Cho Cre Cit RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY Basic MRI principles Yves De...
-
Upload
erin-norris -
Category
Documents
-
view
214 -
download
0
Transcript of Cho Cre Cit RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY Basic MRI principles Yves De...
ChoCreCit
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Nuclear Magnetic ResonanceNMRNMR
MRIMRS MRR
MMagnetic RResonanceSSpectroscopy
MMagnetic RResonance IImaging
MMagnetic RResonanceRRelaxometry
Molecular Composition
Spatial Tissue Differentiation
Molecular Dynamics
Basic MRI principles Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
MRIMRS MRR
MMagnetic RResonanceSSpectroscopy
MMagnetic RResonance IImaging
MMagnetic RResonanceRRelaxometry
Spectra Images Relaxation times,Diffusion coefficients
Yves De Deene
NMR imaging is non-invasive
Strong static magnetic field
Radiofrequent electromagnetic waves
Space and time dependent magnetic fields
Basic MRI principles
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Yves De Deene
Water
H2O
mp = 1,67.10-24 g
mp = 0,00000000000000000000000167 g
+++++++
++ + qp = 1,6.10-19 C
qp = 0,00000000000000000016 C
Properties of the atomic nucleus
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
Isidor Isaac RabiZ
N
Z
Z
N
N
H
z
H
z
Spin reservoirovenMolecular beam apparatus
Basic MRI principles
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Discovery of nuclear magnetic resonance19381938
In resonance
Off resonance
Yves De Deene
Edward Purcell
IDC
N
S
Electromagnetic wavewith fixed frequency f
Block of parafin
IDC ~ B
Absorption
B
2 fB
B
-1/2
+1/2
E
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Nobel price physics (Bloch & Purcell) in 1952
Nuclear magnetic resonance in a block of parafin19461946
Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Nuclear magnetic resonance mathematical descriptionThe Bloch equations19461946
Felix Bloch
L
G
B
Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
B
Precession in a magnetic field
Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
MRI signal generation
Water molecule
Hydrogen proton transmits a radiofrequent electromagnetic wave (yellow) after excitation by an RF pulse (red)
B0 B0B0
EXCITATION PULSE
COIL
Image Processing(2D-FFT)
Cryogenic magnet
Gradient coils
Radiofrequency transmit/receive coil
Basic MRI principles Yves De Deene
Excitation
COILOBJECT:
Spin system
Signal reception
COILOBJECT:
Spin system
MRI signal excitation / reception
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
Raymond V. Damadien
First MRI scan
Resonance conditionfulfilled
f=B
Inhomogeneous magnetic field
Raymond V. Damadien
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
The first MRI scanner
19721972
Yves De Deene
Mobile MR unitOpen MR unit
Interventional MR unitClinical MR scanner Animal MR scanner
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Current MR scanners
Yves De Deene
MRI signal generationYes, but... what about spatial encoding ??
-1210-910-610-3101310610910
6103101-310-610-910-1210-1510
6103101 910 1210 1510 1810 2110
nuclear
Gamma-rays
X-raysUV
visible
inner
electrons
inner & outer
electrons
outer electrons
molecular vibrations
and rotations
electron spin
nuclear spin
IRTera-hertz
micro-wave
radiofrequency
SH
F
Frequencyf (Hz)
Photon energy E (eV)
EH
F
UH
F
VH
F
HF
MF
LFVLF
ULF
SLF
ELF
Wave length (m)
Interaction with matter
MRI X-ray CT
?
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
MRI encodingAn analogon in acoustics
1
2
3
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
MRI encoding: slice selectionAn analogon in acoustics
1
2
3
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
MRI encoding: Slice selection
64.8 MHz
f = 64.8 MHz
1.52 T
B
z
GRADIENT COILS
z-coil
x-coil
y-coil
patient
X-gradient
Y-gradient
Z-gradient
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
MRI frequency encodingAn analogon in acoustics
1
2
3
Frequency encoding
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
MRI frequency encoding
B
B
B
RF COIL
Fouriertransform
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
Richard Ernst
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
2D spatial encoding
Yves De Deene
OUT OF PHASE
In free space In human tissue
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Dephasing – T2* decay
Yves De Deene
IN PHASE
EXCITATIONPULSE(90°)
The spin-echo sequence
Z
N
TURN BACK !!TE/2 TE/2
REFOCUSSINGPULSE(180°)
EXCITATIONPULSE(90°)
REFOCUSSINGPULSE(180°)
19491949
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequenceSlice selection
SLICE SELECTION
B
z
(90°)
f = 64.8 MHz
1.52 T
1.52 T
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequencePhase encoding
(90°)
PHASE ENCODING
B
