RESUMO
The vertical distribution of the anthropogenic radionuclide Cs-137 in the Scots pine (Pinus sylvestris L.) bark was studied in two model trees in the radioactive contamination zone of the Bryansk region. Each tree was divided into 10-cm bars from the trunk base to a length of 17 m, and the bark with the bast was separated from each bar to obtain a separate sample. In addition to Cs-137, the natural radionuclide K-40 was measured in the bark of model tree 2 from the trunk base to a 6.5-m length. Specific activities of Cs-137 and K-40 were measured by γ-ray spectrometry. The vertical distribution of Cs-137 in the bark was for the first time observed to have a wave-like pattern with a period of approximately 1 m. The K-40 distribution showed a similar oscillatory pattern, consistent with a similar mechanism responsible for potassium and cesium behavior in woody plants. The correlation coefficient between specific activities of Cs-137 in model trees 1 and 2 was 0.80; the correlation coefficient between Cs-137 and K-40 activities in model tree 2 was 0.45. Cs-137 was assumed to provide a radiotracer to assess the intake and distribution of chemical elements in Scotch pine tissues. The oscillatory pattern observed for the vertical distributions of cesium and potassium in the pine bark has not been described in the available literature before.
Assuntos
Pinus sylvestris , Pinus sylvestris/química , Radioisótopos de Césio/análise , Casca de Planta , Árvores , PotássioRESUMO
BACKGROUND: Moderate-to-severe atopic dermatitis (AD) is a chronic disease characterized by intense, persistent and debilitating itch, resulting in sleep deprivation, signs of anxiety and depression, impaired quality of life and reduced productivity. The Peak Pruritus Numerical Rating Scale (NRS) was developed and validated as a single-item, patient-reported outcome (PRO) of itch severity. OBJECTIVES: To describe the content validity and psychometric assessment (test-retest reliability, construct validity, known-groups validity, sensitivity to change) of the Peak Pruritus NRS, and to derive empirically a responder definition to identify adults with a meaningful change in itch. METHODS: Content validity was assessed through in-depth patient interviews. Psychometric assessments used data from phase IIb and phase III dupilumab clinical trials and included test-retest reliability, construct validity, known-groups validity and sensitivity to change in patients with moderate-to-severe AD. RESULTS: Interview participants indicated that the Peak Pruritus NRS was a relevant, clear and comprehensive assessment of itch severity. Peak Pruritus NRS scores showed large, positive correlations with existing PRO measures of itch, and weak or moderate correlations with clinician-reported measures assessing objective signs of AD. Peak Pruritus NRS score improvements were highly correlated with improvements in other itch PROs, and moderately correlated with improvements in clinician-reported measures assessing objective signs of AD. The most appropriate threshold for defining a clinically relevant, within-person response was ≥ 2-4-point change in the Peak Pruritus NRS. CONCLUSIONS: The Peak Pruritus NRS is a well-defined, reliable, sensitive and valid scale for evaluating worst itch intensity in adults with moderate-to-severe AD.
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Anticorpos Monoclonais Humanizados/uso terapêutico , Dermatite Atópica/diagnóstico , Medidas de Resultados Relatados pelo Paciente , Prurido/diagnóstico , Qualidade de Vida , Adulto , Idoso , Ensaios Clínicos Fase II como Assunto , Ensaios Clínicos Fase III como Assunto , Dermatite Atópica/complicações , Dermatite Atópica/tratamento farmacológico , Dermatite Atópica/psicologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prurido/tratamento farmacológico , Prurido/etiologia , Prurido/psicologia , Psicometria/métodos , Reprodutibilidade dos Testes , Índice de Gravidade de Doença , Adulto JovemRESUMO
