Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Arguments
Applicant's arguments filed 03/23/2026 have been fully considered but they are not persuasive.
Applicant argues that Srinivasan fails to disclose "counteracting a stray RF magnetic field ... in an external region outside of the imaging region," as recited in amended claim 1.
The Examiner respectfully disagrees. Srinivasan expressly teaches secondary RF coil currents flowing opposite to primary RF coil currents to provide RF screening external to the imaging field of view ("the secondary currents lsub.si will be in the opposite direction to that of the RF coil primary currents lsub.p ... there will be RF screening" col. 7 lines 8-20). Srinivasan further teaches regulating induced currents in the secondary coil to provide adequate screening and reduce external magnetic field effects outside the imaging FOV (col. 13 lines 40-55; Fig. 12c). A person of ordinary skill in the art would have understood such RF screening to involve generation of a secondary magnetic field that at least partially counteracts stray RF magnetic field components produced by the primary RF coil outside the imaging region. The fact that Srinivasan does not expressly use the term "stray RF magnetic field" is not dispositive where the reference teaches the same functionality.
Therefore, the rejection of claim 1 under 35 U.S.C. §103 is maintained. Claims 2-4, 6, 8-11, and 14 fall therewith. Corresponding method claim 16 and claims 17-19 are rejected for substantially similar reasons.
Claim Rejections - 35 USC § 103
3. The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102 of this title, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1-4, 6, 8-11, 14, 16-19 are rejected under 35 U.S.C. 103 as being unpatentable over Srinivasan (U.S. Patent 5777474).
Regarding claim 1, Srinivasan discloses a radio frequency (RF) coil apparatus for facilitating magnetic resonance imaging (MRI) of at least a part of a patient's body that is positioned within an imaging region of an MRI system (“an RF coil with a high S/N over the imaging FOV which is highly desirable for several MR studies” col. 3 lines 19-21), the RF coil (fig. 12c (40, 42, 44)) apparatus comprising:
at least one primary RF coil (fig. 12c 42) configured to emit RF pulses and generate a first magnetic field during operation of the MRI system (“by adjusting the values of the coupling impedances 46 it is possible to achieve a desired net effect on the performance of the RF coil primary 42 and hence the RF coil 40, such as to produce a symmetric or an asymmetric B field profile” col. 7 lines 4-7); and
at least one secondary RF coil (fig. 12c 44) configured to generate a second magnetic field ("If the currents in the RF coil secondary 44 are inductive, then the secondary currents lsub.si will be in the opposite direction to that of the RF coil primary currents lsub.p. Although, this will provide a net effect on the performance of the coil 40, there will be RF screening" col. 7 lines 8-14).
Srinivasan does not explicitly disclose that the second magnetic field, during operation of the MRI system, at least partially counteracts a stray RF magnetic field produced by the at least one primary RF coil
However, Srinivasan teaches RF screening by use of secondary coil currents that oppose the primary RF coil currents in order to reduce external magnetic field effects outside the imaging field of view ("the secondary currents lsub.si will be in the opposite direction to that of the RF coil primary currents lsub.p ... there will be RF screening" col. 7 lines 8-20; see also fig. 12c illustrating reduced external field outside the FOV by secondary screening loop 44 ). Srinivasan further teaches regulating induced currents in the secondary coil "to provide adequate screening" and "divert the remaining flux back into the usable imaging FOV" (col. 13 lines 40-55).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention, to configure the secondary RF coil of Srinivasan such that the second magnetic field generated by the secondary RF coil at least partially counteracts stray RF magnetic field components produced by the primary RF coil in regions external to the imaging region, in order to reduce unwanted RF field propagation and improve signal-to-noise ratio and RF screening performance outside the imaging field of view, as expressly suggested by Srinivasan's teachings regarding RF screening and reduction of external magnetic field effects at least one secondary RF coil (fig. 12c 44) configured to generate a second magnetic field that, during operation of the MRI system, at least partially counteracts the first magnetic field in an external region outside of the imaging region of the MRI system (fig. 12c via coil 44 secondary screening loop carrying current to reduce external field outside of FOV, “If the currents in the RF coil secondary 44 are inductive, then the secondary currents .sub.si will be in the opposite direction to that of the RF coil primary currents (I.sub.p). Although, this will provide a net effect on the performance of the coil 40, there will be RF screening. The extent of this screening including the net effect on the S/N will depend on both I.sub.p and I.sub.si….” col. 7 lines 8-20).
