Aqueous Dispersion of Manganese-Zinc Ferrite Nanoparticles Protected by PEG as a T MRI Temperature Contrast Agent.

Mixed manganese-zinc ferrite nanoparticles coated with PEG were studied for their potential usefulness in MRI thermometry as temperature-sensitive contrast agents. Particles in the form of an 8.5 nm core coated with a 3.

Synthesis of Manganese Zinc Ferrite Nanoparticles in Medical-Grade Silicone for MRI Applications.

The aim of this project is to fabricate hydrogen-rich silicone doped with magnetic nanoparticles for use as a temperature change indicator in magnetic resonance imaging-guided (MRIg) thermal ablations. To avoid clustering, the particles of mixed MnZn ferrite were synthesized directly in a medical-grade silicone polymer solution. The particles were characterized by transmission electron microscopy, powder X-ray diffraction, soft X-ray absorption spectroscopy, vibrating sample magnetometry, temperature-dependent nuclear magnetic resonance relaxometry (20 °C to 60 °C, at 3.

Magnetic particle based MRI thermometry at 0.2 T and 3 T.

This study provides insight into the advantages and disadvantages of using ferrite particles embedded in agar gel phantoms as MRI temperature indicators for low-magnetic field scanners. We compare the temperature-dependent intensity of MR images at low-field (0.2 T) to those at high-field (3.

One-Step Preparation of Highly Stable Copper-Zinc Ferrite Nanoparticles in Water Suitable for MRI Thermometry.

Superparamagnetic ferrite nanoparticles coated with a polymer layer are widely used for biomedical applications. The objective of this work is to design nanoparticles as a magnetic resonance imaging (MRI) temperature-sensitive contrast agent. Copper-zinc ferrite nanoparticles coated with a poly(ethylene glycol) (PEG) layer are synthesized using a one-step thermal decomposition method in a polymer matrix.

On the optimization of imaging parameters for magnetic resonance imaging thermometry using magnetic microparticles.

Magnetic Resonance Imaging thermometry is an extremely useful technique which allows one to determine, noninvasively, the temperature deep in the tissue in two or three dimensions. Many methods of MR thermometry have been developed, including those that rely on the intrinsic MR properties of tissue and those which depend on the addition of contrast agents injected into the tissue to create temperature dependent MR images. One such method is to introduce magnetic particles whose magnetization's temperature dependence influences the MR properties of the surrounding tissue and obtain temperature from calibrated intensity changes of T* weighted MR images.

Measurement of sub-zero temperatures in MRI using T temperature sensitive soft silicone materials: Applications for MRI-guided cryosurgery.

Purpose: One standard method, proton resonance frequency shift, for measuring temperature using magnetic resonance imaging (MRI), in MRI-guided surgeries, fails completely below the freezing point of water. Because of this, we have developed a new methodology for monitoring temperature with MRI below freezing. The purpose of this paper is to show that a strong temperature dependence of the nuclear relaxation time T in soft silicone polymers can lead to temperature-dependent changes of MRI intensity acquired with T weighting.

Microwave interferometer for phase and response time measurements.

We report the development of a microwave interferometer using a quadrature intermediate frequency (IQ) mixer designed to measure the relative phase change and response time of microwave devices tested in the K and upper K bands (22-40 GHz). The interferometer is currently used to test liquid crystal based devices. The system allows for the application of an AC bias beyond the amplitude/frequency limitations imposed on vector network analyzer bias ports.

Development of Ferrite-Based Temperature Sensors for Magnetic Resonance Imaging: A Study of CuZnFeO.

We investigate the use of Cu Zn FeO ferrites (0.60 < < 0.76) as potential sensors for magnetic- resonance-imaging thermometry.

Ferromagnetic particles as magnetic resonance imaging temperature sensors.

Magnetic resonance imaging is an important technique for identifying different types of tissues in a body or spatial information about composite materials. Because temperature is a fundamental parameter reflecting the biological status of the body and individual tissues, it would be helpful to have temperature maps superimposed on spatial maps. Here we show that small ferromagnetic particles with a strong temperature-dependent magnetization, can be used to produce temperature-dependent images in magnetic resonance imaging with an accuracy of about 1 °C.

Early impairment of transmural principal strains in the left ventricular wall after short-term, high-fat feeding of mice predisposed to cardiac steatosis.

Background: myocardial lipid accumulation precedes some cardiomyopathies, but little is known of concurrent effects on ventricular mechanics. We tested the hypothesis that intramyocardial lipid accumulation during a short-term, high-fat diet (HFD) affects 2-dimensional strains in the heart. We examined the hearts of nontransgenic (NTG) mice and of transgenic mice predisposed to elevated triacylglyceride (TAG) storage linked to low-level overexpression of peroxisome proliferator activated receptor (PPAR-α).

Improved cardiac tagging resolution at ultra-high magnetic field elucidates transmural differences in principal strain in the mouse heart and reduced stretch in dilated cardiomyopathy.

Cardiac tagging resolution for regional principal strains E1 and E2 has been a limiting factor for the study of dilated mouse hearts, in which the left ventricle (LV) wall thickness can drop to below 1 mm. Therefore, high resolution tagging was performed at 14.1 T to enable transmural principal strain measurements across the LV wall of normal mouse hearts and average principal strains in thinned LV walls of a transgenic mouse (PKCepsilon TG) that develops dilated LV.

Principal strain changes precede ventricular wall thinning during transition to heart failure in a mouse model of dilated cardiomyopathy.

This study was performed to elucidate the relation between in vivo measurements of two-dimensional principal strains and the progression of left ventricle (LV) wall thinning during development of dilated cardiomyopathy in the protein kinase C-epsilon (PKC-epsilon) transgenic (TG) overexpressing mouse heart. Principal two-dimensional strains, E1 and E2, were determined in the LV wall of the anesthetized mouse using cardiac MRI tagging at 14.1 T.

17O magnetic resonance imaging of the human brain.

Here we show the first example of in vivo oxygen-17 (17O) magnetic resonance imaging of the human in natural abundance. Two-dimensional fast multi-planar gradient recalled 90 deg echo (FMPGR/90) pulse sequence and three-dimensional projection reconstruction pulse sequence methods were used.

Determination of regional cerebral oxygen consumption in the human: 17O natural abundance cerebral magnetic resonance imaging and spectroscopy in a whole body system.

17O natural abundance imaging in a whole body imager is demonstrated using standard MRI spectrometer and 1H imaging methods. A novel design of a highly sensitive 17O/1H doubly tuned surface head coil is shown. The head probe allows simultaneous acquisition of 17O and 1H images using a single coil.