Gold/mercury amalgam (Au/Hg) microelectrodes with a diameter of 25 microm were developed for the detection of environmentally relevant analytes such as manganese and iron by scanning electrochemical microscopy (SECM), and applied to investigate the controlled dissolution of manganese carbonate (MnCO(3); rhodochrosite) in acidic conditions. Characterization of the amalgam electrode geometry ...

Numerous studies over the past decade have shown that magnetic resonance imaging (MRI) has great potential for detecting and quantifying the distribution of iron in the body. With MRI, tissue iron is indirectly identified by the paramagnetic effects of iron on the shortening of water proton MR relaxation times. However, ...

We report on the in vivo assessment of macrophage infiltration in adoptive transfer experimental autoimmune neuritis (AT-EAN), a prototypic Th-1-mediated autoimmune disorder of the peripheral nervous system (PNS). Lewis rats received systemic injections of superparamagnetic iron oxide (SPIO) particles at days 2, 3, 4, 5, or 9 after adoptive transfer ...

The ability to visualize cell infiltration in experimental auto-immune encephalomyelitis (EAE), a well-known animal model for multiple sclerosis in humans, was investigated using a clinical 1.5-T magnetic resonance imaging (MRI) scanner, a custom-built, high-strength gradient coil insert, a 3-D fast imaging employing steady-state acquisition (FIESTA) imaging sequence and a superparamagnetic ...

Magnetic labeling of transplanted cells permits us to monitor their localization non-invasively using MRI. Since most transfection agents for magnetic labeling have the same cationic charge as Fe(3+), the efficiency may be reduced. The hemagglutinating virus-envelope has no charge and utilizes membrane fusion activity to deliver internalized materials. In this ...

Biocompatible magnetic nanosensors have been designed to detect molecular interactions in biological media. Upon target binding, these nanosensors cause changes in the spin-spin relaxation times of neighboring water molecules, which can be detected by magnetic resonance (NMR/MRI) techniques. These magnetic nanosensors have been designed to detect specific mRNA, proteins, enzymatic ...

The magnetic relaxation of a Nb film covered with a random array of permalloy particles has been studied using various procedures. When the sample undergoes a field-cooled process, the magnetic relaxation becomes logarithmic in time. The relaxation rate is nearly temperature independent at low temperature and characteristic glassy dynamics-aging and ...

BACKGROUND: Biotechnology applications of magnetic gels include biosensors, targeted drug delivery, artificial muscles and magnetic buckles. These gels are produced by incorporating magnetic materials in the polymer composites. METHODS: A biocompatible magnetic gel film has been synthesized using polyvinyl alcohol. The magnetic gel was dried to generate a biocompatible magnetic ...

BACKGROUND: MRI has been proposed for non-invasive detection and quantification of liver iron content, but has not been validated as a reproducible and sensitive method, especially in patients with mild iron overload. We aimed to assess the accuracy of a simple, rapid, and easy to implement MRI procedure to detect ...

A systematic study of the magnetic and rheological properties of magneto-rheological (MR) fluids containing micron-size and nano-size iron particles is presented. The MR fluids were prepared with hydraulic oil as the carrier liquid and lecithin as an effective surfactant medium that promotes uniform particle dispersion. Magnetic measurements on micron-, hybrid-(nano ...

Among the few non-invasive methods to quantify liver iron deposits, magnetic resonance imaging (MRI) and biomagnetic liver susceptometry (BLS) have been considered the best to evaluate iron overload in the body. This diagnosis is necessary for patients who regularly receive red blood cells transfusion and that have a genetic disorder ...

The method of determining the longitudinal relaxation time of hyperpolarized 129Xe in the mouse brain has been established in vivo with the ventilation technique under controlled-flow conditions. The uptake and washout processes for nine mice were traced through observation of time-dependent changes in NMR (nuclear magnetic resonance) signal amplitudes and ...

