US 11402454

I'll search for this specific patent number to verify the details and check for any litigation activity.

Let me check for the actual claim set and any litigation specifically naming this patent.

Let me try to retrieve the granted claim language directly.

Search results for US 11,402,454 — verification and litigation check

Important caveat up front: My searches returned no USPTO litigation records, no PTAB (IPR/PGR) proceedings, and no CAFC 2026 docket activity naming US 11,402,454. The apparent "Siemens" hits in the docket searches were a different dispute — Hologic v. Siemens Healthineers at the UPC Düsseldorf over EP 2 352 431 B1 (mammography "Flying Focal Spot"), which is irrelevant to this patent. So the state of the record is: no litigation found, not "confirmed clean." I cannot rule out a filing that simply is not indexed by the sources I could reach.

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Bibliographic data (confirmed against the patent text and the granted-PDF record)

Note on the inventor name: the OCR of the granted PDF renders it "Thorsten Fetweier," but the Google Patents and Justia inventor records both show Thorsten Feiweier. This is an OCR artifact, not a separate person — flagging it because you asked for literal identifiers.

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Abstract (as issued)

The disclosed techniques reduce eddy current-induced magnetic field interferences for a diffusion imaging pulse sequence. A gradient impulse response function (GIRF) is determined, and an interference gradient sequence Gx/y/z(t) is defined on the basis of the diffusion imaging pulse sequence. A time interval (t1, t2) is determined for the acquisition of diffusion image data. From the GIRF and the interference gradient sequence, a time-dependent magnetic field deviation ΔBx/y/z(t) is determined within the interval (t1, t2). An image distortion of a diffusion imaging acquisition performed with that pulse sequence is then compensated on the basis of the determined field deviation.

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Independent claims — plain-language overview

Claim 1 — Method. A method for reducing eddy current-induced magnetic field interferences for a diffusion imaging pulse sequence, with five steps:

1. Determine a generic gradient impulse response function (GIRF) — a system characterization, not a per-protocol calibration.
2. Define an interference gradient sequence from the diffusion imaging pulse sequence (i.e., identify which gradients actually drive the eddy currents).
3. Determine a time interval for acquisition of the diffusion image data (the readout window).
4. Determine a time-dependent magnetic field deviation using the GIRF and the interference gradient sequence within that time interval.
5. Compensate image distortion of the diffusion imaging acquisition using that field deviation.

The word "generic" in step 1 is the point of novelty over the art: the GIRF is characterized once and reused across protocols, avoiding a fresh calibration per clinical protocol (the O'Brien-type approach discussed in the Background).

Claim 14 — Image correction device. The same concept in apparatus form, with matched circuitry:

• an interface to receive diffusion-encoded image data from an examination region and to generate a test pulse sequence;
• determination circuitry to determine the GIRF;
• gradient defining circuitry to define the interference gradient sequence from the diffusion imaging pulse sequence;
• interval determination circuitry to determine the acquisition time interval;
• interference field determination circuitry to determine the time-dependent magnetic field deviation from the GIRF and the interference gradient sequence within that interval; and
• compensation circuitry to compensate the image distortion using the determined field deviation.

Likely third independent claim (magnetic resonance system). The specification repeatedly refers to a third claim category — "the magnetic resonance system embodiments" comprising the basic field magnet system, control device, RF transmit device, gradient system with gradient coils and interface, RF receive device, and the image correction device. I am only directly confident about claims 1 and 14, because the claim listing I could retrieve was cut off at claim 15. A system claim in the ~claim 16 range is very likely present, but I cannot quote it authoritatively, so treat that as an inference rather than a verified fact.

Source note on claim text: the verbatim claim wording above comes from the Justia mirror of US 2021/0231763 A1 (the pre-grant publication of the same application 17/155,380). Because the granted patent issued from that same application, the independent claims should correspond, but post-grant wording can differ slightly; for strict validity or infringement work, pull the granted claim set from PatentCenter/Global Dossier.

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Notable dependent-claim themes (for context)

• Averaged field deviation → local displacement → image correction ("passive" correction) — claim 2.
• Determining a compensation gradient switched during diffusion imaging ("active" correction) — claim 3.
• Determining the GIRF via test gradients (triangular, multi-frequency), magnitude and phase response, plus a reference measurement without test gradients — claims 4–5.
• Interference gradient sequence comprising diffusion gradients, spoiler gradients, or multiple successive diffusion gradient sequences (with history effects ~3× the eddy-current time constant) — claims 6–9.
• First-order and zeroth-order field-deviation determinations via convolution of GIRF self-terms / zeroth-order terms with the gradient sequence — claims 10–11.
• Scalar displacement transformation field applied along the phase-encoding direction — claim 12.
• Integration with an acquisition workflow: acquire diffusion-encoded raw data, reconstruct, then correct — claim 13.

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Bottom line

US 11,402,454 is a Siemens Healthineers (originally Siemens Healthcare GmbH) patent on model-based eddy-current distortion correction in diffusion MRI: characterize the gradient chain once as a GIRF, then use it with the specific gradient sequence and readout window to predict and remove the distortion. Filing 2021-01-22, granted 2022-08-02, priority to German application DE 10 2020 200 786.1 (2020-01-23), expiring 2041-01-22. No litigation or CAFC/PTAB activity specific to this number was found in my searches — which is a negative result, not proof of none.

One correction to watch: the earlier "Siemens patent litigation" search hits relate to a different European patent (EP 2 352 431 B1) and a different technology (mammography), and should not be conflated with this patent.

I'll search for litigation involving US patent 11402454 across the sources you specified.

Initial results are mostly unrelated. Let me refine with targeted searches on the litigation portals.

Let me run a few more targeted searches on docket and litigation databases.

I'll verify the structured "no PTAB activity" finding against live sources before writing the analysis.

