US 9,791,534 B2Granted

Pulse sequence method for MRI

AssigneeCR Development AB

InventorsDaniel Topgaard, Samo Lasic, Markus Nilsson

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Abstract

The present invention describes a method for magnetic resonance (MR) and/or MR imaging, comprising acquisition of signals and MR images originating from a RF and gradient sequence causing isotropic diffusion weighting of signal attenuation, wherein the isotropic diffusion weighting is achieved by one time-dependent dephasing vector q(t) having an orientation, wherein the isotropic diffusion weighting is proportional to the trace of a diffusion tensor D, and wherein the orientation of the time-dependent dephasing vector q(t) is either varied discretely in more than three directions in total, or changed continuously, or changed in a combination of discretely and continuously during the gradient pulse sequence, 0≦t≦echo time, where t represents the time. The method may be performed during a single shot (single MR excitation).

Claims9

Dependent claims

A method for magnetic resonance (MR) and/or MR imaging, the method comprising:

performing a diffusion encoding scheme comprising a radio frequency (RF) and gradient sequence causing an isotropic diffusion weighting;
and
acquiring signals resulting from the diffusion encoding scheme,
wherein the isotropic diffusion weighting is proportional to a trace of a diffusion tensor D,
wherein the isotropic diffusion weighting is achieved by one time-dependent dephasing vector q(t) having an orientation,
wherein the orientation of the time-dependent dephasing vector q(t) is varied discretely in more than three directions in total, changed continuously, or changed in a combination of discretely and continuously during a gradient pulse sequence, 0≦t≦tE, where t represents time and tE represents echo time,
wherein the isotropic diffusion weighting is invariant under rotation of the diffusion tensor D and wherein an equation
∫
0
t
E
⁢
F
⁡
(
t
)
2
⁢
q
^
T
⁡
(
t
)
·
D
·
q
^
⁡
(
t
)
⁢
⁢
d
⁢
⁢
t
=
t
d
⁢
D
_
is fulfilled, F(t) being a time-dependent normalized magnitude of the dephasing vector, {circumflex over (q)}(t) being a time-dependent unit direction vector, td being an effective diffusion time given by
t
d
=
∫
0
t
E
⁢
F
⁡
(
t
)
2
⁢
⁢
d
⁢
⁢
t
and D being an isotropic mean diffusivity.

66 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/398,325Filed 3 May 2013 · us provisional application
Priority: SE 12504524 May 2012
Published: US 2015/0115957 A130 Apr 2015
Granted: 17 Oct 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

G01R 33/565
Image enhancement or correction, e.g. subtraction or averaging techniques , e.g. improvement of signal-to-noise ratio and resolution: correction…
G01R 33/4818
NMR imaging systems: mR characterised by data acquisition along a specific k-space trajectory or by the temporal order of k-space coverage, e.g.…
G01R 33/5615
By reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences: echo train techniques involving acquiring…
G01R 33/56341
Of moving material, e.g. flow contrast angiography: diffusion imaging