An assessment has been made of the association of (239+240)Pu, 241Am and 210Po (in secular equilibrium with 210Pb) with iron minerals using a magnetic extraction technique. Grab samples of beach sand from the Cumbrian (UK) coastline were subjected to successive extractions with an approximately 0.1 T ferrite magnet and an ...

Magnetic particles for medical applications have been developed by many researchers. Since magnetic particles have unique magnetic features not present in other materials, they can be applied to special medical techniques. Separation, immunoassay, magnetic resonance imaging (MRI), drug delivery, and hyperthermia are enhanced by the use of magnetic particles. Magnetite ...

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging in the quantification of hepatic iron concentration. MATERIALS AND METHODS: Between April 1999 and June 2001, 112 patients were recruited prospectively. All had undergone liver biopsy and hepatic iron concentration quantification with spectrophotometry, followed by MR imaging. MR imaging involved ...

In this study, we present a magnetic resonance imaging (MRI) method for quantifying cerebral deoxyhemoglobin content that is based on a measurement of the reversible contribution (R'2) of the transverse relaxation rate under the assumption of a quantitative relationship between R'2 and deoxyhemoglobin content. A numerical simulation was performed assuming ...

Although macrophages represent the major inflammatory cells in cerebral ischemia, the kinetics of macrophage infiltration are largely unknown. To address this issue, we injected superparamagnetic iron oxide (SPIO) particles into the circulation of rats at different time points after focal photothrombotic cerebral infarction and performed magnetic resonance imaging (MRI) 24 ...

The effect of rigor (formation of actomyosin complexes) on magnetization transfer was observed with a 1.5 T clinical magnetic resonance (MR) imaging system. The magnetization transfer ratio of chemically skinned (calcium-sensitive) muscle fiber preparations increased much more in a rigor state than in a relaxed state, while that of calcium-insensitive ...

AIM: To develop a novel, magnetic resonance-based method for in vivo cell localization in the central nervous system (CNS) of the animals without sacrificing them. METHODS: Cells were labeled in vivo by intravenous injection of cell marker-specific antibodies covalently bound to ultrasmall superparamagnetic iron oxide particles (USPIO). This enabled the ...

Transient gray and white matter magnetic resonance signal changes have frequently been reported because of underlying epileptic activity. However, transient subcortical hypointensity on T2 and fluid-attenuated inversion recovery images in the setting of status epilepticus (SE) has rarely been reported. The authors note 3 of 6 retrospective cases with partial ...

PURPOSE: To assess tissue iron concentrations by the use of a gradient echo T2* multiecho technique. MATERIALS AND METHODS: We compared the results of measurements of heart T2* from 32 patients using the established multiple breath-hold variable TR technique with a new multiecho sequence that acquires all images within a ...

The purpose of this study was to determine whether phagocytic activity is measurable by dynamic superparamagnetic iron oxide-enhanced MR imaging. For these experiments on New Zealand White rabbits, which were randomly allocated to normal and silica treated groups, we performed a dynamic MR study and radioisotope study with Tc99m-phytate. In ...

The 1H-magnetic resonance imaging technique was applied for monitoring the extent of the heat coagulation in the shell egg. It is demonstrated that spin-spin relaxation time (T2) is an effective marker to observe the extent of coagulation in egg white and yolk and that the T2 value image is quite ...

A nine-month-old infant presented with fever and loss of milestones. Examination revealed intermittent rigidity and dystonic movements. Magnetic resonance imaging (MRI) shows decreased signal intensity in globus pallidus and substantia nigra, indicative of iron deposition, suggesting Hallervorden Spatz Disease. The dopamine-neuromelanine system has been postulated to be the possible pathogenesis. ...

The purpose of this study was to evaluate if the variations of heart magnetic resonance imaging in beta-thalassemia major patients treated with Deferoxamine B mesylate (DF) or Deferiprone (L1) chelation therapy is a useful tool of the indirect myocardial iron content determination. For this reason, a prospective study was carried ...

