US 9814431

Here's a concise summary of US Patent 9814431:

Title: Methods and systems for retrospective internal gating

Assignee: Memorial Sloan Kettering Cancer Center.

Inventors: Adam L. Kesner.

Filing Date: 2008-05-05.

Issue Date: 2017-11-14 (Publication date for US9814431B2).

Abstract: The patent describes a method for deriving respiratory gated PET image reconstruction from raw PET data. This method uses respiratory motion information, which is derived from signal fluctuations within individual voxels, to create usable respiratory phase information. The invention enables the reconstruction of respiratory gated PET images from PET data without the need for external hardware and in a fully automated manner.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method for retrospective internal gating): This claim describes a multi-step method for correcting motion artifacts in medical images. It involves:

  1. Acquiring a series of images over time.
  2. Extracting "time-activity information" for each small volume element (voxel) within these images.
  3. Assigning "weighting factors" to prioritize which voxels are most important for analyzing the motion, effectively prioritizing them for "phase analysis."
  4. Filtering out unwanted frequencies from the time-activity curves of the voxels.
  5. Using the prioritization to combine the voxel time-activity information into a single "time varying object motion function," which represents the overall movement.
  6. Using this motion function to link the acquired image data to specific phases of the periodic motion (e.g., different points in a breathing cycle).
  7. Finally, using this mapping to create at least one image that has been corrected for motion.

• Claim 21 (Non-transitory computer-readable medium): This claim covers a computer program stored on a non-transitory computer-readable medium. When this program is executed by one or more processors, it causes a machine to perform the exact same steps outlined in Claim 1, essentially automating the retrospective internal gating method.

• Claim 22 (System): This claim describes a system comprising one or more processors and a non-transitory computer-readable medium with instructions stored on it. When these instructions are executed by the processors, they cause the system to carry out all the steps of the method detailed in Claim 1.

CAFC 2026 Dockets:
A search of CAFC 2026 dockets for patent number 9814431 did not return any specific case records for the year 2026. This indicates there are no publicly available docket entries specifically citing US9814431B2 in the Court of Appeals for the Federal Circuit for 2026 at this time. The CAFC provides information on case filings and records, but specific patent numbers in dockets would need a more direct search of their system or a comprehensive legal database.

As of April 26, 2026, a comprehensive search for litigation involving US Patent 9814431 did not yield any publicly available case records from the provided sources (Unified Patents, CAFC, and PACER) that specifically name this patent number. Unified Patents provides litigation case lists, but a direct search for 9814431 on their portal was unsuccessful. Similarly, searches for CAFC and PACER dockets for US9814431B2 did not return specific case records.

Therefore, no known litigation involving US patent 9814431 can be reported at this time based on the search conducted.

Proceedings overview

There are no AIA trial proceedings on file for US Patent 9814431. This indicates that the patent has not been challenged through Inter Partes Review (IPR), Post-Grant Review (PGR), or Covered Business Method (CBM) proceedings at the Patent Trial and Appeal Board (PTAB) to date. This gives a defendant a posture where all claims of the patent remain untested by PTAB.

Strategic summary

As of the current date, all claims (1-22) of US Patent 9814431 remain unchallenged in PTAB proceedings. No claims have been canceled or sustained through an AIA trial, and none are currently under active review. This means there is no estoppel landscape established under 35 U.S.C. § 315(e)(2) concerning prior art grounds that could have been raised in an IPR. All potential prior-art grounds remain available for a defendant facing assertion of this patent. The absence of PTAB activity suggests that the patent has not yet been subject to significant challenges from accused infringers or defensive aggregators.

Recommended next steps

Since there is no PTAB activity on file for US Patent 9814431, a potential defendant has several options. If facing an assertion, a detailed prior art search would be a prudent first step to identify potential grounds for an IPR or other invalidity challenge. Given the patent's issue date (2017-11-14), it is eligible for IPR (challenging claims based on patents or printed publications under § 102 or § 103). It is not eligible for PGR, as PGR must be filed within nine months of the patent's grant or reissue. The absence of PTAB challenges thus far means that a defendant would be initiating the first such proceeding, potentially setting the precedent for how the PTAB views the patent's claims.

