US 5,705,014 AGranted

Carbon fiber magnetic resonance compatible instruments

AssigneeGeneral Electric Company

InventorsJohn Frederick Schenck, Kenneth William Rohling

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Abstract

Instruments are constructed of a carbon fiber material optionally doped with a doping agent such as iron oxide, the instrument having a magnetic susceptibility being adjusted to a portion of a subject being imaged. Therefore there is little effect upon the lines of magnetic flux and the magnetic field homogeneity, reducing distortion in an MR image. These carbon fiber instruments exhibit virtually no magnetic torsional forces when inserted into a magnetic field. This is important, for example when the instrument is a scalpel. Doped carbon fiber has minimal affect on radiofrequency fields. The instruments do not affect the homogeneity of an applied homogeneous magnetic field or an applied radiofrequency field. Doped carbon fiber exhibits a rigidity large enough to allow construction of high strength instruments such as biopsy needles. It also has the ability to retain a sharp edge, allowing construction of scalpels and cutting instruments. Doped carbon fiber surgical instruments may be used inside a magnetic field during magnetic resonance imaging, thereby allowing interactive internal images to be produced and displayed to a surgeon during surgery. A method is also disclosed for imaging a control material and then the instrument to determine the type and amount of doping agent required.

Claims4

Dependent claims

A method for constructing instruments intended for use during magnetic resonance (MR) imaging of a subject having a predetermined magnetic susceptibility, comprising the steps of:

a) selecting a background material having a magnetic susceptibility substantially equal to a portion of a subject intended to be imaged;
b) selecting a control material having a known magnetic susceptibility difference, (.DELTA..sub..chi.) from that of the background material;
c) obtaining a magnetic resonance (MR) image of the control material of a known shape embedded within the background material to result in a distorted control image caused by the difference in susceptability of the materials;
d) measuring the size and direction of distortion of the control image with respect to the shape of the control material shape;
e) determining the size of distortion of the control image per unit of susceptibility difference (.DELTA..sub..chi.);
f) equating a direction of control image distortion with the polarity of magnetic susceptibility difference;
g) constructing an instrument from a composite material;
h) imaging the instrument within the background material to create an instrument image having distortion;
i) measuring a size and a direction of distortion of the instrument image;
j) estimating a susceptibility difference and polarity between the instrument and background material from the instrument image and the computed distortion per unit susceptability difference;
k) computing an amount of a doping agent of a known susceptability to be added to the instrument which would cause the susceptibility difference to become substantially zero;
and
l) adding the computed amount of doping agent to the instrument to result in an instrument which may be used in MR imaging which would distort the image very little.

10 more elements

A method for constructing instruments intended for use during magnetic resonance (MR) imaging of a subject having a predetermined magnetic susceptability, comprising the steps of:

a) selecting a background material having a magnetic susceptibility substantially equal to a portion of a subject intended to be imaged;
b) selecting a control material having a known magnetic susceptibility difference, (.DELTA..sub..chi.) from that of the background material;
c) obtaining a magnetic resonance (MR) image of the control material of a known shape embedded within the background material to result in a distorted control image caused by the difference in susceptability of the materials;
d) measuring the size and direction of distortion of the control image with respect to the shape of the control material shape;
e) determining the size of distortion of the control image per unit of susceptibility difference (.DELTA..sub..chi.);
f) equating a direction of control image distortion with the polarity of magnetic susceptibility difference;
g) constructing an instrument from a composite material;
h) imaging the instrument within the background material to create an instrument image having distortion;
i) measuring a size and a direction of distortion of the intrument image;
j) estimating a susceptibility difference and polarity between the instrument and background material from the instrument image and the computed distortion per unit susceptability difference;
k) computing an amount of a doping agent of a known susceptability to be added to the instrument which would cause the susceptibility difference to become substantially zero;
and
l) constructing another instrument with this amount of doping agent to result in an instrument which may be used in MR imaging which would cause less distortion in an MR image.

10 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/620,143Filed 22 Mar 1996
Granted: 6 Jan 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01R 33/28
Involving magnetic resonance: details of apparatus provided for in groups G01R33/44 - G01R33/64
A61B 2017/00911
Transparent or translucent: for fields applied by a magnetic resonance imaging system
A61B 2090/3954
Markers, e.g. radio-opaque or breast lesions markers: magnetic, e.g. NMR or MRI
G01R
Measuring electric variables

Family

No related US applications are recorded in the indexed filing history.

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