Abstract: A bolus of magnetized blood is formed by at least two radio frequency magnetic fields, and readout gradient magnetic fields are repeatedly applied at a proportion of 1:-2:1 along a blood vessel so as to continuously obtain a first echo signal whose phase change due to velocity is corrected, from the moving bolus. This first echo signal provides velocity information on the blood stream. The sequence of the readout gradient magnetic fields is repeatedly applied at a proportion of (.sqroot.2-1):-2:2:-(.sqroot.2-1) so as to continuously obtain a second echo signal whose phase change due to velocity and acceleration is corrected, from the moving bolus. Acceleration information of the blood stream is extracted by calculating the difference between the first echo signal and the second echo signal. The velocity information and/or the acceleration information is displayed in superposition with a specific blood vessel of an angiogram shot in advance.

Abstract: When image information obtained on the basis of an NMR signal, e.g. MRI, is acquired, a radio frequency pulse is set so that a strong signal can be obtained particularly from a portion of interest among the sample. To accomplish this object, the occurrence of signals from portions of the sample other than the selected portion of interest is inhibited in advance of obtaining information (an image) of the sample. Various radio frequency pulses are then irradiated to the sample and a suitable radio frequency pulse is determined on the basis of the resulting signal.

Abstract: A novel method of magnetic resonance imaging is disclosed, in which a single high-frequency magnetic field signal synthesized from a plurality of high-frequency components associated with a plurality of slice sections respectively is applied to a subject to excite the slice sections at the same time, and a phase encode pulse is applied in the direction perpendicular to a slice section. Information corresponding to the position of a slice section is applied to the phase of an excited spin and a measurement signal is subjected to Fourier transformation thereby to produce a data corresponding to each slice section. The phases of a plurality of high-frequency components of a high-frequency magnetic field signal are controlled to be in a predetermined relationship to each other at a predetermined timing.

Abstract: A method for imaging the coronary artery of a living body using nuclear magnetic resonance, wherein a patient is located in a static magneic field and the heart cycle of the patient is detected with the heart dilation period of the patient being determined in accordance with the detected heart cycle. Then, the coronary artery of the patient is portrayed on the nuclear magnetic resonance signal generated by applying high-frequency energy to the patient during the determined heart dilation period.

Abstract: Based on the relation that the higher the temperature of a portion to be measured, the lower becomes coherence of a nuclear spin at that portion, the present invention measures indirectly the temperature state of the portion to be measured from the change of intensity of NMR signals by utilizing this relationship. A transverse relaxation time is contained as one of the parameters in the relation between the signal intensity and the temperature; hence this transverse relaxation time is determined in advance for the portion to be measured and utilized in for the equation representing their relationship. This application discloses also an invention for determining a blood perfusion rate of the portion to be measured from the temperature data obtained in the manner described above.

Abstract: A radio frequency magnetic field is applied to a sample or object to be examined which is placed in a static magnetic field and oscillates periodically, and nuclear magnetic resonance signals are generated from the sample. The NMR signal is transformed to a signal having a form wherein a still image component and an artifact component resulting from the periodic oscillation, that are contained in the NMR signal, are mutually separated, and then processing is applied to the signal thus transformed so as to remove the artifact component therefrom. Inverse transform to the transform described above is applied to the signal thus processed.

Abstract: A spin in a predetermined voxel of the brain surface is excited to cause the spin to perform steady state free precession which causes signals, of which a time-reversed FID signal relating to spin-spin relaxation time T2 is enhanced to form an image representative of a thickness of cerebrospinal fluid existent in the brain surface, that is, of a brain surface structure. The spin can be caused to perform the steady state free precession by applying a pulse at the rate of a short repetition time and therefore an image of the brain surface can be obtained within a short period of time.

Abstract: When the center of an object of interest imaged and the center of a display screen or image area deviate from each other, a Fourier transformation imaging method includes (a) a step of representing the amount of deviation of those centers from each other by the amount of deviation in a frequency encoding direction and the amount of deviation in a phase encoding direction, (b) a step of converting each of the amounts of deviation in the frequency and phase encoding directions into a value calculated in terms of the amount of rotation of the phase angle of a measured resonance signal, (c) a step of correcting the amount of rotation of the phase angle of the measured resonance signal on the basis of the values obtained by the conversion, and (d) a step of Fourier-transforming the corrected signal to display an image in which there is no deviation or the center of the object of interest is located at the center of the image area.

