M R I Physics Course - cvut.czkfe.fjfi.cvut.cz/~sinor/tmp/edu/pmbafy/mri/ · M R I Physics Course. ... spin-spin splitting—refers to the interaction of ... • Water is scanned

M R I Physics CourseM R I Physics Course

Tom Lavin, M.S.M.P.Tom Lavin, M.S.M.P.

Jerry Allison, Ph.D.Jerry Allison, Ph.D.

Nathan Yanasak, Ph.D.Nathan Yanasak, Ph.D.Department of RadiologyDepartment of Radiology

Medical College of GeorgiaMedical College of Georgia

Magnetic ResonanceMagnetic ResonanceSpectroscopySpectroscopy

(MRS)(MRS)

Basic PrinciplesBasic PrinciplesSingle Voxel TechniquesSingle Voxel Techniques

Chemical Shift Imaging (CSI)Chemical Shift Imaging (CSI)Water SuppressionWater Suppression

Clinical ApplicationsClinical Applications

M R I Physics CourseM R I Physics Course

MR SpectroscopyMR Spectroscopy• Magnetic Resonance Spectroscopy (MRS) Magnetic Resonance Spectroscopy (MRS)

provides a non-invasive method of studying provides a non-invasive method of studying metabolism in vivo. metabolism in vivo.

• The tissue’s chemical environment The tissue’s chemical environment determines the frequency of a metabolite determines the frequency of a metabolite peak in an MRS spectrum.peak in an MRS spectrum.

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MR SpectroscopyMR Spectroscopy• Candidates for MRS include:Candidates for MRS include:

• 11H, H, 3131P, P, 1313C, C, 2323Na, Na, 77Li, Li, 1919F, F, 1414N, N, 1515N, N, 1717O, O, 3939KK

• The most commonly studied nuclei are The most commonly studied nuclei are 11H H and and 3131PP

• This lecture is focused on Proton (This lecture is focused on Proton (11H) H) SpectroscopySpectroscopy

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MR SpectroscopyMR Spectroscopy• Because we divide the signal from each voxel into Because we divide the signal from each voxel into

a smaller number of components (chemically a smaller number of components (chemically distinct species) the SNR of spectra is lower than distinct species) the SNR of spectra is lower than that of MR images-- to obtain an acceptable level that of MR images-- to obtain an acceptable level of SNR in reasonable imaging times, much larger of SNR in reasonable imaging times, much larger voxels are required for MRS than MRI—typically voxels are required for MRS than MRI—typically MRS uses voxel sizes of 1 to 8 cmMRS uses voxel sizes of 1 to 8 cm33, whereas , whereas voxels for imaging are 1 to 5 mmvoxels for imaging are 1 to 5 mm33..

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• Recall that the Larmor equation describes the resonant Recall that the Larmor equation describes the resonant precessional frequency of a nuclear magnetic moment in precessional frequency of a nuclear magnetic moment in an applied static magnetic field.an applied static magnetic field.

ωω = = γ γ BBoo

Where: Where: ω = ω = precessional frequency precessional frequency (resonant frequency)(resonant frequency)

γ γ = gyromagnetic ratio = gyromagnetic ratio (MHz/Tesla)(MHz/Tesla)

[42.58 MHz[42.58 MHz//Tesla for hydrogen nuclei]Tesla for hydrogen nuclei]

BBoo = magnetic field (Tesla) = magnetic field (Tesla)

Proton SpectroscopyProton Spectroscopy

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• If all the proton nuclei in a mixture of molecules If all the proton nuclei in a mixture of molecules had the same Larmor frequency, the MR spectra had the same Larmor frequency, the MR spectra would be limited to a single peak. However, the would be limited to a single peak. However, the magnetic Bmagnetic B00 field “seen” by a nucleus is shielded field “seen” by a nucleus is shielded by the covalent electron structure surrounding the by the covalent electron structure surrounding the nucleus. Electrons are negatively charged and nucleus. Electrons are negatively charged and have spin properties. Thus, when placed in an have spin properties. Thus, when placed in an externally applied magnetic field, electrons will externally applied magnetic field, electrons will precess and induce a small magnetic field around precess and induce a small magnetic field around the nuclei.the nuclei.

