Electricity: measuring and testing – Particle precession resonance – Spectrometer components
Reexamination Certificate
1999-05-18
2001-03-27
Arana, Louis (Department: 2862)
Electricity: measuring and testing
Particle precession resonance
Spectrometer components
C324S320000
Reexamination Certificate
active
06208144
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the magnetic resonance arts. It finds particular application in conjunction with magnetic resonance imaging systems for imaging portions of a patient in a surgical site and will be described with particular reference thereto. However, it is to be appreciated that the present invention will also find application in conventional imaging, spectroscopy, combined spectroscopic and imaging applications, and the like.
Heretofore, magnetic resonance imaging systems have surrounded the subject with relatively large and bulky equipment. High field magnetic resonance imaging systems typically receive the patient within a long bore with the imaging region at the geometric center of the bore. Access for surgical procedures is limited at best.
“Open” magnet systems, such as magnetic resonance imaging systems with “C” magnets, provide better physician access. However, large diameter pole pieces are positioned immediately above and below the region of interest of the patent. Typically, the pole pieces have a diameter on the order of 1.5-3 times the space between them for receiving the patient. Reaching into this narrow gap is sufficiently awkward that the patient is typically moved into the bore for imaging and out of the bore for the surgical procedure. Because a patient undergoing surgery is typically interconnected with a plurality of monitors, electrical leads, tubes, intravenous and intra-arterial injections, and the like, moving the patient is considered highly undesirable.
To provide better surgical access, proposals have been made in which the magnet and ferrous flux path structure are enlarged to the size of a small room. To minimize magnetic flux losses, the room is typically small with a low ceiling. The main magnet is positioned low which limits head room, often closely adjacent the region of interest which is typically coincident with the surgeon's work area. Although providing improved access to the patient, these rooms still have drawbacks. The ferrous panels of the flux return path in the ceiling, walls, and floor are heavy. The rooms tend to be claustrophobic. Moreover, the magnet and associate structures still limit surgical access to the region of concern.
The present invention provides a new and improved method and apparatus which overcomes the above-referenced problems and others.
SUMMARY OF THE INVENTION
In accordance with one aspect of the present invention, a magnetic resonance imaging room includes a ferrous pedestal supported on a floor. A lower imaging coil assembly including a gradient coil and a radio frequency coil are supported above the ferrous pedestal. An upper imaging coil assembly including an upper gradient coil and a ferrous pole piece is disposed opposite to the lower imaging coil to define a region of interest therebetween. A main field magnet is disposed asymmetrically adjacent only one of a ceiling above the pedestal or the floor for generating a main magnetic field through the region of interest.
In accordance with another aspect of the present invention, a method of magnetic resonance imaging is provided. A region of interest of a subject is positioned above a ferrous pedestal. A main magnetic field is generated through the region of interest with a main field magnet that is positioned either below an attendant supporting floor surface surrounding the pedestal or adjacent a ceiling above the attendants. The magnetic field is shaped with a lower pole piece disposed below the region of interest and above the pedestal and with an upper pole piece disposed above the region of interest. Gradient magnetic field pulses and radio frequency pulses are generated in the region of interest. Magnetic resonance signals from the region of interest are received and reconstructed into diagnostic images.
One advantage of the present invention is that it improves access to the subject.
Another advantage of the present invention resides in the less claustrophobic atmosphere.
Another advantage of the present invention resides in the high performance imaging capabilities.
Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the preferred embodiments.
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patent: 5519372 (1996-05-01), Palkovich
patent: 5675305 (1997-10-01), DeMeester et al.
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patent: 5864236 (1999-01-01), Li
patent: 5882304 (1999-03-01), Ehnholm et al.
patent: 5923169 (1999-07-01), Ehnholm et al.
patent: 0 609 604 A1 (1994-08-01), None
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FONAR Corporation Web Page, printed May 5, 1999.
U.S. Ser. No. 09/141,708, McGinley et al., Aug. 28, 1998.
U.S. Ser. No. 09/141,990, DeMeester et al., Aug. 28, 1998.
U.S. Ser. No. 09/044,425, DeMeester et al., Mar. 19, 1998.
U.S. Ser. No. 08/972,192, Ehnholm et al., Nov. 18, 1997.
DeMeester Gordon D.
McGinley John V. M.
Young Ian R.
Arana Louis
Fay Sharpe Fagan Minnich & McKee LLP
Picker International Inc.
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