Abstract: An MRI method is disclosed, by which, when liquid moving in a body to be examined stays in a predetermined region, this region is excited by using the nuclear magnetic resonance phenomenon and when the liquid thus excited moves from that excited region, a nuclear magnetic resonance signal produced by the excited spin and emitted during the relaxation time thereof is detected.

Abstract: A sequence for detecting variations in the blood flow speed in the blood vessel is added before a measurement of imaging signals so as to determine the highest and/or the lowest speed points of time and an examined body is imaged two times at those timings. In this way the timing for setting the delay time measured from the R wave can be determined automatically and thus it is possible to obtain a blood vessel image of high quality in a short time with the minimum number of two images.

Abstract: A method of and apparatus for generating nuclear magnetic resonance of an object. It is desirable that a nuclear magnetic resonance image be obtained in such a maner that a portion of the image in which the user is interested in is displayed in a greater scale. To this end, nuclear magnetic resonance signals from a specific region of the image are picke-up by an aliasing phenomenon, into a predetermined signal band which is different from the signal band of the above-mentioned specific region.

Abstract: A nuclear magnetic resonance imaging apparatus for deriving a signal from a moving part of an object to be imaged, includes a gradient magnetic field generator for applying a gradient magnetic field to the object; and a radio frequency magnetic field generator for applying a radio frequency magnetic field to the object to present a nuclear magnetic resonance phenomenon.

Abstract: A slice selection gradient magnetic field used in a pulse sequence for generating a spin echo signal is applied in such a fashion that its polarity at the time of a 90.degree. pulse becomes opposite to the one at the time of 180 .degree. pulse, in order to expand a dynamic range of blood flow speed measurement. When the blood flow speed contains a component in a slice vertical direction, the gradient magnetic field in the slice vertical direction is adjusted so that the phase changes of two sets of flow encoded pulses contained in the slice vertical direction are opposite to each other.The flow speed in the direction of the readout gradient magnetic field, which is a lateral direction of the slice plane, is purely measured by cancelling influences of the flow in the slice vertical direction.

Abstract: This invention relates to a selection method of a specific region of a sample which is suitable for use in a nuclear magnetic resonance (NMR) imaging. Selection of a specific region suitable for obtaining multi-dimensional spatial information can be preferably made. To satisfy this requirement, the spin of the specific region of the sample is brought down in a direction at right angles to a static magnetic field, the regions other than the specific region are, in the mean time, brought down in a direction at right angles to the static magnetic field, and thereafter the static magnetic field is rendered non-uniform to that the spins of the regions other than the specific region become saturated.

Abstract: In order to make an accurate display possible even in case image data having been subjected to a Fourier transformation have negative values, the sampling timing deviations of measured signals having phase errors based on various factors are detected from the gradient of the linear components of the image data having been subjected to the Fourier transformation, and the density values of the image having the detected timing deviations corrected are displayed.

Abstract: An NMR imaging method for measuring a magnetization distribution of an article under test, particularly the magnetization distribution including a longitudinal relaxation effect, by a Fourier imaging method with identification of polarity of the magnetization distribution.A homogeneous phantom is measured by the Fourier imaging method and image-reconstructed so that a reference image data which reflects a phase rotation inherent to an NMR imaging apparatus is obtained. Then, a magnetization distribution of an article under test is obtained in a similar measurement and image reconstruction sequence, and products of the reference image data and the image data of the article under test are stored as the signs to represent the polarity of magnetization of the article under test.

Abstract: A slice selection gradient magnetic field used in a pulse sequence for generating a spin echo signal is applied in such a fashion that its polarity at the time of a 90.degree. pulse becomes opposite to the one at the time of 180.degree. pulse, in order to expand a dynamic range of blood flow speed measurement. When the blood flow speed contains a component in a slice vertical direction, the gradient magnetic field in the slice vertical direction is adjusted so that the phase changes of two sets of flow encoded pulses contained in the slice vertical direction are opposite to each other.The flow speed in the direction of the readout gradient magnetic field, which is a lateral direction of the slice plane, is purely measured by canceling influences of the flow in the slice vertical direction.