New Patents

5221898

FLOW IMAGING METHOD USING AN MRI APPARATUS

Kenji Takiguchi, Hidemi Shiono, Etsuji Yamamoto, Ryuichi Suzuki, Kodaira, Japan as- signed to Hitachi Ltd

This invention relates to a ultra-high speed nuclear magnetic resonance fluid imaging method for selectively reconstructing projected images of a fluid from an echo train generated by the use of a readout gradient magnetic field which inverses periodically. A pulse-like encoding gradient magnetic field is used in com- bination with a readout gradient magnetic field which inverses periodically, so as to generate an echo train containing alternately echoes whose phase change of magnetization due to a flow is emphasized and echoes whose phase change of magnetization due to the flow is corrected, and subjected sequentially to phase encoding. A data train containing only the echoes whose phase change of magnetization due to the flow is em- phasized and a data train containing only the echoes whose phase change of magnetization due to the flow is corrected are formed from sam- pling data of these echoes, respectively, and two images are then obtained by subjecting them in- dividually to two-dimensional Fourier trans- form. Both of these images are then subtracted.

5221899

SIGNAL ACQUISITION IN MAGNETIC RESONANCE

ANALYSIS

Oded Gonen, Glyn Johnson assigned to The Trustees of Columbia University in the City of New York

For use in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), a method and apparatus for signal ac- quisition are disclosed. Preferred processing in- volves elimination of an unwanted signal by subtraction, in the time domain, of a cancella- tion signal from a free-induction-decay actual signal. A cancellation signal may be obtained, e.g., by smoothing a free-induction-decay signal, by curve fitting, or by computer simulation.

5221900

MAGNET STRUCTURE FOR FOCUSING OF MAGNETIC

RESONANCE IMAGES

John D Larson assigned to Hewlett-Packard Company

Apparati and methods for magnetic resonance imaging a selected interrogation volume in a tis- sue of a human or animal body, to provide in- creased signal-to-noise ratios for fixed data acquisition times. The method involves excita- tion of magnetic resonance in a selected inter- rogation volume that may be as small as 500- 3,000 cm3, through controllable focusing or steering of a rotating magnetic field signal used to induce magnetic resonance. The response signals issued by the excited volume element are then collected by focusing of these response signals, using a phased array of antennae for this purpose. Use of the invention with well known nuclear magnetic resonance excitation pro- cedures, such as spin echo, echo planar, gradient recalled and backprojection, are discussed.

5221901

DOUBLE SURFACE COIL FOR A NUCLEAR MAGNETIC

RESONANCE APPARATUS

Guenthe Decke, Herman Requardt, Hemhofen, Federal Republic Of Germany assigned to Siemens Aktiengesellschaft

A double surface coil for a nuclear magnetic resonance apparatus as two individual coils, each individual coils being formed by two sub- coils connected in parallel. A series circuit of a capacitor and an inductor is connected in each sub-coil, with a series circuit of a capacitor and a controllable switch being connected in parallel with each inductor. By appropriate drive of swit- ches, both individual coils, one individual coil by itself, or both individual coils in alternating operation can be activated.

5221902

NMR NECK COIL WITH PASSIVE DECOUPLING

Randall Jones, Thomas E Schubert assigned to Medical Advances Inc

New Patents XI

A whole volume neck coil for MRI includes an anterior and posterior saddle coil, the latter at- tached to a base. The anterior coil is held in an open framework, hinged against an extension tower attached to the base. The hinge axis is angled to the medial axis to provide greater entry area for the patient’s head and shoulders. The ex- tension tower also provides adjustment of the anterior coil toward and away from the base by means of a sliding carriage attached to the exten- sion tower. The coils are passively decoupled from the RF excitation field by means of back- to-back diodes which insert a pole forming network into the coils. A method of calculating the values of the network components is taught that accounts for significant diode junction capacitance.

5222500

MAGNETIC RESONANCE IMAGING METHOD AND

APPARATUS FOR THE SAME

Hiroshi Sugimoto, Tochigi, Japan assigned to Kabushiki Kaisha Toshiba

A magnetic resonance imaging apparatus dis- closed by this invention has a magnet assembly including a static magnetic field coil, a gradient magnetic field coil, an excitation coil, and a detection coil. A magnetic resonance signal detected by the detection coil is subjected to im- age reconstructing processing to obtain an im- age. The excitation coil can generate an exciting radio frequency pulse magnetic field for causing magnetic resonance excitation of a plurality of regions of an object to be examined simul- taneously. Such an exciting radio frequency pulse magnetic field is formed by a mixed carrier

having a plurality of carriers of different center frequencies.

5224026

ALTERNATABLE CONSTANT CURRENT CIRCUIT

Tsutomu Okayama, Katsuta, Japan assigned to Hitachi Ltd

An alternatable constant current circuit is pro- vided which supplies positive and negative polarities of rectangular wave current to an in- ductive load such as in an exciting circuit of an electromagnetic flowmeter and in a slanted magnetic field system of a nuclear magnetic resonance imaging device at a high current inver- sion speed and a low power loss, wherein the capacitance of an output capacitor in a switching power source circuit is lowered, the regenerative output voltage of the output capacitor is applied to the inductive load during the current inversion period therein via a polarity inversion circuit, further the load current is controlled by a current control circuit at a predetermined value and the output voltage of the switching power source cir- cuit is also controlled so as to maintain the collector-emitter voltage Vce of a current control transistor in the current control circuit constant, whereby an oscillation is generated in the circuit including the inductive load and the output capacitor during the current inversion to charge the output capacitor to an excessively high vol- tage and further the output voltage of the output capacitor in the switching power source circuit rises due to a decrease of the collector-emitter voltage Vce thereof to thereby cause an output voltage jump-up of the output capacitor and to hasten the current inversion in the inductive load.