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1.
Molecules ; 26(16)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34443574

RESUMO

Natural extracts are a rich source of biomolecules that are useful not only as antioxidant drugs or diet supplements but also as complex reagents for the biogenic synthesis of metallic nanoparticles. The natural product components can act as strong reducing and capping substrates guaranteeing the stability of formed NPs. The current work demonstrates the suitability of extracts of Camellia sinensis, Ilex paraguariensis, Salvia officinalis, Tilia cordata, Levisticum officinale, Aegopodium podagraria, Urtica dioica, Capsicum baccatum, Viscum album, and marine algae Porphyra Yezoensis for green synthesis of AgNPs. The antioxidant power of methanolic extracts was estimated at the beginning according to their free radical scavenging activity by the DPPH method and reducing power activity by CUPRAC and SNPAC (silver nanoparticle antioxidant capacity) assays. The results obtained by the CUPRAC and SNAPC methods exhibited excellent agreement (R2~0.9). The synthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), dynamic light scattering (DLS) particle size, and zeta potential. The UV-vis absorption spectra showed a peak at 423 nm confirming the presence of AgNPs. The shapes of extract-mediated AgNPs were mainly spherical, spheroid, rod-shaped, agglomerated crystalline structures. The NPs exhibited a high negative zeta potential value in the range from -49.8 mV to -56.1 mV, proving the existence of electrostatic stabilization. FTIR measurements indicated peaks corresponding to different functional groups such as carboxylic acids, alcohol, phenol, esters, ethers, aldehydes, alkanes, and proteins, which were involved in the synthesis and stabilization of AgNPs. Among the examined extracts, green tea showed the highest activity in all antioxidant tests and enabled the synthesis of the smallest nanoparticles, namely 62.51, 61.19, and 53.55 nm, depending on storage times of 30 min, 24 h, and 72 h, respectively. In turn, the Capsicum baccatum extract was distinguished by the lowest zeta potential, decreasing with storage time from -66.0 up to -88.6 mM.


Assuntos
Antioxidantes/síntese química , Antioxidantes/farmacologia , Nanopartículas Metálicas , Extratos Vegetais/química , Prata/química , Prata/farmacologia , Antioxidantes/química , Compostos de Bifenilo/química , Técnicas de Química Sintética , Química Verde , Picratos/química
2.
Materials (Basel) ; 14(6)2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33803965

RESUMO

Nowadays, using fly ash for zeolites production has become a well-known strategy aimed on sustainable development. During zeolite synthesis in a hydrothermal conversion large amount of post-reaction solution is generated. In this work, the solution was used as a substrate for Na-A and Na-X zeolites synthesis at laboratory and technical scale. Obtained materials were characterized using particle size analysis, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), and nitrogen adsorption/desorption isotherm. Produced zeolites revealed high purity (>98%) and monomineral zeolitic phase composition. The SiO2 content was in the range 39-42% and 40-38%, whereas Al2O3 content was 23-22% and 25-26% for Na-X and Na-A, respectively. TEM and BET analyses revealed Na-X zeolite pores were almost identical to commercial 13X with SBET in the range 671-734 m2/g. FTIR indicated slight differences between materials obtained at laboratory and technical scale in Si-O-(Si/Al) bridges of the zeolitic skeleton. The results showed good replicability of the laboratory process in the larger scale. The proposed method allows for waste solution reusability with a view to highly pure zeolites production in line with circular economy assumptions.

3.
Materials (Basel) ; 13(22)2020 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-33233399

RESUMO

Zeolites are materials with known sorption properties. The sorption is thought to progress mainly by ion exchange with Na+, K+, Mg2+, Ca2+ or H+ from the zeolite exchange sites. The aim of the study was to compare the sorption properties of natural and synthetic zeolites on the example of the removal of selected metals from aqueous acidic solutions. Uptake experiments for selected ions of chromium, manganese, selenium, nickel, cobalt, and iron were performed using the batch and kinetic column methods. The sorption of the individual metal ions in mg per 1g of sorbent was determined for each sorbent. The relative affinity sequence of the examined cations toward the various sorbent was presented. The Langmuir model was used to model the adsorption equilibrium. Vermiculite under 1 mm of diameter (SF), Na-X, and Na-A were proved to be the most suitable for the individual uptake of studied metal ions. It was observed that the behavior of selenium ions differed from the remaining ones which was interpreted that selenium undergoes adsorption in the anionic form. The fixed-bed column studies were performed using Na-A, ensuring the sorption of selenium in the presence of iron(III) ions. The experiments were conducted using Na-X zeolite pre-loaded by Fe(III) as well as unmodified sorbent eluted by an equimolar mixture containing 100 ppm of Fe and Se. Obtained results prove that selenium sorption improves if other metal ions such as iron appear in the acidic solution. That efficient selenium sorption conditions can be applied to remove selenium which was recognized as toxic at higher levels.

