Abstract: A nuclear magnetic resonance imaging apparatus, comprises: a means which generates a static magnetic field, a means which generates a gradient magnetic field in three directions, a means which generates a radiofrequency magnetic field, a means which detects a nuclear magnetic resonance signal generated from the subject to be inspected, a means which detects a periodic physiological signal from the subject to be inspected, and a control means which (1) detects a physiological signal, and generates a synchronizing signalwhich initiates apulse sequence which detects a nuclear magnetic resonance signal from the physiological signal, and (2) synchronizes a radiofrequency burst pulse comprising plural sub-pulses formed at equidistant intervals on the time axis whereof the amplitudes are modulated by a sinc function, and the gradient magnetic field in one direction, with the synchronizing signal, applies them, and assigns tags by modulating the nuclear magnetization of the subject to be inspected in one direction.

Abstract: A system and method for the acquisition of preferential arterial and venous images is disclosed. The invention includes setting a noise level in the phase image, that is proportional to the velocity encoding value, at a threshold level above the venous signal but below the arterial signal during a systolic portion of the cardiac cycle and acquiring a phase contrast MR image during the systolic portion that effectively acquires the arterial signal and suppresses the venous signal. During the diastolic portion of the same R—R interval, the velocity encoding value is then set to establish a noise threshold level in the phase image lower to a value below the venous signal but above the arterial signal to acquire the venous signal and suppress the arterial signal. In this manner, either an arterial only image or a venous only image can be displayed. Alternatively, the images can be combined to create a higher SNR arterial and venous image.

Abstract: Coronary arteries are imaged using a cardiac gated, 3DFT fast gradient recalled echo MRA pulse sequence. A scout scan is performed to measure motion during a cardiac or respiratory cycle and a quiescent period of minimal artery motion is identified. Image data is acquired during a succession of cardiac cycles, and the view order is selected to sample the center of k-space during the quiescent period of each cardiac and or respiratory cycle to reduce motion artifacts.

Abstract: A system and method for arterial and venous discrimination in MR venography is disclosed. By setting a noise level in the phase image (that is proportional to the velocity encoding value) at a threshold level between that of the arterial signals and the venous signals during the diastole portion of the cardiac cycle and acquiring a phase contrast MR image during the diastole portion, the arterial signals are effectively suppressed and a venous only image can be reconstructed. Post-processing steps are disclosed which can alternatively provide an arterial only image. By separately reconstructing a magnitude image and a phase image map to produce a magnitude image and a phase image, a masking module can create an output displaying venous only or arterial only images based on a user selection. The present invention allows for a complete noninvasive angiography exam to be completed within approximately 30 minutes.

Abstract: NMR data required to reconstruct an image is divided into central k-space views and peripheral k-space views. NMR navigator signals are acquired during a scan to indicate patient respiration and a first gating signal is produced when respiration is within a narrow acquisition window and a second gating signal is produced when respiration is within a wider acquisition window. Central k-space views are acquired when the first gating signal is produced and peripheral k-space views are acquired when the second gating signal is produced.

Abstract: In order to perform an ECG-gating imaging MR scan with an exact ECG-gating time predetermined, in an MRI system and MR imaging method, an ECG signal of a patient is acquired. A preparing MR scan with a region containing an object to be imaged of the patient starts at each of a plurality of time instants when a plurality of different delay times elapse respectively from a plurality of reference waves included and repeated in series in the signal, thus a plurality of preparing images being produced. An appropriate or optimum ECG-gating time instant is determined using the plurality of preparing images. The imaging MR scan with the region of the patient is then performed in synchronization with the appropriate or optimum ECG-gating time instant. For example, both of the preparing MR scan and the imaging MR scan are based on the same type of pulse sequences. The pulse sequences include a fast SE sequence, a sequence rooted in the fast SE sequence, or a segmented fast FE sequence.

Abstract: A method is provided for determining errors in MR imaging which result from translational motion of an object. In accordance with the method, an MR point source is rigidly joined to the object in selected spatial relationship, and for movement in unison therewith. An MR system is operated to acquire an overall k-space signal which represents an image of the object and of the point source collectively, the overall k-space signal being contaminated by phase errors which result from the motion. A k-space data set which represents an image of the point source alone, and which remains contaminated by the phase errors, is filtered or separated out from the overall k-space signal. The MR system is operated in selected association with the point source to acquire a reference k-space data set, which represents an image of the point source alone but which is unaffected by the phase errors resulting from the motion.

Abstract: A method and system for gating therapeutic or diagnostic energy to a tissue volume of a medical patient during a selected portion of the patient's respiratory cycle, to thereby diminish inaccuracies in the assumed spatial position of the tissue volume arising from displacements induced by the patient's respiration. The gases flowing to and from the patient's lungs are monitored to provide quasi-continuous measurements as a function of time, of (a) flow rate, (b) pressure, (c) patient lung volume and (d) carbon dioxide concentration. The measurements are utilized to trigger the time period during which the energy is gated on, at the beginning of the selected portion of the respiration cycle; and the time period during which the energy is gated on, is terminated at the end of the selected portion of the respiration cycle.

Abstract: An MRI system includes a detector system which receives an ECG signal from a patient being scanned and produces a gating signal. The gating signal is produced when a detected peak in the ECG signal meets a set of R-wave criteria which includes a specified positive slope on the leading segment of the detected peak, a minimum duration of the leading segment, specified negative slope on the segment trailing the detected peak and a minimum peak amplitude.

