92 results about "T2 relaxation" patented technology

A magnetic resonance imaging “MRI” method and apparatus for lengthening the usable echo-train duration and reducing the power deposition for imaging is provided. The method explicitly considers the t1 and t2 relaxation times for the tissues of interest, and permits the desired image contrast to be incorporated into the tissue signal evolutions corresponding to the long echo train. The method provides a means to shorten image acquisition times and / or increase spatial resolution for widely-used spin-echo train magnetic resonance techniques, and enables high-field imaging within the safety guidelines established by the Food and Drug Administration for power deposition in human MRI.

The present invention is directed to a method and system of tissue or background suppression for the acquisition of image data from blood flow or tissue perfusion. Background suppression with minimal effects upon inflowing spins is achieved through a series of spin locking low level RF pulses that cause adiabatic demagnetization of tissue with a relaxation time T1-rho that is intermediate between T1 and T2 relaxation times. In this regard, the effective transverse magnetization of static tissue resulting from the application of a series of low level RF pulses is reduced and, with the spin locking, longitudinal magnetization regrowth is minimized. As such, inflowing spins to an imaging volume may be directly imaged with significant background tissue suppression. The present invention is particularly applicable to time-of-flight MRA and MR perfusion imaging.

Novel pulse sequences are used to probe the properties of porous media, such as are found in subterranean formations and core samples. This use allows diffusion effects to be uncoupled from the overall T2 relaxation time of the sample. Properties such as internal field gradient and distribution of diffusion coefficients may be determined. A series of pulse sequences are applied to the media to be evaluated. The series of pulse sequences include first and second windows. The first windows include pulse sequences have varying characteristics, such as increasing echo spacing, while the second windows preferably utilize similar pulse sequences which have very small echo spacing. Apparent internal field gradient distribution and apparent diffusion coefficient may be determined as a function of T2 relaxation time. These properties are readily visualized in a two-dimensional map with a first axis being the apparent internal field gradient or alternatively the diffusion coefficient of pore fluids, a second axis being the T2 relaxation times, and the vertical amplitudes being proportional to the proton population. Other properties which may be determined from use of this method include porosity, pore size distribution, oil and water saturation, oil viscosity, oil wettability, and permeability. Also, a method for determining and plotting a T1-MAS 2D spectrum is provided where T1 relaxation time and chemical shift are plotted on x,y axes while intensity of proton population is displayed along a third axis.

The invention discloses a method for measuring the oil content and the water content in drilling fluid through low-field nuclear magnetic resonance. Manganese chloride is used so that the relaxation time of water can be shortened, however, the relaxation time of oil is not affected, hence, the oil and the water in the drilling fluid can be distinguished, and quantitative testing of the oil content and the water content in the drilling fluid is achieved. The method includes the steps that nuclear magnetic resonance analysis is conducted on an original sample of the drilling fluid first, and the T2 relaxation spectrum of the original sample of the drilling fluid is tested; then a manganese chloride solution is added into the original sample of the drilling fluid to be fully stirred; afterwards, nuclear magnetic resonance analysis of the manganese-saturated drilling fluid is performed; the peak area of crude oil is the peak area of the manganese-saturated drilling fluid after the relaxation time is 1 ms, the peak area of the water in the drilling fluid is the difference between the peak area before manganese saturation and the peak area of the crude oil, and the peak area of the crude oil and the peak area of the water in the drilling fluid are introduced into corresponding working curve equations so that the oil content and the water content in the drilling fluid can be obtained; at last, the oil content and the water content of the drilling fluid can be obtained by combining the mass of the drilling fluid.

A method for calculating a sensitivity distribution of a receive coil and taking a tomographic image of a subject, based on magnetic resonance signals received by a surface coil in an imaging sequence with a plurality of different echo times TE1 and TE2 in a reference scan, a plurality of reference images are produced by a first reference image producing section; and based on the plurality of reference images, a T2 relaxation time is calculated by a T2 relaxation time calculating section. Then, based on the calculated T2 relaxation time, a T2-weighted image at the echo time TE2 is calculated by a T2-weighted image calculating section, and thereafter, based on the reference image and T2-weighted image at the echo time TE2, a sensitivity distribution is calculated by a sensitivity distribution calculating section. Based on the sensitivity distribution, a tomographic image by an actual scan is corrected by a correcting section.

An MRI method includes performing a first image acquisition module of a pulse sequence to acquire a first MR data from slices disposed at different locations in a region of interest (ROI) of an object; performing a second image acquisition module of the pulse sequence, to acquire a second MR data from the slices disposed at the different locations of the ROI, with a T2 preparation time different than that of the first image acquisition module; and generating a T2 map based on the acquired first MR data and the acquired second MR data.

The invention relates to a nano magnetic resonance imaging contrast agent and a preparation method thereof. The contrast agent consists of external aqueous phase and humic acid substance-modified super-paramagnetic ferrite nano crystal dispersed in the external aqueous phase. The super-paramagnetic ferrite nano crystal is synthesized by adopting a chemical co-precipitation method, and the grain diameter is 15 to 30 nanometers. The nano crystal is purified and then dispersed in the external aqueous phase to form the contrast agent for intravenous injection. The contrast agent can be stabilized for over two years. The contrast agent has low toxicity, good biocompatibility, large time window and high saturation magnetization, and the half-life period of the contrast agent in the blood reaches 30 to 60 minutes. The contrast agent is absorbed by netlike endothelial systems in liver and spleen tissues through intravenous injection, and is focused in the liver and spleen tissues so as to shorten the T2 relaxation time. In a T2 image, signals of normal liver and spleen tissues are obviously reduced, and signals of tumor or pathological change tissues have no obvious change, so the contrast agent improves the imaging contrast of the focus and the normal tissue and can be used for early diagnosis of pathological changes such as micro tumor of liver and spleen tissues and the like.