PTAB proceedings on file — US 11,402,454 B2

Data provenance: The structured PTAB-proceedings block supplied for this analysis is the canonical list (USPTO Open Data Portal / PTAB ingest). Live web checks against PTAB-related dockets, PTAB E2E-style document repositories, and general litigation reporting returned no proceedings naming U.S. Patent No. 11,402,454 or its application number 17/155,380. I therefore report a verified null result rather than a reconstructed list. No proceeding numbers are invented below.

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Proceedings overview

Total AIA trial proceedings on US 11,402,454: 0. Breakdown by status: 0 active, 0 with claims invalidated, 0 with claims sustained, 0 settled, 0 institution denials. There is no AIA trial history — no IPR, PGR, or CBM — and no Federal Circuit appeal arising from one.

Bottom line for a defendant: the patent is completely untested at the PTAB. That is not the same as "hardened." There are no canceled claims you can point to, but there is also no Final Written Decision, no Board claim construction, no estoppel on any ground, and no petitioner-funded invalidity record you can reuse. If you are asserting a defense, you are building the invalidity case from scratch — which cuts both ways, because every § 102/§ 103 ground is still available to you and none is barred.

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Proceedings

None. No AIA trial proceeding has been filed against US 11,402,454 B2 as of 2026-09-29.

Verification trail

Caveat on ingestion lag. USPTO ODP AIA-trial data can trail filings by days to weeks. A petition filed very recently could be missing from the structured block. However, nothing in live web results surfaced a pending petition either, so the null result is supported by two independent sources rather than one. If a petition has been filed within the last ~2–4 weeks, it would not be reflected here — re-check PTAB E2E before relying on this for a filing deadline.

Patent posture context (grounded in the patent record)

• Assignee: Siemens Healthineers AG (originally Siemens Healthcare GmbH); reassignment recorded 2023-12-20. This is a large operating company / medical-device manufacturer, not a monetization entity. That factually correlates with the absence of PTAB activity — the patent appears to be held for product protection (MR scanner diffusion-imaging correction) rather than asserted against third parties.
• Priority / expiry: DE 10 2020 200 786.1 (2020-01-23); US filing 2021-01-22; granted 2022-08-02; anticipated expiration 2041-01-22. Status: Active (Google Patents).
• Claim count: 17 claims per the printed patent (US 11,402,454 B2, front page, "17 Claims, 7 Drawing Sheets"). None has been tested in an AIA trial.
• Technology: eddy-current distortion correction for diffusion-weighted / dw-EPI sequences using a gradient impulse response function (GIRF). The cited prior art on the face of the patent (Haselgrove 1996; Vannesjo; Rahmer; Stich; O'Brien) is a roadmap for obviousness arguments, but none of it has been run through the Board.

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Strategic summary

Cancelled vs. sustained vs. untested. Every one of the 17 claims of US 11,402,454 is untested. There is no FWD, no certificate of cancellation or correction, and no Board-ordered amendment. Any representation that a claim of this patent "has been invalidated" or "has survived IPR" would be false — including a representation made by opposing counsel. If you receive a demand letter or an infringement complaint citing claim 1 (or any other claim), you cannot dispose of it by pointing to a prior PTAB outcome, because none exists.

Estoppel landscape. Because there are no AIA trials, § 315(e)(2) estoppel is entirely absent — there is no petitioner, no privy, and no ground that anyone is barred from raising in district court or before the Board. Every prior-art ground on the patent's face and in its prosecution history remains available to you:

• The references cited in the patent's IDS (Haselgrove 1996; Bodammer; O'Brien 2013; Rahmer 2019; Vannesjo 2014/2015; Stich 2018/2019; Robison 2018) — usable, subject to the usual caveat that art already of record invites § 325(d) discretion against institution.
• Art not considered during prosecution — the strongest IPR candidate set, because it sidesteps Advanced Bionics / § 325(d) discretion. This is the highest-value hunting ground given the crowded GIRF-correction literature from ~2013–2020.
• § 112 written-description / enablement and § 101 theories are wholly untested and un-reviewed by any adjudicator. The claims recite a mix of signal-processing steps (convolution of GIRF terms, averaged field deviation, displacement computation) that has not been construed by any tribunal.

Note the asymmetry: because no IPR has been filed, a defendant who files first will create the estoppel that binds them under § 315(e)(2) against later-raised grounds — so ground selection up front matters more than usual here.

Pattern signals. None of the classic PTAB patterns are present: no repeat petitioner, no patent-owner appeal activity (there is nothing to appeal), and no defensive aggregator (e.g., Unified Patents) in the chain. The absence of an aggregator challenge is itself informative — Unified typically targets patents being asserted in the wild, and this patent shows no assertion footprint.

Flags and contradictions. The litigation-summary section generated earlier in this analysis reported no relevant litigation involving this patent (initial hits were unrelated). That is consistent with the PTAB null result, and together they support the conclusion that the patent is enforcement-dormant as of today. If any section of this analysis elsewhere implies a PTAB trial history for US 11,402,454, treat this section as controlling — the live checks found none, and the structured block is silent.

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Recommended next steps

If you are a defendant:

1. Do not rely on a prior PTAB result that does not exist. Before responding to a demand letter, verify the current state directly: PTAB E2E (search patent number 11,402,454) and USPTO Patent Center for the file history of application 17/155,380. Also confirm no AIA trial certificate has issued via the USPTO patent full-text search.
2. Preserve your § 315(b) window. If you are ever served with a complaint alleging infringement of this patent, the one-year clock to file an IPR runs from that service date. Nothing about the patent's current unasserted status removes that deadline once it starts.
3. Commission a prior-art search against the GIRF literature, prioritizing art not of record. The patent's own background cites Vannesjo, Rahmer, Stich, Campbell-Wasburn, and Robison for exactly the GIRF-based gradient/field correction the claims cover. A 2013–2020 non-patent-literature sweep (non-Cartesian and dw-EPI correction using measured gradient impulse responses) is the most likely source of a winning § 103 combination, and being not before the Examiner also reduces § 325(d) risk.
4. Get a claim-construction position early. No tribunal has construed terms such as "interference gradient sequence," "time-dependent magnetic field deviation," and the averaged-field-deviation/displacement relationship in the claims. A narrower reading of the "interference gradient sequence" limitation (which gradients must be included; whether cross-terms and higher-order terms are required) may drive both non-infringement and invalidity.
5. Watch the clock on the patent itself. It is in force through 2041-01-22 and maintenance fees appear paid (Active status). Do not plan around expiry.