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• These local magnetic fields generated by the These local magnetic fields generated by the surrounding electrons can add or subtract from surrounding electrons can add or subtract from the applied magnetic field Bthe applied magnetic field B00. Consequently, the . Consequently, the

nuclei experience slightly different magnetic nuclei experience slightly different magnetic fields based on chemical structures. Due to this fields based on chemical structures. Due to this small change in the local magnetic field, nuclei small change in the local magnetic field, nuclei will resonate at slightly shifted Larmor will resonate at slightly shifted Larmor frequencies.frequencies.

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Proton SpectroscopyProton Spectroscopy Nuclei with different chemical neighbors will Nuclei with different chemical neighbors will

have slightly different resonance frequencies have slightly different resonance frequencies given by: given by:

ωω = = γ γ BBoo(1- (1- σσ))Where Where σσ is a screening constant ( is a screening constant (││σσ│ << 1).│ << 1).

This small change in the resonance frequency, This small change in the resonance frequency, referred to as referred to as chemical shiftchemical shift, is the basis for , is the basis for magnetic resonance spectrosocpy.magnetic resonance spectrosocpy.

Note that both the overall molecular structure and the Note that both the overall molecular structure and the proton(s) position within the molecule will determine proton(s) position within the molecule will determine σσ..


• J coupling, also known as scalar coupling or J coupling, also known as scalar coupling or spin-spin splitting—refers to the interaction of spin-spin splitting—refers to the interaction of two nuclear spins on the same molecule by means two nuclear spins on the same molecule by means of distortions in their electron clouds. J coupling of distortions in their electron clouds. J coupling interactions are responsible for the fine-line interactions are responsible for the fine-line splitting (doublets, multiplets) seen in high splitting (doublets, multiplets) seen in high resolution MRS.resolution MRS.

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• The spin multiplets are the result of an indirect The spin multiplets are the result of an indirect interaction between the protons in the group we interaction between the protons in the group we are observing and the protons in the neighboring are observing and the protons in the neighboring group via the molecular electrons. If there are n group via the molecular electrons. If there are n protons in the neighboring group it splits the first protons in the neighboring group it splits the first group into (n+1) components. group into (n+1) components.

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Proton SpectroscopyProton Spectroscopy• For example, consider ethanol:For example, consider ethanol:

CHCH33-CH-CH22-OH-OH

There are two protons in the CHThere are two protons in the CH2 2

(methylene) group so it splits the CH(methylene) group so it splits the CH33

resonance into a triplet; there are three resonance into a triplet; there are three protons in the CHprotons in the CH3 3 (methyl) group so it splits (methyl) group so it splits

the CHthe CH22 resonance into a quartet. The resonance into a quartet. The splittings are small, independent of the field splittings are small, independent of the field strength Bstrength B00..

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13http://www.steve.gb.com/science/spectroscopy.htmlhttp://www.steve.gb.com/science/spectroscopy.html

Ethanol spectrumEthanol spectrum

OHOH CHCH22 CHCH33

Proton SpectroscopyProton Spectroscopy• Chemical shiftsChemical shifts in in ppmppm are are independentindependent

of the strength of the applied field Bof the strength of the applied field B00 and and correspondingly, the instrument frequencycorrespondingly, the instrument frequency

• Chemical shiftsChemical shifts in in HzHz are field and are field and frequency frequency dependentdependent

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Proton SpectroscopyProton Spectroscopy In the frequency domain, the area under a In the frequency domain, the area under a

specific peak is proportional to the number of specific peak is proportional to the number of protons precessing at that frequencyprotons precessing at that frequency

• However, there is a problem with using a However, there is a problem with using a frequency axis to display MR spectra:frequency axis to display MR spectra:– The axis is proportional to BThe axis is proportional to B00 which means that peak which means that peak

locations on the axis will depend on the field strength locations on the axis will depend on the field strength used for measurement.used for measurement.