4.
Phys Med ; 77: 92-99, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32818774

RESUMO

PURPOSE: To evaluate the use of pseudo-monoenergetic reconstructions (PMR) from dual-energy computed tomography, combined with the iterative metal artefact reduction (iMAR) method. METHODS: Pseudo-monoenergetic CT images were obtained using the dual-energy mode on the Siemens Somatom Definition AS scanner. A range of PMR combinations (70-130 keV) were used with and without iMAR. A Virtual Water™ phantom was used for quantitative assessment of error in the presence of high density materials: titanium, alloys 330 and 600. The absolute values of CT number differences (AD) and normalised standard deviations (NSD) were calculated for different phantom positions. Image quality was assessed using an anthropomorphic pelvic phantom with an embedded hip prosthesis. Image quality was scored blindly by five observers. RESULTS: AD and NSD values revealed differences in CT number errors between tested sets. AD and NSD were reduced in the vicinity of metal for images with iMAR (p < 0.001 for AD/NSD). For ROIs away from metal, with and without iMAR, 70 keV PMR and pCT AD values were lower than for the other reconstructions (p = 0.039). Similarly, iMAR NSD values measured away from metal were lower for 130 keV and 70 keV PMR (p = 0.002). Image quality scores were higher for 70 keV and 130 keV PMR with iMAR (p = 0.034). CONCLUSION: The use of 70 keV PMR with iMAR allows for significant metal artefact reduction and low CT number errors observed in the vicinity of dense materials. It is therefore an attractive alternative to high keV imaging when imaging patients with metallic implants, especially in the context of radiotherapy planning.


Assuntos
Algoritmos , Artefatos , Humanos , Metais , Imagens de Fantasmas , Interpretação de Imagem Radiográfica Assistida por Computador , Tomografia Computadorizada por Raios X
5.
Materials (Basel) ; 13(5)2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-32106436

RESUMO

Coal combustion product in the form of fly ash has been sieved and successfully utilised as a main substrate and a carrier of silicon and aluminium in a set of hydrothermal syntheses of zeolites. The final product was abundant in zeolite X phase (Faujasite framework). Raw fly ash as well as its derivatives, after being sieved (fractions: ≤ 63, 63-125, 125-180 and ≥ 180 µm), and the obtained zeolite materials were subjected to mineralogical characterisation using powder X-ray diffraction, energy-dispersive X-ray fluorescence, laser diffraction-based particle size analysis and scanning electron microscopy. The influence of fraction separation on the zeolitization process under hydrothermal synthesis was investigated. Analyses performed on the derived zeolite X samples revealed a meaningful impact of the given fly ash fraction on synthesis efficiency, chemistry, quality as well as physicochemical properties, while favouring a given morphological form of zeolite crystals. The obtained zeolites possess great potential for use in many areas of industry and environmental protection or engineering.

6.
Sensors (Basel) ; 18(12)2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30469506

RESUMO

Development of new, faster methods of biosensor construction is a huge challenge for current science and industry. In this work, biosensor construction was carried out using a new soft plasma polymerization (SPP) method in which a bio-recognition layer of laccase enzyme was polymerized and bonded to a glassy carbon electrode (GCE) substrate under atmospheric pressure with a corona discharge jet. Laccase belongs to the oxidoreductase enzyme group with four copper atoms in its active center. Application of the corona SPP plasma method allows reduction of the time needed for biosensor construction from several hours to minutes. The presented work includes optimization of the laccase bio-recognition layer deposition time, structural studies of the deposited laccase layer, as well as study of the fabricated biosensor applicability for the determination of Rutin in real pharmaceutical samples. This method produces a biosensor with two linear ranges from 0.3 µmol/dm³ to 0.5 µmol/dm³ and from 0.8 µmol/dm³ to 16 µmol/dm³ of Rutin concentration. Results shown in this work indicate that application of the one-step, corona SPP method enables biosensor construction with comparable analytical parameters to biosensors fabricated by conventional, multi-step, wet methods.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Lacase/química , Rutina/isolamento & purificação , Carbono/química , Enzimas Imobilizadas/química , Humanos , Nanopartículas Metálicas/química , Gases em Plasma , Rutina/química
7.
J Colloid Interface Sci ; 513: 72-81, 2018 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-29132107