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Regarding claims 2, 17, Srinivasan as modified further teaches wherein the first magnetic field extends over at least a portion of the imaging region (“the RF coil (i.e., the field of view (FOV) of the RF coil) covers a larger volume than the region of interest. In other words, the coil FOV is larger than the desired FOV. This is because the B field profile of the typical RF coil changes gradually in all directions due to the magnetic field properties” col. 1 lines 47-54) and the external region outside of the imaging region (“The RF coil exhibits a modified current distribution which is different from the prior art. The RF coil generally includes an RF coil primary, an RF coil secondary, and coupling impedances that connect the two at several points along the coil peripheries. The coupling impedances are primarily reactive, and may be fixed or variable, depending on the purpose of use” col. 3 lines 43-50).
Regarding claims 3, 18, Srinivasan as modified further teaches wherein current in the at least one secondary RF coil is 180 degrees out of phase with current in the at least one primary RF coil (“the currents in the RF coil secondary 44 are inductive, then the secondary currents.sub.si will be in the opposite direction to that of the RF coil primary currents” col. 2 lines 55-60).
Regarding claims 4, 19, Srinivasan as modified further teaches wherein operation of the at least one secondary RF coil at least partially reduces a strength of an effective magnetic field in the external region outside of the imaging region of the MRI system (“a) regulate the amount of induced currents in the secondary to provide adequate screening; and b) divert the remaining flux back into the usable imaging FOV. Consequently, it is possible to maintain a high S/N when compared to the prior art of FIG. 12b, for example, and close to the same S/N in the unscreened case as in FIG. 12a. It is noted that the S/N for the invention will be slightly lower than the un-screened case due to loss of flux in the secondary to provide RF screening. However, the combination of RF screening and S/N is superior than in either conventional coil.” Col. 13 line 40-55 also col. 5 lines 1-14).
Regarding claim 6, Srinivasan as modified further teaches wherein the at least one primary RF coil and the at least one secondary RF coil are electrically coupled (fig. 12c, 42a, 44a).
Regarding claim 8, Srinivasan as modified further teaches wherein the at least one primary RF coil and the at least one secondary RF coil are not electrically coupled (“Both loops 32 and 34 are magnetically coupled through space, and hence are mutually coupled to one another” col. 2 lines 35-40).
Regarding claim 9, Srinivasan as modified further teaches wherein the at least one secondary RF coil consists of a single conductor (fig. 6 “The center conductor of these two coaxial cables are connected to capacitors across ports A and B, via reactive means to match the individual ports to 50 ohms. Also, coaxial cables (not shown) exiting the RF coil primary at VG1 are tied to VG2, before exiting to the MRI system” col. 9 lines 64-col. 10 line 9).
Regarding claim 10, Srinivasan as modified further teaches wherein the single conductor is connected in series with the at least one primary RF coil (fig. 6 “The center conductor of these two coaxial cables are connected to capacitors across ports A and B, via reactive means to match the individual ports to 50 ohms. Also, coaxial cables (not shown) exiting the RF coil primary at VG1 are tied to VG2, before exiting to the MRI system” col. 9 lines 64-col. 10 line 9).
Regarding claim 11, Srinivasan as modified further teaches wherein the at least one secondary RF coil comprises multiple conductors (fig. 9 “The RF coil 40d includes a primary RF coil 42d which is a 16 leg, birdcage volume coil of the low-pass configuration. Each of the 16 legs is broken by a C12 capacitor” col. 11 lines 35-40).
Regarding claim 14, Srinivasan as modified further teaches wherein the second magnetic field generated by the at least one secondary RF coil comprises a first component along a first axis and a second component along a second axis substantially perpendicular to the first axis (secondary coils arranged in quadrature configuration to generate counter filed along two axes col. 12 lines 14-32).
Regarding claim 16, the method recited is intrinsic to the apparatus recited in claim 1, as disclosed by Srinivasan (U.S. Patent 5777474) as the recited method steps will be performed during the normal operation of the apparatus, as discussed above with regard to claim 1.
Claims 5, 7, 12-13, 15 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Srinivasan (U.S. Patent 5777474) in view of Boskamp (U.S. Patent 6249121).