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Proton SpectroscopyProton Spectroscopy• A parts per million (ppm) scale is used instead:A parts per million (ppm) scale is used instead:

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( ( ωωii - - ωωrr))____________________________ωω00 x 10 x 10 -6-6 δδ = =

• δδ is dimensionless and is measured in parts is dimensionless and is measured in parts per million (ppm) . per million (ppm) . The significance of The significance of δδ is that the chemical shift positions of nuclei is that the chemical shift positions of nuclei with the same atomic number measured in parts per million are with the same atomic number measured in parts per million are independentindependent of the field strength used. of the field strength used.

Proton Spectroscopy Proton Spectroscopy • Water is scanned at the center frequency, that Water is scanned at the center frequency, that

position is then assigned 4.7 ppmposition is then assigned 4.7 ppm• Also note that the resonance frequency of water Also note that the resonance frequency of water

is dependent on temperature, with frequency is dependent on temperature, with frequency increasing as temperature decreases ( increasing as temperature decreases ( ΔΔ ppm/ ppm/ ΔΔ °°C = -0.01 ppm/ C = -0.01 ppm/ °°C )C )

• At 37 At 37 °°C, C, δδ of water is 4.70 ppm; at 20 of water is 4.70 ppm; at 20 °°C,C, δδ of water is 4.87 ppm. Therefore, the correct of water is 4.87 ppm. Therefore, the correct

temperature must be entered when scanning a temperature must be entered when scanning a phantom.phantom.

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Proton SpectroscopyProton Spectroscopy• Local magnetic field inhomogeneities widen and Local magnetic field inhomogeneities widen and

distort the spectral lines. distort the spectral lines. • Improved magnetic field homogeneity increases Improved magnetic field homogeneity increases

SNR and narrows peak widths-thus improves both SNR and narrows peak widths-thus improves both sensitivity and spectral resolution.sensitivity and spectral resolution.

• Maximum homogeneity is accomplished by Maximum homogeneity is accomplished by adjusting DC currents in the gradient coils and adjusting DC currents in the gradient coils and room temperature shim coils—a process known as room temperature shim coils—a process known as shimmingshimming

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An alternative to images: MR offers the possibility to An alternative to images: MR offers the possibility to “visualize” the chemical environment via spectroscopy, “visualize” the chemical environment via spectroscopy, examining the metabolism of areas in question.examining the metabolism of areas in question.

How? Transmit a broadband RF pulse (which excites How? Transmit a broadband RF pulse (which excites multiple nuclear species) and analyze the receive signal multiple nuclear species) and analyze the receive signal for the amplitude of different for the amplitude of different frequencyfrequency components components abundance of different speciesabundance of different species..

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· · The two common approaches in MR spectroscopy The two common approaches in MR spectroscopy are single voxel spectroscopy (are single voxel spectroscopy (SVSSVS) and chemical ) and chemical shift imaging (shift imaging (CSICSI).).· · For SVS techniques, the two main acquisition For SVS techniques, the two main acquisition schemes are spin echo (SE), or Point-RESolved schemes are spin echo (SE), or Point-RESolved Spectroscopy (Spectroscopy (PRESSPRESS), and stimulated echo ), and stimulated echo acquisition method (acquisition method (STEAMSTEAM).).· · Essential: suppress the water signal, CHEmical-Essential: suppress the water signal, CHEmical-Shift-Selective (Shift-Selective (CHESSCHESS), and for regions outside the ), and for regions outside the central nervous system, also the lipid signal. One can central nervous system, also the lipid signal. One can perform this by applying appropriate preparatory RF perform this by applying appropriate preparatory RF pulses before the main sequence.pulses before the main sequence.


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· · The concentration of pure water is 55.6 M or 111 M The concentration of pure water is 55.6 M or 111 M for for 11H. The water concentration in the brain, H. The water concentration in the brain, calculated from an average MR visible brain water calculated from an average MR visible brain water content of 70%, is 36 M. In vivo content of 70%, is 36 M. In vivo 11H spectroscopy H spectroscopy requires water suppression because the 36 M water requires water suppression because the 36 M water signal overpowers the 1-10 mM signal of the signal overpowers the 1-10 mM signal of the metabolites.metabolites.


