83 results about "Inversion pulse" patented technology

Featured are methods for magnetic resonance imaging in which MR signals of selected tissues, fluid or body components in a target area are desired to be essentially eliminated, which method includes applying an initial RF inversion pulse to invert the magnetization of the selected tissues or to apply any other T1 preparation aimed at nulling one or more tissue species and successively applying one or more RF inversions pulses thereafter. More particularly, the successively applied RF inversion pulses are applied so as to essentially maintain the magnetization of the selected tissues at or about the zero-crossing point of the longitudinal magnetization. Such methods further include interleaving a plurality of excitation pulses for acquiring image data and the RF inversion pulses so that at least one of the plurality of excitation pulses follows in a time sequence the application of one of the applied RF inversion pulses such that the image data is acquired following an inversion pulse.

A pulse-width modulation (PWM) amplifier is adapted to a class-D amplifier in which an analog input signal is subjected to integration, pulse-width modulation, and switched amplification, wherein a glitch elimination circuit eliminates noise from a pulse-width modulated signal, from which a high pulse signal and a low pulse signal are isolated such that each pulse is delayed by a dead time at the leading-edge timing thereof. When both of them are simultaneously set to a high level, one of them is reduced in level. In response to the occurrence of clipping, an integration constant applied to an operational amplifier is automatically changed from a primary integration constant to a secondary integration constant. When the clipped state is sustained for a prescribed time, an inversion pulse is compulsorily introduced into the pulse-width modulated signal.

In a method and apparatus for MR imaging, a data acquisition sequence is executed wherein at least two slices of an examination subject are imaged in parallel with a gradient echo method for spatially resolved quantification of the T1 relaxation time. At least one first acquisition sequence is implemented to acquire MR data from a first slice of the examination subject and at least one second acquisition sequence is implemented to acquire MR data from a second slice of the examination subject. The acquisition sequences each include an inversion pulse and at least two successive readout steps. The first and second acquisition sequences are temporally offset from one another such that they at least partially overlap.

In a method and apparatus for magnetic resonance imaging on the basis of a gradient echo sequence by excitation of nuclear spins and measurement of radio-frequency signals arising from the excited nuclear spins:(a) the magnetization of the spins is prepared by an inversion pulse;(b) a number of steps for spin excitation are implemented as well as acquisition of an RF response signal for a first image contrast, with the measurement data being acquired along a first two-dimensional slice, and this first two-dimensional slice being parallel to a plane spanned by two coordinate axes x, y standing orthogonal to one another;(c) implementation of a number of steps for spin excitation as well as acquisition of an RF response signal for a second image contrast, with the measurement data being acquired along the first two-dimensional slice that exist in (b); and(d) repetition of steps (a) through (c) for further two-dimensional slices that are offset parallel to the first two-dimensional slice along a third coordinate axis z that is orthogonal to the first two coordinate axes x and y.

In the black blood method using a double inversion pulse, images in the systole of the cardiac cycle can be captured in a reliable manner even in the presence of a cycle-to-cycle variance in the heart beat cycle. A pulse sequence of the black blood method composed of a double inversion pulse DIV and an imaging pulse train SEQima is used. This sequence is applied in sync with an ECG signal of a subject to be imaged, and magnetic resonance imaging is thereby performed. The double inversion DIV is applied in sync with an R-wave:R1 appearing on the ECG signal at a given timing, with a first delay time td1 (fixed value), and the imaging pulse train SEQima is applied in sync with the following R-wave:R2 with a second delay time td2 (fixed value: set in accordance with the systole). A variance of the cardiac cycle is absorbed in an inversion time BBTI.

In imaging a first species having a short T2 magnetic resonance parameter in the presence of a second and third species having longer T2 parameters, a method of suppressing signals from the longer T2 species comprises the steps of: a) applying a RF saturation pulse with multiple suppression bands for the second and third species to excite nuclei spins of the longer T2 species with the magnitude of the RF pulse being sufficiently low so as not to excite nuclei spins of the short T2 species, the RF saturation pulse being sufficiently long to rotate the longer T2 species nuclei spins into a transverse plane, and b) dephasing the longer T2 species nuclei spins in the transverse plane. An imaging pulse sequence is then applied to image the short T2 species. Alternatively, the method can comprise the steps of a) applying a first inversion pulse for selective inverting species of the second longer T2 species, b) obtaining first image signals after step a, c) applying a second inversion pulse for selectively inverting species of the third longer T2 species, d) obtaining second image signals after step c), and e) combining the first image signals and the second image signal to image the first short T2 species with the longer second and third species cancelling in the combination. In each of these methods, either the second or third longer T2 species can be suppressed without suppressing the other by applying the RF saturation or inversion pulse only to the species to be suppressed.

A myocardium T1 value measuring method includes the steps that after when delay time is triggered through electrocardiograph gating, non-layer-selection inversion pulses are applied to a detected object; real-time data are acquired in the whole cardiac cycle many times through a fast spoiled gradient echo small-angle excitation sequence, and a set of sampling images are obtained; the images in the diastole period are selected from the sampling images to serve as effective images, and motion correction and registration are performed on the effective images; curve fitting is performed on the registered images, and a Ti value image is obtained. Through the method, the acquisition efficiency is improved, and the T1 value can be effectively measured. The invention further provides a myocardium T1 value measuring system.

In a magnetic resonance measurement sequence, an inversion pulse is applied that acts on a longitudinal magnetization of a first spin species and a second spin species, for example on a water portion and a fat portion. An excitation pulse is applied after a predetermined time period. At least one manipulation pulse is subsequently applied, respectively with associated gradient pulse.

The invention discloses a dynamic myocardium activity detection method. The dynamic myocardium activity detection method comprises the steps that a non-layer-selection inversion pulse is applied on a detected object; a balanced steady-state free procession is used for carrying out real-time sampling on the inversion recovery process of signals in the whole cardiac cycle including a diastole period and a systole period, and a set of heart cine-MRI images; a small-angle excitation balanced steady-state free procession within a preset range is used for collecting a reference image; phase sensitivity inversion recovery reconstruction is carried out on the collected heart cine-MRI images through the reference image. By the adoption of the dynamic myocardium activity detection method, the collection efficiency and imaging efficiency can be improved, and the dynamic myocardium activity is effectively measured. The invention further provides a dynamic myocardium activity detection system.