RESUMO

The possibility and effectiveness of removal of phosphate from aqueous solutions with the use of new low-cost synthetic zeolites obtained from fly ash and modified with lanthanum, was studied. Physicochemical properties of the zeolites were characterized by different techniques such as X-ray diffraction, low-temperature nitrogen sorption and scanning electron microscopy. It has been established that lanthanum is preferentially located in the zeolites channels and cages, which is related to the ion-exchange method of modification. Introduction of lanthanum cations leads to a reduction in BET surface area, mainly due to a decrease in the area of micropores and reduction in the pore volume. The key element of the study was a series of tests of phosphate adsorption from aqueous solutions. The efficiency of adsorption process was found to depend on the concentration of adsorbate, pH of its solution and temperature. The sorption capacity of zeolites obtained from fly ashes (La-P1, La-A) towards phosphate was compared with that of a natural zeolite - clinoptilolite, modified with lanthanum (La-CLP). The sorption capacities of the particular samples were as follows: La-P1 - 58.2 mg/g, La-A - 44.0 mg/g and La-CLP - 24.6 mg/g. The experimental data were well fitted by the Langmuir isotherm model. The sorption capacities of all samples towards phosphate increased with temperature increasing from 25 to 60 °C. The values of the thermodynamic parameters ΔH0 and ΔG0 revealed that the adsorption was spontaneous and endothermic.

8.
Int J Radiat Oncol Biol Phys ; 100(2): 306-316, 2018 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-29229323

RESUMO

PURPOSE: To determine the 3-dimensional (3D) intrafractional motion of head and neck squamous cell carcinoma (HNSCC). METHODS AND MATERIALS: Dynamic contrast-enhanced magnetic resonance images from 56 patients with HNSCC in the treatment position were analyzed. Dynamic contrast-enhanced magnetic resonance imaging consisted of 3D images acquired every 2.9 seconds for 4 minutes 50 seconds. Intrafractional tumor motion was studied in the 3 minutes 43 seconds of images obtained after initial contrast enhancement. To assess tumor motion, rigid registration (translations only) was performed using a region of interest (ROI) mask around the tumor. The results were compared with bulk body motion from registration to all voxels. Motion was split into systematic motion and random motion. Correlations between the tumor site and random motion were tested. The within-subject coefficient of variation was determined from 8 patients with repeated baseline measures. Random motion was also assessed at the end of the first week (38 patients) and second week (25 patients) of radiation therapy to investigate trends of motion. RESULTS: Tumors showed irregular occasional rapid motion (eg, swallowing or coughing), periodic intermediate motion (respiration), and slower systematic drifts throughout treatment. For 95% of the patients, displacements due to systematic and random motion were <1.4 mm and <2.1 mm, respectively, 95% of the time. The motion without an ROI mask was significantly (P<.0001, Wilcoxon signed rank test) less than the motion with an ROI mask, indicating that tumors can move independently from the bony anatomy. Tumor motion was significantly (P=.005, Mann-Whitney U test) larger in the hypopharynx and larynx than in the oropharynx. The within-subject coefficient of variation for random motion was 0.33. The average random tumor motion did not increase notably during the first 2 weeks of treatment. CONCLUSIONS: The 3D intrafractional tumor motion of HNSCC is small, with systematic motion <1.4 mm and random motion <2.1 mm 95% of the time.


Assuntos
Imageamento Tridimensional/métodos , Imageamento por Ressonância Magnética/métodos , Carcinoma de Células Escamosas de Cabeça e Pescoço/radioterapia , Meios de Contraste , Humanos , Aumento da Imagem , Movimento (Física) , Carcinoma de Células Escamosas de Cabeça e Pescoço/diagnóstico por imagem
9.
Eur J Nucl Med Mol Imaging ; 45(5): 759-767, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29164301

RESUMO

OBJECTIVE: To assess the optimal timing and predictive value of early intra-treatment changes in multimodality functional and molecular imaging (FMI) parameters as biomarkers for clinical remission in patients receiving chemoradiation for head and neck squamous cell carcinoma (HNSCC). METHODS: Thirty-five patients with stage III-IVb (AJCC 7th edition) HNSCC prospectively underwent 18F-FDG-PET/CT, and diffusion-weighted (DW), dynamic contrast-enhanced (DCE) and susceptibility-weighted MRI at baseline, week 1 and week 2 of chemoradiation. Patients with evidence of persistent or recurrent disease during follow-up were classed as non-responders. Changes in FMI parameters at week 1 and week 2 were compared between responders and non-responders with the Mann-Whitney U test. The significance threshold was set at a p value of <0.05. RESULTS: There were 27 responders and 8 non-responders. Responders showed a greater reduction in PET-derived tumor total lesion glycolysis (TLG40%; p = 0.007) and maximum standardized uptake value (SUVmax; p = 0.034) after week 1 than non-responders but these differences were absent by week 2. In contrast, it was not until week 2 that MRI-derived parameters were able to discriminate between the two groups: larger fractional increases in primary tumor apparent diffusion coefficient (ADC; p < 0.001), volume transfer constant (Ktrans; p = 0.012) and interstitial space volume fraction (Ve; p = 0.047) were observed in responders versus non-responders. ADC was the most powerful predictor (∆ >17%, AUC 0.937). CONCLUSION: Early intra-treatment changes in FDG-PET, DW and DCE MRI-derived parameters are predictive of ultimate response to chemoradiation in HNSCC. However, the optimal timing for assessment with FDG-PET parameters (week 1) differed from MRI parameters (week 2). This highlighted the importance of scanning time points for the design of FMI risk-stratified interventional studies.


