advanced imaging techniques · 2018. 11. 29. · computer assisted clinical medicine medical...
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Advanced Imaging TechniquesX-Nuclei Imaging
Prof. Dr. Frank G. ZöllnerComputer Assisted Clinical MedicineMedical Faculty Mannheim Heidelberg University
Theodor-Kutzer-Ufer 1-3D-68167 Mannheim, Germany
[email protected]/inst/cbtm/ckm
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Learning Goals
� introduction to advanced imaging techniques in MR, CT and CBCT
� basic MRI principles -> Physics of Imaging Techniques
� Goals:
1. How does the technique work ?
2. What kind of images do we receive?
3. Where is this applied to ?
� Literature is given in the respective lectures
� Slides of the lectures at https://www.umm.uni-heidelberg.de/inst/cbtm/ckm/lehre/index.html
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Reading� Wetterling et al., Sodium-23 magnetic resonance imaging during and
after transient cerebral ischemia: multinuclear stroke protocols fordouble-tuned 23Na/1H resonator systems . Phys. Med. Biol. 2012(57) 6929
� Konstandin & Schad. 30 years of sodium/X-nuclei magnetic resonance imaging. Magn Reson Mater Phy (2014) 27: 1
� Konstandin, S. Development of 2D Radial Techniques for Sodium MRI with Application to Abdominal Imaging at 3Tesla.PhD Thesis, Heidelberg University, 2012
� Konstandin & Nagel. Measurement techniques for magnetic resonance imaging of fast relaxing nuclei. Magn Reson Mater Phy(2014) 27: 5
� Eisele, et al. Heterogeneity of acute multiple sclerosis lesions on sodium (23Na) MRI. Multiple Sclerosis.(2016). http://doi.org/10.1177/1352458515609430
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Outline
�Motivation
�Challenges of X-Nuclei MRI
� Imaging Techniques of 23Na
�Applications
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Motivation
� Ion fluxes in cells play an important role of cell activity� sodium–potassium pump (Na+–K+-ATPase), which pumps
3 Na+ ions out of and 2 K+ into the cell. � active transport mechanism is one factor
to keep the resting membrane potentialin cells at about −70 mV
https://www.slideshare.net/Amirrezagholizadeh1/sodium-potassium-pump
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Motivation
� Different ion-specific channels are able to transmit information via electrical signals by gating the flow of ions across the cell membrane.
� pathological change in concentration canbe visualized by X-nuclei MRI
� can give additional functional information Dr. John W. Kimball,
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/W/Welcome.html
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MR Properties of X-nuclei
nucleus spin Igyromagnetic
ratio γ[108 rad s-1 T-1]
natural abundanceof isotope
in %
sensitivityfor B0 = const.in % (rel. to 1H)
1H 1/2 2,675 99,98 100,00 MRI: 111 mol
25Mg 5/2 -0,164 10,00 2,68 × 10-2
33S 3/2 0,205 0,75 1,70 × 10-3
23Na23Na 3/23/2 0,7080,708 100,00100,00 9,279,27 MRI: 45 mmol
19F 1/2 2,518 100,00 83,40
31P 1/2 1,084 100,00 6,65
2H 1 0,410 0,01 9,60 × 10-1
1 0,193 99,63 1,00 × 10-114N16O 0 - 99,76 -17O 5/2 -0,363 0,04 1,11 × 10-3
13C 1/2 0,673 1,11 1,75 × 10-2
12C 0 - 98,89 -
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MR Properties of X-Nuclei – Exp. Sodium
Konstandin, S., PhD Thesis, Heidelberg University, 2012
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MR properties of X-nuclei
� low in vivo signal 10 000 – 50 000 times lowerthan 1H-signal
� short relaxation timesbrain tissue: T2f
* ≈ 4 ms, T2s* ≈ 30 ms, T1 ≈ 30 ms
relative sensitivity 19.27 ⋅ 10-2
in-vivo concentration [M] 11145 ⋅ 10-3
in-vivo sensitivity 14.59 ⋅ 10-5
signal deficit 22 000 0
Na23
11H1
1
Chalifa Tower, Dubai1H - 830 m
23Na - 183 mm35Cl - 48 mm39K - 4 mm
high SNR-efficiency & short echo times !!
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Imaging of 23Na
� broadband transmitter
� dedicated rf coils needed
� single tuned coils vs. double resonant coils
� dual-RF resonator allows for
� homogeneous transmit B+1
field
� highly sensitive receive B-1
field
preclinical coils
clinical coilsZöllner et al., NMR Biomed 2015
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Imaging of 23Na
� aim to record a proton density weighted image
� quantification of tissue sodium concentration
� relatively long TRs and UTEs are required to avoid T1 and T2* weighting in the images
� need for UTE sequences, radial readouts, rectangular RF pulse
� SNR increased by uniform k-space sampling
� measurement time: twisted projection, density adapted, etc.
Zöllner et al., NMR Biomed 2015
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k-space
2D
3D
TEmin ~ 0.4 ms !!