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This figure demonstrates the importance of suppressing the This figure demonstrates the importance of suppressing the water signal. The metabolites of interest have a signal water signal. The metabolites of interest have a signal one hundred times smaller than that of the water peak, one hundred times smaller than that of the water peak, and without water suppression would be poorly resolvedand without water suppression would be poorly resolved

© Scott & White 2004© Scott & White 2004

10001000

800800

600600

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Proton Spectroscopy (SVS with PRESS)Proton Spectroscopy (SVS with PRESS)

Basic diagram of SVS with spin echo (ref #1)Basic diagram of SVS with spin echo (ref #1)• Water-suppressionWater-suppression• The 90° pulse excites a slice. The 90° pulse excites a slice. • The first 180° pulse refocuses the transverse The first 180° pulse refocuses the transverse

magnetization in a row of tissue within the magnetization in a row of tissue within the slice. slice.

• The second 180° pulse refocuses the The second 180° pulse refocuses the magnetization within a column of the row, magnetization within a column of the row, leaving a single voxel. leaving a single voxel.

• Then, the signal represents a combination of Then, the signal represents a combination of spins in that voxel precessing at slightly spins in that voxel precessing at slightly different frequencies (function of time).different frequencies (function of time).

• Fourier transform of signal Fourier transform of signal number of number of spins at a given frequency in a voxel spins at a given frequency in a voxel (function of frequency).(function of frequency).


For one acquisition scheme– Point RESolved Spectroscopy For one acquisition scheme– Point RESolved Spectroscopy (PRESS)(PRESS)

Proton Spectroscopy Proton Spectroscopy (SVS with PRESS)(SVS with PRESS)

The effect of echo time in SE single voxel spectroscopy (SVS).The effect of echo time in SE single voxel spectroscopy (SVS).

Left: TE=30ms; Right: TE=144 ms. TE controls the TLeft: TE=30ms; Right: TE=144 ms. TE controls the T 22 “contrast” of the spectral “contrast” of the spectral

peaks in the same way tissue Tpeaks in the same way tissue T22 contrast is controlled in MR imaging. As contrast is controlled in MR imaging. As

shown, Glx (glutamine) and myoinositol (mI) have short Tshown, Glx (glutamine) and myoinositol (mI) have short T 22 values and are not values and are not

visible on long TE spectra.visible on long TE spectra.

24© Scott & White 2004© Scott & White 2004

Proton Spectroscopy Proton Spectroscopy (SVS with PRESS)(SVS with PRESS)

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Major healthy brain metabolite peaks:Major healthy brain metabolite peaks:

long TE spectra: 1) N-acetylaspartate (NAA) at 2.02 ppm, 2) choline (Cho) at long TE spectra: 1) N-acetylaspartate (NAA) at 2.02 ppm, 2) choline (Cho) at 3.20 ppm, and 3) creatine (Cr) at 3.02 ppm and 3.9 ppm. 3.20 ppm, and 3) creatine (Cr) at 3.02 ppm and 3.9 ppm.

short TE spectra (add’l peaks): 4) myoinositol (mI) at 3.56 ppm, 5) glutamine short TE spectra (add’l peaks): 4) myoinositol (mI) at 3.56 ppm, 5) glutamine and glutamate (Glx) between 2.05-2.5 ppm and 3.65-3.8 ppm, and 6) glucose and glutamate (Glx) between 2.05-2.5 ppm and 3.65-3.8 ppm, and 6) glucose at 3.43 ppm.at 3.43 ppm.


Proton Spectroscopy Proton Spectroscopy (SVS with STEAM)(SVS with STEAM)

Basic diagram of SVS with STEAM: Basic diagram of SVS with STEAM:

•Water-suppressionWater-suppression•The 90° pulse excites a slice. The 90° pulse excites a slice. •A second 90° pulse refocuses the transverse A second 90° pulse refocuses the transverse magnetization in a row of tissue within the magnetization in a row of tissue within the slice. slice.

•A third 90° pulse refocuses the magnetization A third 90° pulse refocuses the magnetization within a column of the row, leaving a single within a column of the row, leaving a single voxel.voxel.