BACKGROUND: Dupilumab, a human anti-interleukin-4 receptor alpha monoclonal antibody, significantly improved clinical signs and symptoms in adults with moderate-to-severe atopic dermatitis in a randomized, double-blind, placebo-controlled, phase IIa trial. OBJECTIVES: We evaluate health-related quality of life (HRQoL) and correlation of HRQoL with secondary clinical and patient-reported outcomes in a subset of patients from this trial of dupilumab. METHODS: Patients were randomized to 300 mg weekly subcutaneous dupilumab or placebo for 12 weeks (trial registration: NCT01548404). The Quality of Life Index of Atopic Dermatitis (QoLIAD) score (exploratory outcome) and its correlation with efficacy outcomes [Eczema Area and Severity Index (EASI); primary end point; SCORing Atopic Dermatitis (SCORAD), SCORAD visual analogue scale (VAS) scores for sleep and pruritus, pruritus numerical rating scale (NRS) and 5-dimensional pruritus] were assessed in 64 adults with moderate-to-severe atopic dermatitis. RESULTS: Mean QoLIAD scores at baseline ± standard error (SE) were 13·3 ± 1·34 and 11·3 ± 1·09 for the placebo and dupilumab groups, respectively. Dupilumab significantly improved QoLIAD score after 12 weeks of treatment vs. placebo (mean % change from baseline in QoLIAD score ± SE: -64·0 ± 6·91 vs. -11·1 ± 9·31). Least squares mean % difference from baseline vs. placebo in QoLIAD score ±SE was -52·0 ± 11·43, P < 0·001). QoLIAD scores significantly correlated with changes in efficacy outcomes, including EASI (r = 0·44), 5-dimensional pruritus (r = 0·49), pruritus NRS (r = 0·41), total SCORAD (r = 0·56) and SCORAD VAS scores for sleep (r = 0·47) and pruritus (r = 0·54); all P < 0·05. CONCLUSIONS: Dupilumab improved QoLIAD scores in adults with atopic dermatitis and was significantly associated with improvements in study outcomes.
Assuntos
Anti-Inflamatórios/administração & dosagem , Anticorpos Monoclonais/administração & dosagem , Dermatite Atópica/tratamento farmacológico , Qualidade de Vida , Adulto , Anticorpos Monoclonais Humanizados , Método Duplo-Cego , Esquema de Medicação , Feminino , Humanos , Injeções Subcutâneas , Masculino , Resultado do TratamentoRESUMO
BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disease that may require systemic therapy. Ciclosporin A (CsA) is a widely used, potent immunosuppressant but it is not effective in all patients with atopic dermatitis, and side-effects limit its use. Dupilumab, a fully human anti-interleukin 4 receptor-alpha monoclonal antibody, inhibits signaling of IL-4 and IL-13, key drivers of Type 2/Th2-mediated inflammation, and is approved in the U.S.A. and the European Union for the treatment of inadequately-controlled moderate-to-severe atopic dermatitis in adults. OBJECTIVES: To evaluate efficacy and safety of dupilumab with concomitant topical corticosteroids (TCS) in adults with atopic dermatitis with inadequate response to/intolerance of CsA, or for whom CsA treatment was medically inadvisable. METHODS: In this 16-week, double-blind, randomized, placebo-controlled, phase III trial, patients were randomized 1 : 1 : 1 to subcutaneous dupilumab 300 mg weekly (qw) or every 2 weeks (q2w) or placebo. All received concomitant medium-potency TCS from Week -2 through Week 16; dosage could be tapered if lesions cleared, or stopped for adverse reactions to TCS. RESULTS: In total, 390 patients were screened, 325 were randomized, and 318 completed the trial. Treatment groups had similar baseline characteristics. Significantly more patients in the dupilumab qw + TCS and q2w + TCS groups achieved ≥ 75% improvement from baseline in the Eczema Area and Severity Index at Week 16 vs. the placebo + TCS group (primary end point) (59·1% and 62·6% vs. 29·6%, respectively; P < 0·001 vs. placebo + TCS, both doses). Other clinical outcomes and atopic dermatitis symptoms were significantly improved in the dupilumab qw + TCS and q2w + TCS groups, including pruritus, pain, sleep disturbance, symptoms of anxiety and depression, and quality of life (QoL). Treatment groups had similar overall rates of adverse events (qw + TCS, q2w + TCS and placebo + TCS groups: 69·1%, 72·0% and 69·4%, respectively) and serious adverse events (1·8%, 1·9% and 1·9%, respectively). Conjunctivitis was more frequent with dupilumab + TCS; skin infections were more frequent with placebo + TCS. CONCLUSIONS: Dupilumab + TCS significantly improved signs and symptoms of atopic dermatitis and QoL in adults with a history of inadequate response to/intolerance of CsA, or for whom CsA treatment was medically inadvisable. No new safety signals were identified.
