 images, the rest-stress difference in myocardial uptake was equivalent between dual- and single-procedures for identifying ischemic segments (respective areas-under-curves: 0.83 ± 0.03 and 0.81 ± 0.03). CONCLUSION: This original dual-isotope procedure provides acceptable radiation doses and consistent results, as compared with conventional single-isotope.


Assuntos
Imagem de Perfusão do Miocárdio/métodos , Compostos Radiofarmacêuticos , Tecnécio Tc 99m Sestamibi , Radioisótopos de Tálio , Tomografia Computadorizada de Emissão de Fóton Único/métodos , Cádmio , Humanos , Doses de Radiação , Telúrio , Zinco
12.
J Nucl Cardiol ; 25(1): 249-256, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27677613

RESUMO

PURPOSE: Gamma-cameras, with Cadmium-Zinc-Telluride (CZT) detectors, allow to perform myocardial perfusion imaging (MPI) with limited injected activities and recorded times. This study aimed at determining whether the routine assessment of left ventricular (LV) function with such limited counts protocols compares well with reference values from cardiac MRI. METHODS: The study included patients who have undergone cardiac MRI and an MPI routinely planned on a CZT camera with a low-dose protocol (120 MBq of Sestamibi for stress and 360 MBq at rest for 75 kg body weight), while targeting the recording of only 500 myocardial kcounts in order to limit the recording times (<10 minutes for stress, <4 minutes for rest). SPECT images were reconstructed with a method maintaining rather high spatial (8 mm) and temporal (16 frames/cycle) resolutions. RESULTS: Seventy-six patients were included, and mean effective dose was 3.5 ± 1.7 mSv for the total MPI protocol. Correlations between CZT-SPECT and MRI were good to excellent for ejection fraction (r 2 = 0.77), end-diastolic (r 2 = 0.88) and end-systolic (r 2 = 0.93) volumes, and the analysis of segmental contractility correlated well between the two techniques (kappa score = 0.72 ± 0.02). CONCLUSION: LV function, assessed on a CZT camera with low injected activities and limited recording times, correlates well with the reference assessment from cardiac MRI.


Assuntos
Cádmio , Imagem por Ressonância Magnética , Imagem de Perfusão do Miocárdio , Telúrio , Tomografia Computadorizada de Emissão de Fóton Único , Função Ventricular Esquerda , Zinco , Idoso , Peso Corporal , Feminino , Câmaras gama , Coração/diagnóstico por imagem , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagem Tridimensional , Masculino , Pessoa de Meia-Idade , Doses de Radiação , Compostos Radiofarmacêuticos , Estudos Retrospectivos , Sístole , Tecnécio Tc 99m Sestamibi , Fatores de Tempo
13.
Br J Radiol ; 91(1084): 20170803, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29271237

RESUMO

OBJECTIVE: In diffuse Grade II-III gliomas, a high 3,4-dihydroxy-6-(18F)-fluoro-L-phenylalanine (18F-FDOPA) positron emission tomography (PET) uptake, with a standardized uptake value (SUVmax)/contralateral brain tissue ratio greater than 1.8, was previously found to be consistently associated with the presence of an isocitrate dehydrogenase (IDH) mutation, whereas this mutation is typically associated with a better prognosis. This pilot study was aimed to ascertain the prognostic value of this high 18F-FDOPA uptake in diffuse Grade II-III gliomas with regard to the velocity of diameter expansion (VDE), which represents an established landmark of better prognosis when below 4 mm per year. METHODS: 20 patients (42 ± 10 years, 10 female) with newly-diagnosed diffuse Grade II-III gliomas (17 with IDH mutation) were retrospectively included. All had a 18F-FDOPA PET, quantified with SUVmax ratio, along with a serial MRI enabling VDE determination. RESULTS: SUVmax ratio was above 1.8 in 5 patients (25%) all of whom had a VDE <4 mm/year (100%) and IDH mutation (100%). Moreover, a SUVmax ratio above 1.8 was associated with higher rates of VDE <4 mm/year in the overall population (45 vs 0%, p = 0.04) and also in the subgroup of patients with IDH mutation (45 vs 0%, p = 0.10). CONCLUSION: This pilot study shows that in diffuse Grade II-III gliomas, a high 18F-FDOPA uptake would be predictive of low tumour growth, with a different prognostic significance than IDH mutation. Advances in knowledge: 18F-FDOPA PET in a single session imaging could have prognostic value in initial diagnosis of diffuse Grade II-III gliomas.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/metabolismo , Di-Hidroxifenilalanina/análogos & derivados , Glioma/diagnóstico por imagem , Glioma/metabolismo , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/farmacocinética , Adulto , Neoplasias Encefálicas/patologia , Di-Hidroxifenilalanina/farmacocinética , Progressão da Doença , Feminino , Glioma/patologia , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Projetos Piloto , Prognóstico , Estudos Retrospectivos
14.
Bioorg Med Chem ; 25(20): 5603-5612, 2017 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-28893600