The quantification of a BNCT 10B-carrier, L-p-boronophenylalanine-fructose complex (BPA-F), was evaluated using 1H magnetic resonance spectroscopy (1H MRS) with phantoms at 1.5 and 3.0 T. For proper quantification, relaxation times T1 and T2 are needed. While T1 is relatively easy to determine, the determination of T2 of a coupled spin ...

By deploying a functioning electrochemical cell inside a Magnetic Resonance Imaging (MRI) instrument, images of the electrically-induced diffusion of water through a Li+ ion-exchanged Nafion ionic polymer film in the form of two-dimensional maps of proton density and transverse relaxation time, T2, were generated and changes in these images over ...

Technical magnetic materials are increasingly used for the development of magnetic retained dental prosthetic and orofacial epithetic devices. Since most of the magnets based on rare earth metals, such as samarium-cobalt based alloys have a high tendency for corrosion they were first coated by tin and then encapsulated by titanium. ...

A clinical magnetic resonance imaging (MRI) system was used to measure proton transverse relaxation rates (R2) in agar gels with varying concentrations of ferrimagnetic iron oxide nanoparticles in a field strength of 1.5 T. The nanoparticles were prepared by coprecipitation of ferric and ferrous ions in the presence of either ...

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate superparamagnetic iron oxide (SPIO) nanoparticles to discriminate infarcted from normal tissue after myocardial infarction using high field MR imaging (7 tesla). MATERIALS AND METHODS: Permanent myocardial infarction was induced in rats. SPIO nanoparticles (1 mg Fe/kg) were assessed with ...

OBJECTIVE: The aim of our study was to determine the sensitivity of double-contrast MR imaging in the detection of hepatocellular carcinomas in patients with a cirrhotic liver. SUBJECTS AND METHODS: Thirty-one patients underwent double-contrast MR imaging and subsequent liver transplantation. Breath-hold T1- and T2-weighted MR images were obtained before and ...

Pixel-by-pixel calculation of T1 values (T1 mapping) has been used in different tissues to focus on T1 changes in a quantitative fashion. The aim of this study was to establish T1 mapping of human myocardium on a 1.5 Tesla system and to examine its diagnostic potential in patients with acute ...

Basal ganglia bilateral symmetric hyperintensity in T1-weighted sequences at magnetic resonance imaging (MRI) is recognized to be due to the presence of manganese deposits. This abnormal finding has been reported in occupational exposures, liver cirrhosis and total parenteral nutrition with unbalanced solutions. However, the same imaging is often observed "by ...

PURPOSE: To investigate the feasibility of macrophage magnetic resonance (MR) imaging in rats by using an experimental soft-tissue infection model. MATERIALS AND METHODS: Thirteen rats with unilateral calf-muscle infection were imaged with a 4.7-T MR imager at an early chronic stage of infection (day 4 before contrast material injection, days ...

Signal changes in activated brain areas are detectable by MRI and MR spectroscopy (MRS). Shifts in pH occur during brain activation. Our aim was to investigate the relationship between changes in pH and T2 relaxation times. T2 was determined in vitro at 24 MHz in various liquids at different pH ...

RATIONALE AND OBJECTIVES: The purpose of this study was to examine the dose dependency of the intravascular signal intensity after injection of ultrasmall superparamagnetic iron oxide (USPIO) particles (SH U 555 C) in a rabbit model studied with a low-field-strength magnetic resonance (MR) imaging system. The results were used to ...

PURPOSES: To define the relation between pathologic inflammatory activity and magnetic resonance imaging (MRI) grades of iron deposition in patients with liver cirrhosis. PATIENTS AND METHODS: In 53 patients with biopsy-proven liver cirrhosis, T2*-weighted gradient echo MRI (echo time > or =6 milliseconds) was reviewed. Grading of parenchymal iron deposition ...

Stacks of CR-39 plastic nuclear track detectors were mounted inside the MIR spacecraft during the EUROMIR95 space mission for a period of 6 months. This long exposure time resulted in a large number of tracks of HZE-particles in the detector foils. All trajectories of stopping iron nuclei could be reconstructed ...