Inventors

• Adam L. Kesner (Memorial Sloan Kettering Cancer Center)

Original assignee

Memorial Sloan Kettering Cancer Center is a prominent cancer treatment and research institution. They are an operating entity focused on medical care and scientific discovery. Their primary line of business is healthcare and medical research, and they are currently operating. While they are a research institution, the direct "shipping of a product embodying the claims" in the traditional commercial sense is not their primary function; rather, the invention would likely be integrated into their clinical imaging and diagnostic processes.

Assignment timeline

• 2016-10-05 (executed) / recorded 2016-10-10 — Reel 039975/0193

  • Conveyance: Assignment
  • Assignor: KESNER, ADAM
  • Assignee: SITKO, JOHN
  • Correspondent: MCDERMOTT WILL & EMERY LLP, 500 NORTH CAPITAL STREET, N.W., WASHINGTON, DISTRICT OF COLUMBIA, 20001
  • Context: Inventor to individual transfer

• 2016-10-05 (executed) / recorded 2016-10-10 — Reel 039975/0226

  • Conveyance: Assignment
  • Assignor: SITKO, JOHN
  • Assignee: KESNER, ADAM
  • Correspondent: MCDERMOTT WILL & EMERY LLP, 500 NORTH CAPITAL STREET, N.W., WASHINGTON, DISTRICT OF COLUMBIA, 20001. This correspondent recurs in this chain.
  • Context: Individual to inventor transfer

• 2017-05-30 (executed) / recorded 2017-05-30 — Reel 042532/0318

  • Conveyance: Assignment
  • Assignor: KESNER, ADAM
  • Assignee: MEMORIAL SLOAN KETTERING CANCER CENTER
  • Correspondent: MCDERMOTT WILL & EMERY LLP, 500 NORTH CAPITAL STREET, NW, WASHINGTON, DISTRICT OF COLUMBIA, 20001. This correspondent recurs in this chain.
  • Context: Inventor to original assignee transfer

Timeline diagram

timeline
    title Ownership of US 9814431
    2008 : Filed by Memorial Sloan Kettering
    2016 : Inventor Kesner to Sitko
         : Sitko to Inventor Kesner
    2017 : Inventor Kesner to MSKCC
    2017 : Issued to MSKCC

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The transfers involve individuals and the original operating entity (Memorial Sloan Kettering Cancer Center).
2. Known asserter in the chain — not present. None of the named assignees or assignors are identified as known NPEs.
3. Repeat correspondent across the chain — present. MCDERMOTT WILL & EMERY LLP appears as the correspondent for all three recorded assignments (Reel 039975/0193, Reel 039975/0226, and Reel 042532/0318).
4. Cascading transfers — not present. While there are two transfers on the same day in 2016, they represent a circular transfer between an inventor and another individual, rather than a chain of transfers through multiple LLCs.
5. Pre-litigation transfer — not present. No litigation has been identified, and the latest assignment to Memorial Sloan Kettering Cancer Center occurred five months before the patent issued.
6. Bankruptcy fire-sale — not present. Memorial Sloan Kettering Cancer Center is an active, operating institution.
7. Privateering — not present. No evidence suggests a privateering arrangement.
8. Defensive aggregator (anti-NPE) — not present. The patent remains with the original operating/research institution.

Verdict

Insufficient data. While there is a repeat correspondent, this alone is not enough to confidently label Memorial Sloan Kettering Cancer Center as an NPE or suggest a troll pattern. The assignments show a transfer from an inventor to an individual and then back to the inventor, followed by a transfer from the inventor back to the original assignee, Memorial Sloan Kettering Cancer Center, which is an operating entity.

USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/

To identify the most relevant prior art for US patent 9814431, I will examine the patent citations listed within the patent itself. Under 35 U.S.C. § 102, a claim is anticipated if every element of the claimed invention is disclosed, either specifically or inherently, by a single prior art reference, arranged in substantially the same manner as in the claim under review. Prior art must have existed before the effective filing date of the claimed invention.

The effective filing date for US9814431B2 is May 4, 2007 (priority date).

Here are the patent citations listed in US9814431B2, along with their details and potential anticipation:

Cited References:

1. US6144874A

   • Full Citation: US6144874A - Respiratory gating method for MR imaging
   • Publication Date: 2000-11-07
   • Priority Date: 1998-10-15
   • Brief Description: This patent describes a method for respiratory gating in Magnetic Resonance (MR) imaging. It involves acquiring MR data over several respiratory cycles, determining the respiratory phase for each acquisition based on signals from the imaging process itself (e.g., diaphragm motion), and then reconstructing images by grouping data from similar respiratory phases. This method aims to reduce motion artifacts without external respiratory transducers.
   • Potential Anticipation (35 U.S.C. § 102): US6144874A appears highly relevant to the concept of "retrospective internal gating" and "generating at least one motion corrected image" from internally derived motion signals. It specifically addresses using image data to determine respiratory motion and then reconstructing images based on phases of that motion. Claims 1, 21, and 22, particularly the steps related to acquiring images, identifying cyclical signals, correlating times with motion phases, and generating motion-corrected images, could be potentially anticipated by this reference. The use of "voxel time-activity information" to create a "time varying object motion function" might be a distinguishing feature, but the core idea of internal retrospective gating for respiratory motion is present.

2. US6298260B1

   • Full Citation: US6298260B1 - Respiration responsive gating means and apparatus and methods using the same
   • Publication Date: 2001-10-02
   • Priority Date: 1998-02-25
   • Brief Description: This patent describes a respiration-responsive gating apparatus and method, primarily focused on radiotherapy. It involves using an electromagnetic tracking system to monitor the position of internal organs (e.g., lungs) and gating radiation treatment based on the detected respiratory motion. While it deals with motion correction related to respiration, it relies on an external tracking system rather than deriving motion directly from image voxel signals for retrospective gating.
   • Potential Anticipation (35 U.S.C. § 102): Less likely to directly anticipate the core claims of US9814431B2 under 35 U.S.C. § 102 due to its reliance on an external tracking system. Claims 1, 21, and 22 of US9814431B2 emphasize "extracting time-activity information for individual voxels" and creating a motion function "from many voxels' time-activity values," which implies an internal, image-based derivation of motion.

3. US6501981B1

   • Full Citation: US6501981B1 - Apparatus and method for compensating for respiratory and patient motions during treatment
   • Publication Date: 2002-12-31
   • Priority Date: 1999-03-16
   • Brief Description: This patent describes a system and method for compensating for patient motion, specifically respiratory motion, during medical procedures such as radiation therapy. It uses external sensors (e.g., infrared tracking) to monitor patient motion and adjust the treatment delivery accordingly.
   • Potential Anticipation (35 U.S.C. § 102): Similar to US6298260B1, this patent relies on external motion detection, which distinguishes it from the "internal gating" aspect of US9814431B2's claims. Therefore, it is less likely to directly anticipate claims 1, 21, and 22.

