1 July 2009 Recent advances in quantitative MR spectroscopy Anke Henning, PhD Institute for Biomedical Engineering, University and ETH Zurich, Switzerland AAPM 2009 – Quantitative MRI and MRS Symposium Cho tCr Ins tCr Glx Glx NAA Gln NAA 3T Courtesy: Dept. of Radiology, University of Bonn, Germany Courtesy: Dept. of Radiology, University of Bonn, Germany MOTIVATION: non-invasive metabolite quantification
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Recent advances in quantitative MR spectroscopy · Recent advances in quantitative MR spectroscopy Anke Henning, PhD Institute for Biomedical Engineering, University and ETH Zurich,
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1
July 2009
Recent advances in quantitative MR spectroscopy
Anke Henning, PhDInstitute for Biomedical Engineering, University and ETH Zurich, Switzerland
AAPM 2009 – Quantitative MRI and MRS Symposium
Cho tCr
Ins
tCr
GlxGlx
NAA
Gln
NAA
3T
Courtesy: Dept. of Radiology, University of Bonn, GermanyCourtesy: Dept. of Radiology, University of Bonn, Germany
coil loadreceive gain settingsvolumetemperaturpHconductivity
are considered
B1 inhomogeneities power optimization
are considered forthe same type of nucleus (f.i. internalwater reference for 1H MRS)
internal water or referencemetabolite concentrations as well as all relaxation times depend on:
agevoxel composition (f.i. CSF content)
and change in pathologies
B1 inhomogeneities PO
are not considered fordifferent types of nuclei(f.i. internal water referencefor 31P and 13C MRS)
AAPM 2009 – Quantitative MRI and MRS Symposium
QUANTIFICATION: external reference calibration
External reference calibrationphantom with known concentrationB1 variations should be taken into account especiallyfor surface coilsbe sure the same preparation settings are used
(f.i. receiver gain & power optimizations, shimming)
additional reference spectrumneeded each timereceive gain settingsvolumetemperaturpHconductivityB1 inhomogeneitiespower optimizationrelaxation times of in vivo metabolites
need to be consideredby adjustments or correctionfactors determined byadditional measurements
known & stableconcentration forreference standard
known relaxation timesfor reference standard
coil load is directlyconsidered
AAPM 2009 – Quantitative MRI and MRS Symposium
QUANTIFICATION: symmetrical phantom calibration
Symmetric phantom calibrationphantom with known concentrationbe sure the same preparation settings are used for localized version(f.i. receiver gain & power optimizations, shimming)
additional reference spectrumneeded each timereceive gainvolumetemperaturpHconductivityrelaxation times of in vivo metabolites
need to be consideredby adjustments or correctionfactors determined byadditional measurements
known & stableconcentration forreference standard
known relaxation timesfor reference standard
coil load is directlyconsideredB1 inhomogeneities aredirectly considered ifconductivity of phantom isadjusted to in vivo valuesand PO is not repeated forphantom measurement
AAPM 2009 – Quantitative MRI and MRS Symposium
QUANTIFICATION: phantom replacement method
make sure to adjust coil load to in-vivo condition by moving the saline tube in or out each time
correction for receiver gain is necessary
power optimization & shim differences are not considered
coil load (additional reference spectrumneeded each time)receive gain settingsvolumetemperaturpHconductivityB1 inhomogeneities PO relaxation times of in vivo metabolites
need to be consideredby adjustments or correctionfactors determined byadditional measurements
known & stableconcentration forreference standardknown relaxation timesfor reference standard
AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: Electric REference To access In vivo Concentrations
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
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AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: Fitting with LC Model & TDFD fit
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: Electric REference To access In vivo Concentrations
Why ERETIC?
1H MRS @ 1.5T and 3T: reliable reference standard in lesions where waterconcentration is unknown
no internal reference availablewater reference is unreliable sincetransmit and receive fields of waterand heavy nucleus are very different at 3T & 7T
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AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: optical signal transmission
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: optical vs. electrical signal transmission
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
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AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: scaling with coil load
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: stability over time
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
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AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: phantom calibration
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
AAPM 2009 – Quantitative MRI and MRS Symposium
ERETIC: cross validation with internal water reference
Heinzer-Schweizer et al, ISMRM 2009: 232
courtesy of IBT, University and ETH Zurich
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AAPM 2009 – Quantitative MRI and MRS Symposium
31P MRS: simultaneous 1H decoupling and ERETIC
Schweizer et al, ISMRM 2008: 193.
ATP ATP
courtesy of IBT, University and ETH Zurich
AAPM 2009 – Quantitative MRI and MRS Symposium
JPRESS & ERETIC
ERETIC NAA Cho Cr Cr
in vivo, 3T, GM rich voxel
H2OMM
Fuchs et al, ISMRM 2009: 2405.
courtesy of IBT, University and ETH Zurich
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AAPM 2009 – Quantitative MRI and MRS Symposium
QUANTIFICATION: ERETICAdvantages Disadvantages
volumetemperaturpHconductivityB1 inhomogeneities PO relaxation times of in vivo metabolites
need to be considereddue to adjustments orcorrection factorsdetermined byadditional measurements
known & stablereference standardknown relaxation timesfor calibration metabolitesreceive gain settingsconsideredcoil load directlyconsideredphantom calibration needsto be performed only once
AAPM 2009 – Quantitative MRI and MRS Symposium
IBT spectroscopy group
Mateo PavanNicola de Zanches Rolf F. SchulteKlaas Pruessmann