Assuntos
Anticorpos Monoclonais/administração & dosagem , Dermatite Atópica/tratamento farmacológico , Fármacos Dermatológicos/administração & dosagem , Administração Cutânea , Adolescente , Corticosteroides/administração & dosagem , Adulto , Idoso , Anticorpos Monoclonais/efeitos adversos , Anticorpos Monoclonais Humanizados , Ciclosporina/efeitos adversos , Fármacos Dermatológicos/efeitos adversos , Método Duplo-Cego , Esquema de Medicação , Hipersensibilidade a Drogas/etiologia , Quimioterapia Combinada , Feminino , Humanos , Injeções Subcutâneas , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto JovemRESUMO
Dynamics of radiation situation in settlements, agriculture and forestry on the Russian Federation areas af- fected by the Chernobyl accident is presented. A set of challenging problems on public radiation protection and rehabilitation of territories was determined. The main objective at a long-term period after the accident is a stage-wise return of the affected areas to normal activity without any radiological criteria restrictions. For practical realization of this process it is necessary to change the national statutes and regulations consid- ering the contemporary international approaches, to pass to the current exposure situation and to establish reference levels, to define criteria of transition of the areas affected after the Chernobyl accident to normal activity. The change of conceptual approaches will allow one to revise the boundaries of settlement zoning and to develop the regulatory framework on procedures of changing their status from radioactively contami- nated zone to normal activity zone; to develop the regulatory framework on the procedures of transition of agricultural and forest lands classified as radioactively contaminated zones to territories where the traditional husbandry is possible. The Russian Federation has positive experience of transition of areas contaminated as a result of the Chernobyl accident to normal activity.
Assuntos
Acidente Nuclear de Chernobyl , Contaminação Radioativa de Alimentos/prevenção & controle , Monitoramento de Radiação/métodos , Proteção Radiológica/métodos , Agricultura , Radioisótopos de Césio/toxicidade , Descontaminação/métodos , Exposição Ambiental/prevenção & controle , Humanos , Doses de Radiação , Liberação Nociva de Radioativos , Federação Russa , UcrâniaRESUMO
PURPOSE: To evaluate quantitative perfusion measurements of dynamic indocyanine green (ICG)-enhanced optical imaging for monitoring synovitis in the hands of patients with inflammatory arthritis compared with dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging and clinical outcome. MATERIALS AND METHODS: This study was approved by the ethics committee at the institution. Individual joints (n = 840) in the hands and wrists of 28 patients (14 women; mean age, 53.3 years) with inflammatory arthritis were examined at three different time points: before start of therapy and 12 and 24 weeks after start of therapy or therapy escalation. Treatment response was assessed by using clinical measures (simple disease activity index [SDAI]), ICG-enhanced optical imaging, and DCE MR imaging. Dynamic images were obtained for optical imaging and DCE MR imaging. The rate of early enhancement (REE) of the perfusion curves of each joint was calculated by using in-house developed software. Correlation coefficients were estimated to evaluate the associations of changes of imaging parameters and SDAI change. RESULTS: Quantitative perfusion measurements with optical imaging and MR imaging correctly identified patients who responded (n = 18) and did not respond to therapy (n = 10), as determined by SDAI. The difference of REE after 24 weeks of treatment compared with baseline in responders was significantly reduced in optical imaging and MR imaging (optical imaging: mean, -21.5%; MR imaging: mean, -41.0%; P < .001 for both), while in nonresponders it was increased (optical imaging: mean, 10.8%; P = .075; MR imaging: mean, 8.7%; P = .03). The REE of optical imaging significantly correlated with MR imaging (ρ = 0.80; P < .001) and SDAI (ρ = 0.61; P < .001). CONCLUSION: Quantitative analysis of contrast-enhanced optical imaging allows for potential therapeutic monitoring of synovitis in patients with inflammatory arthritis.