4. US6539074B1

   • Full Citation: US6539074B1 - Reconstruction of multislice tomographic images from four-dimensional data
   • Publication Date: 2003-03-25
   • Priority Date: 2000-08-25
   • Brief Description: This patent focuses on reconstructing multi-slice tomographic images from 4D data, where the fourth dimension is time, often used for cardiac or respiratory motion. It discusses sorting projection data according to cardiac or respiratory phases and reconstructing images for different phases. It implies the need for gating information but doesn't explicitly detail the internal derivation of this information from voxel time-activity curves as in US9814431B2.
   • Potential Anticipation (35 U.S.C. § 102): This reference is relevant to the idea of motion-gated image reconstruction, particularly the "mapping of image data to corresponding motion phases" and "generating at least one motion corrected image" steps in claims 1, 21, and 22. However, it does not explicitly disclose the specific method of deriving the motion function from individual voxel time-activity information, weighting, and filtering as taught by US9814431B2. Therefore, while it describes the purpose and result of motion correction, the method of determining the motion function may differ.

5. US6556695B1

   • Full Citation: US6556695B1 - Method for producing high resolution real-time images, of structure and function during medical procedures
   • Publication Date: 2003-04-29
   • Priority Date: 1999-02-05
   • Brief Description: This patent describes a method for real-time imaging that involves acquiring data at high speed and then processing it to produce high-resolution images, potentially with motion correction. It mentions the use of "physiologic gating" but does not elaborate on how the gating signal is derived, particularly from internal image information.
   • Potential Anticipation (35 U.S.C. § 102): This reference is too general in its description of motion correction to directly anticipate the specific steps of US9814431B2's claims 1, 21, and 22, especially regarding the internal derivation of the object motion function from voxel time-activity.

6. US20040218794A1

   • Full Citation: US20040218794A1 - Method for processing perfusion images
   • Publication Date: 2004-11-04
   • Priority Date: 2003-05-01
   • Brief Description: This publication describes a method for processing perfusion images, which involves generating a time-activity curve for regions of interest. It's related to analyzing temporal changes in image signals, but not specifically for deriving a global object motion function for gating purposes.
   • Potential Anticipation (35 U.S.C. § 102): This reference touches on "extracting time-activity information for individual voxels" (or regions), but it does not disclose the subsequent steps of prioritizing, filtering, combining into a time varying object motion function for gating, mapping to motion phases, and generating motion-corrected images as required by claims 1, 21, and 22.

7. US20050123183A1

   • Full Citation: US20050123183A1 - Data driven motion correction for nuclear imaging
   • Publication Date: 2005-06-09
   • Priority Date: 2003-09-02
   • Brief Description: This publication describes data-driven motion correction for nuclear imaging, where patient motion is estimated from the imaging data itself without external hardware. It mentions identifying a "motion signal" from the raw data and using it to correct for motion. This is highly relevant to the concept of retrospective internal gating.
   • Potential Anticipation (35 U.S.C. § 102): This reference is very strong prior art for claims 1, 21, and 22. It explicitly teaches "data driven motion correction" for nuclear imaging, which means deriving motion information from the acquired images, and using it for correction. The specific steps of "extracting time-activity information for individual voxels," "prioritizing voxels," "applying frequency filter," and "combining voxel time-activity information into a time varying object motion function" would need careful comparison to determine if every element of these claims is identically disclosed or inherently present. However, the overarching concept of deriving motion internally from image data for correction is clearly present.

8. US20070081704A1

   • Full Citation: US20070081704A1 - System, program product, and methods for attenuation correction of emission data on PET/CT and SPECT/CT
   • Publication Date: 2007-04-12
   • Priority Date: 2005-03-17
   • Brief Description: This publication relates to attenuation correction in PET/CT and SPECT/CT imaging, which is a different aspect of image processing than motion correction. It does not primarily deal with deriving motion signals from image data.
   • Potential Anticipation (35 U.S.C. § 102): Unlikely to anticipate claims 1, 21, or 22 as its focus is on attenuation correction, not motion gating.

9. US20070127797A1

   • Full Citation: US20070127797A1 - Methods and systems to facilitate reducing banding artifacts in images
   • Publication Date: 2007-06-07
   • Priority Date: 2005-11-23
   • Brief Description: This publication discusses methods for reducing banding artifacts in images, which are typically caused by factors like motion or scanner instabilities. While motion can cause artifacts, this reference does not detail a method for deriving motion information from internal image signals for retrospective gating.
   • Potential Anticipation (35 U.S.C. § 102): Unlikely to anticipate claims 1, 21, or 22 as its focus is on reducing a specific type of artifact, not the comprehensive retrospective internal gating method described.

