PTAB

IPR2016-00357

General Electric Company v. UNIVERSITY OF VIRGINIA PATENT FOUNDATION

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1. Case Identification

2. Patent Overview

  • Title: Method and apparatus for spin-echo-train MR imaging using prescribed signal evolutions
  • Brief Description: The ’644 patent discloses methods and apparatuses for magnetic resonance (MR) imaging using spin-echo pulse sequences. The purported invention is a technique for determining a variable-flip-angle series for refocusing radio-frequency (RF) pulses that explicitly considers the T1 and T2 relaxation times of tissues to permit a desired image contrast and lengthen the usable echo-train duration.

3. Grounds for Unpatentability

Ground 1: Claims 75-76, 78-82, 84-92, 94-96, 107, 111, 139, 157, 160, 169-78, 180-84, 186-94, 196-98, 209, 213, 241, and 254-260 are anticipated under 35 U.S.C. §102 by Mugler 2000.

  • Prior Art Relied Upon: Mugler 2000 (an abstract from the Proceedings of the International Society for Magnetic Resonance in Medicine, April 2000).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Mugler 2000, an abstract by the named inventor published more than one year before the patent’s effective filing date, disclosed every element of the challenged claims. Mugler 2000 described using "very long SE trains based on prescribed signal evolutions which explicitly consider the T1s and T2s of interest" to calculate a "variable flip-angle RF-pulse series." Petitioner asserted that Mugler 2000 disclosed an identical variable flip-angle series, an identical effective echo time (328 ms), and identical image contrast characteristics to the only examples provided in the ’644 patent. For apparatus claims, Petitioner argued that the required components (e.g., magnet system, control unit) were inherently disclosed because Mugler 2000 stated the method was implemented on a specific commercial MR scanner.

Ground 2: Claims 75-76, 78-82, 84-92, 94-96, 107, 111, 139, 157, 160, 169-78, 180-84, 186-94, 196-98, 209, 213, 241, and 254-260 are obvious under §103 over Mugler 1999 in view of Alsop.

  • Prior Art Relied Upon: Mugler 1999 (an abstract from the Proceedings of the International Society for Magnetic Resonance in Medicine, May 1999) and Alsop (a 1997 journal article in Magnetic Resonance in Medicine).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Mugler 1999 taught a nearly identical method for calculating a variable-flip-angle series based on a "computer-based theoretical model" to achieve a desired signal evolution, but for generating proton-density-weighted images rather than T2-weighted images. Alsop, which was cited in the ’644 patent's background, taught extending echo train duration using low-flip-angle pulses and specifically taught how to perform T2-weighted imaging.
    • Motivation to Combine: A person of ordinary skill in the art (POSA) would have been motivated to combine the references because they addressed the same problem: extending echo train duration in fast spin-echo imaging. A POSA seeking to apply the advanced pulse sequence calculation of Mugler 1999 to the well-known application of T2-weighted imaging would have looked to a reference like Alsop, which explicitly taught how to achieve T2-weighting by altering the phase-encoding order.
    • Expectation of Success: A POSA would have had a reasonable expectation of success because converting from proton-density to T2-weighted imaging was a simple, known modification of the phase-encoding gradient pulses. Alsop provided explicit instructions for this conversion. The combination would predictably yield a T2-weighted image with an extended echo train.

Ground 3: Numerous claims are obvious under §103 over Mugler 2000 in view of Mugler Overview.

  • Prior Art Relied Upon: Mugler 2000 and Mugler Overview (a November 1999 review article on MR imaging pulse sequences).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground was presented as an alternative to Ground 1. Petitioner argued that to the extent the Board finds Mugler 2000 does not inherently disclose certain fundamental MRI steps (e.g., a data-acquisition step, an excitation pulse preceding refocusing pulses), Mugler Overview explicitly taught these elements. Mugler Overview, a general review article by the same inventor, described the basic components and functions of MR pulse sequences, such as the necessity of excitation and refocusing pulses, data acquisition, and the use of gradient pulses for spatial encoding.
    • Motivation to Combine: A POSA reading the specific technique in Mugler 2000 would have been motivated to consult a general reference like Mugler Overview by the same author for background information and to understand the fundamental principles upon which the technique was based. The combination amounted to implementing the specific method of Mugler 2000 using the standard, fundamental techniques described in Mugler Overview.

  • Additional Grounds: Petitioner asserted numerous additional obviousness challenges, including combinations of Mugler 2000 and Mugler 1999 with references such as Hennig 1986 (to teach specific phase angle conditions), Rydberg (for alternate data collection methods), and Stuber (for motion correction techniques).

4. Key Claim Construction Positions

  • "effective echo time": Petitioner proposed this term means "the echo time at which the center of k-space is sampled, which can be approximated as ½ of the echo-train duration." This construction was based on the patent owner's infringement contentions and was important for comparing the effective echo times disclosed in the prior art to the claimed requirement that the echo time be "at least twice" that of a conventional sequence.
  • "T2-weighted contrast... that is substantially the same": Petitioner proposed this means "T2-weighted contrast that has substantially the same numerical indicator of contrast or that visually appears similar." This construction, based on language in the patent specification, allowed for both objective (numerical) and subjective (visual) comparison to the prior art, broadening the scope of invalidating evidence.
  • "a value approximately midway between said initial flip angle and the lowest flip angle": Petitioner proposed this means "a value that is approximately 28% to 72% of the way between the lowest flip angle and the initial flip angle." This range was derived by analyzing the single graphical example in the patent and creating a symmetrical range around the disclosed data point, which was critical for mapping the flip angle values shown in the prior art to the claim language.

5. Key Technical Contentions

  • Ineffective Priority Claim: A central argument of the petition was that the ’644 patent was not entitled to the filing date of its provisional application (the ’182 application). Petitioner argued that the ’182 application failed the written description requirement of 35 U.S.C. §112 because it did not disclose key limitations of the challenged claims. Specifically, the provisional allegedly did not disclose that selecting T1 and T2 relaxation times was optional, nor did it describe dephasing transverse magnetization or the "at least twice" ratio for the effective echo time. By invalidating the priority claim, the patent's effective filing date would be no earlier than December 21, 2001, making Mugler 2000 and Mugler 1999 available as prior art under §102(b).

6. Relief Requested

  • Petitioner requested that the Board institute an inter partes review and cancel the challenged claims of the ’644 patent as unpatentable.