If you are the patent owner:

1. The unasserted, untested posture means your first assertion will be met with a fresh-IPR strategy that has no estoppel constraints — assume a petition follows close behind any complaint.
2. Consider whether the claim set has been reissued, disclaimed, or narrowed in a way not captured here; if any certificate exists, it would change the analysis materially and is not reflected in the sources checked.

Bottom line. There is no PTAB story to tell on US 11,402,454. No claims are dead, no claims are endorsed, and no ground is estopped. The patent is a clean slate — which is a defensive advantage (all art available, no petitioner roadmap for the owner, no Board precedent against you) and a defensive gap (no ready-made invalidity record to borrow).

I'll research the assignment record for US 11402454 across the specified sources.

Let me run additional targeted checks on litigation, assignment reel/frame data, and the Siemens corporate history.

Assignment & Ownership Analysis — US 11,402,454 B2

Cross-reference note: The previously-generated litigation summary found no litigation involving this patent. My searches corroborate that — the "Siemens litigation" text that surfaced (NeuroGrafix v. UC Regents, C.D. Cal. 2:11-cv-07591) is an unrelated 2011 case using an earlier Siemens patent as a claim-construction reference. No contradiction with the prior section.

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Inventors

All five are named on the face of the patent (Appl. No. 17/155,380, filed 2021-01-22) with their residences clustered in Bavaria — the Erlangen/Forchheim headquarters region of Siemens' MRI business. Their technology is directly on-point for Siemens' MAGNETOM MR scanner line (diffusion-weighted EPI correction via gradient impulse response functions).

Unusual-pattern check: None. There is no evidence of inventors departing the assignee within 12 months of filing, and no inventor-side assignment or reversion. The inventors' rights were assigned up into the corporate assignee (see timeline below), not out of it. This is the opposite of the fire-sale precursor pattern.

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Original assignee

Siemens Healthcare GmbH, Erlangen, Germany (assignee of record on the issued patent; original applicant on the face of the specification).

• Product line: Yes — ships products embodying the claims. Siemens Healthineers' MAGNETOM family of MR scanners implements diffusion-weighted echo-planar imaging with eddy-current/distortion correction; the patent's own background ties the problem to "diffusion-weighted echo planar imaging, abbreviated as dw-EPI."
• Primary line of business: Medical imaging hardware and software (MR, CT, X-ray, molecular imaging) — a large operating company, not a licensing vehicle.
• Current status: Operating. It is the principal German operating subsidiary of Siemens Healthineers AG. On 18 August 2023 Siemens Healthcare GmbH and Siemens Healthineers AG signed a spin-off-for-absorption agreement transferring nearly all of Siemens Healthcare GmbH's assets and liabilities to Siemens Healthineers AG (advised by Hengeler Mueller), effective 1 October 2023 and perfected in the commercial register thereafter. That transaction is the direct cause of the 2023 assignment of this patent (below).

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Assignment timeline

Records visible via Google Patents legal events for US11402454B2 and the USPTO assignment record. Two post-filing recorded transfers; inventor-to-company and intra-group only.

• 2021-01-22 (filed) / recorded 2021-01-22 — no reel/frame cited

  • Conveyance: Application filing (applicant: Siemens Healthcare GmbH)
  • Assignor: n/a (initial filing)
  • Assignee: Siemens Healthcare GmbH
  • Correspondent: Banner & Witcoff, Ltd. appears as attorney/agent of record on the printed patent (item 74); this is prosecution counsel, not necessarily the assignment recorder.
  • Context: Initial filing of the US national case claiming priority to DE 10 2020 200 786.1 (filed 2020-01-23).

• 2021-05-17 (recorded) / execution dates not surfaced — reel/frame not surfaced in available records

  • Conveyance: Assignment (Assignment of inventors' interest)
  • Assignor: ZELLER, MARIO; FEIWEIER, THORSTEN; STICH, MANUEL; KETTINGER, ADAM; PFEUFFER, JOSEF (all five named inventors)
  • Assignee: SIEMENS HEALTHCARE GMBH
  • Correspondent: not surfaced in the retrievable record.
  • Context: Ordinary employment-obligation assignment — inventors conveying rights to their corporate employer. Not a monetization signal.

• 2023-12-19 / 2023-12-20 (recorded) — Reel 066088 / 0256

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: SIEMENS HEALTHCARE GMBH
  • Assignee: SIEMENS HEALTHINEERS AG
  • Correspondent: not surfaced in the retrievable record.
  • Context: Internal corporate reorganization — the Siemens Healthcare GmbH → Siemens Healthineers AG intra-group spin-off (spin-off agreement 2023-08-18; asset transfer effective 2023-10-01), not a sale to a third party.
  • Caveat on the reel/frame: The reel 066088/0256 citation was retrieved from the legal-events record of a related Siemens patent in the same corporate family (the Siemens Healthineers AG "FORMER OWNER: SIEMENS HEALTHCARE GMBH" event dated 2023-12-19). The identical date and the mass-recording character of the Siemens spin-off strongly indicate this is the same assignment batch, but I could not independently confirm reel 066088/0256 is stamped on this patent's record. Treat the reel/frame as probable, not verified.

No other assignments are recorded. There is no third-party transfer, no security agreement, no license record, and no transfer to a licensing entity.

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Timeline diagram

timeline
    title Ownership of US 11402454
    2020 : German priority application filed
    2021 : US application filed by Siemens Healthcare GmbH
         : Inventors assign rights to Siemens Healthcare GmbH
    2022 : US 11402454 B2 granted
    2023 : Intra group spin off to Siemens Healthineers AG

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NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The only downstream assignee is Siemens Healthineers AG, a publicly listed operating company (Frankfurt: SHL). No "IP/Holdings/Licensing" suffix entity appears, and no registered-agent service address is in the chain. Reels/dates: 2021-05-17 (inventors → Siemens Healthcare GmbH) and 2023-12-19/20, reel 066088/0256 (Siemens Healthcare GmbH → Siemens Healthineers AG).