10. US20070237372A1

    • Full Citation: US20070237372A1 - Cross-time and cross-modality inspection for medical image diagnosis
    • Publication Date: 2007-10-11
    • Priority Date: 2005-12-29
    • Brief Description: This publication describes methods for comparing medical images across different times or modalities for diagnostic purposes. It doesn't focus on motion correction through retrospective internal gating.
    • Potential Anticipation (35 U.S.C. § 102): Not directly relevant to the core claims of US9814431B2 for retrospective internal gating.

11. US7359535B2

    • Full Citation: US7359535B2 - Systems and methods for retrospective internal gating
    • Publication Date: 2008-04-15
    • Priority Date: 2003-06-20
    • Brief Description: This patent (from General Electric Company) shares the exact same title as US9814431B2 and was published before the filing date of US9814431B2 (2008-05-05). It describes a method for retrospective internal gating by identifying temporally cyclical signals from image data to create a time varying object motion function, which correlates image acquisition times with phases of periodic motion. It mentions analyzing individual voxels over time and combining these signals.
    • Potential Anticipation (35 U.S.C. § 102): This is extremely strong prior art and appears to anticipate claims 1, 21, and 22 of US9814431B2. The description in US7359535B2, including "acquiring images at different times t1 . . . tn, and identifying temporally cyclical signals, which are combined to create a time varying object motion function which correlates times t1 . . . tn and the phases of the periodic motion," directly covers many aspects of US9814431B2's independent claims. A detailed claim-by-claim analysis against this reference would be crucial to determine if any specific limitations in US9814431B2's claims provide a patentably distinct feature. The elements of extracting time-activity information, creating a time varying object motion function, and using it for mapping to motion phases and generating motion-corrected images are explicitly or inherently disclosed.

12. US20080226149A1

    • Full Citation: US20080226149A1 - Motion Compensation in Functional Imaging
    • Publication Date: 2008-09-18
    • Priority Date: 2005-08-04
    • Brief Description: This publication describes methods for motion compensation in functional imaging, involving estimating motion from image data (e.g., PET) and then correcting for it during reconstruction or post-reconstruction. It refers to deriving motion information directly from the acquired data.
    • Potential Anticipation (35 U.S.C. § 102): This is another strong piece of prior art, as it discusses estimating motion directly from functional imaging data for compensation. It would require a close comparison with claims 1, 21, and 22 to see if the specific details of prioritizing, weighting, and the iterative combination of voxel time-activity information as taught in US9814431B2 offer distinguishing features. However, the core concept of internally deriving motion for correction is present.

13. US20090076369A1

    • Full Citation: US20090076369A1 - Method For Reducing Motion Artifacts In Highly Constrained Medical Images
    • Publication Date: 2009-03-19
    • Priority Date: 2007-09-17
    • Brief Description: This publication describes a method for reducing motion artifacts in medical images, particularly in highly constrained imaging scenarios. While it addresses motion artifacts, its priority date (2007-09-17) is after the priority date of US9814431B2 (2007-05-04), meaning it would not be prior art under 35 U.S.C. § 102 for US9814431B2.
    • Potential Anticipation (35 U.S.C. § 102): Not prior art due to later priority date.

14. US7574249B2

    • Full Citation: US7574249B2 - Device-less gating of physiological movement for improved image detection
    • Publication Date: 2009-08-11
    • Priority Date: 2005-02-08
    • Brief Description: This patent describes a method for "device-less gating" of physiological movement, meaning it estimates physiological motion (like respiration or cardiac motion) from the imaging data itself without external devices. It identifies a "motion artifact characteristic" in the raw data to generate a gating signal.
    • Potential Anticipation (35 U.S.C. § 102): This is another strong prior art reference. "Device-less gating" aligns directly with "retrospective internal gating" and deriving motion from the image data. Claims 1, 21, and 22 would need careful comparison to determine if the specific methodologies for extracting, prioritizing, filtering, and combining voxel time-activity information in US9814431B2 present novel distinctions.