Assuntos
Artrite Reumatoide/terapia , Mãos , Imageamento por Ressonância Magnética/métodos , Imagem Óptica/métodos , Sinovite/diagnóstico , Sinovite/terapia , Meios de Contraste , Feminino , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador , Verde de Indocianina , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Software , Resultado do TratamentoRESUMO
Clinical challenges in pediatrics dose estimation by the displayed computed tomography (CT) dose indices may lead to inaccuracy, and thus size-specific dose estimate (SSDE) is introduced for better-personalized dose estimation. This study aims to estimate pediatric dose adapted to specific size. This retrospective study involved pediatric population aged 0-12 y. SSDE was derived from scanner reported volume CT dose index (CTDIvol), based on individual effective diameter (Deff) with corresponding size correction factors. The correlations of Deff with other associated factors such as age, exposure setting, CTDIvol and SSDE were also studied. The average Deff of Malaysian pediatric was smaller than reference phantom size (confidence interval, CI = 0.28, mean = 14.79) and (CI = 0.51, mean = 16.33) for head and abdomen, respectively. These have led to underestimation of pediatric dose as SSDE was higher than displayed CTDIvol. The percentage differences were statistically significant (p < .001) ranged from 0 to 17% and 37 to 60% for head and abdominal CT, respectively. In conclusion, the clinical implementation of SSDE in pediatric CT imaging is highly relevant to reduce radiation risk.
Assuntos
Pediatria , Tomografia Computadorizada por Raios X , Criança , Humanos , Imagens de Fantasmas , Doses de Radiação , Estudos Retrospectivos , Tomografia Computadorizada por Raios X/métodosRESUMO
BACKGROUND: Recent studies suggest that blockade of the NLRP3 (cryopyrin) inflammasome interleukin 1beta (IL1beta) pathway may offer a new treatment strategy for gout. OBJECTIVE: To explore the potential utility of rilonacept (IL1 Trap) in patients with chronic active gouty arthritis in a proof-of-concept study. METHODS: This 14-week, multicentre, non-randomised, single-blind, monosequence crossover study of 10 patients with chronic active gouty arthritis included a placebo run-in (2 weeks), active rilonacept treatment (6 weeks) and a 6-week post-treatment follow-up. RESULTS: Rilonacept was generally well tolerated. No deaths and no serious adverse events occurred during the study. One patient withdrew owing to an injection-site reaction. Patients' self-reported median pain visual analogue scale scores significantly decreased from week 2 (after the placebo run-in) to week 4 (2 weeks of rilonacept) (5.0 to 2.8; p<0.049), with sustained improvement at week 8 (1.3; p<0.049); 5 of 10 patients reported at least a 75% improvement. Median symptom-adjusted and severity-adjusted joint scores were significantly decreased. High-sensitivity C-reactive protein levels fell significantly. CONCLUSIONS: This proof-of-concept study demonstrated that rilonacept is generally well tolerated and may offer therapeutic benefit in reducing pain in patients with chronic refractory gouty arthritis, supporting the need for larger, randomised, controlled studies of IL1 antagonism such as with rilonacept for this clinical indication.
Assuntos
Artrite Gotosa/tratamento farmacológico , Supressores da Gota/uso terapêutico , Interleucina-1beta/antagonistas & inibidores , Proteínas Recombinantes de Fusão/uso terapêutico , Idoso , Artrite Gotosa/sangue , Proteína C-Reativa/metabolismo , Doença Crônica , Métodos Epidemiológicos , Feminino , Supressores da Gota/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor/métodos , Proteínas Recombinantes de Fusão/efeitos adversos , Resultado do TratamentoRESUMO
The dependence of trans factor of radionuclides on the soil to the vegetation (wood etc.) caused by natural-climatic conditions determine a duration period of the rehabilitation of ecological and social-economic functions of forests landscapes polluted by radionuclides. It firstly allows to classify forest ecosystems by groups of their radioecological stability with division into three appropriate radioecological districts. The forest ecosystems characterized by a rather short-term duration of the rehabilitation period of ecological and social-economic functions after the radiation contamination (till 30 years) are relatively stable in the radioecological reference. They are typical to steppe and forest-steppe zones and appropriate radiological district (related to natural zone). The forests ecosystems with the intermediate-term rehabilitation period after the radiation impact (30-60 years) are weakly stable in the radioecological reference and typical to broadleaved and coniferous-broadleaved forest zones and appropriate radiological district. The forest ecosystems with a long-term rehabilitation period after the radiation contamination (more than 60 years) are characterized as radioecologically unstable. The appropriate radiological district is include north-taiga forests and pre-tundra open woodlands.