Negative to STEAM: rephasing only about Negative to STEAM: rephasing only about 50% of the original generated transverse 50% of the original generated transverse magnetization (low SNR). magnetization (low SNR). ~ (sort of ) Positive to STEAM: shorter echo ~ (sort of ) Positive to STEAM: shorter echo times than PRESS sequence.times than PRESS sequence.


Multivoxel Spectroscopy Multivoxel Spectroscopy (Chemical Shift Imaging)(Chemical Shift Imaging)

Phase encoding gradients can be utilized, as in imaging, Phase encoding gradients can be utilized, as in imaging, in order to encode spatial information. Figure 4 in order to encode spatial information. Figure 4 illustrates a simple 2D chemical shift imaging (CSI) illustrates a simple 2D chemical shift imaging (CSI) acquisition scheme. acquisition scheme.

• Selective 90° RF pulse and slice-select gradient Selective 90° RF pulse and slice-select gradient generates a transverse magnetization within the slice. generates a transverse magnetization within the slice.

• Orthogonal magnetic field gradients of short duration Orthogonal magnetic field gradients of short duration serve to phase-encode the data in 2D.serve to phase-encode the data in 2D.

• Data are sampled at multiple timesData are sampled at multiple times..• 3D Fourier inverse transform gives frequency 3D Fourier inverse transform gives frequency

information over the 2D slice. information over the 2D slice. 27

Figure 4Figure 4


Multivoxel Spectroscopy Multivoxel Spectroscopy (Chemical Shift Imaging)(Chemical Shift Imaging)

Figure 5 illustrates the imaging setup for a 2D Figure 5 illustrates the imaging setup for a 2D CSI acquisition. A single slice is defined through CSI acquisition. A single slice is defined through the area of interest, and then a box is specified the area of interest, and then a box is specified within this (white lines). Spectra will then be within this (white lines). Spectra will then be generated for all voxels within the box. generated for all voxels within the box.

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Figure 5Figure 5

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This figure presents the spectra for a low grade brainstem glioma. This figure presents the spectra for a low grade brainstem glioma. SE CSI acquisition: two spectra (TE=30 ms--second column, and SE CSI acquisition: two spectra (TE=30 ms--second column, and 144 ms--third column). The first column shows the voxel 144 ms--third column). The first column shows the voxel corresponding to the spectra on the same row. Rows: 1st=lesion corresponding to the spectra on the same row. Rows: 1st=lesion spectra, 2nd= normal brain spectra.spectra, 2nd= normal brain spectra.


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The lesion spectra demonstrate decreased The lesion spectra demonstrate decreased NAANAA (a marker of (a marker of neuronal integrity) and increased neuronal integrity) and increased cholinecholine (a marker of myelin (a marker of myelin breakdown). The short TE spectrum demonstrates elevated breakdown). The short TE spectrum demonstrates elevated myo-myo-inositolinositol (a marker of glial cells). (a marker of glial cells).

Figure 6 (next slide) presents a color-coded choline metabolite Figure 6 (next slide) presents a color-coded choline metabolite map.map.


Figure 5Figure 5

Figure 6Figure 6

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Multivoxel SpectroscopyMultivoxel Spectroscopy


• The clinical utility of the brain spectrum rests The clinical utility of the brain spectrum rests upon 2 important properties:upon 2 important properties:– The nature and concentration of brain chemicals The nature and concentration of brain chemicals

identified is remarkably constant—identified is remarkably constant—• A “normal” brain spectrum is readily recognizedA “normal” brain spectrum is readily recognized

– The particular neurochemicals concerned are of The particular neurochemicals concerned are of clinical relevance in healthy and diseased brain.clinical relevance in healthy and diseased brain.