15. US20090290774A1

    • Full Citation: US20090290774A1 - Dynamic computed tomography imaging
    • Publication Date: 2009-11-26
    • Priority Date: 2006-05-26
    • Brief Description: This publication relates to dynamic CT imaging, where multiple image acquisitions are made over time. It may involve motion correction, but the focus is on the acquisition technique rather than a specific internal retrospective gating algorithm using voxel time-activity curves.
    • Potential Anticipation (35 U.S.C. § 102): While broadly related to time-resolved imaging, this reference does not appear to anticipate the specific internal gating methodology of claims 1, 21, and 22.

16. US20090299184A1

    • Full Citation: US20090299184A1 - Imaging or communications system utilizing multisample apodization and method
    • Publication Date: 2009-12-03
    • Priority Date: 2008-02-16
    • Brief Description: This publication describes an imaging or communications system using multisample apodization, a signal processing technique. Its priority date (2008-02-16) is after the priority date of US9814431B2 (2007-05-04), meaning it would not be prior art under 35 U.S.C. § 102 for US9814431B2.
    • Potential Anticipation (35 U.S.C. § 102): Not prior art due to later priority date.

17. US7734078B2

    • Full Citation: US7734078B2 - System and method for generating composite substraction images for magnetic resonance imaging
    • Publication Date: 2010-06-08
    • Priority Date: 2002-09-18
    • Brief Description: This patent describes a system and method for generating composite subtraction images in MRI, often used for angiography. It's focused on image subtraction techniques rather than motion gating.
    • Potential Anticipation (35 U.S.C. § 102): Not directly relevant to the core claims of US9814431B2.

18. US7756307B2

    • Full Citation: US7756307B2 - Method of, and software for, conducting motion correction for a tomographic scanner
    • Publication Date: 2010-07-13
    • Priority Date: 2003-10-17
    • Brief Description: This patent describes a method and software for motion correction in a tomographic scanner. It involves identifying an image feature that moves with the patient and using its motion to correct for overall patient movement. This is a form of internal motion correction.
    • Potential Anticipation (35 U.S.C. § 102): This is strong prior art, as it teaches using an image feature to derive motion for correction in tomographic scanning. Similar to US7359535B2, US20050123183A1, and US7574249B2, it would require a detailed claim comparison to see if the specific details of voxel-based time-activity processing, weighting, and the iterative combination method as claimed in US9814431B2 provide patentable distinctions.

19. US20100183206A1

    • Full Citation: US20100183206A1 - Adjusting acquisition protocols for dynamic medical imaging using dynamic models
    • Publication Date: 2010-07-22
    • Priority Date: 2007-06-21
    • Brief Description: This publication discusses adjusting acquisition protocols for dynamic medical imaging using dynamic models. Its priority date (2007-06-21) is after the priority date of US9814431B2 (2007-05-04), meaning it would not be prior art under 35 U.S.C. § 102 for US9814431B2.
    • Potential Anticipation (35 U.S.C. § 102): Not prior art due to later priority date.

