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1.
Cardiovasc Intervent Radiol ; 46(3): 392-399, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36513764

RESUMO

PURPOSE: Magnetic particle imaging (MPI) is a tomographic imaging modality with the potential for cardiovascular applications. In this context, the extent to which stents are heated should be estimated from safety perspective. Furthermore, the influence of the measurement parameters and stent distance to the isocenter of the MPI scanner on stent heating were evaluated. MATERIALS AND METHODS: Nine different endovascular stents and stent grafts were tested in polyvinyl-chloride tubes. The stents had diameters from 10 to 31 mm, lengths between 25 and 100 mm and were made from stainless steel, nitinol or cobalt-chromium. The temperature differences were recorded with fiber-optic thermometers. All measurements were performed in a preclinical commercial MPI scanner. The measurement parameters were varied (drive field strengths: 3, 6, 9, 12 mT and selection field gradients: 0, 1.25 and 2.5 T/m). Furthermore, measurements with different distances to the scanner's isocenter were performed (100 to 0 mm). RESULTS: All stents showed heating (maximum 53.1 K, minimum 4.6 K). The stent diameter directly correlated with the temperature increase. The drive field strength influenced the heating of the stents, whereas the selection field gradient had no detectable impact. The heating of the stents decreased with increasing distance from the scanner's isocenter and thus correlated with the loss of the scanner's magnetic field. CONCLUSION: Stents can cause potentially harmful heating in MPI. In addition to the stent diameter and design, the drive field strength and the distance to the MPI scanner's isocenter must be kept in mind as influencing parameters.


Assuntos
Procedimentos Endovasculares , Calefação , Stents , Tomografia , Humanos , Fenômenos Magnéticos , Correção Endovascular de Aneurisma
2.
Nanomaterials (Basel) ; 12(10)2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35630979

RESUMO

The purpose of this work was to develop instrument markers that are visible in both magnetic particle imaging (MPI) and magnetic resonance imaging (MRI). The instrument markers were based on two different magnetic nanoparticle types (synthesized in-house KLB and commercial Bayoxide E8706). Coatings containing one of both particle types were fabricated and measured with a magnetic particle spectrometer (MPS) to estimate their MPI performance. Coatings based on both particle types were then applied on a segment of a nonmetallic guidewire. Imaging experiments were conducted using a commercial, preclinical MPI scanner and a preclinical 1 tesla MRI system. MPI image reconstruction was performed based on system matrices measured with dried KLB and Bayoxide E8706 coatings. The bimodal markers were clearly visible in both methods. They caused circular signal voids in MRI and areas of high signal intensity in MPI. Both the signal voids as well as the areas of high signal intensity were larger than the real marker size. Images that were reconstructed with a Bayoxide E8706 system matrix did not show sufficient MPI signal. Instrument markers with bimodal visibility are essential for the perspective of monitoring cardiovascular interventions with MPI/MRI hybrid systems.

3.
Cardiovasc Intervent Radiol ; 44(7): 1109-1115, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33723668

RESUMO

PURPOSE: To evaluate heating of a redilatable stent for the treatment of aortic coarctation in neonates and small children in the new imaging modality magnetic particle imaging and established magnetic resonance imaging. MATERIALS AND METHODS: The cobalt-chromium stent (BabyStent, OSYPKA AG, Rheinfelden, Germany) has a stent design which allows for redilatation and adjustment of the diameter from 6 to 16 mm for a use in aortic coarctation. The stent loses its radial integrity while opening at predetermined breaking points at a diameter of 14 mm or 16 mm, respectively. We measured the temperature increase in the stent at different diameters during 7-min magnetic particle imaging and magnetic resonance imaging scans with fiber optic thermometers under static conditions surrounded by air. In magnetic particle imaging, stents with diameters from 6 to 16 mm were tested while in magnetic resonance imaging only stents with diameters of 6 mm and 14 mm were investigated exemplarily. RESULT: In magnetic particle imaging, the measured temperature differences increased up to 4.7 K with growing diameters, whereas the opened stents with discontinuous struts at 14 and 16 mm showed only minimal heating of max. 0.5 K. In contrast to magnetic particle imaging, our measurements showed no heating of the stents during magnetic resonance imaging under identical conditions. CONCLUSION: The BabyStent did show only slight heating in magnetic particle imaging and no detectable temperature increase in magnetic resonance imaging.