Regarding claim 5, Srinivasan does not explicitly teach the coils are driven by common drive circuit, secondary RF coil comprises a plurality of counter rotating current loops connected in series with the at least one primary RF coil.
However, Boskamp teaching a whole body RF coil system teaches multiple coil components are driven by common transmit/receive circuit (col. 5 lines 20-30), a plurality of conductor segments that carry opposing currents to control homogeneity field (col. 6 lines 54-66) and return path conductors that are serially connected to primary conductor segments (col. 7 lines 25-43).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the teaching of Boskamp in Srinivasan to gain the advantage of improve the homogeneity of field with imaging volume [Boskamp [col. 7 lines 2-6]].
Regarding claim 7, Srinivasan does not explicitly teach at least one primary RF coil and the at least one secondary RF coil are coupled to different drive circuits.
However, Boskamp teaching a whole body RF coil system teaches at least one primary RF coil and the at least one secondary RF coil are coupled to different drive circuits (fig. 2 (coils 36, 38 connected to different channels of 53) col. 6 lines 1-15).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the teaching of Boskamp in Srinivasan to gain the advantage of improve the homogeneity of field with imaging volume [Boskamp [col. 7 lines 2-6]].
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Regarding claim 12, Srinivasan does not explicitly teach wherein the multiple conductors are connected in series with the at least one primary RF coil.
However, Boskamp teaching a whole body RF coil system teaches wherein the multiple conductors are connected in series with the at least one primary RF coil (“Each of first and second return path conductors 104 and 106 is serially-connected to each set of primary path conductor segments 82 and 94 to form a continuous circuit” col. 7 lines 28-40).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the teaching of Boskamp in Srinivasan to gain the advantage of improve the homogeneity of field with imaging volume [Boskamp [col. 7 lines 2-6]].
Regarding claims 13, 20, Srinivasan does not explicitly teach the second magnetic field generated by the at least one secondary RF coil is directed substantially along a single axis.
However, Boskamp teaching a whole body RF coil system teaches the second magnetic field generated by the at least one secondary RF coil is directed substantially along a single axis (“Similarly, posterior coil set 38 comprises I-channel coil 66 and Q-channel coil 68 structurally and electrically positioned at about 180 degrees and 270 degrees, respectively. The primary path conductors 70 and 72 from I-channel coils 62 and 66 make an angle of about 90 degrees with the primary path conductors 74 and 76 of the Q-channel coils 64 and 68. As such, the associated magnetic fields from the I-channel coils 62 and 66 are substantially perpendicular to the associated magnetic fields from the Q-channel coils 64 and 68. Thus, these substantially perpendicular magnetic fields result in a substantially circular, polarized B.sub.1 field 40 when the coils are driven with the phase shifting described herein” col. 6 lines 1-13).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the teaching of Boskamp in Srinivasan to gain the advantage of improve the homogeneity of field with imaging volume [Boskamp [col. 7 lines 2-6]].
Regarding claim 15, Srinivasan does not explicitly teach at least one secondary RF coil is tilted relative to a third axis substantially perpendicular to the first and second axes.
However, Boskamp teaching a whole body RF coil system teaches at least one secondary RF coil is tilted relative to a third axis substantially perpendicular to the first and second axes (“Primary path conductors 72 additionally comprise a second set of primary path conductor segments 94 disposed symmetric to first set of primary path conductor segments 82 about central axis 86. Second set 94 also comprises first and preferably second primary path conductor segments 96 and 98, and capacitors 100-103, having similar current amplitude and capacitive characteristics as first and second conductor segments 90 and 92 and capacitors 78-81, respectively. The relative positioning of primary path conductor segments 90, 92, 96 and 98 is symmetric about central axis 86” col. 6 lines 57-67).
It would have been obvious to a person of ordinary skill in the art, before the effective filing date of the claimed invention to incorporate the teaching of Boskamp in Srinivasan to gain the advantage of improve the homogeneity of field with imaging volume [Boskamp [col. 7 lines 2-6]].
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAQI R NASIR whose telephone number is (571)270-1425. The examiner can normally be reached 9AM-5PM EST M-F.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Lee Rodak can be reached at (571) 270-5628. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TAQI R NASIR/ Examiner, Art Unit 2858
/LEE E RODAK/ Supervisory Patent Examiner, Art Unit 2858
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