2. Known asserter in the chain — Not present. Neither assignee matches any entity on the RPX / Unified Patents asserter lists (Acacia, Marathon, IV, Wi-LAN, Conversant, Vringo, etc.). Both are Siemens operating entities.

3. Repeat correspondent across the chain — Unclear (no data). The USPTO correspondent of record for the two assignment recordings could not be retrieved through the sources available to me. The one attorney-of-record name I can ground is Banner & Witcoff, Ltd. (printed on the patent, item 74), a mainstream IP firm that represents both operating companies and others — a single appearance is expressly not a finding under the task's own standard. I decline to call this signal without the recorder data.

4. Cascading transfers — Not present. There are exactly two recorded transfers: inventor→company (2021) and one intra-group step (2023), roughly 2.5 years apart. No chained LLCs, no shared correspondent address, no serial flips inside 24 months.

5. Pre-litigation transfer — Not present. No infringement suit naming this patent is on record, so there is no litigation anchor; and the 2023 transfer was a corporate spin-off dated ~8 months after the spin-off agreement and not tied to any filed action.

6. Bankruptcy fire-sale — Not present. No Chapter 7/11 proceeding involving Siemens Healthcare GmbH or Siemens Healthineers AG. The 2023 transfer was a solvent intra-group reorganization.

7. Privateering — Not present. The patent was never transferred to an NPE to assert on Siemens' behalf; it remained inside the Siemens corporate group.

8. Defensive aggregator — Not present. The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN.

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Verdict

Operating-company assertion (with an explicit caveat — see below).

US 11,402,454 has a two-link, purely corporate ownership chain: the five named Siemens inventors assigned to Siemens Healthcare GmbH (recorded 2021-05-17, the assignee named on the issued patent), and that entity subsequently conveyed the patent intra-group to Siemens Healthineers AG (recorded 2023-12-19/20, reel 066088/0256, the spin-off perfected by the 2023-08-18 spin-off agreement). The current owner is a large, publicly traded medical-imaging manufacturer whose MAGNETOM MR scanners practice the claimed diffusion/eddy-current correction, and no NPE signal is present on any of the eight tests.

Caveat on the label: the enumerated option "Operating-company assertion" presupposes the owner is "suing actual competitors." No litigation naming this patent is on record, so the "assertion" prong is unmet; strictly speaking this is clean operating-company ownership with no assertion activity. I selected the operating-company tier because it is the only category that correctly describes the owner type, and I flag the missing-assertion element rather than paper over it.

Verify at: USPTO Assignment Center — https://assignmentcenter.uspto.gov/ (search patent number 11402454). Underlying legal events: https://patents.google.com/patent/US11402454B2/en

Data gaps I could not close (stated rather than guessed): (a) the reel/frame for the 2021-05-17 inventor assignment; (b) the recorded correspondent attorney/firm for either assignment; (c) independent confirmation that reel 066088/0256 is the frame stamped on this specific patent rather than a sibling in the same Siemens batch.

I'll research the prior art citations for US 11402454 using targeted searches.

Let me dig into the specific "References Cited" section of the granted patent.

Let me look for the complete patent-citation list for this patent.

Preliminary note on data access and scope

Two constraints shaped what follows, and I want to flag them up front rather than paper over them:

1. The authoritative patent text supplied to me does not contain the "References Cited" (front-page) section. The Google Patents text provided begins at the Abstract/Description; the bibliographic "References Cited" block was not included. I therefore had to retrieve citation data from secondary reproductions of the granted front page (patentimages/Google, Justia) rather than from the supplied authoritative text.
2. My searches did not return a complete, verified "References Cited" list for US 11,402,454 B2. I obtained a partial list (see below). Where I could not verify a reference's title, subject matter, or exact date, I say so explicitly instead of filling it in. I also did not obtain a direct USPTO PatentCenter / USPTO full-text (PatFT) hit; the citation data came from Google Patents, Justia, and the EPO/patentimages reproduction of the granted front page. Treat the list below as incomplete and requiring USPTO verification.

This also connects to the earlier Litigation summary, which found no litigation — the same source pool produced no litigation here either.

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1. Patent identification (literal, per the authoritative text)

Per the assignment record: inventor name appears as "Fetweier, Thorsten" on the printed front page (OCR) and "Feiweier, Thorsten" in the assignment/Google record — I flag this as an inconsistency in the source, not a correction I am making.

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2. Patent citations appearing on the face of US 11,402,454 B2 (partial retrieval)

The following were recovered from reproductions of the granted front page. Notably, the granted front page's U.S. citation list is short — the examiner relied only lightly on U.S. patent art, with the bulk of the supporting art being the Applicant's own background NPL.

U.S. Patent Documents

I am deliberately not guessing at the titles or disclosures of Wiesler, Heid, or Doddrell. My searches did not return their text, and inventing a "brief description" for them would be fabrication. Recommend pulling each full text from USPTO PatentCenter before any § 102 analysis is finalized.

Foreign Patent Documents

Non-Patent Literature cited (from the granted front page)

• Haselgrove et al., "Correction for Distortion of Echo-Planar Images Used to Calculate the Apparent Diffusion", Magn. Reson. Med. 36:960–964 (1996).
• Bodammer et al., Magn. Reson. Med. 51:188 (2004).
• O'Brien et al., IEEE Trans. Med. Imag. 32:1515 (2013).
• Rahmer, Mazurkewitz, Börnert, Nielsen, "Rapid acquisition of the 3D MRI gradient impulse response function using a simple phantom measurement," Magn. Reson. Med. 2019; 82:2146–2159.
• Vannesjo et al., "Field camera measurements of gradient and shim impulse responses using frequency sweeps," Magn. Reson. Med. 2014; 72:570–583.
• Vannesjo et al., Magn. Reson. Med. 76:45 (2015).
• Campbell-Washburn et al., Magn. Reson. Med. 75:2278 (2015).
• Stich et al., Magn. Reson. Med. 80:1521 (2018) (GIRF for non-Cartesian sequences).
• Stich et al., "Temperature-dependent gradient system response," Magn. Reson. Med. 2019.
• Robison et al., Magn. Reson. Med. 81:2501 (2018).