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Brain SpectroscopyBrain Spectroscopy

• Important brain metabolites:Important brain metabolites:

NAANAA ( (N-acetyl aspartateN-acetyl aspartate) – considered to be present only in ) – considered to be present only in neurons and dendrites, reflects health of neurons neurons and dendrites, reflects health of neurons (neuronal marker) --decreased in global brain disease, (neuronal marker) --decreased in global brain disease, or large necrotic tumor -- ~2.0 ppmor large necrotic tumor -- ~2.0 ppm

CrCr ( (creatine/phosphocreatinecreatine/phosphocreatine) – a reservoir for high energy ) – a reservoir for high energy phosphate for generation of adenosine triphosphate phosphate for generation of adenosine triphosphate [ATP] (energy metabolism marker)—usually used as a [ATP] (energy metabolism marker)—usually used as a reference peak to generate NAA/Cr and Cho/Cr ratiosreference peak to generate NAA/Cr and Cho/Cr ratios

~3.0 ppm~3.0 ppm 34



ChoCho ( (choline/phosphocholine/glycerophosphorylcholinecholine/phosphocholine/glycerophosphorylcholine) ) – associated with glial cell membrane integrity – associated with glial cell membrane integrity (cell membrane marker)-shows cell destruction-(cell membrane marker)-shows cell destruction-elevated in tumor, ischemia, MS—it’s abundant, elevated in tumor, ischemia, MS—it’s abundant, so it can be used to monitor MS or tumor so it can be used to monitor MS or tumor

~ 3.25 ppm~ 3.25 ppm

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GlxGlx (Glutamine/Glutamate)—neurotransmitter (Glutamine/Glutamate)—neurotransmitter --elevated in stroke, lymphoma, hypoxia ~ 2.1---elevated in stroke, lymphoma, hypoxia ~ 2.1-2.5 ppm2.5 ppm

mImI (Myo-inositol)- cell membrane marker (shows (Myo-inositol)- cell membrane marker (shows cell destruction) –elevated in Alzheimer’s, cell destruction) –elevated in Alzheimer’s, diabetes, recovered hypoxia ~3.56 ppmdiabetes, recovered hypoxia ~3.56 ppm

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Lipid—Lipid—indicatesindicates tissue necrosis ~ .9 – 1.4 ppmtissue necrosis ~ .9 – 1.4 ppm

LactateLactate—indicates hypoxia—elevated in infarcts, —indicates hypoxia—elevated in infarcts, abscess, mitochondrial disorders, malignant abscess, mitochondrial disorders, malignant tumors, MS plaques ~ 1.33 ppmtumors, MS plaques ~ 1.33 ppm

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• Single Voxel prescription:Single Voxel prescription:– Avoid blood, blood products, air, CSF, fat, metal, Avoid blood, blood products, air, CSF, fat, metal,

calcification and bone.calcification and bone.– Sometimes useful to place another voxel in the Sometimes useful to place another voxel in the

contralateral normal appearing tissue for referencecontralateral normal appearing tissue for reference

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39Single Voxel Prescription/positioningSingle Voxel Prescription/positioning

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Single Voxel Spectra from PhantomSingle Voxel Spectra from PhantomOn Left: STEAM 35 TE On Right: PRESS 35 TEOn Left: STEAM 35 TE On Right: PRESS 35 TE

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Single Voxel Spectra PRESS TE 144Single Voxel Spectra PRESS TE 144

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Single Voxel Spectra PRESS TE 288Single Voxel Spectra PRESS TE 288


• Voxel placementVoxel placement43

• SpectrumSpectrum


• Voxel placementVoxel placement• With saturation bandsWith saturation bands

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• Spectrum from GBMSpectrum from GBM

• Elevated choline, lactateElevated choline, lactate

• decreased NAAdecreased NAA

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Spectroscopy at 3T vs 1.5TSpectroscopy at 3T vs 1.5T

1.5T1.5T3T3T

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2D CSI of phantom --processed result2D CSI of phantom --processed result

Mutlivoxel spectroscopyMutlivoxel spectroscopy

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3D CSI from 3D CSI from phantom—phantom—processed result processed result with composite with composite metabolite mapmetabolite map

Spectroscopy of the ProstateSpectroscopy of the Prostate

• Prostate cancer is associated with Prostate cancer is associated with proportionately proportionately lowerlower levels oflevels of citratecitrate and and higher levels of choline and creatine than higher levels of choline and creatine than are seen in benign prostatic hyperplasia are seen in benign prostatic hyperplasia (BPH) or in normal prostate tissue.(BPH) or in normal prostate tissue.

