# US 11,112,479 B2 · Method and a MRI apparatus for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI)

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,112,479 B2
- Document ID: US11112479B2
- Status: Granted
- Kind: B2
- Application number: 16/757,098
- Filed: 2018-10-15
- Published: 2020-07-30
- Granted: 2021-09-07
- Earliest claimed: 2017-10-19
- Assignees: Universiteit Maastricht; Academisch Ziekenhuis Maastricht
- Applicants: Universiteit Maastricht; Academisch Ziekenhuis Maastricht
- Inventors: Alard Roebroeck; Benedikt Poser; Francisco Lagos Fritz
- Web page: https://patentgrep.com/patent/US11112479B2

## CPC

- G01R 33/561: by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
- G01R 33/288: {Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room}
- G01R 33/4835: {of multiple slices}
- G01R 33/5602: {by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse}
- G01R 33/5659: {caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

The invention also relates to a MRI apparatus for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI), said MRI apparatus at least comprising: a housing defining a target area for accommodating said human and/or animal subject; at least one main magnet unit and at least one magnetic gradient unit for applying—during use—one or more magnetic field gradients along three independent orthogonal spatial axes in said target area, as well as at least one radiofrequency (RF) pulse generation unit for applying one or more sets of RF pulses towards said target area; a RF receiving unit for acquiring MRI signals possibly having multi-channel spatially sensitive characteristics; and a computer processing unit for processing said acquired MRI signals and for producing said magnetic resonance image data.

## Claims

### Claim 1

A method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI), said method comprising at least the steps of:
A applying, to said human and/or animal subject being positioned in an MRI scanning apparatus, during subsequent total block times TBj with j ϵ [1, 2, . . . , K] a first set of spatially selective RF pulses (Exc0-Sto0-Rec0) in a sequence block SB(j,0), with in a sub-sequence block SBA(j,0) of said sequence block SB(j,0) at least a first RF pulse (Exc0) at t=t1(j,0) and a second RF pulse (Sto0) at t=t2(j,0) and in a sub-sequence block SBB(j,0) of said sequence block SB(j,0) at least a third RF pulse (Rec0) at t=t3(j,0), with t1(j,0)<t2(j,0)<t3(j,0), with each RF pulse simultaneously exciting respective M0 slices in the target volume of the human and/or animal subject, thereby causing the subject to emit MRI signals, said MRI signals at least comprising stimulated-echo (STE) MRI signals producing data for M0 slices in said target volume;
B acquiring during said total block times TBj at least the MRI signals with at least a RF receiving unit having spatial sensitive characteristics; and
C computer-processing the MRI signals as acquired with said RF receiving unit in order to produce magnetic resonance image data for each of said M0 slices of the target volume; and wherein the method further comprises the step of:
D applying, to said human and/or animal subject being positioned in said MRI scanner, at least a further sequence block SB(j,i) (with i ϵ [1, N]) of spatially selective RF pulses (Exci-Stoi-Reci), with in a sub-sequence block SBA(j,i) of said further sequence block SB(j,i) at least a first RF pulse (Exci) at t=t1(j,i) and a second RF pulse (Stoi) at t=t2(j,i) and in a sub-sequence block SBB(j,i) of said sequence block SB(j,i) at least a third RF pulse (Reci) at t=t3(j,i) with t1(j,i)<t2(j,i)<t3(j,i) and with sub-sequence block SBA(j,i) taking place after sub-sequence block SBA(j,i-1) but prior to sub-sequence block SBB(j,i-1) and with sub-sequence block SBB(j,i) taking place after sub-sequence block SBB(j,i-1) with each RF pulse simultaneously exciting respective Mi slices in the target volume of the human and/or animal subject, thereby causing the subject to emit further MRI signals, said further MRI signals at least comprising stimulated-echo (STE) MRI signals producing further data for ΣNi=1Mi slices in said target volume.

