Abstract: A nuclear magnetic resonance imaging scheme suitable for an imaging of a physiological function information on a living body. The scheme uses a pulse sequence for realizing a first imaging scheme for obtaining the blood vessel image and a second imaging scheme for obtaining the physiological function image such as a brain function image by a single execution of the pulse sequence, where the first imaging scheme is executed before the second imaging scheme by controlling resolutions and imaging regions for the respective imaging schemes appropriately. The pulse sequence can also realize a third imaging scheme for obtaining the physical shape image, which is to be executed between the first imaging scheme and the second imaging scheme. The physiological function image can be obtained by selecting valid data from the image data acquired with/without stimulation or load by using the t-test, and determining active portions from the selected valid data by using the paired t-test.

Abstract: A gradient magnetic field generation apparatus according to the present invention comprises a gradient coil, an assistant voltage selector for generating first and second control signals in accordance with an input waveform signal, the first control signal being the same as or similar to, the input waveform signal, a delay circuit for delaying the first control signal for a first delay time, a delay circuit for delaying the second control signal for a second delay time, a main power for amplifying the delayed first control signal and applying a voltage to a gradient coil, an assistant power for generating an assistant voltage for assisting the main power in accordance with the delayed second control signal, and a delay controller for individually controlling the first and second delay times.

Abstract: A gradient magnetic field power supply includes an amplifier for supplying current to a gradient coil. Between input and output of the amplifier is connected a feedback circuit which feeds a portion of an output current at the output back to the input and has a built-in phase compensating circuit for compensating the phase of the feedback current. The frequency response of the phase compensating circuit is made variable and adjusted to fit variations in the load impedance of the amplifier with time. This ensures optimum phase compensation.

Abstract: An active shield type gradient coil apparatus comprises main coils for generating a gradient magnetic field and shield coils for generating a magnetic field to reduce the leak magnetic field from the main coils. In the active shield type gradient coil apparatus, a stimulation output section for outputting stimulation to a subject is incorporated. In this incorporation, the main coils are arranged at the outside of an area sandwiched between the stimulation output section and the subject such that the simulation can be transmitted to the subject from the stimulation output section without being blocked by the main coils. By this arrangement, both the use of the active shield type as the gradient coil apparatus and good transmission of stimulation to the subject can be realized.

Abstract: A magnetic resonance imaging apparatus capable of obtaining a brain functional image without spending much time and of facillitating to distinguish a vein portion from a cortex portion. The magnetic resonance imaging apparatus includes: a first unit which acquires at least one of data emphasizing a signal from a blood portion in a region of interest in a biological body to be examined and data least affected by inhomogeneity of a static magnetic field; a second unit which acquires data in which a change of magnetic field inhomogeneity (T.sub.2 *) in the region of interest is emphasized; and a control unit which executes simultaneously the first acquiring unit and the second acquiring unit during a predetermined pulse sequence after a radio-frequency magnetic field is applied to the biological body.

Abstract: A magnetic resonance diagnostic apparatus sequentially generates a high-frequency magnetic field and a gradient magnetic field to generate a MR signal from a subject in a imaging space and reconstructs a MR image of the subject on the basis of the MR signal. As a result, a stimulative magnetic field that stimulates part of the subject develops so as to cross the gradient magnetic field. The stimulative magnetic field occurs in synchronization with the gradient magnetic field. A canceling magnetic field that opposes the stimulative magnetic field is generated. The canceling magnetic field has the reversed polarity to that of the stimulative magnetic field. As a result, the resultant magnetic field of the stimulative magnetic field and canceling magnetic field has a lower intensity than that of the stimulative magnetic field, so that the stimulus the subject feels becomes smaller.

