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Mota AM, Clarkson MJ, Almeida P, Peralta L, Matela N. Impact of total variation minimization in volume rendering visualization of breast tomosynthesis data. Comput Methods Programs Biomed 2020; 195:105534. [PMID: 32480190 DOI: 10.1016/j.cmpb.2020.105534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 04/23/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
BACKGROUND AND OBJECTIVE Total Variation (TV) minimization algorithms have achieved great attention due to the virtue of decreasing noise while preserving edges. The purpose of this work is to implement and evaluate two TV minimization methods in 3D. Their performance is analyzed through 3D visualization of digital breast tomosynthesis (DBT) data with volume rendering. METHODS Both filters were studied with real phantom and one clinical DBT data. One algorithm was applied sequentially to all slices and the other was applied to the entire volume at once. The suitable Lagrange multiplier used in each filter equation was studied to reach the minimum 3D TV and the maximum contrast-to-noise ratio (CNR). Imaging blur was measured at 0° and 90° using two disks with different diameters (0.5 mm and 5.0 mm) and equal thickness. The quality of unfiltered and filtered data was analyzed with volume rendering at 0° and 90°. RESULTS For phantom data, with the sequential filter, a decrease of 25% in 3D TV value and an increase of 19% and 30% in CNR at 0° and 90°, respectively, were observed. When the filter is applied directly in 3D, TV value was reduced by 35% and an increase of 36% was achieved both for CNR at 0° and 90°. For the smaller disk, variations of 0% in width at half maximum (FWHM) at 0° and a decrease of about 2.5% for FWHM at 90° were observed for both filters. For the larger disk, there was a 2.5% increase in FWHM at 0° for both filters and a decrease of 6.28% and 1.69% in FWHM at 90° with the sequential filter and the 3D filter, respectively. When applied to clinical data, the performance of each filter was consistent with that obtained with the phantom. CONCLUSIONS Data analysis confirmed the relevance of these methods in improving quality of DBT images. Additionally, this type of 3D visualization showed that it may play an important complementary role in DBT imaging. It allows to visualize all DBT data at once and to analyze properly filters applied to all the three dimensions. Concise Abstract Total Variation (TV) minimization algorithms are one compressed sensing technique that has achieved great attention due to the virtue of decrease noise while preserve edges transitions. The purpose of this work is to solve the same TV minimization problem in DBT data, by studying two 3D filters. The obtained results were analyzed at 0° and 90° with a 3D visualization through volume rendering. The filters differ in their application. One considers a slice-by-slice optimization, sequentially traversing all slices of the data. The other considers the intensity values of adjacent slices to make this optimization on each voxel. The performance of each filter was also tested with a clinical case. The results obtained were very encouraging with a significantly increased contrast to noise ratio at 0° and 90° and a small reduction in blur at 90° (slight reduction of the out-of-plane artifact).
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Affiliation(s)
- A M Mota
- Faculdade de Ciências, Instituto de Biofísica e Engenharia Biomédica, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
| | - M J Clarkson
- Department of Medical Physics and Biomedical Engineering and the Centre for Medical Image Computing, University College London, London, UK
| | - P Almeida
- Faculdade de Ciências, Instituto de Biofísica e Engenharia Biomédica, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - L Peralta
- Departamento de Física da Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal; Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal
| | - N Matela
- Faculdade de Ciências, Instituto de Biofísica e Engenharia Biomédica, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
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Kumar MP, Mota AM, Gonçalves MLS. Influence of UV-B radiation on lead speciation in the presence of natural particles of estuarine waters. Environ Sci Pollut Res Int 2016; 23:17503-17510. [PMID: 27230154 DOI: 10.1007/s11356-016-6877-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 05/10/2016] [Indexed: 06/05/2023]
Abstract
The influence of UV-B irradiation on filtered and non-filtered water samples collected in a non-polluted area of Tagus estuary was evaluated in this study. In the laboratory, both samples were titrated with lead (Pb(+2)) followed by differential pulse anodic stripping voltammetry (DPASV), before and after 1 and 10 days under UV-B irradiation. Metal-ligand complexing parameters were obtained based on a macromolecular heterogeneous ligand described by two distinct sites with a labile behavior, and a third small homogeneous weaker group, which concentration was determined from a potentiometric titration. Under UV-B radiation, the complexing strength decreased with time in both (filtered and non-filtered) irradiated samples, but this effect was more pronounced in the non-filtered water, which might be due to some adsorption of dissolved macromolecular ligands on the particles and/or to further degradation of dissolved organic matter (DOM). Furthermore, the presence of particles favored the break-down of the macromolecular ligand under long UV-B exposure time. These results present ecological implications for the estuarine ecosystems such as bioavailability and toxicity.