Assuntos
Carcinoma de Células Escamosas/diagnóstico por imagem , Quimiorradioterapia , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Imagem Multimodal , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Adulto , Idoso , Carcinoma de Células Escamosas/terapia , Imagem de Difusão por Ressonância Magnética , Feminino , Fluordesoxiglucose F18 , Neoplasias de Cabeça e Pescoço/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons
10.
Br J Cancer ; 117(6): 791-800, 2017 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-28787429

RESUMO

BACKGROUND: The use of clinical MRI scanners to conduct pre-clinical research facilitates comparisons with clinical studies. Here the utility and sensitivity of anatomical and functional MRI data/biomarkers acquired from transgenic mouse models of neuroblastoma using a dedicated radiofrequency (RF) coil on a clinical 3T scanner was evaluated. METHODS: Multiparametric MRI of transgenic mice bearing abdominal neuroblastomas was performed at 3T, and data cross-referenced to that acquired from the same mice on a pre-clinical 7T MRI system. T2-weighted imaging, quantitation of the native longitudinal relaxation time (T1) and the transverse relaxation rate (R2*), and dynamic contrast-enhanced (DCE)-MRI, was used to assess tumour volume, phenotype and response to cyclophosphamide or cabozantinib. RESULTS: Excellent T2-weighted image contrast enabled clear tumour delineation at 3T. Significant correlations of tumour volume (R=0.98, P<0.0001) and R2* (R=0.87, P<0.002) measured at 3 and 7T were established. Mice with neuroblastomas harbouring the anaplastic lymphoma kinase mutation exhibited a significantly slower R2* (P<0.001), consistent with impaired tumour perfusion. DCE-MRI was performed simultaneously on three transgenic mice, yielding estimates of Ktrans for each tumour (median Ktrans values of 0.202, 0.168 and 0.114 min-1). Cyclophosphamide elicited a significant reduction in both tumour burden (P<0.002) and native T1 (P<0.01), whereas cabozantinib induced significant (P<0.01) tumour growth delay. CONCLUSIONS: Simultaneous multiparametric MRI of multiple tumour-bearing animals using this coil arrangement at 3T can provide high efficiency/throughput for both phenotypic characterisation and evaluation of novel therapeutics, and facilitate the introduction of functional MRI biomarkers into aligned imaging-embedded clinical trials.


Assuntos
Imageamento por Ressonância Magnética/métodos , Imãs , Neuroblastoma/diagnóstico por imagem , Neoplasias Gástricas/diagnóstico por imagem , Quinase do Linfoma Anaplásico , Anilidas/uso terapêutico , Animais , Antineoplásicos/uso terapêutico , Meios de Contraste , Ciclofosfamida/uso terapêutico , Modelos Animais de Doenças , Feminino , Imageamento por Ressonância Magnética/instrumentação , Masculino , Camundongos , Camundongos Transgênicos , Mutação , Proteína Proto-Oncogênica N-Myc/metabolismo , Neuroblastoma/tratamento farmacológico , Neuroblastoma/genética , Neuroblastoma/patologia , Imagens de Fantasmas , Fenótipo , Piridinas/uso terapêutico , Receptores Proteína Tirosina Quinases/genética , Razão Sinal-Ruído , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/genética , Neoplasias Gástricas/patologia , Carga Tumoral/efeitos dos fármacos
11.
Br J Radiol ; 90(1071): 20160768, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28256151

RESUMO

Head and neck cancer (HNC) is a challenging tumour site for radiotherapy delivery owing to its complex anatomy and proximity to organs at risk (OARs) such as the spinal cord and optic apparatus. Despite significant advances in radiotherapy planning techniques, radiation-induced morbidities remain substantial. Further improvement would require high-quality imaging and tailored radiotherapy based on intratreatment response. For these reasons, the use of MRI in radiotherapy planning for HNC is rapidly gaining popularity. MRI provides superior soft-tissue contrast in comparison with CT, allowing better definition of the tumour and OARs. The lack of additional radiation exposure is another attractive feature for intratreatment monitoring. In addition, advanced MRI techniques such as diffusion-weighted, dynamic contrast-enhanced and intrinsic susceptibility-weighted MRI techniques are capable of characterizing tumour biology further by providing quantitative functional parameters such as tissue cellularity, vascular permeability/perfusion and hypoxia. These functional parameters are known to have radiobiological relevance, which potentially could guide treatment adaptation based on their changes prior to or during radiotherapy. In this article, we first present an overview of the applications of anatomical MRI sequences in head and neck radiotherapy, followed by the potentials and limitations of functional MRI sequences in personalizing therapy.


