1 research topics 08/01/2013luis agulles pedrós. 2 hyperpolarized gases monitoring of fruits...
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Luis Agulles Pedrós 2
• Hyperpolarized gases
• Monitoring of fruits ripening
• MRI Spectroscopy
• Diffusion and perfusion
• Fractional Fourier Transform
• X-ray phase contrast imaging
Research topics
08/01/2013
Medical Physics Master Thesis
Luis Agulles Pedrós 4
Gas transfer by artificial lung
• Use of porous membranes for blood oxygenation
• Possibility of continuous flow polarized Xe in liquid
Pore size ~ 0.03 µm
Gas
Liquid
Pump NMRCoil
Membrane
Gas
Hyperpolarized gases
08/01/2013 Paul Zänker’s work
Luis Agulles Pedrós 5
129Xe NMR spectra for different solvents
LipofundinD = 193.4 ppm
Albumin D = 197.7 ppm
Gelafundin D = 192.3 ppm
Glucose D = 203.7 ppm
gaseous Xe
NM
R s
igna
l [a
.u]
050100150200 050100150200
D
0
10
10
10
1
d [ppm]dissolved Xe
Delivery of polarized Xenon through membranes into
different potential carrier liquids possible without
destruction of polarization and bubbling
Hyperpolarized gases
08/01/2013 Paul Zänker’s work
Luis Agulles Pedrós 6
“volunteer”
3He applicator coil
10% 3He in 4He 10% 3He in N2 10% 3He in SF6
rati
o
(weak/s
trong
)
stro
ngly
diff
usi
on
weig
hte
d
weakly
diff
usi
on
weig
hte
db
= 3
890
0 s/
m2
b =
15
00 s
/m2
SNR gain is highest for large airspaces
(trachea).
SNR decreases from 4He to SF6
(slowed down of diffusion more
effectively by the heavier BG).
Ratio images can be obtained in the
smaller airspaces up to bronchi, clearly
visible for helium.
images of different gas mixtures for 2 different b-values
Acq. αr.f.
Gfreq
Gphase time
time
Hyperpolarized gases
08/01/2013
Luis Agulles Pedrós 7
• Hyperpolarized gases
• Diffusion and perfusionOn-going Master thesis“professionalizer”
08/01/2013
Luis Agulles Pedrós 8
Diffusion and perfusion
IVIM model )()0()( *
1 DDbbDS
bS efef
Koh et al. AJR, 160, p1352 june 2011Jensen NMR Biomed. 2010 August ; 23(7): 698–710
bDS
bS ef 1)0()(
6/ln 22)0()( KDbbDfS
bS
D: Diffusion D*: pseudo-diff, perfusionK: Kurtosis, Gausss. differ.f : Perfusion frac. (#D* vs. #D* )
>D
low b-val
Comparison of different approximations of the IVIM model in prostate cancer
08/01/2013
D* (velocity, distance): capillary
D: Gaussian distribution (PSF), tissue diff
Luis Agulles Pedrós 908/01/2013
f-map prostate
to improve: better fit, filters, more data…
Diffusion and perfusion
)()0()( *
1 DDbbDS
bS efef
bDS
bS ef 1)0()(
6/ln 22)0()( KDbbDfS
bS
Objectives: Comparison• Contrast• SNR• Acq. time• Optimization of parameters• …
bDS
bS e)0()(