MRS Demo ACRN 6684 3Dsiemens Final

7/31/2019 MRS Demo ACRN 6684 3Dsiemens Final

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ACRIN-6684ACRIN-6684

-- MRS data acquisition and Raw Data

Handling Instructions

For Siemens Data


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In vivoIn vivo MR SpectroscopyMR Spectroscopy

Representative MRS of a normal human brain@3T

NAA

Glu/Gln

Cho Cr

MI

Lipids,macromolecules


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Proton MRS is able to detect the following metabolites:

N-Acetyl Aspartate (NAA) at 2 ppm: Marker of

neuronal density and viability Creatine (Cr) at 3 ppm: Energy metabolism, generation

of ATP

Choline (Cho) at 3.2 ppm: Pathological alterations in

membrane turnover, increased in tumors

Lipids (Lip) between 0.8 1.5 ppm: Breakdown of

tissue, elevated in brain tumors - lipids indicate necrosis


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Lactate (Lac) at 1.3 ppm, inverted at 144ms:

produced by an anaerobic metabolism, found in

tumor containing zones of necrosis

1000 950 900 850 800

-1.00E+008

0.00E+000

1.00E+008

2.00E+008

3.00E+008

Y

AxisTitle

X Axis Title

fft(real)

/ ppm

1000

950 900 850 800

-1.00E+008

0.00E+000

1.00E+008

2.00E+008

3.00E+008

Y

AxisTitle

X Axis Title

fft(real)

/ ppm

Lac

NAA

Cr

Cho


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The SequenceThe Sequence

3D chemical shift imaging using aPoint-resolved spectroscopy(PRESS) excitation pulse

sequence.

3D Volumetric Spectroscopypreferred 2D CSI Spectroscopy is

acceptable


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Optimal Voxel PlacementOptimal Voxel Placement

The ROI will be placed at the center ofthe enhancing tumor covering thelesion and the normal brain as much aspossible but excluding thesubcutaneous fat and sinuses.

b i l l


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Suboptimal VoxelSuboptimal Voxel

PlacementPlacement Proximity to sinuses can result in signal

broadening and susceptibility artifacts Proximity to scull can result in contaminating

lipid signal


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3D MRSI Parameters3D MRSI ParametersTE 144 ms, TR 1140 ms,

FOV > 160 mm2,

Phase encoding arrays 12 x 12 x 8

Numbers of Acquisitions: 1

Spatial zero-filling to 16 x 16 x 8 phaseencoding arrays will result in an individualvoxel size of 1 x 1 x 1 cm3.

Approximate imaging time: ~6 min utilizingelliptical k-space sampling k-space sampling

Manual shimming is recommended before theacquisition to obtain the best magnetic field

homogeneity.


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ShimmingShimming

Shimming = adjusting the magnetic field to make it

more homogeneous 1.5T: Signal line width or full width at half maximum

(FWHM):


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Shimming on SiemensShimming on Siemens


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Manual Shimming onManual Shimming on

SiemensSiemens

Hit the Show tabThen Invalidate AllAdjust AllWait a couple of minutesuntil it says

Adjustments finished

Hit the Show tabThen Invalidate AllAdjust AllWait a couple of minutesuntil it says

Adjustments finished


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Hit the Interactive Shim tabThen hit Measure (1)Numbers will begin to scroll on theabove white box (2)

You can alter the shim by changing Z,then Y, then X. Do this slowly, only acouple of increments at a time, thenstart with z again Stop (3) and Apply (4)

1.

2.

3.

4.


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Saturation BandsSaturation BandsClick SAT and place up to 10 SAT bands around

the voxel to suppress signals from lipid/fat


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Saving the Data in .rdaSaving the Data in .rda

formatformat


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The spectrum appears inone of the quadrantsNote: if another window

appears asking you to selecta protocol for the spectrum,

just select any of theprotocols listed and click OK.


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Go to the top of thescreen Click on

PatientDropdown menu willappearSave data


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Select first option, Selected

results and 3 referenceimages (shown above)This will save the spectrum

and corresponding images in

a DICOM format


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Go to a difference slice and

repeat the process


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In order to use a different

slice:Right click on the ImageA scroll down window willappearSelect 3D CSI Selection


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Under 3D CSI Selection:Choose Plane number

Sav ng t e Data n r aav ng t e ata n r a


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Sav ng t e Data n .r aav ng t e ata n .r aformatformat

Click on Options export raw data (shownabove).


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MRS Demo ACRN 6684 3Dsiemens Final