Assuntos
Coartação Aórtica/cirurgia , Implante de Prótese Vascular/métodos , Calefação/métodos , Imageamento por Ressonância Magnética/métodos , Imagens de Fantasmas , Stents , Coartação Aórtica/diagnóstico , Humanos , Resultado do Tratamento
4.
Int J Nanomedicine ; 16: 213-221, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33469281

RESUMO

PURPOSE: Endovascular stents are medical devices, which are implanted in stenosed blood vessels to ensure sufficient blood flow. Due to a high rate of in-stent re-stenoses, there is the need of a noninvasive imaging method for the early detection of stent occlusion. The evaluation of the stent lumen with computed tomography (CT) and magnetic resonance imaging (MRI) is limited by material-induced artifacts. The purpose of this work is to investigate the potential of the tracer-based modality magnetic particle imaging (MPI) for stent lumen visualization and quantification. METHODS: In this in vitro study, 21 endovascular stents were investigated in a preclinical MPI scanner. Therefore, the stents were implanted in vessel phantoms. For the signal analysis, the phantoms were scanned without tracer material, and the signal-to-noise-ratio was analyzed. For the evaluation of potential artifacts and the lumen quantification, the phantoms were filled with diluted tracer agent. To calculate the stent lumen diameter a calibrated threshold value was applied. RESULTS: We can show that it is possible to visualize the lumen of a variety of endovascular stents without material induced artifacts, as the stents do not generate sufficient signals in MPI. The stent lumen quantification showed a direct correlation between the calculated and nominal diameter (r = 0.98). CONCLUSION: In contrast to MRI and CT, MPI is able to visualize and quantify stent lumina very accurately.


Assuntos
Procedimentos Endovasculares , Fenômenos Magnéticos , Processamento de Sinais Assistido por Computador , Stents , Artefatos , Humanos , Imageamento por Ressonância Magnética , Imagens de Fantasmas , Razão Sinal-Ruído , Tomografia Computadorizada por Raios X
5.
Cardiovasc Intervent Radiol ; 43(2): 331-338, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31578634

RESUMO

PURPOSE: To illustrate the potential of magnetic particle imaging (MPI) for stent lumen imaging in comparison with clinical computed tomography (CT) and magnetic resonance imaging (MRI). MATERIALS AND METHODS: Imaging of eight tracer-filled, stented vessel phantoms and a tracer-filled, non-stented reference phantom for each diameter was performed on a preclinical MPI scanner: eight commercially available coronary stents of different dimensions (diameter: 3-4 mm; length: 11-38 mm) and materials (stainless steel, platinum-chromium) were implanted into silicone vessel phantoms. For comparison, all vessel phantoms were also visualized by MRI and CT. Two radiologists assessed the images regarding stent-induced artifacts using a 5-point grading scale. RESULTS: The visualization of all stented vessel phantoms was achieved without stent-induced artifacts with MPI. In contrast, MRI and CT images revealed multiform stent-induced artifacts. CONCLUSION: Given its clinical introduction, MPI has the potential to overcome the disadvantages of MRI and CT concerning the visualization of the stent lumen.


Assuntos
Artefatos , Processamento de Imagem Assistida por Computador/métodos , Nanopartículas de Magnetita , Imagens de Fantasmas , Stents , Tomografia/métodos , Imageamento por Ressonância Magnética/métodos , Tomografia Computadorizada por Raios X/métodos
6.
Rofo ; 190(4): 348-358, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29495050