### Claim 2

A MRI scanning apparatus for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI), said MRI scanning apparatus at least comprising:
a housing defining a target area for accommodating said human and/or animal subject;
at least one main magnet unit and at least one magnetic gradient unit for applying—during use—one or more magnetic gradient fields in said target area, as well as
at least one radiofrequency (RF) pulse generation unit for applying, during subsequent total block times TBj with j ϵ [1, 2, . . . , K]a first set of spatially selective RF pulses (Exc0-Sto0-Rec0) in a sequence block SB(j,0), with in a sub-sequence block SBA(j,0) of said sequence block SB(j,0) at least a first RF pulse (Exc0) at t=t1(j,0) and a second RF pulse (Sto0) at t=t2(j,0) and in a sub-sequence block SBB(j,0) of said sequence block SB(j,0) at least a third RF pulse (Rec0) at t=t3(j,0), with t1(j,0)<t2(j,0)<t3(j,0), with each RF pulse simultaneously exciting respective M0 slices in the target volume of the human and/or animal subject, thereby causing the subject to emit MRI signals, said MRI signals at least comprising stimulated-echo (STE) MRI signals producing data for M0 slices in said target volume;
a RF receiving unit for acquiring during said total block times TBj said MRI signals having spatial sensitive characteristics; and
a computer processing unit for processing said acquired MRI signals and for producing said magnetic resonance image data, wherein said (RF) pulse generation unit is arranged to apply, to said human and/or animal subject being positioned in said MRI scanner, at least a further set i (with i ϵ [1, . . . , N]) of spatially selective RF pulses (Exci-Stoi-Reci) in a further sequence block SB(j,i) (with i ϵ [1, . . . , N]), with in a sub-sequence block SBA(j,i) of said further sequence block SB(j,i) at least a RF pulse Exci at t=t1(j,i) and a RF pulse Stoi at t=t2(j,i) and in a sub-sequence block SBB(j,i) of said sequence block SB(j,i) at least a RF pulse Reci at t=t3(i,j), with t1(j,i)<t2(j,i)<t3(j,i) and with sub-sequence block SBA(j,i) taking place after sub-sequence block SB(j,i-1) but prior to sub-sequence block SBB(j,i-1) and with sub-sequence block SBB(j,i) taking place after sub-sequence block SBB(j,i-1), with each RF pulse simultaneously exciting respective Mi slices in the target volume of the human and/or animal subject, thereby causing the subject to emit further MRI signals, said further MRI signals at least comprising stimulated-echo (STE) MRI signals producing further data for ΣNi=1Mi slices in said target volume.

### Claim 3 (depends on 1)

Method according to claim 1, wherein said MRI signals also comprises spin-echo (SE) MRI signals acquired in sub-sequence block SBA(j,i).

### Claim 4 (depends on 1)

Method according to claim 1, wherein each set i (with i ϵ [0, 1, . . . , N]) of spatially selective RF pulses comprises:
the RF excitation pulse (Exci) exhibiting a flip angle α1 exciting magnetization into the transverse plane,
the RF storing pulse (Stoi) exhibiting a flip angle α2 for refocussing one part of the magnetization into a spin-echo, thereby causing the subject to emit, during said total block time TBj N+1 spin-echo MRI signals, and storing another part of the magnetization along the longitudinal axis, and
the RF recalling pulse (Reci) exhibiting a flip angle α3 for recalling the magnetization, which was stored along the longitudinal axis, to the transverse plane into a stimulated-echo, thereby causing the subject to emit, during said total block time TBj, N+1 stimulated-echo MRI signals and where each Stoi and Reci RF pulse are each surrounded by two gradient pulses with a defined vector orientation over three orthogonal gradient axes.

### Claim 5 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein for each sequence block SB(j,i) each of the sets of RF pulses being applied comprises a RF pulse Exci applied at t=t1(j,i), a RF pulse Stoi applied at t=t2(j,i) and a RF pulse Reci applied at t=t3(j,i), with t1(j,i)<t2(j,i)<t3 (j,i), and with t1(j,i-1)<t1(j,i), t2(j,i-1)<t2(j,i), t3(j,i-1)<t3(i,j) and with t2(j,i-1)<t1(j,i), . . . , t1(j,N)<t3(j,i-1) and with t2(j,i-1)<t2(j,i), . . . , t2(j,N)<t3(j,i-1).

### Claim 6 (depends on 3)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 3, further comprising the steps of:
between t2(j,i) and t3(j,i) acquiring T2-weighted and diffusion-weighted spin-echo (SE) MRI signals;
after t3(j,i) acquiring T1, T2 and diffusion-weighted stimulated-echo (STE) MRI signals.