Cross-reference: the specification (authoritative text) expressly cites and builds on several of these — Haselgrove, Bodammer, O'Brien, Rahmer, Vannesjo, Stich, Campbell-Washburn, Robison. So the NPL set in the "References Cited" block is largely the same literature the Applicant discusses in the Background, which is the standard pattern where the examiner uses the Applicant's own admission of the prior art.

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3. Most relevant prior art and § 102 analysis

Claim 1 (the only independent method claim) requires, in combination:
(a) determining a generic GIRF; (b) defining an interference gradient sequence from the diffusion pulse sequence; (c) determining a time interval for diffusion-image acquisition; (d) determining a time-dependent magnetic field deviation in that interval from the GIRF and the interference gradient sequence; and (e) compensating the distortion using that deviation, the compensation comprising a post-acquisition image correction.

Because § 102 anticipation requires a single reference to disclose every element, the bar is high — and the strongest references here each miss at least one element. My assessment:

Haselgrove 1996 (MRM 36:960). Most relevant for background / § 102(b)/pre-AIA art context. Discloses b=0 reference plus low-b adjustment images and registration/extrapolation to correct EPI distortion. Misses (a), (b), (d) — there is no impulse-response characterization and no interference-gradient-sequence field-deviation computation. Does not anticipate claim 1. It is the classic registration approach the patent explicitly distinguishes.

Bodammer 2004 (MRM 51:188). Relevant. Inverted-polarity diffusion gradients with registration. Same gaps as Haselgrove: no GIRF. Does not anticipate claim 1. Addresses dependent-claim subject matter (inverted polarity of reference gradients, which maps to claim 9's "additional gradients … with inverted polarity" language in the spec) only weakly, since claim 9 as issued recites "additional gradients for diffusion imaging," not polarity inversion.

O'Brien 2013 (IEEE TMI 32:1515). Closest NPL in concept. Discloses characterizing eddy-current behavior during system setup and reusing that characterization to correct diffusion images — conceptually adjacent to (a)+(e). However it is not a GIRF-based method, and the Applicant expressly criticizes it (long recording, per-protocol calibration, calibration timing constraints). Because GIRF determination uses a test-gradient sequence and the field deviation is computed by convolving GIRF with the interference gradient sequence, O'Brien does not disclose (a) "generic GIRF" or (d). Does not anticipate claim 1; at most supports a § 103 obviousness theory against (a)/(e).

Vannesjo 2014/2015; Stich 2018/2019; Campbell-Washburn 2015; Robison 2018; Rahmer 2019. Most technically relevant to the GIRF element (a) and to dependent claims 6, 7, 12, 13. Rahmer (2019) and Vannesjo (2014) teach measuring the gradient system response with phantom/field-camera and frequency-sweep test gradients — i.e., the "test gradients / magnitude response / phase response / reference measurement" of claim 6 and the "triangular test gradients covering a plurality of frequencies" of claim 7. Vannesjo 2015 and Stich 2018/2019 teach using GIRF kernels for zeroth-order (B₀) and linear (first-order) field prediction (claim 12/13). None of these, however, is directed to diffusion-weighted imaging with an interference gradient sequence derived from the diffusion pulse sequence (element (b)) — they are gradient-characterization and non-Cartesian-trajectory papers. They are § 102 anticipation candidates only for individual dependent claims (6, 7, 12, 13), not for claim 1 as a whole.

EP 3640661 A1 (4/2020). The single most likely anticipatory-type patent document on the face of the patent if its effective filing date precedes 2020-01-23 — because it is contemporaneous, likely Siemens-family, and in the same technical space. I could not retrieve its text, so I cannot say which of (a)–(e) it discloses and cannot responsibly tie it to specific claims. This is the one reference I would most strongly recommend verifying first.

US 6,384,601 (Wiesler, 2002) and US 6,636,038 (Heid, 2003). Neither title nor disclosure could be verified. On their face, both share the CPC space of the patent (G01R 33/48–33/54) and both are Siemens-era MR system art. Verification needed before any § 102 mapping; I will not speculate.

US 2005/0024051 A1 (Doddrell, 2005). Verified as to number/inventor/date only; content unverified.

Bottom line on anticipation

• No reference I was able to verify anticipates claim 1 under § 102 — each lacks at least the "generic GIRF" element (a) and/or the "time-dependent field deviation from GIRF × interference gradient sequence in a defined acquisition interval" elements (c)/(d) as applied to diffusion imaging.
• The highest-value § 102 targets for dependent claims are Rahmer 2019 and Vannesjo 2014 (claims 6–7), and Vannesjo 2015 / Stich 2018 (claims 12–13).
• The highest-value § 103 combination theory is O'Brien 2013 (eddy-current characterization reused for correction) in view of Rahmer 2019 / Vannesjo 2014 (GIRF measurement), which together reach (a), (d) and (e) but still leave element (b) — deriving the interference gradient sequence from the diffusion pulse sequence and, per the spec, including the reference-measurement gradients with inverted polarity.
• EP 3640661 A1 is the wildcard and should be checked first.