RESUMO

PURPOSE: Calculation of process-orientated costs for inpatient endovascular treatment of peripheral artery disease (PAD) from an interventional radiology (IR) perspective. Comparison of revenue situations in consideration of different ways to calculate internal treatment charges (ITCs) and diagnosis-related groups (DRG) for an independent IR department. MATERIALS AND METHODS: Costs (personnel, operating, material, and indirect costs) for endovascular treatment of PAD patients in an inpatient setting were calculated on a full cost basis. These costs were compared to the revenue situation for IR for five different scenarios: 1) IR receives the total DRG amount. IR receives the following DRG shares using ITCs based on InEK shares for 2) "Radiology" cost center type, 3) "OP" cost center type, 4) "Radiology" and "OP" cost center type, and 5) based on DKG-NT (scale of charges of the German Hospital Society). RESULTS: 78 patients (mean age: 68.6 ±â€Š11.4y) with the following DRGs were evaluated: F59A (n = 6), F59B (n = 14), F59C (n = 20) and F59 D (n = 38). The length of stay for these DRG groups was 15.8 ±â€Š12.1, 9.4 ±â€Š7.8, 2.8 ±â€Š3.7 and 3.4 ±â€Š6.5 days Material costs represented the bulk of all costs, especially if new and complex endovascular procedures were performed. Revenues for neither InEK shares nor ITCs based on DKG-NT were high enough to cover material costs. Contribution margins for the five scenarios were 1 = €â€Š1,539.29, 2 = €â€Š-1,775.31, 3 = €â€Š-2,579.41, 4 = €â€Š-963.43, 5 = €â€Š-2,687.22 in F59A, 1 = €â€Š-792.67, 2 = €â€Š-2,685.00, 3 = €â€Š-2,600.81, 4 = €â€Š-1,618.94, 5 = €â€Š-3,060.03 in F59B, 1 = €â€Š-879.87, 2 = €â€Š-2,633.14, 3 = €â€Š-3,001.07, 4 = €â€Š-1,952.33, 5 = €â€Š-3,136.24 in F59C and 1 = €â€Š703.65, 2 = €â€Š-106.35, 3 = €â€Š-773.86, 4 = €â€Š205.14, 5 = €â€Š-647.22 in F59 D. InEK shares return on average €â€Š150 - 500 more than ITCs based on the DKG-NT catalog. CONCLUSION: In this study positive contribution margins were seen only if IR receives the complete DRG amount. InEK shares do not cover incurred costs, with material costs representing the main part of treatment costs. Internal treatment charges based on the DKG-NT catalog provide the worst cost coverage. KEY POINTS: · Internal treatment charges based on the DKG-NT catalog provide the worst cost coverage for interventional radiology at our university hospital.. · Shares from the InEK matrix such as the cost center "radiology" or "OP" as revenue for IR are not sufficient to cover incurred costs. A positive contribution margin is achieved only in the case of a compensation method in which IR receives the total DRG amount.. CITATION FORMAT: · Vogt FM, Hunold P, Haegele J et al. Comparison of the Revenue Situation in Interventional Radiology Based on the Example of Peripheral Artery Disease in the Case of a DRG Payment System and Various Internal Treatment Charges. Fortschr Röntgenstr 2017; 190: 348 - 357.


Assuntos
Grupos Diagnósticos Relacionados/economia , Custos de Cuidados de Saúde/estatística & dados numéricos , Preços Hospitalares/estatística & dados numéricos , Reembolso de Seguro de Saúde/economia , Programas Nacionais de Saúde/economia , Doença Arterial Periférica , Radiologia Intervencionista/economia , Angiografia/economia , Custos e Análise de Custo , Alemanha , Humanos , Classificação Internacional de Doenças/economia , Doença Arterial Periférica/economia , Doença Arterial Periférica/terapia , Recursos Humanos em Hospital/economia
8.
PLoS One ; 12(1): e0168902, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28056102

RESUMO

Magnetic Particle Imaging (MPI) is able to provide high temporal and good spatial resolution, high signal-to-noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs). Because of that, MPI is proposed to be a promising future method for cardiovascular imaging. Here, an interesting application may be the quantification of vascular pathologies like stenosis by utilizing the proportionality of the SPIO concentration and the MPI signal strength. In this study, the feasibility of MPI based stenosis quantification is evaluated based on this application scenario. Nine different stenosis phantoms with a normal diameter of 10 mm each and different stenoses of 1-9 mm and ten reference phantoms with a straight diameter of 1-10 mm were filled with a 1% Resovist dilution and measured in a preclinical MPI-demonstrator. The MPI signal intensities of the reference phantoms were compared to each other and the change of signal intensity within each stenosis phantom was used to calculate the degree of stenosis. These values were then compared to the known diameters of each phantom. As a second measurement, the 5 mm stenosis phantom was used for a serial dilution measurement down to a Resovist dilution of 1:3200 (0.031%), which is lower than a first pass blood concentration of a Resovist bolus in the peripheral arteries of an average adult human of at least about 1:1000. The correlation of the stenosis values based on MPI signal intensity measurements and based on the known diameters showed a very good agreement, proving the high precision of quantitative MPI in this regard.