• radial projection technique• nonuniform k-space coverage
• SNR loss of 25.5 %α
readout
phase
TE
Lauterbur Nature 1973
23Na-Imaging: Radial Readout
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23Na-Imaging: Radial Readout
Konstandin & Nagel. Magn Reson Mater Phy (2014) 27: 5
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Imaging of 23Na: Quantification
� PD weighted images needed
� reference vials + CSF
� estimate T1 and T2 relaxation time
� T2reff= 7.15 msec, T2refl
= 33.7 msec
� tissue T1 and T2 relaxation time
� T1 = 34 ms
� T2tissf= 2.2 msec, T2tissl
= 20.4 msec
correction for T1 effects correction for T2 effectsHaneder et al, Radiology 2011Maril et al, Kidney Int., 2004
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Imaging of 23Na: Quantification
� accurate TSC quantification requires a reliable correction of the RF excitation field and coil sensitivity
� 3% deviation in B1 map → 5% error in concentration
� different techniques in 1H MRI proposed
� phase sensitive (PS)
� double angle method(DAM)
Lommen et al, NMR Biomed 2015Paschke et al, ESMRMB 2015
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Renal Sodium Imaging – Initial Studies in Human
� coronal projection of a 3D 23Na image of the human abdomen @3T
� (a) 25-min � (b) 12-min
� in-house build quadrature surface coil
� 3D gradient-echo sequence � TR/TE 30/1.8 ms, FOV 38 x 38 x
24 cm, and matrix 128x128 x16
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Renal Sodium Imaging – Cortico-Medullary SodiumGradient
normal condition 12h water deprivation
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Renal Sodium Imaging – Quantitative Approaches
� 3D DA-RAD sequence� TR/TE 120/0.55ms, FA
85°,FOV 320x320 mm� readout length per spoke was
20 msec, and 8000 projections
� total acquisition time of 16 minutes
� quantification of 23Na
T2w 23Na
normal condition water load
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Renal Sodium Imaging – Quantitative Approaches
T2w 23Na
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Renal Sodium Imaging – Quantitative Approaches
23Na concentration[mmol/l WTV]
Slope 23Na gradient[mmol/l /mm WTV]
cortex medulla
59 ± 17 99 ± 26 3.2 [1.5 6.3]
Conclusion� cortico-medullary sodium concentration gradient� wide inter-individual ranges � no significant correlations with age, gender, [23Na]serum, BMI, GFR, ADC, or
R2* values
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Renal Sodium Imaging – Studies of PathophysiologicProcesses
� assess post-radiotherapeuticrenal changes� 56-year-old patient
after adrenal stereotactic body radiotherapy
� cortico-medullary sodium gradient and sodium concentration are decreased in the left kidney
Haneder et al, Strahlenther. Onkol. 2012
[23Na] map 23Na/1H fusion 1H T2w
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Renal Sodium Imaging – Studies of PathophysiologicProcesses
� central diabetes insipidus� intranasal
administration of 20 µg desmopressin
Haneder et al, Magn. Reson. Mater. Phys. 2014
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Renal Sodium Imaging – Studies of PathophysiologicProcesses
� sodium removal from tissue stores in hemodialysis patients�
23Na-MRI quantitatively detects sodium stored in skin and muscle
� allows studying sodium storage reduction in ESRD patients
Dahlmann et al, Kidney Int. 2014
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Renal Sodium Imaging – Studies of PathophysiologicProcesses
� transplanted kidneys/ renal allograft loss� Sodium concentration was
lower in transplanted kidneys than in native kidneys(153.5± 11.9 vs. 192.9±9.6 mM)
� Sodium gradient of transplanted kidneys was lower than for native kidneys(8.9±1.5 vs. 10.5±0.9 mM/ mm)
Moon et al, Eur. Radiol. 2014
nativ
etr
ansp
lant
ed
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Bain Sodium Imaging – Multiple Sclerosis
� MRI the most practical and widely applied biomarker to detect signs of pathological change and inflammatory activity
� sodium MRI is a sensitive marker of very subtle tissue normalities
� recent studies that identified elevated TSC values in chronic lesions
Eisele, et al. Multiple Sclerosis.(2016)
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Bain Sodium Imaging – Stroke
� final infarction in acute stroke dependent on several factors
� individual vascular collateral flow,
� admission glucose levels, hematocrit level and blood pressure,
� the most determining factor though is the time until recanalization and reperfusion is achieved
� concept of DWI/PWI mismatch strongly underestimates the amount of still viable tissue
Neumaier-Probst et al. (2015). International Journal of Stroke, 10(SA100), 56–61
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Sodium Cancer Imaging
Madelin and Regatte J Magn Reson Imaging. 2013
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Muscle Skeleton Imaging
Madelin and Regatte J Magn Reson Imaging. 2013
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Muscle Skeleton Imaging
Madelin and Regatte J Magn Reson Imaging. 2013