Assuntos
Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Imageamento por Ressonância Magnética/métodos , Medicina de Precisão/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Cabeça/diagnóstico por imagem , Humanos , Pescoço/diagnóstico por imagem , Oncologistas
12.
J Appl Clin Med Phys ; 18(2): 154-162, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28300372

RESUMO

An Active Breathing Coordinator (ABC) can be employed to induce breath-holds during CT imaging and radiotherapy of lung, breast and liver cancer, and recently during lung cancer MRI. The apparatus measures and controls respiratory volume, hence subject lung volume reproducibility is its principal measure of effectiveness. To assess ABC control quality, the intra-session reproducibility of ABC-induced lung volumes was evaluated and compared with that reached by applying the clinical standard of operator-guided self-sustained breath-holds on healthy volunteers during MRI. Inter-session reproducibility was investigated by repeating ABC-controlled breath-holds on a second visit. Additionally, lung volume agreement with ABC devices used with different imaging modalities in the same institution (MR, CT), or for a breast trial treatment, was assessed. Lung volumes were derived from three-dimensional (3D) T1-weighted MRI datasets by three observers employing semiautomatic lung delineation on a radiotherapy treatment planning system. Inter-observer variability was less than 6% of the delineated lung volumes. Lung volume agreement between the different conditions over all subjects was investigated using descriptive statistics. The ABC equipment dedicated for MR application exhibited good intra-session and inter-session lung volume reproducibility (1.8% and 3% lung volume variability on average, respectively). MR-assessed lung volumes were similar using different ABC equipment dedicated to MR, CT, or breast radiotherapy. Overall, lung volumes controlled by the same or different ABC devices agreed better than with self-controlled breath-holds, as suggested by the average ABC variation of 1.8% of the measured lung volumes (99 mL), compared to the 4.1% (226 mL) variability observed on average with self-sustained breath-holding.


Assuntos
Neoplasias da Mama/patologia , Suspensão da Respiração , Pulmão/efeitos da radiação , Imageamento por Ressonância Magnética/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Adulto , Neoplasias da Mama/radioterapia , Feminino , Voluntários Saudáveis , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/instrumentação , Masculino , Pessoa de Meia-Idade , Movimento , Posicionamento do Paciente , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Reprodutibilidade dos Testes , Respiração , Técnicas de Imagem de Sincronização Respiratória/métodos
13.
Clin Cancer Res ; 23(15): 4233-4241, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28314789

RESUMO

Purpose: To evaluate intrinsic susceptibility (IS) MRI for the identification of cycling hypoxia, and the assessment of its extent and spatial distribution, in head and neck squamous cell carcinoma (HNSCC) xenografts and patients.Experimental Design: Quantitation of the transverse relaxation rate, R2*, which is sensitive to paramagnetic deoxyhemoglobin, using serial IS-MRI acquisitions, was used to monitor temporal oscillations in levels of paramagnetic deoxyhemoglobin in human CALR xenografts and patients with HNSCC at 3T. Autocovariance and power spectrum analysis of variations in R2* was performed for each imaged voxel, to assess statistical significance and frequencies of cycling changes in tumor blood oxygenation. Pathologic correlates with tumor perfusion (Hoechst 33342), hypoxia (pimonidazole), and vascular density (CD31) were sought in the xenografts, and dynamic contrast-enhanced (DCE) MRI was used to assess patient tumor vascularization. The prevalence of fluctuations within patient tumors, DCE parameters, and treatment outcome were reported.Results: Spontaneous R2* fluctuations with a median periodicity of 15 minutes were detected in both xenografts and patient tumors. Spatially, these fluctuations were predominantly associated with regions of heterogeneous perfusion and hypoxia in the CALR xenografts. In patients, R2* fluctuations spatially correlated with regions of lymph nodes with low Ktrans values, typically in the vicinity of necrotic cores.Conclusions: IS-MRI can be used to monitor variations in levels of paramagnetic deoxyhemoglobin, associated with cycling hypoxia. The presence of such fluctuations may be linked with impaired tumor vasculature, the presence of which may impact treatment outcome. Clin Cancer Res; 23(15); 4233-41. ©2017 AACR.