Assuntos
Diagnóstico por Imagem/métodos , Nanopartículas de Magnetita/química , Constrição Patológica , Humanos , Imagens de Fantasmas , Razão Sinal-Ruído
9.
Phys Med Biol ; 61(16): N415-26, 2016 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-27476675

RESUMO

Magnetic particle imaging (MPI) uses magnetic fields to visualize the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). Guidance of cardiovascular interventions is seen as one possible application of MPI. To safely guide interventions, the vessel lumen as well as all required interventional devices have to be visualized and be discernible from each other. Until now, different tracer concentrations were used for discerning devices from blood in MPI, because only one type of SPIO could be imaged at a time. Recently, it was shown for 3D MPI that it is possible to separate different signal sources in one volume of interest, i.e. to visualize and discern different SPIOs or different binding states of the same SPIO. The approach was termed multi-color MPI. In this work, the use of multi-color MPI for differentiation of a SPIO coated guide wire (Terumo Radifocus 0.035″) from the lumen of a vessel phantom filled with diluted Resovist is demonstrated. This is achieved by recording dedicated system functions of the coating material containing solid Resovist and of liquid Resovist, which allows separation of their respective signal in the image reconstruction process. Assigning a color to the different signal sources results in a differentiation of guide wire and vessel phantom lumen into colored images.


Assuntos
Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Processamento de Imagem Assistida por Computador/métodos , Nanopartículas de Magnetita/química , Modelos Cardiovasculares , Imagens de Fantasmas , Cor , Humanos , Imageamento Tridimensional/instrumentação , Imageamento Tridimensional/métodos , Nanopartículas de Magnetita/administração & dosagem
10.
IEEE Trans Med Imaging ; 35(10): 2312-2318, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27164580

RESUMO

Magnetic particle imaging (MPI) is able to provide high temporal and good spatial resolution, high signal to noise ratio and sensitivity. Furthermore, it is a truly quantitative method as its signal strength is proportional to the concentration of its tracer, superparamagnetic iron oxide nanoparticles (SPIOs), over a wide range practically relevant concentrations. Thus, MPI is proposed as a promising future method for guidance of vascular interventions. To implement this, devices such as guide wires and catheters have to be discernible in MPI, which can be achieved by coating already commercially available devices with SPIOs. In this proof of principle study the feasibility of that approach is demonstrated. First, a Ferucarbotran-based SPIO-varnish was developed by embedding Ferucarbotran into an organic based solvent. Subsequently, the biocompatible varnish was applied to a commercially available guidewire and diagnostic catheter for vascular interventional purposes. In an interventional setting using a vessel phantom, the coating proved to be mechanically and chemically stable and thin enough to ensure normal handling as with uncoated devices. The devices were visualized in 3D on a preclinical MPI demonstrator using a system function based image reconstruction process. The system function was acquired with a probe of the dried varnish prior to the measurements. The devices were visualized with a very high temporal resolution and a simple catheter/guide wire maneuver was demonstrated.


Assuntos
Catéteres , Diagnóstico por Imagem/instrumentação , Diagnóstico por Imagem/métodos , Processamento de Imagem Assistida por Computador/métodos , Nanopartículas de Magnetita , Desenho de Equipamento , Imagens de Fantasmas
11.
Int J Nanomedicine ; 10: 3097-114, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25960650