Assuntos
Acidente Nuclear de Chernobyl , Monitoramento de Radiação , Radioisótopos/análise , Conservação dos Recursos Naturais/métodos , Federação Russa , Árvores/classificação , Árvores/efeitos da radiaçãoRESUMO
Acute allergic symptoms are caused by allergen-induced crosslinking of allergen-specific immunoglobulin E (IgE) bound to Fc-epsilon receptors on effector cells. Desensitization with allergen-specific immunotherapy (SIT) has been used for over a century, but the dominant protective mechanism remains unclear. One consistent observation is increased allergen-specific IgG, thought to competitively block allergen binding to IgE. Here we show that the blocking potency of the IgG response to Cat-SIT is heterogeneous. Next, using two potent, pre-selected allergen-blocking monoclonal IgG antibodies against the immunodominant cat allergen Fel d 1, we demonstrate that increasing the IgG/IgE ratio reduces the allergic response in mice and in cat-allergic patients: a single dose of blocking IgG reduces clinical symptoms in response to nasal provocation (ANCOVA, p = 0.0003), with a magnitude observed at day 8 similar to that reported with years of conventional SIT. This study suggests that simply augmenting the blocking IgG/IgE ratio may reverse allergy.
Assuntos
Anticorpos Monoclonais/farmacologia , Dessensibilização Imunológica/métodos , Glicoproteínas/imunologia , Hipersensibilidade/terapia , Imunoglobulina G/farmacologia , Receptores de IgE/imunologia , Adolescente , Adulto , Alérgenos/administração & dosagem , Alérgenos/imunologia , Alérgenos/isolamento & purificação , Pelo Animal/química , Pelo Animal/imunologia , Animais , Anticorpos Monoclonais/biossíntese , Ligação Competitiva , Gatos , Misturas Complexas/química , Misturas Complexas/imunologia , Modelos Animais de Doenças , Feminino , Glicoproteínas/administração & dosagem , Glicoproteínas/isolamento & purificação , Humanos , Hipersensibilidade/imunologia , Hipersensibilidade/fisiopatologia , Imunoglobulina E/química , Imunoglobulina E/imunologia , Imunoglobulina E/metabolismo , Imunoglobulina G/biossíntese , Masculino , Camundongos , Pessoa de Meia-Idade , Ligação Proteica/efeitos dos fármacos , Receptores de IgE/química , Receptores de IgE/metabolismoRESUMO
In order to determine the biological effects of activation of the c-fos protooncogene on growth and differentiation of BALB/MK mouse keratinocytes, these cells were transfected with the plasmid pMAN-fos, which encompasses the human c-fos coding region under transcriptional control of a mouse mammary tumor virus promoter, as well as the gene encoding neomycin phosphotransferase. Of approximately 70 individual clones obtained by selection in Geneticin, 5 clones that constitutively expressed c-fos mRNA as well as p55fos protein were selected for phenotypic analysis. Each of these clones displayed density-dependent growth arrest at confluency when deprived of serum and mitogens. DNA synthesis could be reinitiated in quiescent cultures by treatment with epidermal growth factor to a similar extent as in the parental line. In four of five fos transfectants, insulin-like growth factor 1 potentiated the mitogenic response to epidermal growth factor more than 10-fold, compared to only 2.5-fold in the parental cells. The enhanced response to insulin-like growth 1 could not be attributed to changes in the number or the affinity of receptors for the growth factor. Finally, the constitutive expression of c-fos did not interfere with the induction of terminal differentiation by calcium.
Assuntos
Fator de Crescimento Insulin-Like I/farmacologia , Queratinócitos/citologia , Proteínas Proto-Oncogênicas/genética , Proto-Oncogenes , Animais , Cálcio/farmacologia , Diferenciação Celular/efeitos dos fármacos , DNA/metabolismo , Expressão Gênica , Camundongos , Proteínas Proto-Oncogênicas c-fos , RNA Mensageiro/análise , Receptores de Superfície Celular/análise , Receptores de Somatomedina , TransfecçãoRESUMO
Transfection of the wild-type p53 gene into malignant cell lines usually results in an inhibition of proliferation. However, the physiological function of the endogenous p53 gene product has been difficult to ascertain. In order to examine whether p53 is involved in the regulation of proliferation and/or differentiation of hematopoietic tissue, we modified a recently developed flow cytometric assay to assess p53 protein expression in normal human hematopoietic cells, primary leukemias, and selected leukemia cell lines. In normal human bone marrow, p53 protein was not detected in the proliferative, progenitor cell populations identified by the cell surface antigens CD34 (progenitor cells of multiple lineages) or glycophorin (erythroid precursors). In contrast, low but detectable levels of p53 protein were observed in the nonproliferative, mature lymphoid, granulocytic, and monocytic cell populations. Similarly, p53 levels increased and DNA synthesis decreased during 12-O-tetradecanoylphorbol-13-acetate-induced differentiation of ML-1 myeloblastic leukemia cells. Both of these results suggest that endogenous, wild-type p53 protein may play a role in hematopoietic cell maturation, possibly by contributing to the inhibition of proliferation that occurs during terminal differentiation. Leukemia cells deviated from this pattern of expression: (a) in contrast to the normal, proliferative bone marrow progenitor cells, a significant percentage of patient leukemia samples expressed detectable levels of p53 protein; and (b) leukemia cell lines exhibited lineage-specific abnormalities in p53 expression, with overexpression in lymphoid cell lines and lack of expression in myeloid cell lines.
