Imageriecellulaire IRM Darrasse Septembre 2010

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Apramen 7 sept. 2010 / Luc Darrasse

DDtection de cellules individuelles marqutection de cellules individuelles marques en IRM in vivo :es en IRM in vivo :

preuves de concept sur petit animalpreuves de concept sur petit animal

Luc DarrasseLuc DarrasseImagerie par RImagerie par Rsonance Magnsonance Magntiquetique MMdicaleetdicaleet MultiMulti--ModalitModalits (IR4M)s (IR4M)UMR 8081 CNRSUMR 8081 CNRS--UnivUnivParisParis--SudSud www.u2r2m.uwww.u2r2m.u--psud.frpsud.fr

quipequipe ddveloppements mveloppements mthodologiques et instrumentaux (X. Mathodologiques et instrumentaux (X. Matre)tre)JCJC GinefriGinefri, M Poirier, M Poirier--QuinotQuinot NN GargamGargam, O Girard, E, O Girard, E LaistlerLaistler, S Lambert, S Lambert

CollaborationsCollaborationsGuerbetGuerbet--ResearchResearch P RobertP RobertLaboratoire MatiLaboratoire Matires et Systres et Systmes Complexes (Paris7)mes Complexes (Paris7) FF GazeauGazeau, C. Wilhelm ..., C. Wilhelm ...Laboratoire de Recherche en Imagerie (Paris 5)Laboratoire de Recherche en Imagerie (Paris 5) -- O ClO Clment ...ment ...


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Signal et contrasteSignal et contraste

Agents ciblAgents cibls paramagns paramagntiquestiques

Agents ciblAgents ciblss superparamagnsuperparamagntiquestiques


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Vers une IRM molVers une IRM molculaire/cellulaireculaire/cellulaire

Objectif : couplageObjectif : couplage / morphologie/ morphologie l'l'chelle des organes, lchelle des organes, lsionssions/ biologie/ biologie l'l'chelle des cellules, tissuschelle des cellules, tissus

Enjeu : amEnjeu : amliorer la spliorer la spcificitcificit diagnostique de l'imagerie mdiagnostique de l'imagerie mdicaledicale

-- pathologie : dpathologie : dtection prtection prcoce des premiers signes et de l'coce des premiers signes et de l'volution pathologiquesvolution pathologiques

-- ththrapie : administration ciblrapie : administration cible de me de mdicaments, approchesdicaments, approches ththragnostiquesragnostiques

PotentialitPotentialit s de l'IRMs de l'IRM

+ outi l "+ outil " multiphysiquemultiphysique" : analyse de ph" : analyse de phnomnomnes physicochimiques survenantnes physicochimiques survenantauxaux chelles macrochelles macro--,, mesomeso--, micro, micro-- etet nanoscopiquesnanoscopiques (organes mtabolites)tabolites)

-- sensibilitsensibilit intrinsintrinsque


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MRI: resonant interaction with nuclear spinsMRI: resonant interaction with nuclear spins

CLINICAL MRI (RF)CLINICAL MRI (RF)

thermal energy 310 Kthermal energy 310 K

(( kkBoltzmannBoltzmannTT))

10-12

pm

Angstrm

10 -9 nm

10-6

m

10-3

mm

cm

1 m

103

km

106

WAVELENGTH

(Meter)

cosmic

rays

audio

gammarays

X rays

UV

IR

microwaves

radio

waves

Light

ZHz 1021

EHz 1018

PHz 1015

THz 1012

GHz 109

MHz 106

kHz 103

Hz 1

FREQUENCY(Hertz)

MeV 106

keV 10 3

eV 1

meV 10 -3

eV 10 -6

neV 10 -9

peV 10 -12

ENERGY

(electronvolt)h =

0

h

2

= 0

B

Planck's constanth

energy / frequency

gyromagnetic ratio

(static) magnetic field0

B

-- low sensitivity !low sensitivity !