RESUMO

This study describes the synthesis and radiosynthesis of eight new [18F]fluoro-inositol-based radiotracers in myo- and scyllo-inositol configuration. These radiotracers are equipped with a propyl linker bearing fluorine-18. This fluorinated arm is either on a hydroxyl group, i.e. O-alkylated inositols, or on the cyclohexyl backbone, i.e. C-branched derivatives. To modulate lipophilicity, inositols were synthesized in acetylated or hydroxylated form. Automated radiosynthesis was performed on the AllInOne module and the radiotracers were produced in good radiochemical yields (15-31.5% dc). Preliminary in vivo preclinical evaluation of these eight [18F]fluoro-inositols as Positron Emission Tomography (PET) imaging agents in a breast tumour-bearing mouse model was performed and compared with [18F]-2-fluoro-2-deoxy-d-glucose ([18F]FDG). Amongst the different inositols, [18F]myo-2 showed the highest tumour uptake 2.34±0.39%ID/g, revealing the potential of this tracer for monitoring breast cancer.


Assuntos
Radioisótopos de Flúor , Inositol/química , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos , Animais , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Modelos Animais de Doenças , Feminino , Radioisótopos de Flúor/normas , Humanos , Inositol/análogos & derivados , Inositol/síntese química , Camundongos , Estrutura Molecular
15.
Mol Imaging Biol ; 19(5): 731-735, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28108871

RESUMO

PURPOSE: The Statistical Parametric Mapping (SPM) software is frequently used for the quantitative analysis of patients' brain images obtained from 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography ([18F]FDG PET). However, its adaptation to small animals is difficult, particularly for the initial step of spatial normalization which requires a specific brain anatomical template. This study was aimed at determining whether SPM analysis can be applied to rat, and more specifically to the lithium-pilocarpine model of epilepsy, by using an adaptive template. This template developed for PET clinical imaging is constructed from a block matching algorithm. PROCEDURES: SPM analysis of brain [18F]FDG PET images from Sprague-Dawley rats was used with the block matching (BM) adaptive template for the detection of brain abnormalities (1) artificially inserted within the initially normal brain images of 10 rats (50 % decrease in signal intensity within 40 spheres of 0.5 to 1.0 mm in diameter) and (2) occurring at 4 h (n = 16), 48 h (n = 15), and 8 days (n = 13) after lithium-pilocarpine treatment. RESULTS: Concordant positive clusters were documented for all inserted abnormalities, whereas no aberrant clusters were documented in remote brain areas. Positive clusters were also detected on sites known to be involved in the epileptogenesis process of the lithium-pilocarpine model (piriform and entorhinal cortex, hippocampus), with the expected time-specific changes involving an early hypermetabolism followed by a severe hypometabolism and a subsequent partial recovery. CONCLUSION: A quantitative SPM analysis of brain [18F]FDG PET images may be applied to the monitoring of rat brain function when using an adaptive BM template.