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Affiliation(s)
- M Praveen Kumar
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
| | - A M Mota
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal
| | - M L S Gonçalves
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal
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Oliveira N, Mota AM, Matela N, Janeiro L, Almeida P. Dynamic relaxation in algebraic reconstruction technique (ART) for breast tomosynthesis imaging. Comput Methods Programs Biomed 2016; 132:189-196. [PMID: 27282238 DOI: 10.1016/j.cmpb.2016.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 02/05/2016] [Accepted: 05/04/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND AND OBJECTIVES A major challenge in Digital Breast Tomosynthesis (DBT) is handling image noise since the 3D reconstructed images are obtained from low dose projections and limited angular range. The use of the iterative reconstruction algorithm Algebraic Reconstruction Technique (ART) in clinical context depends on two key factors: the number of iterations needed (time consuming) and the image noise after iterations. Both factors depend highly on a relaxation coefficient (λ), which may give rise to slow or noisy reconstructions, when a single λ value is considered for the entire iterative process. The aim of this work is to present a new implementation for the ART that takes into account a dynamic mode to calculate λ in DBT image reconstruction. METHODS A set of initial reconstructions of real phantom data was done using constant λ values. The results were used to choose, for each iteration, the suitable λ value, taking into account the image noise level and the convergence speed. A methodology to optimize λ automatically during the image reconstruction was proposed. RESULTS Results showed we can dynamically choose λ values in such a way that the time needed to reconstruct the images can be significantly reduced (up to 70%) while achieving similar image quality. These results were confirmed with one clinical dataset. CONCLUSIONS With simple methodology we were able to dynamically choose λ in DBT image reconstruction with ART, allowing a shorter image reconstruction time without increasing image noise.
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Affiliation(s)
- N Oliveira
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - A M Mota
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal.
| | - N Matela
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
| | - L Janeiro
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal; Escola Superior de Saúde da Cruz Vermelha Portuguesa, Avenida de Ceuta, Edifício UrbiCeuta, 6°, 1300-125 Lisboa, Portugal
| | - P Almeida
- Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, 1749-016 Lisboa, Portugal
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Mota AM, Pinheiro JP, Simões Gonçalves ML. Electrochemical Methods for Speciation of Trace Elements in Marine Waters. Dynamic Aspects. J Phys Chem A 2012; 116:6433-42. [DOI: 10.1021/jp2124636] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. M. Mota
- CQE, Instituto
Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001
Lisboa, Portugal
| | - J. P. Pinheiro
- IBB/CBME, Department
of Chemistry and Pharmacy, Faculty of Sciences and Technology, University of Algarve, 8005-139 Faro, Portugal
| | - M. L. Simões Gonçalves
- CQE, Instituto
Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001
Lisboa, Portugal
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Pereira S, Fonseca LP, Capelo JL, Armas T, Vilhena F, Pinto AP, Gonçalves MLS, Mota AM. Comparative study between probe focussed sonication and conventional stirring in the evaluation of cadmium and copper in plants. Anal Bioanal Chem 2010; 398:2315-24. [PMID: 20890593 DOI: 10.1007/s00216-010-4178-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/30/2010] [Accepted: 08/30/2010] [Indexed: 11/28/2022]
Abstract
Ultrasound (US)-assisted extraction has been widely used for metal ion extraction in plants due to its unique properties of decreased extraction time, minimal contamination, low reagent consumption and low cost. However, very few papers present a sound comparison between probe-focussed sonication and conventional stirring in the evaluation of metal ion extraction in plants. In this study, ultrasonic-assisted digestion has been evaluated and compared to magnetic stirring for total copper and cadmium determination by atomic absorption spectrometry in biological samples (plants, plankton and mussels). The same experimental conditions of sample amount and particle size, extractant solution and extraction time were applied for both ultrasound and magnetic stirring-assisted extraction methods in order to truly compare their effect on metal ion solubilisation. To gain further insight in this issue, dried and fresh plants were tested. The results obtained indicated that osmotic tension in cell walls, produced when dried and powdered samples were immersed in the extractant solution, had an important contribution to metal ion solubilisation, the enhancement due to US for the same purpose being negligible.