Most Relevant Prior Art:

Based on the analysis, the following prior art references are considered the most relevant for potentially anticipating claims of US patent 9814431 under 35 U.S.C. § 102:

• US7359535B2 (Systems and methods for retrospective internal gating): This patent has the same title and directly addresses the core concept of retrospective internal gating by identifying cyclical signals from image data to create a time-varying object motion function. Its priority date is well before US9814431B2's filing date.
• US20050123183A1 (Data driven motion correction for nuclear imaging): This publication teaches data-driven motion correction from imaging data itself, without external hardware, which is a key aspect of US9814431B2.
• US7574249B2 (Device-less gating of physiological movement for improved image detection): This patent's concept of "device-less gating" aligns strongly with the internal, image-based motion detection described in US9814431B2.
• US6144874A (Respiratory gating method for MR imaging): This patent demonstrates the application of internally-derived respiratory motion for gating in MR imaging, pre-dating US9814431B2.
• US7756307B2 (Method of, and software for, conducting motion correction for a tomographic scanner): This patent describes identifying image features to track and correct for motion in tomographic scanning, which is highly relevant to internal motion correction.

These references, particularly US7359535B2, appear to disclose many, if not all, of the fundamental steps claimed in the independent claims of US9814431B2 (claims 1, 21, and 22), specifically the acquisition of images, extraction of internal motion signals, creation of a motion function, and subsequent motion correction. A detailed, element-by-element claim chart analysis would be necessary to precisely determine the extent of anticipation.

Obviousness Analysis of US Patent 9814431 Under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the independent claims of US Patent 9814431 obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention (priority date 2007-05-04). The primary prior art references considered are US7359535B2 and US7574249B2, both of which predate the critical date of US9814431B2.

Claim 1: A method for retrospective internal gating

Claim 1 details a method comprising several steps for generating motion-corrected images using retrospective internal gating. A PHOSITA would find this claim obvious in light of the combination of US7359535B2 and US7574249B2.

Prior Art References:

1. US7359535B2 (GE Medical Systems Global Technology Company, Llc): "Systems and methods for retrospective internal gating"

   • Disclosure: This patent describes reconstructing images from 4D data by correlating a respiratory signal to image data. An exemplary method includes reconstructing a composite image, determining a breathing pattern based on activity in a region of interest (ROI), and reconstructing a gated image set by associating image data with respective phases of the breathing pattern. It also mentions analyzing data of a selected voxel in the composite image over time and filtering time data to remove high and low frequencies.
   • Relevance: This reference directly teaches the overarching concept of "retrospective internal gating" using image-derived motion signals, including acquiring image series, extracting time-activity information (from ROIs/voxels), filtering, mapping to motion phases, and generating motion-corrected images.

2. US7574249B2 (General Electric Company): "Device-less gating of physiological movement for improved image detection"

   • Disclosure: This patent discloses a method for device-less gating of physiological movement by acquiring images, processing them to identify an ROI related to physiological movement, generating a motion function based on the ROI, and gating the images using this motion function to reduce artifacts. It explicitly states that an ROI may correspond to a voxel, and a single voxel or a plurality of voxels can be selected to derive the motion function. Importantly, it teaches selecting these voxels based on criteria such as "signal amplitude, frequency, and signal to noise ratio," and filtering the motion function to remove unwanted noise.
   • Relevance: This reference complements US7359535B2 by further elaborating on the "device-less" aspect and specifically teaching how to derive a motion function from individual or multiple voxels within the image data, including criteria for selecting these voxels.

Obviousness Argument for Claim 1:

All limitations of Claim 1 are taught or rendered obvious by the combination of US7359535B2 and US7574249B2:

• "acquiring a series of images at times t 1 . . . tn;" is taught by US7359535B2, which discloses "acquiring time-varying image data" and "4D data," and by US7574249B2, which teaches "acquiring a set of images of an object".
• "extracting time-activity information for individual voxels;" is taught by US7359535B2, which mentions analyzing "the data of a selected voxel in the composite image over the entire time period". US7574249B2 explicitly teaches that an ROI can be a voxel and that "a single voxel... or a plurality of voxels may be selected and used to derive the motion function," directly covering the extraction of time-activity information for individual voxels.
• "prioritizing voxels for phase analysis, and assigning weighting factors;" US7574249B2 teaches "selecting voxels" based on "various criteria, such as, but not limited to, signal amplitude, frequency, and signal to noise ratio". This selection process effectively prioritizes voxels for their contribution to the motion function, which is subsequently used for phase analysis (gating). A PHOSITA, seeking to improve the accuracy of the motion function, would find it obvious to apply explicit "weighting factors" based on these selection criteria (e.g., higher weight for voxels with better SNR or amplitude, or zero weight for unimportant voxels as described in US9814431B2's dependent claims) to quantify and emphasize the importance of more reliable voxels. This is a common and predictable optimization technique in signal processing when combining data from multiple sources.
• "applying frequency filter to voxel time-activity curves;" is taught by US7359535B2 ("filtering the time data to remove high and low frequencies") and US7574249B2 ("filtering the motion function to remove unwanted noise and non-physiological frequencies").
• "using prioritization, combining voxel time-activity information into a time varying object motion function;" Both references teach combining voxel/ROI information to create a motion signal. US7359535B2 forms a "respiratory pattern signal" from filtered time-activity data. US7574249B2 generates a "motion function based on the region of interest" (which can be multiple voxels). The "prioritization" aspect is addressed by the motivation to explicitly weight voxels as discussed above.
• "using the time varying object motion function for the mapping of image data to corresponding motion phases;" is taught by US7359535B2 ("associating image data with respective phases of the breathing pattern") and US7574249B2 ("gating the set of images...utilizing the motion function," including identifying "gating points" corresponding to different phases).
• "using the mapping of image data to corresponding motion phases to generate at least one motion corrected image." is taught by US7359535B2 ("reconstructing a gated image set...corrected for patient motion") and US7574249B2 ("gating the set of images to reduce motion artifacts").

Motivation for a PHOSITA to Combine:

A PHOSITA in the field of medical imaging, seeking to improve the accuracy, robustness, and automation of retrospective internal gating techniques, would have been motivated to combine the teachings of US7359535B2 and US7574249B2. US7359535B2 provides the fundamental framework for image-based retrospective gating. US7574249B2 offers specific, detailed methods for enhancing the derivation of the internal motion signal by considering individual voxels and their characteristics.

The motivation to explicitly "prioritize voxels and assign weighting factors" (as described in Claim 1 and its dependent claims 3, 4, 6 of US9814431B2) when combining voxel time-activity information would stem directly from the desire to leverage US7574249B2's teaching on selecting voxels based on signal quality (e.g., amplitude, frequency, SNR). A PHOSITA would recognize that formalizing this selection into a weighting scheme would allow for a more nuanced and potentially more accurate contribution of each voxel to the final "time varying object motion function." Furthermore, standard signal processing techniques for combining multiple signals, such as considering phase differences (implicitly addressed by addition/subtraction scenarios in dependent Claim 14 of US9814431B2) and optimizing for signal strength or periodicity (e.g., by maximizing standard deviation as in dependent Claim 15), are well-known approaches that a PHOSITA would routinely apply to improve the quality of a derived physiological motion signal.

Claims 21 and 22: Non-transitory computer-readable medium and System

Claims 21 and 22 cover a non-transitory computer-readable medium encoded with a program and a system, respectively, that when executed, cause a machine to perform the method of Claim 1.

Obviousness Argument for Claims 21 and 22:

Given that the method described in Claim 1 would be obvious to a PHOSITA in light of the combination of US7359535B2 and US7574249B2, implementing this method on a computer system or storing the instructions on a computer-readable medium would also be obvious. At the time of the invention (priority date 2007-05-04), it was well-established practice in the field of medical imaging to implement complex image processing and reconstruction algorithms as software programs executable by general-purpose computers. The patent itself states the advantages of "software derived respiratory signals" as being "image based, and thus machine independent," and capable of being used with "existing scans, or scanners." This indicates that the implementation of such algorithms in software was a known and desired approach for PHOSITAs. Therefore, Claims 21 and 22, being directed to the computerized implementation of an obvious method, would themselves be obvious.