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4. Caveats and recommended next steps

1. The citation list above is incomplete. I could not extract the full "References Cited" block for US 11,402,454 B2 from USPTO sources. The authoritative patent text supplied does not include it. Any final prior-art chart must be built from the actual front page at USPTO PatentCenter (application 17/155,380).
2. Three U.S. references (Wiesler, Heid, Doddrell) are unverified as to content — do not rely on my table for their disclosures.
3. EP 3640661 A1's effective date is the pivotal question: if it predates 2020-01-23, it may be the most serious anticipation-type reference; if it postdates without earlier priority, it is not § 102(b) art and is at most § 102(a)(2)/§ 102(d) material and/or § 103 fodder.
4. The patent is classified in G01R 33/56518 (eddy-current distortion correction), so searches in that class — plus the "similar documents" list on Google Patents (e.g., US 10,451,696; US 10,459,054; DE 10 2013 224 406 B4) — are likely more productive for § 103 art than the face-of-patent citations.

If you can supply the actual "References Cited" block (or the full front page as an image/text), I will complete the per-reference claim mapping — including the verified titles and disclosures for Wiesler, Heid, Doddrell, and EP 3640661 — without the gaps flagged above.

I'll verify the pivotal references flagged as unverified in the prior-art section before building the § 103 combinations.

Good — this surfaced key details (O'Brien 2013 co-authored by an inventor on this patent, plus several GIRF-art patents). Let me pin down the remaining wildcard and the GIRF-correction family.

Obviousness Analysis under 35 U.S.C. § 103 — US 11,402,454 B2

Built on the previously-generated Prior Art and Assignment sections. Two data points from that work drive this analysis, and I verified both again here: (i) the closest reference, O'Brien 2013, is a printed publication co-authored by Thorsten Feiweier — a named inventor on this patent; and (ii) EP 3640661 A1 has a date problem that needs flagging. Both are addressed below.

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⚠️ Flagged contradiction between prior sections (resolve before relying on claim numbers)

The "Patent summary" section states the independent claims are claim 1 (method), claim 14 (device), claim 2 (CRM), and maps dependent themes to claims 2–13. The "Prior art" section states the claims are "17 (1 method; 2 device; 3 CRM; 4–17 dependent)." These are inconsistent.

I retrieved the granted-claim listing directly this session, and it supports the Prior Art section:

Treat the "Patent summary" section's "claim 14 = device" as an error (it appears to import the pre-grant publication US 2021/0231763 A1 numbering into the granted set). This analysis uses the granted numbering. Two consequences matter for § 103:

1. Claim 2 (device) drops the word "generic." The only limitation distinguishing the asserted point of novelty (a generic, protocol-independent characterization) is absent from independent claim 2. Claim 2 is therefore materially broader and materially more vulnerable than claim 1.
2. Independent claim 3 (CRM) keeps "generic"; so does claim 1.

Source: https://patents.justia.com/patent/[11402454](/patent/11402454)

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1. The person of ordinary skill in the art (PHOSITA)

A person with an M.S. or Ph.D. in medical physics, biomedical engineering, or electrical engineering and 2–5 years of experience in MR pulse-sequence design and image reconstruction, familiar with: dw-EPI distortion mechanisms; eddy-current/pre-emphasis compensation; gradient characterization; and image registration/distortion-correction toolboxes (FSL eddy_correct, etc.). This is the level reflected in the references themselves — the O'Brien, Vannesjo, Rahmer, Stich and Robison papers are all work product of MR physicists/scientists, and the patent's own inventors are Siemens MR scientists.

Because the patent's earliest effective filing date (2020-01-23, via DE 10 2020 200 786.1) is post-AIA, AIA § 102/§ 103 governs.

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2. Claim 1 — element decomposition

Element E is important: the claim is expressly not limited to pre-emphasis/real-time filtering. It is limited to a post-acquisition image correction.

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3. Combination 1 (Primary): O'Brien 2013 in view of Rahmer 2019 (and/or Vannesjo 2014)

3.1 Why O'Brien 2013 is the anchor — and why its provenance is decisive

O'Brien K, Daducci A, Kickler N, Lazeyras F, Gruetter R, Feiweier T, Krueger G. "3-D residual eddy current field characterisation: applied to diffusion weighted magnetic resonance imaging," IEEE Trans. Med. Imaging 32(8):1515–1525 (Aug. 2013), doi 10.1109/TMI.2013.2259249.

Verified content (abstract, verbatim points):

• It predicts, using linear response theory, the residual 3-D eddy current field required for geometric distortion correction, based on phantom eddy current field measurements.
• The "predicted 3-D eddy current field induced by the diffusion-weighting gradients" reduced residual-field RMS error to ~1 Hz.
• The correction was applied to diffusion-weighted images and outperformed registration (FSL) at high b-values because it is not hindered by low SNR.
• Critically, the authors state the characterization "enables the prediction of the 3-D eddy current field required to correct eddy current induced geometric distortions for a wide range of clinical and high b-value protocols."
• The model is time-resolved and spatially expanded in spherical harmonics, with the induced field expressed as a linear sum over each preceding gradient ramp on each gradient coil (their Eq. 3): A_n^m(t) = Σ_i Σ_{j=X,Y,Z} a_nm^j ΔG_i^j · exp((t−T_i)/τ_C^j).

Source: https://pubmed.ncbi.nlm.nih.gov/23674437/ ; https://ieeexplore.ieee.org/abstract/document/[6514081](/patent/6514081)

Mapping to claim 1:

Two points that materially weaken the patent's stated novelty position:

1. The applicant's own specification admits O'Brien. The Background section of US 11,402,454 recites O'Brien by citation and criticizes it — an admission that it is prior art and an admission of what it teaches.
2. The "generic / any-protocol" advantage the patent touts is already recited in O'Brien's own abstract. The specification's stated point of novelty (avoiding "a separate appropriate calibration … for each clinical measuring protocol") is undercut by O'Brien's express statement of applicability across "a wide range of clinical and high b-value protocols." This is the single most dangerous sentence in the prior art for this patent.

Inventor-overlap caveat (flagging, not asserting): O'Brien's co-author Thorsten Feiweier is a named inventor of US 11,402,454. This does not help the patent owner: the AIA § 102(b)(1)(A) grace period covers only inventor disclosures made ≤1 year before the effective filing date, and O'Brien published in 2013, ~7 years before. O'Brien is therefore unquestionably § 102(a)(1) prior art. If anything, the overlap is adverse — it forecloses any "different inventors / independent development" narrative and shows the inventors were intimately aware of the linear-response approach they later claimed.

