Hitachi, Ltd.

Hitachi Medical Corporation

Hitachi Instrument Engineering Co., Ltd.

Hitachi Instrument Eng. Co.

Ryuzaburo Takeda

Hideaki Koizumi

Koichi Sano

Tetsuo Yokoyama

Yoshiyuki Miyamoto

Shinichi Sato

Etsuji Yamamoto

Hideki Kohno

Toshiaki Aritomi

Yo Taniguchi

Atsushi Takane

Naoki Satoh

Yasuhiko Ozawa

Shigeru Watanabe

Shimbu Yamagata

Koichi Haruna

Jun'ichi Taguchi

Kenji Takiguchi

Toshihiro Ishizuka

Tuyosi Shudo

Katsunori Suzuki

Mitsunobu Nagashima

Makoto Yoshida

Hidehiko Asoh

Shoji Kondo

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.

Fluid measurement method using nuclear magnetic resonance imaging and

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.

Method and apparatus for regulating radio frequency pulse

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.

Method of magnetic resonance imaging

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.

Coronory artery imaging method and apparatus

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.

Method and apparatus for measuring temperature of subject

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.

Magnetic resonance imaging method

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.

Magnetic resonance imaging method and system therefor

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.

Fourier transformation imaging method

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.

MRI method

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.

Blood flow imaging method

Method and apparatus for causing nuclear magnetic resonance of an object

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. Pulses of a 180 degree pulse method are generated to remove an adverse effect of ununiformity of a static magnetic field; two gradient magnetic fields having the same amplitude and grading oppositely to each other are applied at a certain time interval therebetween to the moving part of the object in the direction of motion of the moving object; a radio frequency magnetic field is generated by applying a pulse in the pulses of the 180 degree pulse method succeeding a 180 degree pulse at the time corresponding to the center of an echo signal generated by the 180 degree pulse, the radio frequency magnetic field making a nuclear spin vector at the stationary part of the object in parallel to the static magnetic field; a resonance signal is detected which is produced from the object upon application of the radio frequency magnetic field; the above process is performed to further obtain another resonance signal, reversing the polarities of the gradient magnetic fields; and a difference between the two resonance signals is derived as a signal from the moving part of the object.

Nuclear magnetic resonance imaging apparatus

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.

NMR imaging method

Method of selecting specific region of sample

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.

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Mito, Japan

Ryuzaburo Takeda