US4707664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
QD MRI RE coil using non-homogeneous and non-uniform RF field distribution
Assignee: University of California
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Filing: 1986-06-25
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Granted: 1987-11-17
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Expires: 2006-06-25
Abstract
Abstract A pair of co-located RF surface coils extend axially and part-circumferentially about a volume to be imaged. Because surface coils are employed, the RF field distribution will be non-symmetric, non-homogeneous and non-uniform within the volume. Nevertheless, if the two coils are rotationally offset by the proper amount (and possibly including capactive isolation coupling therebetween), the coils produce a pair of RF signals to/from the volume which are in quadrature phase thus providing signal-to-noise ratio improvements due to: (a) the fact that quadrature detection techniques are employed and (b) the fact that only a portion of the cross-sectional volume is effectively addressed by the surface coils (i.e., due to their non-symmetric, non-homogeneous and non-uniform field distribution).
Inventors
- 👤 John H. Fehn
- 👤 Mitsuaki Arakawa
- 👤 Barry M. McCarten
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:40
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/28; G01R33/32; G01R33/34; G01R33/34046; G01R33/34007
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
A quadrature detection magnetic resonance imaging RF coil comprising: a first RF coil structure extending axially and part-circumferentially about a volume to be imaged, said first coil having one pair of axially extending conductive legs circumferentially spaced apart by an angle β which is substantially less than 180° and having ends respectively interconnected by circumferentially extending conductors so as to produce substantially non-symmetric, non-homogeneous, non-uniform RF fields within said volume; a second RF coil structure substantially the same as said first RF coil structure, said second RF coil structure also extending axially and part-circumferentially about said volume to be imaged, said second RF coil structure being rotationally offset by an angle α with respect to said first RF coil structure so as to achieve minimum RF inductive coupling between said first and second RF coil structures and to produce quadrature detection RF input/output to/from said first and second coils in spite of said non-symmetric, non-homogeneous, non-uniform RF field distribution.
Claim 2
Dependent Claim
159 words
A quadrature detection magnetic resonance imaging RF coil comprising: a first RF coil structure extending axially and part-circumferentially about a volume to be imaged, said first coil having one pair of axially extending conductive legs circumferentially spaced apart by an angle β which is substantially less than 180° and having ends respectively interconnected by circumferentially extending conductors so as to produce substantially non-symmetric, non-homogeneous, non-uniform RF fields within said volume; a second RF coil structure substantially the same as said first RF coil structure, said second RF coil structure also extending axially and part-circumferentially about said volume to be imaged, said second RF coil structure being rotationally offset by an angle α with respect to said first RF coil structure so as to achieve minimum RF inductive coupling between said first and second RF coil structures and to produce quadrature detection RF input/output to/from said first and second coils in spite of said non-symmetric, non-homogeneous, non-uniform RF field distribution.
Claim 3
Dependent Claim
35 words
A quadrature detection magnetic resonance imaging RF coil as in claim 1 further comprising: a capacitive coupling connected between predetermined portions of said first and second coils so as to increase the effective isolation therebetween.
Claim 4
Dependent Claim
26 words
A quadrature detection magnetic resonance imaging RF coil as in claim 1 wherein said first and second coil structures are mounted for adjustable rotational movements therebetween.
Claim 5
Dependent Claim
26 words
A quadrature detection magnetic resonance imaging RF coil as in claim 2 wherein said first and second coil structures are mounted for adjustable rotational movements therebetween.
Claim 6
Dependent Claim
26 words
A quadrature detection magnetic resonance imaging RF coil as in claim 1 wherein β is approximately equal to 120° and α is approximately equal to 100°.
Claim 7
Dependent Claim
47 words
A quadrature detection magnetic resonance imaging RF coil as in claim 5 wherein each of said RF coil structures includes a non-conductive substrate formed to define an at least partial cylinder one of said substrates being mechanically encaptured by the other and slidably rotatable with respect thereto.
Claim 8
Dependent Claim
59 words
A QD MRI RF coil structure comprising: first and second co-located RF surface coils extending axially and part-circumferentially about a volume to be imaged but being rotationally offset so as to produce a pair of RF signals from said volume which are in quadrature phase while the RF fields produced thereby are non-symmetric, non-homogeneous and non-uniform within said volume.
Claim 9
Dependent Claim
59 words
A QD MRI RF coil structure comprising: first and second co-located RF surface coils extending axially and part-circumferentially about a volume to be imaged but being rotationally offset so as to produce a pair of RF signals from said volume which are in quadrature phase while the RF fields produced thereby are non-symmetric, non-homogeneous and non-uniform within said volume.
Claim 10
Dependent Claim
33 words
A QD MRI RF coil structure as in claim 7 further comprising: a capacitive coupling connected between predetermined portions of said first and second coils so as to increase the effective isolation therebetween.
Claim 11
Dependent Claim
24 words
A QD MRI RF coil structure as in claim 7 wherein said first and second coil structures are mounted for adjustable rotational movements therebetween.
Claim 12
Dependent Claim
24 words
A QD MRI RF coil structure as in claim 8 wherein said first and second coil structures are mounted for adjustable rotational movements therebetween.
Claim 13
Dependent Claim
37 words
A QD MRI RF coil structure as in claim 9 wherein each coil structure subtends approximately 120° of the circumference about said volume and wherein the coils are rotated with respect to one another by approximately 100°.
Claim 14
Dependent Claim
45 words
A QD MRI RF coil structure as in claim 11 wherein each of said RF coil structures includes a non-conductive substrate formed to define an at least partial cylinder one of said substrates being mechanically encaptured by the other and slidably rotatable with respect thereto.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-16 | 1991-05-18 | 1991-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-16 | 1995-05-18 | 1995-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-16 | 1999-05-18 | 1999-11-17 | $7700.00 | Window Closed / Lapsed |