3.2 What Rahmer 2019 supplies (the "GIRF" refinement)

Rahmer J, Mazurkewitz P, Börnert P, Nielsen T. "Rapid acquisition of the 3D MRI gradient impulse response function using a simple phantom measurement," Magn. Reson. Med. 82:2146–2159 (2019) — cited on the face of the patent and in the specification.

It teaches measuring the GIRF with a simple phantom, using test gradients, and expressly states the GIRF is protocol-independent and broadly applicable. This is exactly the subject matter of dependent claim 6 (test gradients + magnitude response + phase response + reference measurement) and claim 7 (triangular test gradients covering a plurality of frequencies). Vannesjo 2014 (frequency sweeps / field camera) is an alternative or cumulative teaching for the same elements.

3.3 Motivation to combine (why O'Brien + Rahmer)

The motivation is supplied by O'Brien itself, satisfying the KSR "articulated reasoning" requirement without hindsight:

• O'Brien states that "current eddy current measurement techniques are too time intensive to be performed on every patient" and that acquiring 2-D eddy-current field maps on a phantom "for the large diffusion-weighted-EPI data sets … would become cumbersome and would be limited to a specific parameter choice of the diffusion-weighted imaging protocol." → an express incentive to move to a reusable, protocol-independent characterization.
• Rahmer 2019 answers that need directly: a rapid, single phantom measurement yielding a generic GIRF.
• Predictable results: both are linear time-invariant descriptions of the same physical gradient chain. Replacing a fitted few-exponential parametric model with a measured, broadband GIRF is a substitution that a PHOSITA would expect to improve fidelity without changing the result sought (better distortion correction).
• Finite number of identified, predictable solutions (KSR): as of 2020 the known options for characterizing gradient-chain error were (a) parametric multi-exponential eddy-current models, (b) measured GIRFs via phantom, (c) field-camera sweeps, (d) pre-emphasis filters. Choosing (b) over (a) is a routine design choice in a small, enumerated solution space.

3.4 Conclusion — Combination 1

Claim 1 would have been obvious over O'Brien 2013 alone, and a fortiori over O'Brien 2013 in view of Rahmer 2019 (and/or Vannesjo 2014). O'Brien supplies elements A–E for a diffusion imaging sequence, including the "generic / wide range of protocols" characteristic. Rahmer/Vannesjo supply the specific GIRF measurement technique (and, if a strict reading requires a measured impulse response rather than a fitted mono-exponential response, close that gap with a routine implementation choice).

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4. Combination 2: O'Brien 2013 + US 10,890,638 B2 (Koninklijke Philips) — the strongest non-of-record ground

US 10,890,638 B2, "Determination of higher order terms of the three-dimensional gradient impulse response function" — verified this session as Philips art. Its specification expressly states:

"The information gained from 3D gradient system characterization can be used for improving gradient coil design. It can also be used for improving system calibration (eddy current compensation), which is especially desirable when measuring with demanding gradient waveforms, such as in diffusion or non-Cartesian scans. Image reconstruction could be improved by using actual k-space coordinates calculated from GMTFs instead of using the nominal k-space trajectory."

Source: https://patents.google.com/patent/[US10890638B2](/patent/US10890638B2)

Why this combination is the best IPR candidate:

• It supplies an express motivation to apply a measured 3D GIRF to diffusion imaging — bridging the exact gap the patent owner would argue exists between the GIRF-characterization literature (Rahmer/Vannesjo/Stich, all non-diffusion) and the diffusion correction.
• It is not a reference cited on the face of US 11,402,454 or discussed in its specification, so it avoids the § 325(d) discretionary-denial risk that attaches to O'Brien, Rahmer, Vannesjo, Haselgrove and Bodammer (all of which are of record).
• It teaches the higher-order field terms that map to the specification's discussion of higher-order B-field interferences (relevant to the broader claim scope and to claims 12–13).

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5. Combination 3: GIRF-measurement art for dependent claims 6, 7, 12, 13

For claims that recite how the GIRF is measured and how the field deviation is decomposed by order, the following are direct § 103 references:

Sources: https://www.patents-review.com/a/20180136298-method-determining-gradient-impulse-response-function-or.html ; https://patents.justia.com/patent/[11137468](/patent/11137468) ; https://patentimages.storage.googleapis.com/50/1d/ca/11c7f2c8fd6fb8/US9829554.pdf

Note on claim 13: vendor documentation of the zero-order field deviation via a time-derivative of a convolution of the gradient waveform with the zeroth-order transfer term appears in a later Siemens filing (US 11,681,002: ΔB_{k,l=0}(t) = … {G_nom,k(t)} · GSTF_{k,l}(f)). I flag this only as corroborating that the computation is conventional — its own effective date must be checked before use as art (likely post-dates this patent's priority date).

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6. Combination 4: EP 3640661 A1 (Siemens) for the active-compensation dependent claim — with a serious date caveat

EP 3640661 A1, "Method and control unit for active compensation of eddy current induced magnetic fields in magnetic resonance imaging," Siemens Healthcare GmbH, filed 2018-10-16, published 2020-04-22 (verified from the citation list of DE 10 2015 204 953 B3).

• Relevance: directly on point for dependent claim 5 (determining a compensation gradient and switching it during diffusion imaging) and for the specification's "active compensation" embodiment.
• ⚠️ Date problem I must flag honestly: the EP publication date (2020-04-22) is ~3 months AFTER this patent's priority date (2020-01-23). As a European publication it is not eligible under AIA § 102(a)(2) (which reaches only U.S. patents, U.S. application publications, and WIPO publications designating the U.S.), and it published too late for § 102(a)(1). So as an EP document, EP 3640661 A1 appears not to be prior art at all to US 11,402,454.
• Action item: verify whether EP 3640661 A1 has a WO or U.S. counterpart with the 2018-10-16 effective date. If yes, that counterpart is § 102(a)(2) art and becomes a highly valuable § 103 reference for claim 5 (same applicant field, same problem, express "active compensation of eddy current induced magnetic fields"). If no counterpart exists, EP 3640661 A1 should be excluded from any ground.
• This also explains — and partly calls into question — its appearance on the patent's face, which the Prior Art section already flagged as the "wildcard."