RESUMO

Magnetic particle imaging (MPI) is a novel imaging method that was first proposed by Gleich and Weizenecker in 2005. Applying static and dynamic magnetic fields, MPI exploits the unique characteristics of superparamagnetic iron oxide nanoparticles (SPIONs). The SPIONs' response allows a three-dimensional visualization of their distribution in space with a superb contrast, a very high temporal and good spatial resolution. Essentially, it is the SPIONs' superparamagnetic characteristics, the fact that they are magnetically saturable, and the harmonic composition of the SPIONs' response that make MPI possible at all. As SPIONs are the essential element of MPI, the development of customized nanoparticles is pursued with the greatest effort by many groups. Their objective is the creation of a SPION or a conglomerate of particles that will feature a much higher MPI performance than nanoparticles currently available commercially. A particle's MPI performance and suitability is characterized by parameters such as the strength of its MPI signal, its biocompatibility, or its pharmacokinetics. Some of the most important adjuster bolts to tune them are the particles' iron core and hydrodynamic diameter, their anisotropy, the composition of the particles' suspension, and their coating. As a three-dimensional, real-time imaging modality that is free of ionizing radiation, MPI appears ideally suited for applications such as vascular imaging and interventions as well as cellular and targeted imaging. A number of different theories and technical approaches on the way to the actual implementation of the basic concept of MPI have been seen in the last few years. Research groups around the world are working on different scanner geometries, from closed bore systems to single-sided scanners, and use reconstruction methods that are either based on actual calibration measurements or on theoretical models. This review aims at giving an overview of current developments and future directions in MPI about a decade after its first appearance.


Assuntos
Diagnóstico por Imagem , Nanopartículas de Magnetita , Diagnóstico por Imagem/métodos , Diagnóstico por Imagem/tendências
12.
Int J Nanomedicine ; 9: 4203-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25214784

RESUMO

BACKGROUND: Magnetic particle imaging (MPI) uses magnetic fields to visualize superparamagnetic iron oxide nanoparticles (SPIO). Today, Resovist(®) is still the reference SPIO for MPI. The objective of this study was to evaluate the in vivo blood half-life of two different types of Resovist (one from Bayer Pharma AG, and one from I'rom Pharmaceutical Co Ltd) in MPI. METHODS: A Resovist concentration of 50 µmol/kg was injected into the ear artery of ten New Zealand White rabbits. Five animals received Resovist distributed by I'rom Pharmaceutical Co Ltd and five received Resovist by Bayer Pharma AG. Blood samples were drawn before and directly after injection of Resovist, at 5, 10, and 15 minutes, and then every 15 minutes until 120 minutes after the injection. The MPI signal of the blood samples was evaluated using magnetic particle spectroscopy. RESULTS: The average decline of the blood MPI signal from the two distributions differed significantly (P=0.0056). Resovist distributed by Bayer Pharma AG showed a slower decline of the MPI signal (39.7% after 5 minutes, 20.5% after 10 minutes, and 12.1% after 15 minutes) compared with Resovist produced by I'rom Pharmaceutical Co Ltd (20.4% after 5 minutes, 7.8% after 10 minutes, no signal above noise level after 15 minutes). CONCLUSION: In MPI, the blood half-life of an SPIO tracer cannot be equalized to the blood half-life of its MPI signal. Resovist shows a very rapid decline of blood MPI signal and is thus not suitable as a long circulating tracer. For cardiovascular applications in MPI, it may be used as a bolus tracer.


Assuntos
Dextranos/química , Dextranos/farmacocinética , Nanopartículas de Magnetita/química , Imagem Molecular/métodos , Animais , Dextranos/administração & dosagem , Dextranos/sangue , Feminino , Cinética , Nanopartículas de Magnetita/administração & dosagem , Coelhos
13.
J Healthc Eng ; 5(1): 79-93, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24691388

RESUMO

Magnetic particle imaging (MPI) has emerged as a new imaging method with the potential of delivering images of high spatial and temporal resolutions and free of ionizing radiation. Recent studies demonstrated the feasibility of differentiation between signal-generating and non-signal-generating devices in Magnetic Particle Spectroscopy (MPS) and visualization of commercially available catheters and guide-wires in MPI itself. Thus, MPI seems to be a promising imaging tool for cardiovascular interventions. Several commercially available catheters and guide-wires were tested in this study regarding heating. Heating behavior was correlated to the spectra generated by the devices and measured by the MPI. The results indicate that each instrument should be tested separately due to the wide spectrum of measured temperature changes of signal-generating instruments, which is up to 85°C in contrast to non-signal-generating devices. Development of higher temperatures seems to be a limitation for the use of these devices in cardiovascular interventions.


