US RE49,978 E1
Method of performing diffusion weighted magnetic resonance measurements on a sample
Samo Lasic, Lund (SE); Daniel Topgaard, Lund (SE); Markus Nilsson, Oxie (SE); and Hans Magnus Henrik Lundell, Fredensborg (DK)
Assigned to THE BRIGHAM AND WOMEN'S HOSPITAL, INC., Boston, MA (US)
Appl. No. 17/555,944
Filed by The Brigham and Women's Hospital, Inc., Boston, MA (US)
PCT Filed Nov. 9, 2017, PCT No. PCT/SE2017/051126
§ 371(c)(1), (2) Date May 9, 2019,
PCT Pub. No. WO2018/088955, PCT Pub. Date May 17, 2018.
Application 17/555,944 is a reissue of application No. 16/348,580, filed on Nov. 9, 2017, granted, now 10,948,560, issued on Mar. 16, 2021.
Claims priority of application No. 1651469-7 (SE), filed on Nov. 9, 2016.
Int. Cl. G01R 33/563 (2006.01); A61B 5/055 (2006.01); G01R 33/483 (2006.01); G01R 33/54 (2006.01); G01R 33/56 (2006.01)
CPC G01R 33/56341 (2013.01) [G01R 33/4835 (2013.01); G01R 33/543 (2013.01); G01R 33/5608 (2013.01); A61B 5/055 (2013.01)] 16 Claims
OG exemplary drawing
 
[ 16. A method of performing diffusion weighted magnetic resonance measurements on a sample comprising partial volumes having different diffusion characteristics, and extracting information relating to the different diffusion characteristics and microscopic structures of the sample, the method comprising:
performing on the sample a first diffusion weighted magnetic resonance measurement with a first diffusion encoding sequence having a first diffusion weighting tensor representation B1 with at least two non-zero eigenvalues, and acquiring a first signal attenuation,
performing on the sample a second diffusion weighted magnetic resonance measurement with a second diffusion encoding sequence having a second diffusion weighting tensor representation B2 with at least two non-zero eigenvalues, and acquiring a second signal attenuation,
wherein the first tensor representation B1 and the second tensor representation B2 have a same number of non-zero eigenvalues;
wherein for the first diffusion encoding sequence,

OG Complex Work Unit Math
where n is a positive real number and μi(n) denotes eigenvalues of a tensor m(n) with elements

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where Fi(ω) and Fj*(ω) are ith and jth components of a normalized dephasing vector, respectively, of a normalized dephasing spectrum F(ω) representation of the first diffusion encoding sequence, and
for the second diffusion encoding sequence,

OG Complex Work Unit Math
where n is a positive real number and μi(n) denotes eigenvalues of a tensor m(n) with elements

OG Complex Work Unit Math
where Fi(ω) and Fj*(ω) are ith and jth eigenvector, respectively, of a normalized dephasing spectrum F(ω) representation of the second diffusion encoding sequence;
wherein the first and the second diffusion encoding sequences are configured to:
present a matching average spectral content in a sense that the custom characterμ(n)custom character calculated for the first diffusion encoding sequence matches the custom characterμ(n)custom character calculated for the second diffusion encoding sequence, and
to present a different degree of spectral anisotropy in a sense that the SA(n) calculated for the first diffusion encoding sequence differs from the SA(n) calculated for the second diffusion encoding sequence; and
generating an output indicative of a difference between the first and second signal attenuations. ]