Abstract: A magnetic resonance imaging system includes a magnetic field applying section for applying a static field, gradient field pulses, and an RF field to an object to be examined, a signal detecting section, including a homogeneous coil and a plurality of surface coils arranged to surround a desired region of the object, for detecting magnetic resonance signals from the object through the homogeneous coil and the surface coils, and an image data processing section for obtaining an image of the desired region by synthesizing image data based on the magnetic resonance signals respectively detected by the surface coils upon weighting/adding processing. The system uses differential surface coils as the surface coils. A magnetic resonance signal is detected through the homogeneous coil within the same time interval in which magnetic resonance signals are detected through the surface coils. Weighting functions for weighting/adding processing of image data are determined on the basis of these magnetic resonance signals.

Abstract: In an MRI system, an RF field and slicing, phase encoding, and read-out gradient fields are applied to an object to be examined which is placed in a homogeneous static field in a predetermined sequence. An MR signal from a region of interest in the object is received through a probe, and is detected by a detection circuit using a predetermined reference wave. A detection output from the synchronous detection circuit is sampled to acquire MR signal data and to obtain diagnostic data. The system includes a reference wave control section for shifting the frequency and phase of the reference wave, by predetermined amounts, from the frequency and phase of an MR signal when the phase encoding and read-out gradient fields are zero. The reference wave control section changes a frequency shift value of the reference wave to positive and negative phases in synchronism with switching of the gradient fields, and changes a phase shift value of the reference wave stepwise.

Abstract: An MRI system applies a phase encoding gradient field, a read-out gradient field, and an RF field to an object which is placed in a homogeneous static field in accordance with a predetermined pulse sequence so as to excite MR at a specific slice plane of the object, thereby detecting an MR signal from the object and visualizing the slice plane.

Abstract: A magnetic resonance imaging system collects all the data required for image reconstruction of a predetermined portion of an object under examination by one excitation process in accordance with a pulse sequence in which, after excitation of spins within the predetermined portion by a radio frequency magnetic field and a gradient magnetic field, a predetermined readout gradient magnetic field is applied switched positive and negative at high speed to produce multiechoes on both sides of a spin echo center and a predetermined phase encoding gradient magnetic field is applied whose amount and sequence in encode steps are controlled so that multiecho data or its complex conjugate data may scan substantially the half of a Fourier data plane. By taking the complex conjugate of the magnetic resonance data collected in that way and then two-dimensional Fourier transforming the magnetic resonance data and the complex conjugate data, a magnetic resonance image of the predetermined portion of the object is obtained.

Abstract: A magnetic resonance imaging system includes magnetic resonance signal detecting means (1, 2, 3, 4, 7, 8, 10) for detecting a magnetic resonance signal from an object to be examined, receiving means (9) for phase-sensitive detecting and amplifying the magnetic resonance signal, data acquiring means (11) for sampling and digitizing the magnetic resonance signal obtained by the receiving unit (9), and image reconstructing means (12) for performing image reconstruction on the basis of the magnetic resonance signal and the sampling data obtained by the data acquiring means (11).

Abstract: A magnetic resonance system is arranged to invert the polarity of a slicing gradient magnetic field pulse each time the selective excitation is repeated, and additively combine two types of imaging data corresponding to the opposite polarities of the slicing gradient field pulse to form a magnetic resonance image.

Abstract: In an imaging apparatus and a method for producing a two-dimensional image of an object under medical examination, a composite selective RF pulse is produced in a transmitter unit. The composite selective RF pulse is constituted of a second RF 90.degree. pulse and a third RF 90.degree. pulse. Under the control of a system processor, the second RF 90.degree. pulse is firstly applied to the object and the third RF 90.degree. pulse is secondly applied thereto under the same polarity of the field gradient after providing an time interval.

Abstract: In a magnetic resonance imaging system, a radio frequency field for exciting a magnetic resonance phenomenon, a first gradient field for determining a image slice, a second gradient field for phase-encoding, and a third gradient field for reading out an echo signal of the magnetic resonance, are applied to a subject in the static field. Thus, the echo signal is acquired, and image reconstruction data is obtained from the echo signal, whereby reconstructed image information is obtained. A correction data generating section uses the second gradient field as a gradient field for reading out the echo signal, and applies the first and second gradient fields, and the radio frequency field to the subject in the static field, in accordance with a predetermined sequence, without applying a gradient field for phase-encoding, and acquires the echo signal, so as to obtain correction data corresponding to the image reconstruction data along an encoding axis.

Abstract: In an MRI system of this invention, a pulsed RF magnetic field, and pulsed slice, phase encoding, and read gradient fields are applied to an object to be examined placed in a uniform static magnetic field in accordance with a predetermined sequence by a controller, thereby causing an MR phenomenon. Echo signals based on the MR phenomenon are acquired so as to obtain an image of MR data. The controller alternately and repetitively executes a first operation for applying the read gradient field while repetitively inverting it so as to produce the echo signal, and a second operation for applying, as the radio-frequency magnetic field, a 180.degree. pulse which can compensate for an echo signal phase error due to a nonuniformity and offset of the static magnetic field so as to generate the echo signal. The controller also inverts the phase encoding gradient field each time the 180.degree. pulse is applied.

Abstract: Nuclear magnetic resonance diagnostic apparatus including means for applying a gradient magnetic field to form an equivalent plane in the magnetic field corresponding to the slice in the predetermined region to be measured for the acquisition of projection data, means for selectively saturating magnetization vectors in the entire region other than the region corresponding to the slice by applying radio frequency signal composed of continuous waves the frequency of which is successively varied in the range of the resonance frequency of the specified atomic nuclei and means for obtaining the projection data in the predetermined directions in the slice by measuring the resonance signals obtained by applying the 90.degree. pulses of resonance frequency of the specified atomic nuclei to the region to be measured while the saturation state of magnetization vectors is maintained.

Abstract: Nuclear magnetic resonance diagnostic apparatus including a magnet for generating a uniform static magnetic field, a first coil for generating a gradient magnetic field, a selective detector for detecting the free induction decay signals from the selective slice portion of an object, a current controller for controlling the current in the first coil to the shift the selective slice portion, a second coil for generating the gradient magnetic field direction in the selective plane of the object, a projection data producer for obtaining a one-directional projection data on the basis of the detected free induction signals, and an image synthesizer for producing the extensive one-directional projection of the specified atomic nuclei distribution in the object by placing a plurality of one-directional projection data.