-- BB00

radiotracersradiotracers

biophotonicsbiophotonics


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Signal et contraste en IRMSignal et contraste en IRM

aimantation d'aimantation d'quilibre issue d'une grande population de spinsquil ibre issue d'une grande population de spins

observable aprobservable aprs une impulsion d'excitation (antenne radiofrs une impulsion d'excitation (antenne radiofrquence)quence)

volution de l'aimantation par un jeu de perturbations magnvolution de l'aimantation par un jeu de perturbations magntiquestiques

-- locales : interaction spinlocales : interaction spin--spin, gradients de susceptibil itspin, gradients de susceptibil it......

-- exogexognes : impulsions RF et gradients appliqunes : impulsions RF et gradients appliquss

constante de temps T1 : renouvellement de l'aimantationconstante de temps T1 : renouvellement de l'aimantation

perturbations haute frperturbations haute frquence (= mouvements rapides)quence (= mouvements rapides)

constante de temps T2 : disparition du signal aprconstante de temps T2 : disparition du signal aprs une excitations une excitation

radiofrradiofrquence (dquence (dphasage irrphasage irrversible entre les spins)versible entre les spins)

perturbations haute frperturbations haute frquence + basse frquence + basse frquence (mouvements lents)quence (mouvements lents)

marquage paramagnmarquage paramagntique (tique (egeg Gd3+)Gd3+)

-- interactioninteraction courte distance + transport de l'effetcourte distance + transport de l'effet

-- effets T2 et T1effets T2 et T1

marqueursmarqueurs superparamagnsuperparamagntiquestiques ((egeg nanoparticules de fer)nanoparticules de fer)

interactioninteraction grande distance (rgrande distance (rgime de dgime de dphasage statique) : effet T2*phasage statique) : effet T2*

A 7 2010 / L D


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SNR limitation in MRI applicationsSNR limitation in MRI applications

signalsignal--toto--noisenoise volumevolume elementelement

((voxelvoxel))scanningscanning timetime

SNR =SNR = FF .. rrxx .. rryy .. rrzz .. TTscanscan

StaticStatic fieldfield intensityintensity

Acquisition techniqueAcquisition technique

ContrastContrast enhancementenhancement

RFRF coilcoil probeprobe efficiencyefficiency

SensitivitySensitivity factorfactor < 100 ms< 100 ms fastfast MRIMRI3 mm3 mm

1 mm1 mm 1 min1 min .. standard MRIstandard MRI

micromicro--MRIMRI1010 mm

(1(1 picoliterpicoliter))

hourshours,, daysdays

A 7 t 2010 / L D


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UltraUltra--highhighfieldfieldMRIMRI

HighHigh fieldfield prospros HighHigh fieldfield conscons

-- LinearLinearmagnetizationmagnetization increaseincrease -- inefficientinefficient withwith hyperpolarizedhyperpolarized substancessubstances

-- Small boreSmall bore -->> strongstrong gradientsgradients -- reducedreduced accessaccess

--

ImprovedImproved

spectral dispersionspectral dispersion

--

T1T1

increasesincreases

, T2 et T2* are, T2 et T2* are

reducedreduced

((IRMfIRMfBold,Bold, SpectroscopySpectroscopy)) -- artefacts (local signalartefacts (local signal losseslosses))

-- Effective forEffective for targetedtargeted constrastconstrast media ?media ? => short TE , large acquisition=> short TE , large acquisition bandwidthbandwidth

MagnexMagnex 9.49.4 TT -- 400400 MHzMHz

6565 cmcm borebore

heightheight 3.48 m3.48 m

lengthlength 3.14 m3.14 m

CMRRCMRR U.U. MinnesotaMinnesota

clinical scanners

BrukerBrukerAvance 750Avance 750 WBWB

17.617.6 TT -- 749 MHz749 MHz

66 cmcm borebore

EP5EP5 U.U. WWrzburg (courtesy C. Faber)rzburg (courtesy C. Faber)

small animal microscopes

Apramen 7 sept 2010 / Luc Darrasse


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Fischer et al, MRM 1990Fischer et al, MRM 1990 Cole et Cole,Cole et Cole,J. Chem. Phys. 1941J. Chem. Phys. 1941

=> Contraste/bruit en fonction de la fr=> Contraste/bruit en fonction de la frquence/du champ ?quence/du champ ?