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© Reviews in Urology 2006© Reviews in Urology 2006

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Spectroscopy of the ProstateSpectroscopy of the Prostate(From image on previous slide)(From image on previous slide) Combined magnetic resonance imaging, diffusion tensor imaging, Combined magnetic resonance imaging, diffusion tensor imaging, and 3-D magnetic resonance spectroscopic imaging (MRSI) of the and 3-D magnetic resonance spectroscopic imaging (MRSI) of the prostate at 1.5 tesla. prostate at 1.5 tesla. A. Axial T2-weighted image and 3-dimensional MRSI spectral A. Axial T2-weighted image and 3-dimensional MRSI spectral grid. The arrows indicate a region of prostate cancergrid. The arrows indicate a region of prostate cancer . . BB. . Corresponding 3-dimensional MRSI spectral array, showing the Corresponding 3-dimensional MRSI spectral array, showing the presence of an aggressive-appearing tumor (presence of an aggressive-appearing tumor (very elevated cholinevery elevated choline and and reduced citratereduced citrate) on the left side of the gland (right side of the ) on the left side of the gland (right side of the image).image). CC. . Image of the mean diffusional coefficient of water Image of the mean diffusional coefficient of water demonstrates a region of prostate cancer (arrows) in the same demonstrates a region of prostate cancer (arrows) in the same location as the T2-weighted image and MRSIlocation as the T2-weighted image and MRSI. . DD. . Representative spectra taken from the region of healthy Representative spectra taken from the region of healthy prostate tissue and prostate cancer. PPM, parts per millionprostate tissue and prostate cancer. PPM, parts per million

© Reviews in Urology 2006© Reviews in Urology 2006

• While MR spectroscopy is already being utilized While MR spectroscopy is already being utilized for prostate cancer detection and staging, for prostate cancer detection and staging, evidence is now emerging that it may also be evidence is now emerging that it may also be helpful in assessing response to treatment, most helpful in assessing response to treatment, most commonly with radiation and/or androgen commonly with radiation and/or androgen deprivation.deprivation.

• Areas of active research include imaging at high Areas of active research include imaging at high field strength (field strength (>> 3 tesla); novel spectroscopic 3 tesla); novel spectroscopic markers of malignancy, such as polyamines and markers of malignancy, such as polyamines and spermine; and MRI-guided biopsy and treatment.spermine; and MRI-guided biopsy and treatment.


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greatly reduced citrategreatly reduced citrate, elevated choline , elevated choline prostate cancer prostate cancer

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Breast MR spectroscopy, usually performed with Breast MR spectroscopy, usually performed with a single-voxel technique, may serve as a useful a single-voxel technique, may serve as a useful adjunct to breast MR imaging in distinguishing adjunct to breast MR imaging in distinguishing between benign and malignant lesions. The between benign and malignant lesions. The diagnostic value of MR spectroscopy is typically diagnostic value of MR spectroscopy is typically based on the detection of elevated levels of based on the detection of elevated levels of choline compounds, which are a marker of active choline compounds, which are a marker of active tumors.tumors.

Spectroscopy of the BreastSpectroscopy of the Breast

© Radiology 2007© Radiology 2007

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(From previous slide) (From previous slide) Palpable mammographically detected and biopsy-proved Palpable mammographically detected and biopsy-proved invasive lobular carcinoma in left breast of 56-year-old invasive lobular carcinoma in left breast of 56-year-old woman. (a) Sagittal fat-suppressed T1-weighted MR woman. (a) Sagittal fat-suppressed T1-weighted MR image of left breast immediately after intravenous image of left breast immediately after intravenous injection of gadopentetate dimeglumine shows 5-cm injection of gadopentetate dimeglumine shows 5-cm regional area of clumped enhancement in 12 o’clock regional area of clumped enhancement in 12 o’clock axis, circumscribed by the voxel (white box). (b) axis, circumscribed by the voxel (white box). (b) Spectrum demonstrates choline Spectrum demonstrates choline (Cho) (Cho) peak at frequency peak at frequency of 3.2 ppm, with SNR greater than 2. This is a true-of 3.2 ppm, with SNR greater than 2. This is a true-positive finding. positive finding. Lac = Lac = lactate, lactate, Lip = Lip = lipid.lipid.