Assuntos
Carcinoma de Células Escamosas/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Linfonodos/diagnóstico por imagem , Imageamento por Ressonância Magnética , Neovascularização Patológica/diagnóstico por imagem , Animais , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/patologia , Hipóxia Celular/genética , Linhagem Celular Tumoral , Meios de Contraste/uso terapêutico , Feminino , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Linfonodos/patologia , Masculino , Camundongos , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/patologia , Nitroimidazóis/administração & dosagem , Tolerância a Radiação/efeitos dos fármacos , Carcinoma de Células Escamosas de Cabeça e Pescoço , Resultado do Tratamento , Ensaios Antitumorais Modelo de Xenoenxerto
14.
Br J Cancer ; 116(1): 28-35, 2017 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-27884018

RESUMO

BACKGROUND: Patients with head and neck squamous cell carcinoma (HNSCC) undergoing radical chemo-radiation (CRT) frequently receive transfusion with packed red cells (PRCT) during radiotherapy on the basis that PRCT increases tumour oxygenation and overcomes hypoxia-induced radio-resistance. This is likely to be a significant oversimplification given the fact that tumour hypoxia is the result of several intrinsic and extrinsic factors, including many that are not directly related to serum haemoglobin (Hb). Therefore, we have studied the effect of PRCT on tumour oxygenation in a prospective cohort of patients who developed low Hb during radical CRT for HNSCC. METHODS: This was a prospective study of 20 patients with HNSCC receiving radical CRT undergoing PRCT for Hb<11.5 g dl-1. Patients underwent pretransfusion and posttransfusion intrinsic susceptibility-weighted (SWI) MRI and dynamic contrast-enhanced (DCE) MRI. Blood samples were obtained at the time of MRI scanning and two further time points for measuring Hb and a panel of serum cytokine markers of tumour hypoxia. 3D T2* and Ktrans maps were calculated from the MRI data for primary tumours and cervical lymph node metastases. RESULTS: PRCT produced no change (11 patients) or reduced (1 patient) T2* (tumour oxygenation) in 12 of the 16 (75%) evaluable primary tumours. Three of the four patients with improved tumour oxygenation progressed or had partial response following treatment completion. There were variable changes in Ktrans (tumour perfusion or vessel permeability) following PRCT that were of small magnitude for most tumours. Pre- and Post-PRCT levels of measured cytokines were not significantly different. CONCLUSIONS: This study suggests that PRCT during radical CRT for HNSCC does not improve tumour oxygenation. Therefore, oncologists should consider changing practice according to NICE and American Association of Blood Banks guidelines on PRCT for anaemia.


Assuntos
Transfusão de Sangue , Carcinoma de Células Escamosas/terapia , Quimiorradioterapia , Neoplasias de Cabeça e Pescoço/terapia , Hipóxia Tumoral , Idoso , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/patologia , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Estudos Longitudinais , Metástase Linfática , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Carcinoma de Células Escamosas de Cabeça e Pescoço , Hipóxia Tumoral/efeitos dos fármacos
15.
Med Phys ; 43(11): 6024, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27806585

RESUMO

PURPOSE: To investigate the effects of different time-resolved angiography with stochastic trajectories (TWIST) k-space undersampling schemes on calculated pharmacokinetic dynamic contrast-enhanced (DCE) vascular parameters. METHODS: A digital perfusion phantom was employed to simulate effects of TWIST on characteristics of signal changes in DCE. Furthermore, DCE-MRI was acquired without undersampling in a group of patients with head and neck squamous cell carcinoma and used to simulate a range of TWIST schemes. Errors were calculated as differences between reference and TWIST-simulated DCE parameters. Parametrical error maps were used to display the averaged results from all tumors. RESULTS: For a relatively wide range of undersampling schemes, errors in pharmacokinetic parameters due to TWIST were under 10% for the volume transfer constant, Ktrans, and total extracellular extravascular space volume, Ve. TWIST induced errors in the total blood plasma volume, Vp, were the largest observed, and these were inversely dependent on the area of the fully sampled k-space. The magnitudes of errors were not correlated with Ktrans, Vp and weakly correlated with Ve. CONCLUSIONS: The authors demonstrated methods to validate and optimize k-space view-sharing techniques for pharmacokinetic DCE studies using a range of clinically relevant spatial and temporal patient derived data. The authors found a range of undersampling patterns for which the TWIST sequence can be reliably used in pharmacokinetic DCE-MRI. The parameter maps created in the study can help to make a decision between temporal and spatial resolution demands and the quality of enhancement curve characterization.