=> Sensibilit=> Sensibilit /sp/spcificitcificit ? D? Dtectabilittectabilit du ciblage moldu ciblage molculaire ?culaire ?

Effet du champ sur le contrasteEffet du champ sur le contraste



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Ciblage du rCiblage du rcepteur au folate avec un chcepteur au folate avec un chlate de Gd :late de Gd :

un manque de sensibilitun manque de sensibilit

30 molGd/kg

-20

-10

0

10

20

30

40

50

60

70

0 40 80 120 160 200 240

Temps (min)

%Rehaussemen

TOTAL_P866 (n=7)

TOTAL_P999 (n=6)

3 molGd/kg

-20

-10

0

10

20

30

40

50

60

70

0 40 80 120 160 200 240

Temps (minutes)

%deRehaussemen

TOTAL_P866 (n=2)TOTAL_P999 (n=2)

P866

Ciblage

FBPFBPFBP

Corot, Robert et al., MRM 2008Corot, Robert et al., MRM 2008



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: cible

: agent de contraste

contrastophore

: ligand

pharmacophore

Liaison spcifique

La limite de dLa limite de dtection en IRM impose destection en IRM impose des

doses cliniquesdoses cliniques levleveses

~100~100 mol/kgmol/kg [AC] de[AC] de 11 100 mM100 mM

Pour de telles concentrations :Pour de telles concentrations :

Saturation des rSaturation des rcepteurs (


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p p

Marquage paramagnMarquage paramagntique / modtique / modle thle thoriqueorique

SphSphre interne :re interne :

ThThorie SBMorie SBMSolomonSolomon, Phys., Phys.RevRev. 1955. 1955

Bloembergen, J. Chem. Phys. 1957Bloembergen, J. Chem. Phys. 1957Bloembergen et Morgan, J. Chem. Phys. 1961Bloembergen et Morgan, J. Chem. Phys. 1961

SphSphre externe :re externe :

ThThorie deorie de FreedFreedFreedFreed, J. Chem. Phys. 1978, J. Chem. Phys. 1978



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p p

Mobilit si AC li ou non (plus grosse molcule)

modification radicale des profils NMRD

Zhou et al, JMR 2004

Nuclear Magnetic Relaxation Dispersion (NMRD) profiles

Effet du champ statique sur le marquage paramagnEffet du champ statique sur le marquage paramagntiquetique



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Rhaussement remarquable du RCB au voisinage de 1,5 T Perte de spcificit haut champ

Girard et al. On the optimal field strength for detection of targeted Gd-based Contrast Agents in Molecular MR Imaging ISMRM 1656 (2008)

Modle : 250 M de Vasovist dans 600M de Human Serum Albumin

=> Sensibil it=> Sensibilit et det dtection optimalestection optimales environ andenviron and specificityspecificity 1 T ?1 T ?