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Affiliation(s)
- Sara Pereira
- Centro de Engenharia Química e Biológica, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
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Guiwei Q, de Varennes A, Martins LL, Mourato MP, Cardoso AI, Mota AM, Pinto AP, Gonçalves ML. Improvement in soil and sorghum health following the application of polyacrylate polymers to a Cd-contaminated soil. J Hazard Mater 2010; 173:570-575. [PMID: 19775813 DOI: 10.1016/j.jhazmat.2009.08.124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 08/25/2009] [Accepted: 08/25/2009] [Indexed: 05/28/2023]
Abstract
Contamination of soils with cadmium (Cd) is a serious global issue due to its high mobility and toxicity. We investigated the application of insoluble polyacrylate polymers to improve soil and plant health. Sorghum was grown in a Cd-contaminated sandy soil. Polyacrylate polymers at 0.2% (w/w) were added to half of the soil. Control soil without plants was also included in the experiment. Growth of sorghum was stimulated in the polymer-amended soil. The concentration of Cd in the shoots, and the activities of catalase and ascorbate peroxidase decreased in plants from polymer-amended soil compared with unamended control. The amount of CaCl(2)-extractable Cd in the polymer-amended soil was 55% of that in the unamended soil. The Cd extracted in sorghum shoots was 0.19 mg per plant grown on soil without polymer and 0.41 mg per plant grown on polymer-amended soil. The total amount of Cd removed from each pot corresponded to 1.5 and more than 6% of soil CaCl(2)-extractable Cd in unamended and polymer-amended soil, respectively. The activities of soil acid phosphatase, beta-glucosidase, urease, protease and cellulase were greatest in polymer-amended soil with sorghum. In conclusion, the application of polyacrylate polymers to reduce the bioavailable Cd pool seems a promising method to enhance productivity and health of plants grown on Cd-contaminated soils.
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Affiliation(s)
- Q Guiwei
- Department of Agricultural and Environmental Chemistry, Instituto Superior de Agronomia, Technical University of Lisbon (TULisbon), Tapada da Ajuda, 1349-017 Lisboa, Portugal
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Capelo JL, Maduro C, Mota AM. Evaluation of focused ultrasound and ozonolysis as sample treatment for direct determination of mercury by FI-CV-AAS. Optimization of parameters by full factorial design. Ultrason Sonochem 2006; 13:98-106. [PMID: 16223694 DOI: 10.1016/j.ultsonch.2004.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Accepted: 09/17/2004] [Indexed: 05/04/2023]
Abstract
Different oxidation methodologies based on ozone and focused ultrasound for the degradation of organic matter and organic-mercury compounds (spiked) present in human urine are discussed. Inorganic and total mercury can be determined in human urine. A flow-injection cold-vapour atomic absorption spectrometer system was used for mercury measurements. Optimization of cold vapour generation was performed with NaBH4 and SnCl2. A two-level full factorial design (2(4)) was applied to understand the cross-effects among the variables influencing the degradation of organic-mercurials and organic matter in urine by KMnO4/HCl/focused ultrasound, namely, KMnO4 and HCl concentration, ultrasonication time and ultrasonication amplitude. Optimization results showed that all variables were significant. New trends in the application of focused ultrasound and ozone are highlighted. As a result of the optimization procedure, one simple, rapid and accurate method was developed for the determination of total mercury in urine samples The method is based on the ultrasound assisted degradation of organo-mercurials and organic matter in urine in the presence of KMnO4/HCl/Focused Ultrasound. The procedure can be accomplished within 3 min, using 50% sonication amplitude provided by a probe ultrasonic device (63 W maximum output power, 22.5 kHz frequency). The method was applied to measure the mercury content in spiked urine from different non-exposed volunteers.
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Affiliation(s)
- J L Capelo
- Instituto Superior Técnico, Centro de Química Estrutural, Universidade Técnica de Lisboa, Torre sul, 11 andar., Avda Rovisco Pais s/n, 1049-001 Lisbon, Portugal.