Assuntos
Encéfalo/diagnóstico por imagem , Fluordesoxiglucose F18/química , Tomografia por Emissão de Pósitrons , Estatística como Assunto , Animais , Imagem Tridimensional , Masculino , Ratos Sprague-Dawley
16.
Ann Nucl Med ; 30(4): 272-8, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26841946

RESUMO

INTRODUCTION: Statistical parametric mapping (SPM) provides useful voxel-by-voxel analyses of brain images from (18)F-fluorodesoxyglucose positron emission tomography (FDG-PET) after an initial step of spatial normalization through an anatomical template model. In the setting of the preoperative workup of patients with temporal epilepsy, this study aimed at assessing a block-matching (BM) normalization method, where most transformations are computed through small blocks, a principle that minimizes artefacts and overcomes additional image-filtering. METHODS: Brain FDG-PET images from 31 patients with well-characterised temporal lobe epilepsy and among whom 22 had common mesial temporal lobe epilepsy were retrospectively analysed using both BM and conventional SPM normalization methods and with PET images from age-adjusted controls. Different threshold p values corrected for cluster volume were considered (0.01, 0.005, and 0.001). RESULTS: The use of BM provided equivalent values to those of SPM with regard to the overall volumes of temporal and extra-temporal hypometabolism, as well as similar sensitivity for detecting the involved temporal lobe, reaching 87 and 94 % for SPM and BM, respectively, at a threshold p value of 0.01. However, the ability to more accurately localize brain lesions within the mesial portion of the temporal lobe was a little higher with BM than with SPM with respective sensitivities reaching 78 % for BM and 45 % for SPM (p < 0.05). CONCLUSIONS: BM normalization compares well with conventional SPM for the voxel-based quantitative analysis of the FDG-PET images from temporal epilepsy patients. Further studies in different population are needed to determine whether BM is truly an accurate alternative to SPM in this setting.


Assuntos
Encéfalo/diagnóstico por imagem , Epilepsia do Lobo Temporal/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Tomografia por Emissão de Pósitrons , Software , Adulto , Encéfalo/metabolismo , Calibragem , Epilepsia do Lobo Temporal/metabolismo , Feminino , Humanos , Masculino , Estudos Retrospectivos
17.
J Labelled Comp Radiopharm ; 59(2): 54-62, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26708055

RESUMO

This work describes the development of new 6-[(18) F]fluoro-carbohydrate-based prosthetic groups equipped with an azido arm that are able to participate in copper(I)-catalyzed cycloadditions for (18) F labeling of biomolecules under mild conditions. The radiolabeling in high radiochemical yields (up to 68 ± 6%) of these different prosthetic groups is presented. The flexibility of the azido arm introduced on the carbohydrate moieties allows efficient click reactions with different alkyne functionalized peptides such as gluthation or Arg-Gly-Asp derivatives in order to prepare glycopeptides. The radiosyntheses of (18) F-labeled glycopeptides proceed in high radiochemical yields (up to 76%) in an automated process with excellent radiochemical purity. The addition of a sugar moiety on peptides should enhance the bioavailability, pharmacokinetic, and in vivo clearance properties of these glycopeptides, compared with the unlabeled native peptide, and these properties are highly favorable for positron emission tomography imaging. A high uptake of (18) F-ß-gluco-c(RGDfC) is shown by positron emission tomography imaging in a subcutaneous abscess model in the rat, revealing the potential of this tracer to monitor integrin expression as a part of inflammation and/or angiogenesis processes.


Assuntos
Radioisótopos de Flúor/química , Glicopeptídeos/química , Compostos Radiofarmacêuticos/síntese química , Animais , Química Click/métodos , Tomografia por Emissão de Pósitrons , Compostos Radiofarmacêuticos/farmacocinética , Ratos , Distribuição Tecidual
18.
Ann Nucl Med ; 29(10): 921-8, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26323854