Assuntos
Divisão Celular , Células-Tronco Hematopoéticas/metabolismo , Proteína Supressora de Tumor p53/genética , Doença Aguda , Adulto , Sequência de Aminoácidos , Medula Óssea/metabolismo , Medula Óssea/patologia , Células da Medula Óssea , Linhagem Celular , Células Cultivadas , Citometria de Fluxo , Expressão Gênica/efeitos dos fármacos , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/patologia , Humanos , Immunoblotting , Cinética , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Leucemia Mieloide/metabolismo , Leucemia Mieloide/patologia , Dados de Sequência Molecular , Oligopeptídeos/síntese química , Oligopeptídeos/imunologia , RNA Mensageiro/análise , RNA Mensageiro/genética , Acetato de Tetradecanoilforbol/farmacologia , Proteína Supressora de Tumor p53/análiseRESUMO
We investigated the effects of low-dose multi detector computed tomography (MDCT) in combination with statistical iterative reconstruction algorithms on trabecular bone microstructure parameters. Twelve donated vertebrae were scanned with the routine radiation exposure used in our department (standard-dose) and a low-dose protocol. Reconstructions were performed with filtered backprojection (FBP) and maximum-likelihood based statistical iterative reconstruction (SIR). Trabecular bone microstructure parameters were assessed and statistically compared for each reconstruction. Moreover, fracture loads of the vertebrae were biomechanically determined and correlated to the assessed microstructure parameters. Trabecular bone microstructure parameters based on low-dose MDCT and SIR significantly correlated with vertebral bone strength. There was no significant difference between microstructure parameters calculated on low-dose SIR and standard-dose FBP images. However, the results revealed a strong dependency on the regularization strength applied during SIR. It was observed that stronger regularization might corrupt the microstructure analysis, because the trabecular structure is a very small detail that might get lost during the regularization process. As a consequence, the introduction of SIR for trabecular bone microstructure analysis requires a specific optimization of the regularization parameters. Moreover, in comparison to other approaches, superior noise-resolution trade-offs can be found with the proposed methods.
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Osso Esponjoso/diagnóstico por imagem , Modelos Anatômicos , Algoritmos , Fenômenos Biomecânicos , Densidade Óssea , Simulação por Computador , Humanos , Processamento de Imagem Assistida por Computador , Doses de Radiação , Tomografia Computadorizada por Raios X/métodosRESUMO
PURPOSE: Spectral Computed Tomography (SCT) systems equipped with photon counting detectors (PCD) are clinically desired, since such systems provide not only additional diagnostic information but also radiation dose reductions by a factor of two or more. The current unavailability of clinical PCDs makes a simulation of such systems necessary. METHODS: In this paper, we present a Monte Carlo-based simulation of a SCT equipped with a PCD. The aim of this development is to facilitate research on potential clinical applications. Our MC simulator takes into account scattering interactions within the scanned object and has the ability to simulate scans with and without scatter and a wide variety of imaging parameters. To demonstrate the usefulness of such a MC simulator for development of SCT applications, a phantom with contrast targets covering a wide range of clinically significant iodine concentrations is simulated. With those simulations the impact of scatter and exposure on image quality and material decomposition results is investigated. RESULTS: Our results illustrate that scatter radiation plays a significant role in visual as well as quantitative results. Scatter radiation can reduce the accuracy of contrast agent concentration by up to 15%. CONCLUSIONS: We present a reliable and robust software bench for simulation of SCTs equipped with PCDs.