Assuntos
Angiografia , Meios de Contraste/farmacocinética , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/metabolismo , Imageamento por Ressonância Magnética , Adulto , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Imagens de Fantasmas , Processos Estocásticos
16.
J Nucl Med ; 57(12): 1843-1850, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27417648

RESUMO

The objective of this study was to assess the predictive value of early assessment (after 1 cycle of induction chemotherapy [IC]) with 18F-FDG PET/CT and diffusion-weighted (DW) MRI for subsequent response to radical chemoradiotherapy in locally advanced head and neck squamous cell carcinoma (HNSCC). METHODS: Twenty patients with stage III-IVa HNSCC prospectively underwent 18F-FDG PET/CT and DW MRI before and 2 wk after each cycle of IC (first cycle, IC1; second cycle, IC2). Response was assessed 3 mo after completion of chemoradiotherapy with clinical examination, MRI, and 18F-FDG PET/CT. Patients with persistent disease were classed as nonresponders. Changes in functional and molecular imaging parameters after IC1 were compared between responders and nonresponders with the Mann-Whitney U test. The significance threshold was set at a P value of less than 0.05. RESULTS: Responders showed a significantly greater reduction in metabolic tumor volume (P = 0.03) and total lesion glycolysis (P = 0.04) after IC1 than nonresponders. Responders also showed a tendency toward a larger but statistically nonsignificant increase in apparent diffusion coefficient after IC1. There was no significant difference in the changes from baseline between the IC1 and IC2 for all functional and molecular imaging parameters, indicating that most biologic response to IC measured by 18F-FDG PET/CT and DW MRI was observed early after the first cycle of IC. CONCLUSION: Our preliminary data indicate that the 18F-FDG PET/CT-derived metabolic tumor volume or total lesion glycolysis, acquired after IC1, are early predictive biomarkers for ultimate response to subsequent chemoradiotherapy. These early biomarkers enable identification of patients at risk of treatment failure at an early time point, permitting treatment individualization and consideration of alternative strategies such as radiotherapy dose escalation or surgery.


Assuntos
Carcinoma de Células Escamosas/terapia , Quimiorradioterapia , Fluordesoxiglucose F18 , Neoplasias de Cabeça e Pescoço/terapia , Quimioterapia de Indução , Imagem Multimodal , Valor Preditivo dos Testes , Idoso , Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/tratamento farmacológico , Imagem de Difusão por Ressonância Magnética , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Fatores de Tempo , Falha de Tratamento
17.
Radiother Oncol ; 120(2): 356-62, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27222296

RESUMO

BACKGROUND AND PURPOSE: Magnetic resonance (MR) and computed tomography (CT) images are degraded in the presence of metallic implants. We investigate whether SEMAC (Slice Encoding for Metal Artifact Correction) MR is advantageous for radiotherapy (RT) planning. METHODS: Conventional and SEMAC MR protocols were compared (1.5T). A spine fixation device suspended in gelatine, two patients with spine fixation devices and six patients with bilateral hip replacements were scanned with both conventional and SEMAC protocols. In spine patients the visibility of the spinal canal and spinal cord was assessed; in prostate patients, the visibility of the prostate, pelvic structures and the pelvic girdle. RESULTS: The signal loss volume surrounding the spine fixation device was reduced by approximately 20% when the SEMAC protocol was employed, and registration errors were reduced. For spine patients, the spinal canal was completely visible only using the SEMAC protocol. In hip replacement patients, metal artifacts were local; the signal loss extended to the internal surface of the acetabulum in eight implants with conventional protocols, but only in four using SEMAC. CONCLUSIONS: SEMAC MR contributes towards correct co-registration of MR and CT images for RT planning, and is particularly relevant when the TV or OARs are close to implants.


Assuntos
Imageamento por Ressonância Magnética/métodos , Próteses e Implantes , Planejamento da Radioterapia Assistida por Computador/métodos , Artefatos , Fixação Interna de Fraturas/instrumentação , Humanos , Aumento da Imagem , Masculino , Metais , Neoplasias da Próstata/radioterapia , Coluna Vertebral/diagnóstico por imagem , Tomografia Computadorizada por Raios X
18.
J Magn Reson Imaging ; 44(1): 72-80, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-26800280

RESUMO

PURPOSE: To determine whether quantitation of T2* is sufficiently repeatable and sensitive to detect clinically relevant oxygenation levels in head and neck squamous cell carcinoma (HNSCC) at 3T. MATERIALS AND METHODS: Ten patients with newly diagnosed locally advanced HNSCC underwent two magnetic resonance imaging (MRI) scans between 24 and 168 hours apart prior to chemoradiotherapy treatment. A multiple gradient echo sequence was used to calculate T2* maps. A quadratic function was used to model the blood transverse relaxation rate as a function of blood oxygenation. A set of published coefficients measured at 3T were incorporated to account for tissue hematocrit levels and used to plot the dependence of fractional blood oxygenation (Y) on T2* values, together with the corresponding repeatability range. Repeatability of T2* using Bland-Altman analysis, and calculation of limits of agreement (LoA), was used to assess the sensitivity, defined as the minimum difference in fractional blood oxygenation that can be confidently detected. RESULTS: T2* LoA for 22 outlined tumor volumes were 13%. The T2* dependence of fractional blood oxygenation increases monotonically, resulting in increasing sensitivity of the method with increasing blood oxygenation. For fractional blood oxygenation values above 0.11, changes in T2* were sufficient to detect differences in blood oxygenation greater than 10% (Δ T2* > LoA for ΔY > 0.1). CONCLUSION: Quantitation of T2* at 3T can detect clinically relevant changes in tumor oxygenation within a wide range of blood volumes and oxygen tensions, including levels reported in HNSCC. J. Magn. Reson. Imaging 2016;44:72-80.