### Claim 7 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein the sets of RF pulses are a sequence of RF pulses with flip angle with flip angle 0°<α1≤180°, in particular the Exci RF excitation pulse of each sequence block exhibits a flip angle 0°<α1<180°, and the Stoi RF storing pulse of each sequence exhibits a flip angle 0°<α2<180° and the Reci RF recalling pulse of each sequence exhibits a flip angle 0°<α3<180°.

### Claim 8 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein each RF pulse is a single-band or multi-band/simultaneous multi-slice RF pulse.

### Claim 9 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein each slice selected by a single-band or multi-band pulse is spatially encoded along the slice direction by additional phase encoding.

### Claim 10 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein Mi=M for i ϵ [0, 1, . . . , N] in which case the total number of slices acquired from in a total block time is (N+1)*M.

### Claim 11 (depends on 1)

The method for obtaining images of a target volume of a human and/or animal subject using magnetic resonance imaging (MRI) according to claim 1, wherein each RF storing pulse (Stoi) is surrounded by two gradient pulses (q1i-q2i, with i ϵ [0, 1, . . . , N]), respectively, with a defined vector orientation over three orthogonal gradient axes, and each RF recalling pulse (Reci) is surrounded by two gradient pulses (q3i-q4i, with i ϵ [0, 1, . . . , N]), respectively, with a defined vector orientation over three orthogonal gradient axes and in a further example q1i=q1 for i ϵ [0, 1, . . . , N], q2i=q2 for i ϵ [0, 1, . . . , N], q3i=q3 for i ϵ [0, 1, . . . , N], and q4i=q4 for i ϵ [0, 1, . . . , N], and q1i=q2i=q4i for i ϵ [0, 1, . . . , N].

### Claim 12 (depends on 2)

The MRI scanning apparatus according to claim 2, wherein said MRI signals also comprises spin-echo (SE) MRI signals.

### Claim 13 (depends on 2)

The MRI scanning apparatus according to claim 2, wherein said RF pulse generation unit is arranged in applying a set i (with i ϵ [0, 1, . . . , N]) of spatially selective RF pulses, of which
the RF excitation pulse (Exci) exhibiting a flip angle α1 exciting magnetization into the transverse plane,
the RF storing pulse (Stoi) exhibiting a flip angle α2 for refocussing one part of the magnetization into a spin-echo, thereby causing the subject to emit, during said total block time TBJ N+1 spin-echo MRI signals, and storing another part of the magnetization along the longitudinal axis, and
the RF recalling pulse (Reci) exhibiting a flip angle α3 for recalling the magnetization, which was stored along the longitudinal axis, to the transverse plane into a stimulated-echo, thereby causing the subject to emit, during said total block time TBj, N+1 stimulated-echo MRI signals and where each Stoi and Reci RF pulse are each surrounded by two gradient pulses with a defined vector orientation over three orthogonal gradient axes.

### Claim 14 (depends on 2)

The MRI scanning apparatus according to claim 2, wherein said (RF) pulse generation unit is furthermore arranged in applying, for each sequence block SB(j,i) and for each of the sets of RF pulses, a RF pulse Exci applied at t=t1(j,i), a RF pulse Stoi applied at t=t2(j,i) and a RF pulse Reci applied at t=t3(j,i), with t1(j,i)<t2(j,i)<t3(j,i), and with t1j, i-1)<t1(j,i), t2(j,i-1)<t2(j,i), t3(j,i-1)<t3(j,i) and with t2(j,i-1)<t1(j,i), . . . , t1(j,N)<t3(j,i-1) and with t2(j,i-1)<t2(j,i), . . . , t2(j,N)<t3(j,i-1).

### Claim 15 (depends on 14)

The MRI scanning apparatus according to claim 14, wherein the RF receiving unit is further arranged in:
acquiring between t2(j,i) and t3(j,i) T2-weighted and diffusion-weighted spin-echo (SE) MRI signals; and
acquiring after t3(j,i) T1, T2 and diffusion-weighted stimulated-echo (STE) MRI signals.

### Claim 16 (depends on 1)

The MRI scanning apparatus according to claim 1, wherein said RF pulse generation unit is furthermore arranged to apply the sets of RF pulses as a sequence of RF pulses with flip angle with flip angle 0°<αi<180°, wherein in particular the Exci RF excitation pulse of each sequence exhibits a flip angle 0°<α1<180°, and the Stoi RF storing pulse of each sequence exhibits a flip angle 0°<α2<180° and the Reci RF recalling pulse of each sequence exhibits a flip angle 0°<α3<180°.