y
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequenceFrequency encoding
(90°)
1.43
FREQUENCY ENCODING
B
y
T1.5 1.53
(180°)
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequence
TE/2 TE/2
90°PULSE
180°PULS
GSL
GRO
GPH
TE/2 TE/2
90°PULSE
180°PULSE
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequence
TE/2 TE/2
90°PULSE
180°PULSE
GSL
TE/2 TE/2
90°PULSE
180°PULSE
fc slice I
TE/2 TE/2
90°PULSE
180°PULSE
GSL
fc+f slice II
fc
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
The spin-echo sequence
SLICE SELECTION
2D-FOURIERTRANSFORM
FREQUENCY AND PHASE ENCODING
AMPLITUDEIMAGE
FREQUENCY
PHASE
z
( , , , ) ( , , , ) ( , , , ) xy x yM x y z t M x y z t j M x y z t
( , , , )0( , , , ) ( , , , ) e j x y z t
xyM x y z t M x y z t
(f)
(f ,
( ) ( , , , )xyV
M t M x y z t dx dy dz
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
K-space
( , , , )0 ( , , , ) e j x y z t
xyM M x y z t
0
0 0 0
( , , , ) ( ') ' ( ') ' ( ') 't t t
x y zx y z t B t x G t dt y G t dt z G t dt with
0 0
( ) ( )( , ) ( , , ) x yj k t x k t y
x yS k k M x y z z e dx dy
For 2D imaging (z = z0)
0
( ) ( ) ( ).( , , ) ( , , ) x y zj k t x k t y k t z
x y z VS k k k M x y z e dx dy dz For 3D imaging (ignoring relaxation)
S(kx,ky)
0
( ) ( )( , , ) ( , ) x yj k t x k t y
x y x yx y z z C S k k e dk dk
2D FFT
(x,y,z=z0)
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
K-space
x xk G t
y yk G t
Spin-echo
Phase EncodingGradient
( , , , )0 ( , , , ) e j x y z t
xyM M x y z t 0
0 0 0
( , , , ) ( ') ' ( ') ' ( ') 't t t
x y zx y z t B t x G t dt y G t dt z G t dt with
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
K-space
FFT
REAL IMAGINARY
MAGNITUDE PHASE
k-space
0 0
( ) ( )( , ) ( , , ) x yj k t x k t y
x yS k k M x y z z e dx dy
REAL IMAGINARY
MAGNITUDE PHASE
Image space
0
( ) ( )( , , ) ( , ) x yj k t x k t y
x y x yx y z z C S k k e dk dk
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
CBA
Walking through K-spaceThe spin echo sequence
GSL
GRO
GPH
TE/2 TE/2
90°PULSE
180°PULS
= Gx
= Gy
= Gz
D
A
B
C
D
E
E
ky
kx
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
CBA
Walking through K-spaceThe spin echo sequence
GSL
GRO
GPH
TE/2 TE/2
90°PULSE
180°PULS
= Gx
= Gy
= Gz
D
A
B
C
D
E
E
ky
kx
Imaging time = TR. NEX.Nphase
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles Yves De Deene
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Spin-lattice and spin-spin decayDipolar interaction
time
B0
time
B0
Spin-spin decay T2Spin-lattice decay T1
Longitudinal relaxation Transverse relaxation
Yves De Deene
INTERMEDIATELAYER
FREEWATER
Hydrogen bridges
C
CO
O
C N BOUNDLAYER+
+ +
+
--
-+
+
- - +
-
- +
+++
Protein, polymer, cell membrane
Low mobility
High mobility
+
M
M
M
t
t
t
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Spin-spin decay and molecular dynamics
Yves De Deene
Anatomical imaging:Multiple sclerosis
Proton density(sagital)
T2 weighted(transverse)
T1 weighted With contrastagent
Proton density(transverse)
Cluster analysis (T1w, T2w, PDw)
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Anatomical imaging: Multiple sclerosis
Yves De Deene
Anatomical Imaging:Arterio venous diseases
Arterio venous malformation (AVM)
T2 weighted(transverse)
MR angiography
Aneurism
MR angiography MR angiography
Thrombosis
MR angiographyT2 weighted
Infarct (‘stroke’)
Proton density
Proton density
Neck trauma
T2 weighted
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Arterio venous diseases
Yves De Deene
Anatomical imaging:Oncology
T2 weighted (chondrosarcoma)
T2 weighted (cyst)
Protondensity(Brain metastasis)
T1 weighted with contrastagent(Breast carcinoma)
T2 weighted(prostate tumor)
T2 weighted (cervix carcinoma)
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Oncology
Yves De Deene
Anatomical imagingBone and soft tissue
Osteoporosis (femur)
T2 weighted(torn ligaments)
rheumatoid arthritiswhrist
rheumatoid arthritisknee
T2 weighted(hernia)
RESEARCH GROUP QUANTITATIVE MRI IN MEDICINE AND BIOLOGY
Basic MRI principles
Bone and soft tissue
Yves De Deene
I visited Copenhagen frequently after the war. At one point, I gave a talk in Copenhagen, and then afterwards we met with Bjerrum. Bjerrum was a chemist and a great friend of Niels Bohr… Bohr said to him: “You know, what these people do is really very clever. They put little spies into the molecules and send radio signals to them, and they have to radio back what they are seeing.” I thought that was a very nice way of formulating it. That was exactly how they were used. It was not anymore the protons as such. But from the way they reacted, you wanted to know in what kind of environment they are, just like spies that you send out. That was a nice formulation.
- Felix Bloch -