Assuntos
Carcinoma de Células Escamosas/diagnóstico por imagem , Carcinoma de Células Escamosas/metabolismo , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/metabolismo , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Oxigênio/metabolismo , Biomarcadores Tumorais/metabolismo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Carcinoma de Células Escamosas de Cabeça e Pescoço
19.
Phys Med Biol ; 61(1): 37-49, 2016 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-26605957

RESUMO

MRI has been extensively used in breast cancer staging, management and high risk screening. Detection sensitivity is paramount in breast screening, but variations of signal-to-noise ratio (SNR) as a function of position are often overlooked. We propose and demonstrate practical methods to assess spatial SNR variations in dynamic contrast-enhanced (DCE) breast examinations and apply those methods to different protocols and systems. Four different protocols in three different MRI systems (1.5 and 3.0 T) with receiver coils of different design were employed on oil-filled test objects with and without uniformity filters. Twenty 3D datasets were acquired with each protocol; each dataset was acquired in under 60 s, thus complying with current breast DCE guidelines. In addition to the standard SNR calculated on a pixel-by-pixel basis, we propose other regional indices considering the mean and standard deviation of the signal over a small sub-region centred on each pixel. These regional indices include effects of the spatial variation of coil sensitivity and other structured artefacts. The proposed regional SNR indices demonstrate spatial variations in SNR as well as the presence of artefacts and sensitivity variations, which are otherwise difficult to quantify and might be overlooked in a clinical setting. Spatial variations in SNR depend on protocol choice and hardware characteristics. The use of uniformity filters was shown to lead to a rise of SNR values, altering the noise distribution. Correlation between noise in adjacent pixels was associated with data truncation along the phase encoding direction. Methods to characterise spatial SNR variations using regional information were demonstrated, with implications for quality assurance in breast screening and multi-centre trials.


Assuntos
Neoplasias da Mama/diagnóstico , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Artefatos , Feminino , Humanos , Imageamento por Ressonância Magnética/normas , Razão Sinal-Ruído
20.
Med Phys ; 42(8): 4833-9, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26233210

RESUMO

PURPOSE: The purpose of this study is to investigate whether the microvascular pseudodiffusion effects resulting with non-monoexponential behavior are present in breast cancer, taking into account tumor spatial heterogeneity. Additionally, methodological factors affecting the signal in low and high diffusion-sensitizing gradient ranges were explored in phantom studies. METHODS: The effect of eddy currents and accuracy of b-value determination using a multiple b-value diffusion-weighted MR imaging sequence were investigated in test objects. Diffusion model selection and noise were then investigated in volunteers (n = 5) and breast tumor patients (n = 21) using the Bayesian information criterion. RESULTS: 54.3% of lesion voxels were best fitted by a monoexponential, 26.2% by a stretched-exponential, and 19.5% by a biexponential intravoxel incoherent motion (IVIM) model. High correlation (0.92) was observed between diffusion coefficients calculated using mono- and stretched-exponential models and moderate (0.59) between monoexponential and IVIM (medians: 0.96/0.84/0.72 × 10(-3) mm(2)/s, respectively). Distortion due to eddy currents depended on the direction of the diffusion gradient and displacement varied between 1 and 6 mm for high b-value images. Shift in the apparent diffusion coefficient due to intrinsic field gradients was compensated for by averaging diffusion data obtained from opposite directions. CONCLUSIONS: Pseudodiffusion and intravoxel heterogeneity effects were not observed in approximately half of breast cancer and normal tissue voxels. This result indicates that stretched and IVIM models should be utilized in regional analysis rather than global tumor assessment. Cross terms between diffusion-sensitization gradients and other imaging or susceptibility-related gradients are relevant in clinical protocols, supporting the use of geometric averaging of diffusion-weighted images acquired with diffusion-sensitization gradients in opposite directions.


Assuntos
Neoplasias da Mama/patologia , Mama/patologia , Imagem de Difusão por Ressonância Magnética , Difusão , Modelos Teóricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Teorema de Bayes , Mama/anatomia & histologia , Mama/fisiologia , Mama/fisiopatologia , Neoplasias da Mama/fisiopatologia , Imagem de Difusão por Ressonância Magnética/instrumentação , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Pessoa de Meia-Idade , Imagens de Fantasmas
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