Abstract: Refractory delay circuitry ensures that induced currents do not falsely rigger the acquisition phase of magnetic-resonance instrumentation. Immediately after the triggering of the acquisition sequence, for example, by the R-wave of a subject's cardiac cycle, the adjustable delay circuit is used to inhibit further trigger signals for a predetermined duration of the acquisition gradient activity. The acquisition sequence will thus not be triggered by extra peaks in the biological signal, which may take the form of non-R-wave signals in the cardiac cycle. In this embodiment of the invention triggering will occur only at most once per heartbeat. As cardiac signals may be divided into two major groups, electrical (ECG) and non-electrical (e.g.

Abstract: To conduct a three-dimensional MRA study of the coronary arteries, the locations in space of the arteries is determined using a scout MR study. Segments (composed of phase-encoding lines, three-dimensional partitions, or both) are created in the volume of interest, each one relating to a particular coronary artery of interest. MR data relating to each one of the segments are acquired during a single cardiac cycle, and at times when the individual coronary arteries of interest are relatively motionless. Advantageously, a paramagnetic contrast agent is used to increase the MR signal from blood, and the study is conducted during a single breath hold.

Abstract: A magnetic resonance (MR) imaging method uses chemical shift and/or slice selective inversion pulse to create angiograms of coronary arteries. In one embodiment blood is doped with a contrast enhancement agent and a sequence of slice selective and chemical shift selective inversion pulses are applied. Detection RF pulses then generate an image signal. In another embodiment two sequential chemical shift inversion pulses are applied followed by detection RF pulses for imaging.

Abstract: A method is disclosed to reconstruct multiphase MR images that accurately depict the entire cardiac cycle. A segmented, gradient-recalled-echo sequence is modified to acquire data continuously. Images are retrospectively reconstructed by selecting views from each heartbeat based on cardiac phase rather than the time elapsed from the QRS complex. Cardiac phase is calculated using a model that compensates for beat-to-beat heart rate changes.

Abstract: A method of imaging a portion of a body placed in a static magnetic field by means of magnetic resonance (MR) includes the measurement of ECG data of the body in the form of a vector cardiogram, and determination of an acquisition period from the ECG data, including directional information in the vector cardiogram, in order to synchronize measurement of MR signals to a cyclic movement of the body.

Abstract: Delays in event detection in time-varying data can be reduced by predicting the time-varying data and then detecting the event in the predicted data. This finds application in the triggering of medical imaging devices, where physiological events can be detected in the time-varying data. An artificial neural network can be trained to predict data such as ECG signals from which a detection algorithm can accurately predict the occurrence of an event that will serve as a reference point for triggering.

Abstract: According to the present invention, during performing an MRA sequence comprising a plurality (N) of pulse sequence units each of which gives blood flow a different phase rotation, one sequence unit is repeated a given number (L) of times in every cardiac cycle gated by ECG or pulse wave signals of the object under examination. A measurement of N cardiac cycles, as one round, is repeated to collect data completely filling a k-space for each sequence unit. In this repetition, the order of phase encoding magnetic fields is controlled so that data in the low frequency region of k-space are acquired at the cardiac phase corresponding to the diastolic phase of one cardiac cycle and data in the high frequency region are acquired at the cardiac phase corresponding to the systolic phase. The MRA of the present invention is not likely to be affected by the changes in blood flow caused by heart beats and does not prolong the time for measurement.

Abstract: After exciting dipoles in an examination region (60), a train of magnetic resonance echoes including echoes (66.sub.1, 66.sub.2, . . . ) is induced, e.g., with a series of refocusing pulses including pulses (68.sub.1, 68.sub.2, . . . ). The echoes are phase and frequency-encoded. A receiver 38 is gated by a gate circuit (82) to sample the even echoes (66.sub.2 -66.sub.10) and the odd echoes (66.sub.5 -66.sub.10) that occur after a threshold odd echo such as the third echo (66.sub.3) so as to generate an image of a common physical region which exhibits reduced motion artifacts.

Abstract: A system for performing pulsed RF FT EPR spectroscopy and imaging includes an ultra-fast excitation subsystem and an ultra-fast data acquisition subsystem. Additionally, method for measuring and imaging in vivo oxygen and free radicals or for performing RF FT EPR spectroscopy utilizes short RF excitations pulses and ultra-fast sampling, digitizing, and summing steps.

Abstract: A subtraction MRA image is formed by subtracting a mask image formed from diastolic MR image data from an angiographic image formed from systolic MR image data. To permit acquisition of diastolic MR image data during regurgitation of arterial bloodflow, a saturation slab is established immediately adjacent the slice of interest and slightly overlapping it on its arterially downstream side.

Abstract: A person to be inspected lies on his back on the tabletop of the patient table. The person is moved together with the tabletop so that the head of the person which is the inspection part, coincides with almost the center of the superconductive magnet. A control circuit controls the operations of a power source for a gradient magnetic field and a radio frequency transmission and reception circuit. The control circuit furthermore outputs a control signal to a light emitter control circuit, which controls a light emitter, which emits light in a predetermined color into a magnet space so as to change the quantity of light and color tone in the magnet space. Light emission and the magnetic resonance inspection sequence are synchronized with each other. An type of irritation may be given to the person to be inspected, such a by sound, heat, or electric signal, in place of light.

Abstract: In an MR imaging method, at least radio frequency pulses for excitation are repetitiously consecutively applied in accordance with predetermined pulse sequences until measurement of NMR signals corresponding to phase encoding numbers necessary for desired image construction ends, an external trigger signal synchronous with periodical motion of an object to be inspected is received during the period of application, and a gradient magnetic field having a phase encoding amount necessary for the image construction is applied at the termination of a predetermined time following the reception of the trigger signal to fetch at least one NMR signal. When a plurality of NMR signals are desired to be fetched, a plurality of gradient magnetic fields having mutually different phase encoding amounts are applied.