Assuntos
Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/patologia , Diagnóstico por Imagem/métodos , Temperatura Alta , Cateterismo Cardíaco , Cateteres Cardíacos , Desenho de Equipamento , Compostos Férricos/química , Humanos , Magnetismo , Nanopartículas Metálicas/química , Fibras Ópticas , Oscilometria , Segurança do Paciente , Imagens de Fantasmas , Fatores de Tempo
14.
Biomed Tech (Berl) ; 58(6): 527-33, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23787462

RESUMO

Magnetic particle imaging (MPI) recently emerged as a new tomographic imaging method directly visualizing the amount and location of superparamagnetic iron oxide particles (SPIOs) with high spatial resolution. To fully exploit the imaging performance of MPI, specific requirements are demanded on the SPIOs. Most important, a sufficiently high number of detectable harmonics of the receive signal spectrum is required. In this study, an assessment of commercial iron oxide-based MRI contrast agents is carried out, and the result is compared with that of a new self-synthesized high-performance MPI tracer. The decay of the harmonics is measured with a magnetic particle spectrometer (MPS). For the self-synthesized carboxymethyldextran-coated SPIO, it can be demonstrated that despite a small iron core diameter, the particle performance is as good as in Resovist, the best-performing commercial SPIO today. However, the self-synthesized particles show the lowest iron concentration compared with Resovist, Sinerem, and Endorem. As the iron dose will be an important issue in human MPI, the synthesis technique and the separation chain for self-synthesis will be pursued for further improvements. In evaluations carried out with MPS, it can be shown in this work that the quality of the self-synthesized nanoparticles outperforms the three commercial tracer materials when the decay of harmonics is normalized by the iron concentration. The results of this work emphasize the importance of producing highly uniform and monodisperse superparamagnetic particles contributing to lower application of tracer concentration, better sensitivity, or a higher spatial resolution.


Assuntos
Dextranos , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Nanopartículas de Magnetita , Imagem Molecular/métodos , Meios de Contraste , Humanos , Imageamento por Ressonância Magnética/instrumentação , Imagens de Fantasmas , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
15.
Magn Reson Med ; 69(6): 1761-7, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22829518

RESUMO

Magnetic particle imaging has emerged as a new technique for the visualization and quantification of superparamagnetic iron oxide nanoparticles. It seems to be a very promising application for cardiovascular interventional radiology. A prerequisite for interventions is the artifact-free visualization of the required instruments and implants. Various commercially available catheters, guide wires, and a catheter experimentally coated with superparamagnetic iron oxide nanoparticles were tested regarding their signal characteristics using magnetic particle spectroscopy to evaluate their performance in magnetic particle imaging. The results indicate that signal-generating and non-signal-generating instruments can be distinguished. Furthermore, coating or loading non-signal-generating instruments with superparamagnetic iron oxide nanoparticles seems to be a promising approach, but optimized nanoparticles need yet to be developed.


Assuntos
Artefatos , Cateteres Cardíacos , Dextranos , Imagem por Ressonância Magnética Intervencionista/instrumentação , Nanopartículas de Magnetita , Meios de Contraste , Desenho de Equipamento , Análise de Falha de Equipamento , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
Radiology ; 265(3): 933-8, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22996744

RESUMO

PURPOSE: To evaluate the feasibility of different approaches of instrument visualization for cardiovascular interventions guided by using magnetic particle imaging (MPI). MATERIALS AND METHODS: Two balloon (percutaneous transluminal angioplasty) catheters were used. The balloon was filled either with diluted superparamagnetic iron oxide (SPIO) ferucarbotran (25 mmol of iron per liter) or with sodium chloride. Both catheters were inserted into a vessel phantom that was filled oppositional to the balloon content with sodium chloride or diluted SPIO (25 mmol of iron per liter). In addition, the administration of a 1.4-mL bolus of pure SPIO (500 mmol of iron per liter) followed by 5 mL of sodium chloride through a SPIO-labeled balloon catheter into the sodium chloride-filled vessel phantom was recorded. Images were recorded by using a preclinical MPI demonstrator. All images were acquired by using a field of view of 3.6 × 3.6 × 2.0 cm. RESULTS: By using MPI, both balloon catheters could be visualized with high temporal (21.54 msec per image) and sufficient spatial (≤ 3 mm) resolution without any motion artifacts. The movement through the field of view, the inflation and deflation of the balloon, and the application of the SPIO bolus were visualized at a rate of 46 three-dimensional data sets per second. CONCLUSION: Visualization of SPIO-labeled instruments for cardiovascular intervention at high temporal resolution as well as monitoring the application of a SPIO-based tracer by using labeled instruments is feasible. Further work is necessary to evaluate different labeling approaches for diagnostic catheters and guidewires and to demonstrate their navigation in the vascular system after administration of contrast material. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120424/-/DC1.