Liquid Gaviscon and Gaviscon Advance are established reflux suppressant formulations. This study describes the use of echo-planar magnetic resonance imaging (EPI) to visualise non-invasively intragastric alginate rafts of Liquid Gaviscon and Gaviscon Advance in healthy subjects. Secondly, the feasibility of using relaxation rate (T2(-1)) measurements to monitor changes in the ...

A central role of iron in the pathogenesis of idiopathic Parkinson's disease (PD), due to its increase in substantia nigra pars compacta dopaminergic neurons and its capacity to enhance production of toxin reactive oxygen radicals, has been discussed for many years. Nuclear magnetic resonance (NMR) relaxation is considered an objective ...

RATIONALE AND OBJECTIVES: Comparison of two different ultrasmall superparamagnetic iron oxide (USPIO) particles in terms of their intracellular cell-labeling properties of macrophages and subsequent visualization by MR imaging. MATERIALS AND METHODS: Cultures containing the macrophage cell line P-388D1 were incubated with a neutral carboxydextran-coated USPIO preparation (DDM 43/34/103) or an ...

An international workshop on the noninvasive measurement of iron was conducted by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) on April 17, 2001, to assess the current state of the science and to identify areas needing further investigation. The workshop concluded that a clear clinical need ...

PURPOSE: To determine the diagnostic value of a new ultrasmall superparamagnetic iron oxide Clariscan, (NC100150) for the evaluation of renal perfusion in an animal model using a 3D-FFE-EPI sequence. MATERIALS AND METHODS: Four groups of four rabbits each were imaged after bolus injection of NC100150, using a 1.5 T MR ...

During the last few years, the therapeutic use of stem and progenitor cells as a substitute for malfunctioning endogenous cell populations has received considerable attention. Unlike their current use in animal models, the introduction of therapeutic cells in patients will require techniques that can monitor their tissue biodistribution noninvasively. Among ...

Highly sensitive, efficient, and high-throughput biosensors are required for genomic and proteomic data acquisition in complex biological samples and potentially for in vivo applications. To facilitate these studies, we have developed biocompatible magnetic nanosensors that act as magnetic relaxation switches (MRS) to detect molecular interactions in the reversible self-assembly of ...

Functional magnetic resonance imaging (MRI), using monocrystalline iron oxide nanoparticles (MION) as a new intravascular contrast agent, was adapted for a rabbit model of pigmented choroidal melanoma. Three-dimensionally spoiled gradient recalled sequences were used for the quantitative assessment of blood volume and cellular uptake. In all ocular tissues studied, MION ...

Thorotrast is a colloidal suspension of radioactive (232)ThO(2) that naturally emits alpha particles (90%), beta particles and gamma rays (10%). Thorotrast was used as a radiographic contrast agent in the 1930s-1950s; it caused liver cancer several decades after injection because of its life-long deposition and exposure. Determination of the amount ...

Arterial embolization hyperthermia (AEH) consists of arterially embolizing liver tumours with ferromagnetic particles that generate hysteretic heating on exposure to an alternating magnetic field. A critical component of AEH is the concentration and distribution of ferromagnetic particles in the normal hepatic parenchyma (NHP), as well as in the tumour tissue. ...

The purpose of this work is to develop a rapid MRI method amenable to profiling with minimal or no T(1) relaxation weighting. The behavior of a signal during a centric SPRITE acquisition is analyzed. It is shown that the technique can be made immune to a broad range of T(1) ...

PURPOSE: To investigate intravascular enhancement of bolus-injectable small and ultrasmall superparamagnetic iron oxides (USPIOs) of different particle sizes and relaxivities for first-pass and blood-pool magnetic resonance (MR) angiography. MATERIALS AND METHODS: Iron oxides with different particle sizes (hydrodynamic diameters, 21, 33, 46, and 65 nm) were bolus injected intravenously at ...