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Suspicious nonmass lesion detected at screening MR Suspicious nonmass lesion detected at screening MR imaging in 38-year-old woman withimaging in 38-year-old woman withBRCA-1 BRCA-1 gene who was imaged at day 11 of her gene who was imaged at day 11 of her menstrual cycle. (a) Postcontrast sagittal fat-suppressed menstrual cycle. (a) Postcontrast sagittal fat-suppressed T1-weighted MR image of left breast shows focal T1-weighted MR image of left breast shows focal clumped enhancement in upper inner region, clumped enhancement in upper inner region, circumscribed by the voxel (white box). (b) Magnified circumscribed by the voxel (white box). (b) Magnified spectrum demonstrates large lipid spectrum demonstrates large lipid (Lip) (Lip) peak, but no peak, but no choline choline (Cho) (Cho) resonance peak was observed at frequency resonance peak was observed at frequency of 3.2 ppm. This is a true-negative finding.of 3.2 ppm. This is a true-negative finding.



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elevatedelevated levels of levels of cholinecholine compounds compounds marker marker of active tumors.of active tumors.


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References:References:

• Proton magnetic resonance spectroscopy in Proton magnetic resonance spectroscopy in the brain: Report of AAPM MR Task group the brain: Report of AAPM MR Task group #9.#9. Drost, D.J., et al., Med Phys 29(9) Drost, D.J., et al., Med Phys 29(9) Sept 2002.Sept 2002.

• Questions and Answers in Magnetic Questions and Answers in Magnetic Resonance ImagingResonance Imaging (2 (2ndnd Edition). Elster, Edition). Elster, A.D. and Burdette, J. H. Mosby, St. Louis A.D. and Burdette, J. H. Mosby, St. Louis 20012001

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• Medical Magnetic Resonance Imaging and Medical Magnetic Resonance Imaging and Spectroscopy.Spectroscopy. Edited by Budinger Edited by Budinger &Margulis. Society of Magnetic &Margulis. Society of Magnetic Resonance in Medicine 1986Resonance in Medicine 1986

• Clinical Applications of MR SpectroscopyClinical Applications of MR Spectroscopy

Edited by Mukherji Wiley & Sons, New Edited by Mukherji Wiley & Sons, New York 1998York 1998

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• MRI from Picture to ProtonMRI from Picture to Proton D.W. D.W. McRobbie et al. Cambridge University McRobbie et al. Cambridge University Press 2003Press 2003

• Magnetic Resonance Spectroscopy of Magnetic Resonance Spectroscopy of Neurological DiseasesNeurological Diseases E. R. Danielsen E. R. Danielsen Marcel Dekker, Inc. New York 1998.Marcel Dekker, Inc. New York 1998.

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• © © Reviews in Urology 2006Reviews in Urology 2006

Carroll, et. al., Carroll, et. al., Magnetic Resonance Magnetic Resonance Imaging and Imaging and Spectroscopy of Prostate CancerSpectroscopy of Prostate Cancer;; REVIEWS IN REVIEWS IN UROLOGY Vol. 8 Suppl. 1 2006UROLOGY Vol. 8 Suppl. 1 2006

• © © Scott & White 2004Scott & White 2004

Runge,VM, Nitz,WR, et al. Runge,VM, Nitz,WR, et al. The Physics of Clinical The Physics of Clinical

MR, for Neuroradiology, Taught Through Images.MR, for Neuroradiology, Taught Through Images. • ©© Radiology 2007 Radiology 2007

Bartella, et al., Bartella, et al., Enhancing Nonmass Lesions in the Enhancing Nonmass Lesions in the Breast: Evaluation with Proton (1H) MR Breast: Evaluation with Proton (1H) MR SpectroscopySpectroscopy Radiology Volume 245 (1) October Radiology Volume 245 (1) October 20072007


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M R I Physics Course - cvut.czkfe.fjfi.cvut.cz/~sinor/tmp/edu/pmbafy/mri/ · M R I Physics Course. ... spin-spin splitting—refers to the interaction of ... • Water is scanned