摘要:
A method for providing spin density distribution images of an object, discriminated with respect to plural chemical shifts. This method is performed by repeating a measurement sequence in a spin warp imaging method, of the spin data plural times, with a time difference .DELTA..tau. between a time interval .tau..sub.1 from spin excitation to a 180.degree. RF pulse and a time interval .tau..sub.2 from the 180.degree. RF pulse to a peak of a spin echo, altering .DELTA..tau. in the ways corresponding the number of chemical shifts to be discriminated from one another, subjecting the respective spin data to two-dimensional Fourier transform to provide plural sets of spin data for respective coordinates in a spatial domain, and solving simultaneous equations of the sets of spin data to provide spin densities corresponding to the respective chemical shifts.
摘要:
The present invention is an imaging method using three-dimensional NMR to which an echo-planar method is applied. After excitation of nuclear spins, the gradient magnetic field Gx for phase-encoding is applied and there is repeated a sequence of measuring and obtaining an echo train of spin-echoes with a constant gradient magnetic field Gx and a periodically-inverted gradient magnetic field Gy, as varying the amount of encoding, so as to obtain the three-dimensional imaging by the Fourier-conversion. Moreover, after the selective excitation of spins within an X-Y surface, a 180.degree. radio frequency pulse is applied. As varying the time difference .tau..sub..epsilon. between the interval from the excitation until the application of the 180.degree. radio frequency pulse and the interval from the application thereof until a peak of a first echo of an echo train, three-dimensional imaging is carried out with a chemical shift axis as one axis by repeating the sequence and accomplishing Fourier-conversion with .tau..sub..epsilon. as a numerical variable.
摘要:
An imaging apparatus using nuclear magnetic resonance is disclosed in which both an image corresponding to the projection of a nuclear spin distribution in a to-be-inspected object on a two-dimensional plane and a display mark indicating a desired measuring position are displayed on a display face of a display device such as a CRT display, the display mark is freely moved on the display face to be set at a desired position on the display face, and magnetic field generating means for generating a static magnetic field, linear gradient field, or radio frequency magnetic field is controlled on the basis of the desired position of the display mark to obtain an image of that cross section of the object which is located at a position indicated by the display mark.
摘要:
In an imaging apparatus using nuclear magnetic resonance which includes apparatus for generating a static magnetic field, a linear gradient magnetic field and a radio frequency magnetic field, respectively, signal detection device for detecting the nuclear magnetic resonant signal from an object to be inspected, a computer for calculating from the detection signal an image and output device for displaying the result of calculation by the computer, the improvement wherein the size of the object to be inspected is detected by use of ultrasonic wave or light beams and a signal indicative of the detected size of the object is applied to the linear gradient magnetic field generation apparatus so as to control the intensity of the linear gradient magnetic field.
摘要:
An electromagnet having a current detecting device for detecting the current flowing through an electromagnet exciting coil, the output of which is utilized to control the power supplied to the coil to stabilize the current flowing through the coil; the electromagnet further including a separate power supply to supply current to the current detecting device which supplies current to the current detecting device when the electromagnet is not on working.
摘要:
A method of measuring a static magnetic field distribution in a nuclear magnetic resonance (NMR) inspection system which comprises magnetic field generator for producing a static magnetic field, inclination or gradient magnetic fields and a high-frequency magnetic field, a signal detector for sensing nuclear magnetic resonance signals from an inspection sample, a computer for processing output signals from the signal detector and an output device for providing a computational result of the computer, wherein a time interval t.sub.1 from the center of a 90.degree.-pulse high-frequency magnetic field to the center of a 180.degree.-pulse high-frequency magnetic field is made different by a time difference t.sub.0 from a time interval t.sub.2 from the center of the 180.degree.-pulse high-frequency magnetic field to a peak of a spin echo, so that static magnetic field distribution is calculated based on the computer output which corresponds to the difference of the two time intervals.
摘要:
An NMR imaging apparatus and method for detecting a nuclear spin resonance signal from an object, which is placed in a magnetic field, to produce images of the object. At an instant when the spins come into phase after the signal detection by a first spin excitation, RF magnetic field pulses are applied for rotating the direction of the spin to that opposite to the initial state. After that, the spin excitation and the signal direction of second time are conducted to measure the data which are different in the effect of the relaxation time from the first measurements. By repeating these sequences, it is possible to produce a plurality of images such as an intensity image or a relaxation time enhanced image.
摘要:
An NMR imaging method is disclosed in which an object is measured in accordance with a pulse sequence capable of expressing a difference between two of a plurality of chemical shifts by a phase difference in a signal, that is, a pulse sequence 90.degree.-.tau..sub.a -180.degree.-.tau..sub.b -spin echo (where .tau..sub.a .noteq..tau..sub.b) to obtain spin distribution data, a histogram with respect to the phase of the spin distribution data is formed to regard a phase corresponding to that one of a plurality of peaks of the histogram which exists at one end of the histogram, as a position-independent offset phase which is contained in the spin distribution data and is peculiar to an NMR imaging apparatus, and the spin distribution data is corrected using the offset value thus obtained, to extract spin density distribution data for each of the chemical shifts from the corrected spin distribution data.
摘要翻译:公开了一种NMR成像方法,其中根据能够通过信号的相位差表示多个化学位移之间的差异的脉冲序列来测量物体,即脉冲序列90°-τa -180°-τb-自旋回波(其中τa NOTEQUAL tau b)为了获得自旋分布数据,形成相对于自旋分布数据的相位的直方图,以考虑与多个峰中的那一个相对应的相位 存在于直方图的一端的直方图作为自旋分布数据中包含的并且是NMR成像设备特有的与位置无关的偏移相位,并且使用由此获得的偏移值来校正自旋分布数据, 从校正的自旋分布数据中提取每个化学位移的自旋密度分布数据。
摘要:
In a magnetic resonance imagining method, using an effect that a fluid flows out of a plane where it is selectively excited between the time of applying a 90.degree. radio frequency pulse and the time of applying of a 180.degree. radio frequency pulse, two, images are separately constructed from multiple echo signals which are sampled before applying the 180.degree. radio frequency pulse and multiple echo signals which are sampled after applying the 180.degree. radio frequency pulse. An image of the fluid flow and an image of a static part are separated from each other based on a difference between the two constructed images.
摘要:
A bobbin for holding a gradient magnetic field coil, having a changeable size and sectional shape (a separable bobbin) is constituted by assembling coil supporters (a bobbin divided into a plurality of segments). The separable bobbin has coil supporters of an upper part a bottom part and a set of side surface parts and at least two supporting rods made of a nonmagnetic substance are fitted to the side surface parts of the coil supporters. Holes permitting the insertion of the supporting rods are bored in the upper and bottom parts of the coil supporters. The length d1 between both side surface parts can be made variable by adjusting the insertion length of the supporting rod into the upper and bottom parts. Accordingly, the distance between a patient and a gradient magnetic field can be reduced, and an intended gradient magnetic field intensity can be generated by a smaller current producing the gradient magnetic field than in the prior art. Setting of the patient to an MRI imaging apparatus becomes also easier, and there can be obtained a gradient magnetic field coil capable of being easily fitted and removed to and from the MRI imaging apparatus.