Samenvatting - DEEL MACRO Biomedical Imaging (1080FBDBMW)

Technieken

Full name ‘Waves’ Processes Image
CT Radiography X-ray Ana –
Computerized Tomography (Phys)

MRI Magnetic Resonance Radiowave Ana – Phys
Imaging s - Meta–
(Mole)
PET Positron Emission γ-wave (Phys) –
SPECT Tomography Meta - Mole
Single Photon CT
Optic Optical imaging Visible light Mole –
al Bioluminescence imaging meta –
(phys)
US UltraSound Soundwave Ana – Phys
(echo) s – (Meta)

,MRI
General:

 Magnet
 Superconducting coils
o Shim coils
o RF coils
o Gradient coils
 Magnetic field (M)
o Has Field strength (B) in Tesla (T)
 Clinical: 0,5-3T  resolution: 1-3mm
 Preclinical: 7-9,3T  resolution: 70-125µm
o Generated by coils
o Higer field  higher resolution (better alignment of + protons in
M)
 NMR (= Nuclear Magnetic Resonance)
o Signal from protons (Hydrogen)!!  has magnetic moment: ½ spin
 electric current  Mz in time
o Alignment towards M
 Parallel (low energy state) OR anti-parallel
 Precision = protons never perfectly aligned with M
 Protons at equilibrium (Mz)  Give F pulse (Mxy)  change
orientation  restore over time  T1 or T2
 Relaxation processes  Gives contrast
o T1 – relaxation (restored to normal Mz)
o T2 – relaxation (not restored 0)

TR / TE time Image Liquid Fat
(ms)
T1 Short (500/15) Brighter Dark Bright
T2 Long (3000/90) Darker Bright Dark

, Structural Measurement

 Volumetric MRI
o Spatial Normalization
o Huntington Disease
 Contrast agents
o Diamagnetic ions  only paired e-  antiparallel to B0
o Paramagnetic ions  one unpaired e-  parallel to B0  shorten
T1 of water
 Gadolinium  leakage in BBB
o Ferromagnetic ions  dephasing faster (T2)  darker contrast
enhanced
 Fe2+ ( vb: to detect Microbleeds)
 Diffusion microstructural MRI
o Isotropic diffusion profile (low FA)  Free diffusion




o
o Anisotropic diffusion profile (high FA)  Preference diffusion
 Axon has preference diffusion (λ1 forward)

λ1 = Axial Diffusity (AD)

λ2 , λ3 = Radial Diffusity
(RD)
o