Picker International, Inc.

Larry Kasuboski

Rao P Gullapalli

Wayne R Dannels

Haiying Liu

Joseph Vilmos Hajnal

William Sattin

Glyn A Coutts

A medical instrument, for use in relation to an MR scanner, comprising body portion having mounted thereon a plurality of positioning elements each of which comprises a reservoir containing a liquid and at least two spaced tuned MR auxiliary receiver coils positioned coaxially with respect to one another and carried by the reservoir, and means for electrically connecting the said auxiliary coils to separate receiver channels of the MR scanner. Flux enhancement is used to enable the positioning elements to be rapidly located without disturbing the magnetization of the patient and thereby permit the position of the medical instrument and the image of the patient to be rapidly cycled between.

Nuclear magnetic resonance imaging apparatus

An examination region (34) is divided into a multiplicity of slices, e.g. slices 1-20. The slices are divided up into groups or slabs, e.g., slabs I-V. A series of magnetization inversion pulses (70.sub.I- 70.sub.V) and slab select gradient pulses (74.sub.I -74.sub.V) are applied at regular intervals. At a duration after each slab inversion at which the magnetization of a material such as CSF is at a minimum or null (80) marks a center of a data acquisition period (84). A plurality of imaging sequences (82) are conducted in each data acquisition period. Each of the imaging sequences collects one or more data lines from each of the slices within the corresponding slab. This process is repeated cyclically until all of the data lines of each slice of each slab have been collected. The data lines are reconstructed (102) into an image representation which is stored in an image memory (104) for selective display on a video monitor (108).

Interleaved slab inversion for enhanced throughput in fluid attenuated

A sequence controller (30) controls gradient pulse amplifiers (20) and a digital transmitter (24) to apply a conventional magnetic resonance imaging or spectroscopy sequence. One or more of the resonance excitation pulses includes a series of very small tip angle RF pulses (52, 70) applied in rapid succession substantially within the time interval of a normal RF excitation pulse (e.g. 10 msec.). A series of gradient pulses (58x, 58y, 72y, 72z) with linearly diminishing amplitudes and a repetition cycle that is an integer multiple of the duration of the very small tip angle RF pulses are applied such that an excitation trajectory in k-space follows a piecewise linear square spiral (FIG. 3 ) when gradients are applied along two axes or an octahedral spiral (FIG. 6 ) when a series of gradient pulses are applied along three axes. The subregion of resonance excitation is selectively shifted along one of the axes by applying a series of frequency offset pulses (66, 76) along one or more of the axes. In this manner, the position of the subregion of resonance excitation is shifted without changing the phase component of the RF pulses.

Two and three-dimensionally selective RF pulses for magnetic resonance

An RF pulse sequence (40, 42, 44) is applied to generate magnetic resonance in which a dipolar or bound spin system component of the magnetic resonance has a quadrature or 90.degree. phase offset from a Zeeman or free spin system component of the magnetic resonance. The resultant resonance signal is encoded with magnetic field gradients (50, 52, 54) and sampled during a dipolar spin system resonance echo (46). The process is repeated altering the relative phase of the three RF pulses (40', 42', 44') and of a digital radio frequency receiver (28) such that the sampled dipolar and Zeeman spin system components are again in quadrature, but 90.degree. offset in the opposite sense. The two resonance signals with their Zeeman components out of phase in the opposite sense are combined (64) such that the dipolar spin system components add and the Zeeman spin system components cancel. The combined or dipolar weighted resonance signals are collected in a data memory (66) with a plurality of different phase encodings and reconstructed (70) into an image representation (72) for selective display on a video monitor (76).

Dipolar weighted MR imaging in-vivo

A radio frequency pulse (32), a gradient pulse (34), and a first frequency offset pulse (38a) are applied to cause the presaturation region (36a) adjacent one face of an imaging volume (30) such that material flowing into the imaging volume from that face is saturated. An imaging sequence is applied which generates magnetic resonance image data that has non-saturated flow in the imaging volume identified by a characteristic phase modulated intensity. The saturation and gradient pulses are applied again with a second frequency offset pulse (38b) to position the saturation region (36b) adjacent the opposite face of the image volume. The exact same imaging sequence is applied to generate a second set of image data in which non-saturated flowing material is identified by a characteristic phase modulated intensity. Magnitude values from these two data sets are reconstructed (72, 74) into image representations that are subtractively combined (76), to form a difference image representation. In the difference image representation, the static material has essentially a zero value, flowing material that entered from one face is strictly positive, and flowing material that entered from the other face is strictly negative. In this manner, two different flowing materials, such as venous and arterial blood, are separately encoded in only two imaging sequences.

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Solon, OH, United States of America

Larry Kasuboski