Assuntos
Método de Monte Carlo , Software , Tomografia Computadorizada por Raios X , Processamento de Imagem Assistida por ComputadorRESUMO
In recent years, dual-energy computed tomography (DECT) has been widely used in the clinical routine due to improved diagnostics capability from additional spectral information. One promising application for DECT is CT colonography (CTC) in combination with computer-aided diagnosis (CAD) for detection of lesions and polyps. While CAD has demonstrated in the past that it is able to detect small polyps, its performance is highly dependent on the quality of the input data. The presence of artifacts such as beam-hardening and noise in ultra-low-dose CTC may severely degrade detection performances of small polyps. In this work, we investigate and compare virtual monochromatic images, generated by image-based decomposition and projection-based decomposition, with respect to CAD performance. In the image-based method, reconstructed images are firstly decomposed into water and iodine before the virtual monochromatic images are calculated. On the contrary, in the projection-based method, the projection data are first decomposed before calculation of virtual monochromatic projection and reconstruction. Both material decomposition methods are evaluated with regards to the accuracy of iodine detection. Further, the performance of the virtual monochromatic images is qualitatively and quantitatively assessed. Preliminary results show that the projection-based method does not only have a more accurate detection of iodine, but also delivers virtual monochromatic images with reduced beam hardening artifacts in comparison with the image-based method. With regards to the CAD performance, the projection-based method yields an improved detection performance of polyps in comparison with that of the image-based method.
RESUMO
PURPOSE: The exciting prospect of Spectral CT (SCT) using photon-counting detectors (PCD) will lead to new techniques in computed tomography (CT) that take advantage of the additional spectral information provided. We introduce a method to reduce metal artifact in X-ray tomography by incorporating knowledge obtained from SCT into a statistical iterative reconstruction scheme. We call our method Spectral-driven Iterative Reconstruction (SPIR). METHOD: The proposed algorithm consists of two main components: material decomposition and penalized maximum likelihood iterative reconstruction. In this study, the spectral data acquisitions with an energy-resolving PCD were simulated using a Monte-Carlo simulator based on EGSnrc C++ class library. A jaw phantom with a dental implant made of gold was used as an object in this study. A total of three dental implant shapes were simulated separately to test the influence of prior knowledge on the overall performance of the algorithm. The generated projection data was first decomposed into three basis functions: photoelectric absorption, Compton scattering and attenuation of gold. A pseudo-monochromatic sinogram was calculated and used as input in the reconstruction, while the spatial information of the gold implant was used as a prior. The results from the algorithm were assessed and benchmarked with state-of-the-art reconstruction methods. RESULTS: Decomposition results illustrate that gold implant of any shape can be distinguished from other components of the phantom. Additionally, the result from the penalized maximum likelihood iterative reconstruction shows that artifacts are significantly reduced in SPIR reconstructed slices in comparison to other known techniques, while at the same time details around the implant are preserved. Quantitatively, the SPIR algorithm best reflects the true attenuation value in comparison to other algorithms. CONCLUSION: It is demonstrated that the combination of the additional information from Spectral CT and statistical reconstruction can significantly improve image quality, especially streaking artifacts caused by the presence of materials with high atomic numbers.
Assuntos
Algoritmos , Artefatos , Metais/química , Fótons , Tomografia Computadorizada por Raios X , Simulação por Computador , Humanos , Processamento de Imagem Assistida por Computador , Modelos Teóricos , Imagens de Fantasmas , Próteses e Implantes , Interface Usuário-Computador , Raios XRESUMO
Intraperitoneal installation of chemotherapy through a Mediport implanted subcutaneously in the abdominal wall is used currently for treatment of peritoneal metastases from ovarian, gastric and colonic carcinoma. There is a variable incidence of complications due to the procedure reported in the literature. The main predisposing factor for these complications is the inhomogeneous distribution of the chemotherapeutic drugs within the peritoneal cavity. We report an unusual case of a rectosigmoid fistula that developed 6 wk following the insertion of a Bardport subcutaneously in the abdominal wall for intraperitoneal therapy. The fistula was clearly demonstrated by dynamic scintigraphic peritoneography. This is a new modification of scintigraphic peritoneography as practiced routinely. We endorse the previous recommendation that scintigraphic peritoneography be performed before every intraperitoneal installation of a chemotherapeutic drug or radiopharmaceutical to ensure the homogeneous distribution of the drugs and to prevent complications.
