US4933639A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Axis translator for magnetic resonance imaging
Assignee: The University of Texas System
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Filing: 1989-02-13
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Granted: 1990-06-12
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Expires: 2009-02-13
Abstract
Abstract An apparatus and a method to permit virtually any magnetic resonance imaging system to image slices of any orientation by converting its three-channel gradient current demand-a set of three time-varying voltages proportional to the instantaneous currents required in the x, y and z gradient coils-into that required for imaging the chosen plane or volume are provided. The method, which is referred to as axis translation, involves taking the input readout, phase-encoding and slice-selecting gradients from the system's host computer and rotating the orientation of these gradients through angles set by the system operator. This is accomplished using a 3x3 analogue matrix which outputs the appropriate imaging demand vector which is thereafter interpreted as current demand in the X, Y and Z coils of the magnetic resonance imaging system in the conventional manner.
Inventors
- 👤 Bruce R. Barker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:27
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/483; G01R33/4833; G01R33/54
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
82 words
A magnetic resonance imaging axis translator comprising: (a) input means comprising readout, phase-encoding and slice-selecting voltage channels; (b) a three-by-three analogue matrix vector multiplier having matrix elements for operating upon signals on said voltage channels to effect axis translation; (c) means for varying said matrix elements to vary the axis translation of signals on said voltage channels; and (d) output means from said vector multiplier to provide signals which develop current demands in the gradient coils of a magnetic resonance imaging system.
Claim 2
Dependent Claim
82 words
A magnetic resonance imaging axis translator comprising: (a) input means comprising readout, phase-encoding and slice-selecting voltage channels; (b) a three-by-three analogue matrix vector multiplier having matrix elements for operating upon signals on said voltage channels to effect axis translation; (c) means for varying said matrix elements to vary the axis translation of signals on said voltage channels; and (d) output means from said vector multiplier to provide signals which develop current demands in the gradient coils of a magnetic resonance imaging system.
Claim 3
Independent Claim
133 words
A method of axis translation in a magnetic resonance imaging system comprising: performing a series of locator scans from whose images rotation angles may be measured directly; receiving input voltages from the MRI system's control computer; equalizing the gain and nulling the input voltage; equally limiting the slew rate of the input voltages to produce tailored input voltages; developing a matrix of values which represent attenuation factors defining the axis translation; applying the attenuation factors to the tailored input voltages to produce tailored and rotated output voltages; applying an equalizing gain and offset to the tailored and rotated output voltages to produce current demand voltages; and outputting the current demand voltages to the MRI system's eddy current compensation and gradient current sources yielding imaging planes selectably rotated by one, two or three angles.
Claim 4
Independent Claim
133 words
A method of axis translation in a magnetic resonance imaging system comprising: performing a series of locator scans from whose images rotation angles may be measured directly; receiving input voltages from the MRI system's control computer; equalizing the gain and nulling the input voltage; equally limiting the slew rate of the input voltages to produce tailored input voltages; developing a matrix of values which represent attenuation factors defining the axis translation; applying the attenuation factors to the tailored input voltages to produce tailored and rotated output voltages; applying an equalizing gain and offset to the tailored and rotated output voltages to produce current demand voltages; and outputting the current demand voltages to the MRI system's eddy current compensation and gradient current sources yielding imaging planes selectably rotated by one, two or three angles.
References Cited (Backward Citations)
US4009380A
Cited
US4115730A
Cited
US4254778A
Cited
US4322684A
Cited
US4422042A
Cited
US4516074A
Cited
US4510448A
Cited
US4599565A
Cited
US4431968A
Cited
US4536712A
Cited
US4545384A
Cited
US4551680A
Cited
US4520316A
Cited
US4667300A
Cited
US4532474A
Cited
US4701876A
Cited
US4634979A
Cited
US4583044A
Cited
US4585992A
Cited
US4777614A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-11 | 1993-12-11 | 1994-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-11 | 1997-12-11 | 1998-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-11 | 2001-12-11 | 2002-06-12 | $7700.00 | Window Closed / Lapsed |