Assuntos
Angioplastia Coronária com Balão/instrumentação , Meios de Contraste/administração & dosagem , Dextranos/administração & dosagem , Imageamento por Ressonância Magnética/métodos , Nanopartículas de Magnetita/administração & dosagem , Artefatos , Meios de Contraste/química , Dextranos/química , Estudos de Viabilidade , Humanos , Aumento da Imagem/métodos , Imageamento Tridimensional , Nanopartículas de Magnetita/química , Imagens de Fantasmas , Cloreto de Polivinila , Cloreto de Sódio/administração & dosagem , Cloreto de Sódio/química
17.
Z Med Phys ; 22(4): 323-34, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22909418

RESUMO

Magnetic Particle Imaging (MPI) is a recently invented tomographic imaging method that quantitatively measures the spatial distribution of a tracer based on magnetic nanoparticles. The new modality promises a high sensitivity and high spatial as well as temporal resolution. There is a high potential of MPI to improve interventional and image-guided surgical procedures because, today, established medical imaging modalities typically excel in only one or two of these important imaging properties. MPI makes use of the non-linear magnetization characteristics of the magnetic nanoparticles. For this purpose, two magnetic fields are created and superimposed, a static selection field and an oscillatory drive field. If superparamagnetic iron-oxide nanoparticles (SPIOs) are subjected to the oscillatory magnetic field, the particles will react with a non-linear magnetization response, which can be measured with an appropriate pick-up coil arrangement. Due to the non-linearity of the particle magnetization, the received signal consists of the fundamental excitation frequency as well as of harmonics. After separation of the fundamental signal, the nanoparticle concentration can be reconstructed quantitatively based on the harmonics. The spatial coding is realized with the static selection field that produces a field-free point, which is moved through the field of view by the drive fields. This article focuses on the frequency-based image reconstruction approach and the corresponding imaging devices while alternative concepts like x-space MPI and field-free line imaging are described as well. The status quo in hardware realization is summarized in an overview of MPI scanners.


Assuntos
Meios de Contraste , Interpretação de Imagem Assistida por Computador/instrumentação , Interpretação de Imagem Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Nanopartículas de Magnetita , Cirurgia Assistida por Computador/instrumentação , Cirurgia Assistida por Computador/métodos , Algoritmos , Computadores , Campos Eletromagnéticos , Desenho de Equipamento , Humanos , Imagem Molecular/instrumentação , Imagem Molecular/métodos , Sensibilidade e Especificidade
18.
J Cardiovasc Comput Tomogr ; 6(3): 149-53, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22682260

RESUMO

Magnetic particle imaging (MPI) is a new medical imaging technique which performs a direct measurement of magnetic nanoparticles, also known as superparamagnetic iron oxide. MPI can acquire quantitative images of the local distribution of the magnetic material with high spatial and temporal resolution. Its sensitivity is well above that of other methods used for the detection and quantification of magnetic materials, for example, magnetic resonance imaging. On the basis of an intravenous injection of magnetic particles, MPI has the potential to play an important role in medical application areas such as cardiovascular, oncology, and also in exploratory fields such as cell labeling and tracking. Here, we present an introduction to the basic function principle of MPI, together with an estimation of the spatial resolution and the detection limit. Furthermore, the above-mentioned medical applications are discussed with respect to an applicability of MPI.


Assuntos
Meios de Contraste/química , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Nanopartículas de Magnetita/química , Animais , Humanos , Injeções Intralinfáticas , Tamanho da Partícula
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