RESUMO

INTRODUCTION: The impact of age is crucial and must be taken into account when applying a voxel-based quantitative analysis on brain images from [¹8F]-fluorodeoxyglucose Positron Emission Tomography (FDG-PET). This study aimed to determine whether age-related changes in brain FDG-PET images are more accurately assessed when the conventional statistical parametric mapping (SPM) normalization method is used with an adaptive template, obtained from analysed PET images using a Block-Matching (BM) algorithm to fit with the characteristics of these images. METHODS: Age-related changes in FDG-PET images were computed with linear models in 84 neurologically healthy subjects (35 women, 19 to 82-year-old), and compared between results provided by the SPM normalization algorithm applied on its dedicated conventional template or on the adaptive BM template. A threshold P value of 0.05 was used together with a family-wise error correction. RESULTS: The age-related changes in FDG-PET images were much more apparent when computed with the adaptive template than with the conventional template as evidenced by: (1) stronger correlation coefficients with age for the overall frontal and temporal uptake values (respective R² values of 0.20 and 0.07) and (2) larger extents of involved areas (13 and 5% of whole brain template volume, respectively), leading to reveal several age-dependent areas (especially in dorsolateral prefrontal, inferior temporal/fusiform and primary somatosensory cortices). CONCLUSION: Age-related changes in brain FDG uptake may be more accurately determined when applying the SPM method of voxel-based quantitative analysis on a template that best fits the characteristics of the analysed TEP images.


Assuntos
Envelhecimento , Encéfalo/diagnóstico por imagem , Encéfalo/metabolismo , Fluordesoxiglucose F18/metabolismo , Processamento de Imagem Assistida por Computador , Tomografia por Emissão de Pósitrons , Adolescente , Adulto , Idoso , Algoritmos , Transporte Biológico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
19.
Clin Nucl Med ; 40(9): e429-35, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26204212

RESUMO

PURPOSE: Glioma grading is necessary for prognostic evaluation and optimal treatment decisions. The aims of this study were to establish whether a correlation between F-FDOPA uptake with tumor grade was observed and to determine which of the SUV-derived indices was the best correlated. PATIENTS AND METHODS: Thirty-one patients were retrospectively included (mean [SD] age, 36.8 [12.1] years) including 21 proven low-grade tumors due to histology, imaging, and clinical follow-up and 10 histologically proven high-grade tumors. Static PET acquisitions were postreconstructed between the 10th and 30th minute after injection of F-FDOPA. Regions of interest of 20 mm were applied to tumors, and isocontoured volumes were defined at levels of 50% and 80% of the peak intensity voxel. Background was quantified with 30-mm-diameter regions of interest on contralateral striatum and centrum semioval. Tumoral uptake was evaluated with the following SUV-derived indices: SUVmax, SUVmean, SUVmax, and SUVmean of isocontoured volume, tumor/striatum ratio (T/S), and tumor/normal brain ratio (T/N). RESULTS: All the SUV-derived indices tested were significantly correlated with tumor grade, considering low-grade and high-grade groups (P < 0.05), except for the SUVmean 50%. The 2 best-correlated indices were SUVmean T/N and SUVmean T/S, with correlation coefficients of 0.561 and 0.522, respectively. Receiver operating characteristic analysis defined optimal thresholds of 1.33 and 1 for sensitivity and specificity of 71% and 100% and 67% and 100%, respectively. CONCLUSIONS: F-FDOPA PET SUV-derived indices are routinely available information that enables accurate discrimination of low-grade and high-grade gliomas. The best-correlated indices were SUVmean T/N and SUVmean T/S with thresholds of 1.33 and 1.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Glioma/diagnóstico por imagem , Tomografia por Emissão de Pósitrons , Adulto , Idoso , Di-Hidroxifenilalanina/análogos & derivados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Compostos Radiofarmacêuticos
20.
Appl Radiat Isot ; 102: 87-92, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26002274

RESUMO

A fully automated production of the imaging agent sodium [(18)F]fluoride ([(18)F]NaF) on two different modules commercialized by Trasis®, the AllInOne and the miniAllInOne, is reported. Both modules allow to prepare [(18)F]NaF in good radiochemical yield (around 97%) in less than 4min with the same specifications. Quality control of [(18)F]NaF produced by this way was performed according to the US and European Pharmacopeia monograph requirements.


Assuntos
Radioisótopos de Flúor/química , Fluoreto de Sódio/síntese química
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