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Mota AM, Cruz P, Vilhena C, Gonçalves MLS. Influence of the sediment on lead speciation in the Tagus estuary. Water Res 2005; 39:1451-60. [PMID: 15878016 DOI: 10.1016/j.watres.2004.11.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 11/04/2004] [Accepted: 11/30/2004] [Indexed: 05/02/2023]
Abstract
The aim of this work is to study the influence of the Tagus estuarine sediment on lead speciation in the overlying natural water. The water sample in the presence of the sediment was contaminated three times with Pb(II) in a laboratory experiment. In different periods of time, at 1-7 days after each contamination, small volumes of water were titrated with lead. The titration was followed by anodic stripping voltammetry in differential pulse mode. Before and after contamination systematic analysis of the voltammetric parameters (peak current, peak potential and peak width) were carried out to get a clear picture of Pb(II) complexation in the soluble fraction in contact with the sediment. Two main types of organic ligands, macromolecular ligands and small compounds, were detected before contamination. Both of them form labile complexes (degree of lability within the timescale of some milliseconds). The small compounds, with a diffusion coefficient similar to that of the free metal ion, present a homogeneous behaviour in terms of Pb complexation. On the other hand macromolecular ligands, with a diffusion coefficient of 1.2 x 10(-6) cm2s(-1), can be described by two different binding groups, which might be of phenolic and carboxylic type as presented by humic matter. The sediment eliminated lead contamination (10(-6) moldm(-3) was the maximum concentration added) from 12 dm3 of water (surface of 8 dm2) within 2 days. It was also found that the sediment released organic ligands responsible for both labile and inert Pb complexes "seen" by voltammetry. The release of organic ligands that decreases the bioavailability of Pb(II) was clearly detected 1 week after contamination. Therefore, the sediment acts as a buffer for lead through two mechanisms against lead contamination: removing lead ions from the solution and releasing organic ligands to the water column. In a short period of time the sediment responds as a self-cleaning system for Pb(II) contamination in the estuarine water, which may have a very important influence in environmental pollution.
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Affiliation(s)
- A M Mota
- Centro de Química Estrutural, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal.
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Pinto AP, Mota AM, de Varennes A, Pinto FC. Influence of organic matter on the uptake of cadmium, zinc, copper and iron by sorghum plants. Sci Total Environ 2004; 326:239-47. [PMID: 15142779 DOI: 10.1016/j.scitotenv.2004.01.004] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2003] [Revised: 01/26/2004] [Accepted: 01/28/2004] [Indexed: 05/05/2023]
Abstract
This article describes an experiment, carried out under controlled environment conditions, to investigate the effects of a fulvic acid fraction of soil organic matter on growth, cadmium (Cd) uptake and redistribution by sorghum. In addition the uptake of copper (Cu), zinc (Zn) and iron (Fe) was also determined. Sorghum was grown in nutrient solutions with 0, 0.1, 1 and 10 mg Cd dm(-3), in the absence and presence of organic matter (32 mg C dm(-3)), for various periods up to 20 days. A decrease in sorghum biomass due to Cd toxicity was observed at 10 mg Cd dm(-3), but for concentrations of 0.1 and 1 mg Cd dm(-3) the biomass was increased compared with control, without visual toxicity symptoms. The presence of organic matter (OM) further increased biomass production. Cadmium was mainly retained in sorghum roots, as usually found in tolerant plants, but Cd accumulation in sorghum was greater than in other Gramineae, or even more tolerant plants such as lettuce. The presence of OM decreased the bioavailability of Cd that was partially retained in solution by the OM ligands. However, OM promoted the translocation of Cd to shoots, an effect that may pose a risk to public health because plant-animal transfer of Cd could be enhanced. The presence of OM decreased the uptake of Cu, Zn and Fe. The presence (vs. absence) of 0.1 mg Cd dm(-3) enhanced the uptake of Fe, both in the absence and presence of OM.
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Affiliation(s)
- A P Pinto
- Departamento de Química, Universidade de Evora, R. Romão Ramalho no. 59, 7000 Evora, Portugal
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Filella M, Klockow D, Mota AM. Metals in environmental compartments. Reflections on the 8th Workshop on Progress in Analytical Methodologies for Trace Metal Speciation, Lisbon, Portugal, September 5, 2000. Fresenius J Anal Chem 2001; 370:793-4. [PMID: 11569854 DOI: 10.1007/s002160100905] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Affiliation(s)
- G Macedo
- Gastroenterology and Liver Transplant Units, H.S. João, Porto, Portugal
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Pinheiro JP, Mota AM, Goncalves MS, van Leeuwen HP. Kinetics of adsorption of humic matter on mercury. Environ Sci Technol 1994; 28:2112-2119. [PMID: 22191751 DOI: 10.1021/es00061a020] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Carvalho AP, Mota AM. The role of ATP and of a bound phosphoryl group acceptor on Ca binding and exchangeability in sarcoplasmic reticulum. Arch Biochem Biophys 1971; 142:201-12. [PMID: 4250972 DOI: 10.1016/0003-9861(71)90276-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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