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7. Combination 5 (fallback): Haselgrove 1996 / Bodammer 2004 + GIRF art

If the patent owner successfully narrows the "interference gradient sequence" or "GIRF" limitations so that O'Brien is avoided, the same result is reached from the registration side:

• Haselgrove 1996 (MRM 36:960) and Bodammer 2004 (MRM 51:188) teach b=0-reference EPI distortion correction and inverted-polarity diffusion gradients with registration — i.e., they establish the post-acquisition image-correction step (element E) and the diffusion-gradient framing (element B) in the same technical context.
• Combining them with the GIRF art (Rahmer/Vannesjo/US 10,890,638) supplies elements A, C, D.
• Motivation: the patent's own Background concedes the insufficiency of registration ("the signal-to-noise ratio of individual images with higher diffusion weightings can be so low that reliable registering … is no longer possible") — an admission that supplies the motivation to replace registration with a physics-based field prediction.

This route is weaker on § 325(d) (both references are of record and are the applicant's own admitted Background art) and should be secondary.

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8. Dependent-claim chart (§ 103)

Verification note on the U.S. front-page citations (Wiesler, Heid, Doddrell): I confirmed US 6,384,601 (Wiesler) — it is a spoiler-gradient/FOV patent, consistent with a citation supporting claim 9's "additional gradients for diffusion imaging," and not eddy-current art. US 6,636,038 (Heid) is confirmed as a pulse-sequence controller patent (Siemens), relevant to gradient-waveform generation. US 2005/0024051 A1 (Doddrell) remains unverified as to content — do not chart it.

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9. Motivation-to-combine synthesis (the KSR / Graham factors)

1. Problem recognized and solution direction disclosed in the art. O'Brien expressly identifies the burden of per-protocol eddy-current calibration and the unsuitability of registration at high b-values. That is the motivation, stated in the prior art, not constructed with hindsight.
2. Reasonable expectation of success. Every reference here operates on the same LTI model of the gradient chain. Substituting a measured GIRF for a fitted multi-exponential response, or combining a predicted field map with post-acquisition unwarping, is a predictable engineering refinement.
3. Finite number of identified, predictable solutions. Parametric eddy-current models, measured GIRFs (phantom/field-camera), and pre-emphasis filters were the known options — KSR's "obvious to try."
4. Design incentives. Reduced calibration burden, robustness at high b-value / low SNR, and protocol independence are all recited benefits in the art and in the patent's own specification.
5. No teaching away. O'Brien's preference for avoiding per-patient measurement is not a teaching away from measuring a generic GIRF once — indeed O'Brien's own method is measurement-based (phantom eddy-current field measurement). The distinction the patent draws ("generic" vs. "per-protocol") is a matter of degree of reuse, not of a different physical principle.

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10. Anticipated rebuttals and weaknesses in the § 103 case (stated candidly)

1. "Generic" is the crux — and it may be supplied by O'Brien itself. Expect the patent owner to argue O'Brien requires a protocol-specific measurement. O'Brien's abstract explicitly claims applicability "for a wide range of clinical and high b-value protocols," which undercuts that argument. The owner's strongest position is the narrower, literal one from the specification's Background (that O'Brien's calibration measurement timing must match the clinical measurement) — a committee-of-experts argument, but not a strong one under KSR.
2. The claim-recited "determining a time interval" step. No verified reference recites a discrete step of "determining a time interval" for the acquisition as a claimed action; this is an implementation detail inherent in any EPI readout and is at most a de minimis drafting distinction. Expect a § 112 indefiniteness/obviousness sandwich here.
3. Claim 2 omits "generic." This cuts in favor of the challenger, not the owner — claim 2 is broader and easier to invalidate; it should be the first claim targeted.
4. § 325(d) risk. O'Brien, Rahmer, Vannesjo, Haselgrove and Bodammer are all of record (front page and/or specification). Building a ground solely on them invites discretionary denial. The best ground uses O'Brien (of record, but with a new, non-cumulative reading — the "wide range of protocols" passage and its express diffusion application) in view of art not of record: US 10,890,638 and US 2018/0136298. That framing both reduces § 325(d) exposure and tightens the motivation.
5. EP 3640661 A1 is not usable as-is. Its publication date (2020-04-22) post-dates the 2020-01-23 priority date, and as a European publication it does not qualify under § 102(a)(2). Verify a WO/US counterpart before relying on it for claim 5.
6. Unverified references. US 2005/0024051 (Doddrell) and claims 7, 10, 16, 17 of the granted set could not be confirmed this session. Do not chart them until retrieved from USPTO PatentCenter (application 17/155,380).

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11. Secondary considerations (objective indicia)

No evidence of secondary considerations was developed in the prior sections, and none surfaced here. The patent's own specification contains admissions that cut against non-obviousness: it concedes the existence and drawbacks of both the registration approach (Haselgrove/Bodammer) and the characterization-and-reuse approach (O'Brien), and frames the invention as an improvement in reuse rather than a new principle. Absent unexpected results, licensing activity, or copying evidence — and given the finding in the earlier sections that the patent is enforcement-dormant with no litigation, no PTAB activity, and no NPE signal — the secondary-considerations record is, on current information, empty.

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12. Bottom line

The decisive, largely avoidable problem for this patent is that its own specification admits the closest reference (O'Brien 2013) — a reference co-authored by one of its named inventors — and that reference's abstract already recites the very protocol-independence the patent touts as its advance. Combined with a claim 2 that omits the word "generic" entirely, the granted claim set presents a § 103 posture that is weak on the independent claims and weaker still on the device claim.