Abstract: A nuclear magnetic resonance imaging scheme suitable for an imaging of a physiological function information on a living body. The scheme uses a pulse sequence for realizing a first imaging scheme for obtaining the blood vessel image and a second imaging scheme for obtaining the physiological function image such as a brain function image by a single execution of the pulse sequence, where the first imaging scheme is executed before the second imaging scheme by controlling resolutions and imaging regions for the respective imaging schemes appropriately. The pulse sequence can also realize a third imaging scheme for obtaining the physical shape image, which is to be executed between the first imaging scheme and the second imaging scheme. The physiological function image can be obtained by selecting valid data from the image data acquired with/without stimulation or load by using the t-test, and determining active portions from the selected valid data by using the paired t-test.

Abstract: A nuclear magnetic resonance imaging scheme capable of reducing the eddy currents induced within the living body outside of the imaging region, so as to protect the patient against the nerve stimulation due to the eddy currents, and obtaining the MR images at high image quality by protecting the image quality against the N/2 and chemical artifacts. The nerve stimulation is prevented by providing a shield member for shielding a nerve stimulation sensitive portion of the patient located outside of the imaging region from a change of the gradient magnetic fields.

Abstract: A magnetic resonance imaging apparatus capable of obtaining a brain functional image without spending much time and of facillitating to distinguish a vein portion from a cortex portion. The magnetic resonance imaging apparatus includes: a first unit which acquires at least one of data emphasizing a signal from a blood portion in a region of interest in a biological body to be examined and data least affected by inhomogeneity of a static magnetic field; a second unit which acquires data in which a change of magnetic field inhomogeneity (T.sub.2 *) in the region of interest is emphasized; and a control unit which executes simultaneously the first acquiring unit and the second acquiring unit during a predetermined pulse sequence after a radio-frequency magnetic field is applied to the biological body.

Abstract: A nuclear magnetic resonance imaging scheme for imaging living body information related to the physiological function change in the living body. In this scheme, the pulse sequence realizes a first imaging scheme sensitive to functional information of the body to be examined and a second imaging scheme insensitive to the functional information of the body to be examined so as to obtain first and second types of the nuclear magnetic resonance images corresponding to the first and second imaging schemes, respectively, by a single execution of this pulse sequence. The functional information of the body to be examined is then obtained by processing the first and second types of the nuclear magnetic resonance images.

Abstract: A nuclear magnetic resonance imaging scheme capable of reducing the eddy currents induced within the living body outside of the imaging region, so as to protect the patient against the nerve stimulation due to the eddy currents, and obtaining the MR images at high image quality by protecting the image quality against the N/2 and chemical artifacts. The nerve stimulation is prevented by providing a shield member for shielding a nerve stimulation sensitive portion of the patient located outside of the imaging region from a change of the gradient magnetic fields.

Abstract: A nuclear magnetic resonance imaging method and apparatus, capable of obtaining images with high spatial resolution arid S/N ratio, reducing the influence of the inhomogeneity of the static magnetic field and the chemical shift artifacts, and improving the contrast in the T.sub.2 enhanced image and T.sub.1 enhanced image. The imaging uses the pulse sequence, including: application of RF pulses and slicing gradient magnetic field for exciting a desired region of the body to be examined; application of reading gradient magnetic fields which regularly fluctuate between a negative value and a positive value; application of initial phase encoding gradient magnetic field before the reading gradient magnetic field is applied; application of a predetermined pulse shaped phase encoding gradient magnetic field every time the reading gradient magnetic field changes polarity; and collection of the echo signals emitted from the desired region every time the reading gradient magnetic field changes polarity.

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: 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 a magnetic resonance exciting unit having an imaging mode which is executed such that a slicing gradient field and a high-frequency field are applied to an object placed in a uniform static field to excite a slice of the object, a read gradient field which is repeatedly switched is applied to the object, and a phase-encoding gradient field is applied to the object, thereby generating a series of echo signals, a data acquiring unit for sampling and acquiring the echo signals generated by the exciting unit, and an image forming unit for performing image reconstruction using sampling data obtained in the imaging mode of the exciting unit. The exciting unit also has an echo position detection mode which is executed such that the fields except for phase-encoded gradient field are applied to the object to excite the slice of the object in the same manner as in the imaging mode, and to generate a series of phase-nonencoded magnetic resonance echo signals.