Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Reexamination Certificate
1999-08-12
2001-08-21
Oda, Christine (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
Reexamination Certificate
active
06278274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a Nuclear Magnetic Resonance imaging apparatus of the type for imaging specific parts of the body, defined in the jargon as “dedicated MRI”, comprising a magnetic structure, having a cavity for accommodating the limb part to be examined which may be accessed from the outside, and designed to generate in this cavity or at least in a part thereof, the magnetic and electromagnetic fields required for Nuclear Magnetic Resonance imaging, which structure is mounted on a support, in such a manner as to be movable.
2. Description of Related Art
U.S. Pat. No. 5,008,624 discloses an apparatus comprising means for supporting the patient in several inclined positions with respect to the horizontal plane, combined with a U-shaped magnetic structure which bears, at the free ends of the U stems, two poles for generating the static field required for Nuclear Magnetic Resonance imaging. The U-shaped magnetic structure is supported on a stationary frame so as to be able to rotate about a horizontal axis, coinciding with the median axis of the U-shaped magnetic structure, perpendicular to its stems. The apparatus is designed for imaging the head of the patient, who can take several inclined positions with respect to the horizontal plane, by operating on the supporting means, typically an arm-chair convertible into a table, having a folded back and an inclinable seat.
The disclosed construction is such that, in the various inclined positions of the magnetic structure, any use of the apparatus for imaging other body parts is difficult. The armchair-table is complex and costly and anyway limits the operating opportunities of the apparatus. The latter is designed so as to be able to accommodate large parts of the body, so the magnetic structure is heavy and cumbersome.
OBJECTS AND SUMMARY
An object of the invention is to provide an apparatus, so that, by simple and inexpensive means, the operational flexibility thereof is increased, allowing examination of a great number of anatomic regions, both of the upper and lower limbs, as well as of the head and neck, by using a single magnetic structure and different positions of the patient.
The invention achieves the above purposes by providing an apparatus, wherein the magnetic structure is supported in such a manner as to be able to oscillate about a horizontal axis, parallel to the static magnetic field generated thereby, whereas the axis of rotation is staggered with respect to the central axis, which is parallel thereto and passes through the cavity volume wherein the static magnetic field has the characteristics required for valid diagnostic imaging, to such an extent that the relevant volume moves from an uppermost position to a lowermost position, the two extreme positions and those intervening therebetween being adjusted to the head and/or neck and/or upper limbs level in the standing and/or sitting position of the patient and to the lower limbs level in the standing and/or sitting positions of the patient respectively.
Particular advantages, with respect to human anatomy, are obtained by a configuration in which the axis of rotation of the magnetic structure is eccentric to the median axis of the overall geometry thereof, whereas the magnetic structure has radial dimensions, with respect to the median axis thereof, parallel to the axis of oscillation, of {fraction (1/10)} to {fraction (4/10)} of the average height of an adult in his/her standing position.
According to a variant embodiment, a configuration may be provided wherein the axis of rotation of the magnetic structure is eccentric to the median axis of the overall geometry thereof, whereas the magnetic structure has radial dimensions, with respect to the median axis thereof, parallel to the axis of oscillation, of ⅛ to {fraction (4/8)} of the average height of an adult in his/her sitting position.
The position of the axis of oscillation of the magnetic structure with respect to the ground is generally higher than the greatest radial dimensions of the magnetic structure with respect to the ground.
The aperture/s for access to the imaging cavity of the magnetic structure are provided in such a position that at least a part thereof has a central axis perpendicular to the axis of rotation, whereas in the two upper and lower positions, they are at least partly turned towards the patient, and in the perpendicular condition of this axis of the apertures, they are substantially turned downwards or upwards.
When the magnet has an annular shape, it is supported in such a manner as to be able to oscillate with an eccentric axis radial to the axis of two apertures for accessing a through cavity. The upper and lower positions are rotationally symmetrical, whereas, in the intermediate position, the axis of the apertures is perpendicular.
The annular shape may be round, oval, non-round, rectangular, square, or polygonal or a combination of these shapes, either symmetrical or asymmetrical to one or more reference axes or points.
Alternatively, a magnetic structure may be used which has two opposite poles, preferably circular and connected together by an axial member perpendicular to the poles and jointed thereto at least at one peripheral point.
When viewed in the direction of the axis of oscillation, the magnet may have any round, oval, non-round, rectangular, square or polygonal shape or a combination of these shapes, either symmetrical or asymmetrical to one or more reference axes or points.
This axial member may have the shape of a column but two or more columns may be also provided, in an appropriate arrangement along the circumference.
Preferably, the two or more columns are grouped in the peripheral area of the two opposite poles in order to provide a wider access aperture.
A further improvement provides that the imaging cavity area in which the magnetic field of the structure has sufficient characteristics to provide valid Nuclear Magnetic Resonance imaging, is substantially located in the median region of the overall radial dimensions of the structure with reference to the median axis thereof, parallel to the axis of oscillation.
A further characteristic of the invention provides that the height of the axis of oscillation of the magnetic structure from the ground is variable. This is possible, for example, by providing a support structure comprising two opposite uprights whereto the respective sides of the magnetic structure are pivoted about the same axis. Here, there may be provided, alternatively or in combination, that the pivot points of the magnetic structure are supported by slidable shoes on said uprights, or that the uprights are extensible or inclinable.
According to an improvement, the magnetic structure is supported upon a wheeled, freely movable cart.
Advantageously, the apparatus of the invention, has, in addition to the movable magnetic structure, also has a console and/or control panel, which may be at least oriented, but even moved away or separated from the structure or anyway disjoined from the apparatus, being provided, in this case, with a connecting wire.
Thanks to the above arrangements a Nuclear Magnetic Resonance imaging apparatus is obtained, which is highly versatile and flexible and may be easily moved or adapted to the conditions or positions of the patient, who may be forced by any possible disease to take a rigid and immobile position with the specific limb under examination.
Particularly, for instance in the upright i.e. standing position and in the sitting position of the patient, the magnetic structure may be moved angularly and/or by a height change of the axis of oscillation thereof at the upper or lower limbs or at the head or neck of the patient. Particularly, for instance, Nuclear Magnetic Resonance imaging may be performed in the region of the lower limbs while the patient is in the upright position, and in a condition wherein the limb, i.e. the leg, the knee, the neck, or similar are loaded or stressed.
By reducing the area of the cavity volume wherein the magnetic field
Biglieri Eugenio
Pugliese Osvaldo
Rezzonico Fabio
Satragno Luigi
Burns Doane Swecker & Mathis L.L.P.
Esaote S.p.A.
Oda Christine
Vargas Dixomara
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