Assuntos
Cateteres de Demora/efeitos adversos , Fístula Intestinal/diagnóstico por imagem , Fístula Retal/diagnóstico por imagem , Doenças do Colo Sigmoide/diagnóstico por imagem , Idoso , Antineoplásicos/administração & dosagem , Feminino , Humanos , Fístula Intestinal/etiologia , Neoplasias Peritoneais/tratamento farmacológico , Cintilografia , Compostos Radiofarmacêuticos , Fístula Retal/etiologia , Doenças do Colo Sigmoide/etiologia , Coloide de Enxofre Marcado com Tecnécio Tc 99m , Fatores de TempoRESUMO
We report our experience with coincidence detection imaging of 18F-fluorodeoxyglucose (FDG) using a dual-head gamma camera. Scanning of the pelvis and abdomen of a patient with recurrent colorectal carcinoma showed recurrent disease in the pelvic floor and the base of the urinary bladder and metastatic disease in the retroperitoneal space of the pelvis. Although the tumor involving the bladder and pelvic floor was detected by CT and magnetic resonance imaging (MRI), metastatic spread to the retroperitoneal nodes on the left side was detected only by 18F-FDG imaging. Based on the ultrasound, CT, MRI and cystoscopy, a local recurrence of cancer was presumed in our patient. An exploratory laparotomy was performed to resect the tumor in its entirety. At the time of surgery, the retroperitoneal metastasis in the pelvis was confirmed. Had the findings of the coincidence detection imaging study been considered, the patient would have been spared the surgical procedure.
Assuntos
Adenocarcinoma/diagnóstico por imagem , Neoplasias Colorretais/diagnóstico por imagem , Fluordesoxiglucose F18 , Recidiva Local de Neoplasia/diagnóstico por imagem , Compostos Radiofarmacêuticos , Idoso , Neoplasias Colorretais/patologia , Câmaras gama , Humanos , Metástase Linfática/diagnóstico por imagem , Masculino , Invasividade Neoplásica , Cintilografia , Neoplasias da Bexiga Urinária/diagnóstico por imagemRESUMO
These investigations were performed to clarify the molecular basis for the enhanced expression of cytosolic aldehyde dehydrogenase (ALDH-1) enzymatic activity in the cyclophosphamide-resistant L1210/CPA murine leukemia cell line, as compared to the parental L1210/O strain. Western immunoblot analysis was performed using a 15-fold greater quantity of cytosolic protein from the L1210/O as compared to the L1210/CPA cell line. Nevertheless, ALDH-1 immunoreactive protein could be detected only in the L1210/CPA cells. Northern analyses, performed using total cellular and polyadenylated RNA, again demonstrated ALDH-1-specific transcripts only in the L1210/CPA cell line. This transcript was identical in size to the ALDH-1 message expressed by normal murine hepatocytes. On Southern analysis, no evidence of gene amplification, gene rearrangement, or significant mutations of length was detected. These studies suggest that the ALDH-1 protein produced by the L1210/CPA cell line is structurally normal. Moreover, overexpression of the gene does not appear to have arisen as a result of an incremental process, such as gene amplification. Rather, a qualitative abnormality in the regulation of this gene appears to exist in the L1210/CPA cells, which distinguishes them from L1210/O cells and from normal murine lymphocytes.
Assuntos
Aldeído Desidrogenase/genética , Ciclofosfamida/metabolismo , Regulação Enzimológica da Expressão Gênica , Leucemia L1210/genética , Animais , Biotransformação , Citosol/enzimologia , Resistência a Medicamentos , Immunoblotting , Leucemia L1210/enzimologia , Camundongos , Células Tumorais CultivadasRESUMO
Both pure systolic, and systolic plus diastolic hypertension are risk factors for cerebrovascular and cardiovascular disease in patients over 65 years old, but the efficacy of antihypertensive therapy in preventing the complications of hypertension in the elderly has been questioned. The risks associated with such therapy seem to have been overemphasized. Although the evidence is incomplete, elderly patients should be treated when the systolic blood pressure exceeds 160 mm Hg or the diastolic pressure exceeds 95 mm Hg, or both. A revised stepped-care approach, with use of vasodilating agents as the Step-2 drugs, is proposed.