DDtection d'agents paramagntection d'agents paramagntiques cibltiques ciblss



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Labeled lymphocytesControl

In vitro cellularIn vitro cellular imagingimaging

B0

Voxels dephasing due to static magnetic field deformation

MagneticMagnetic labelinglabeling withwith nanoparticlesnanoparticles (1.5(1.5 pgpg Fe/Fe/cellcell))



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SuperparamagneticSuperparamagneticparticulesparticulesdetection at 1.5 Tdetection at 1.5 T

Representative of most clinical applicationsRepresentative of most clinical applications

Decreased AMNPDecreased AMNP--induced contrast at higher fieldsinduced contrast at higher fields

InducedInduced intravoxelintravoxel phase dispersionphase dispersion

AMNPAMNP

rr

TETE

(relative permeability(relative permeabilityrr ,, quasistaticquasistatic dephasingdephasing assumption)assumption)

AMNPsAMNPs are reaching 95 % of their maximum magnetization at 1.5 Tare reaching 95 % of their maximum magnetization at 1.5 T

Increased endogenous susceptibility effects at higher fieldsIncreased endogenous susceptibil ity effects at higher fieldsInherentInherent intravoxelintravoxel phase dispersionphase dispersion

B0 TEB0 TE

Source susceptibil ity dif ferenceSource susceptibil ity dif ference , main field strength, main field strength BB00 , echo time, echo time TETE

=> shorter echo times to reduce local signal=> shorter echo times to reduce local signal--loss (loss (T2*T2*) artifacts) artifacts

=> larger acquisit ion bandwidths=> larger acquisit ion bandwidths BWBW => noise increase=> noise increase

BWBW

=> presumably poorer labeled=> presumably poorer labeled--cellcell detectabilitydetectability above 1.5 Tabove 1.5 T



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B1/I : coil-sample inductive coupling(magnetic field / unit current)

Radiofrequency coil noise : equivalent

coil resistance RC and temperature TC

Noise from biological tissues : equivalent

sample resistance RS and temperature RS

mT

transverse magnetization, tO/ t

Robservation/repetition times

ScalingScalingthethe sensitivitysensitivityof the MRof the MR detectiondetection

2 3

0SR a

1/ 2 0

0CR a

01

01/ aB I

0 1 )/(+ S S

Onorm transvers

RC

e

C

tSNR mR TR TI

tB

IntrinsicIntrinsic SNRSNR aa--5/25/2 001/21/2 => prefer higher fields and/or smaller samples

to acquire smaller voxels

Use cryogenically cooled / superconducting coils whenRCTC > RS RS(small samples and/or low fields )

ScalingScalingrulesrules ::aa samplesamplesizesize

001/21/2 MRMR frequencyfrequency(

)

per unit volume

and unit time

1

0Ot



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MRI applications of HTS radiofrequency coilsMRI applications of HTS radiofrequency coils

HighHigh--Temperature Superconductivity (Temperature Superconductivity (TcTc > 77 K)> 77 K) Bednorz and Muller,1986Bednorz and Muller,1986

lowlow--field MRIfield MRI Hall A.S. et al., 1991Hall A.S. et al., 1991

=> whole=> whole--body clinical scannersbody clinical scanners < 0.5 T< 0.5 T

rationale : cost reductionrationale : cost reduction

dedicated MR microscopesdedicated MR microscopes Black R.D. et al., 1993Black R.D. et al., 1993

=> MR histology of ex=> MR histology of ex--vivo specimensvivo specimens at > 2 T .... 10 Tat > 2 T .... 10 T

rationale : biological studies andrationale : biological studies and phenotypingphenotyping

conventional body scanners (typical 1.5 T)conventional body scanners (typical 1.5 T) GinefriGinefri J.C. et al., 2001J.C. et al., 2001

=> miniature surface coils=> miniature surface coils

rationale : highrationale : high--resolution MRI at the periphery of the human body (skin,resolution MRI at the periphery of the human body (skin,

small joints...), insmall joints...), in --vivo microvivo micro--MRI of small animals (transfer)MRI of small animals (transfer)



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1.5 T body scanner (GE)1.5 T body scanner (GE)

64 MHz64 MHz -- 2222 mT/mmT/m gradientsgradients

12 mm YBCO surface coi l12 mm YBCO surface coi l

TransmissionTransmission--line resonatorline resonator

Unloaded quality factor Q > 100000Unloaded quality factor Q > 100000

Transmit/Receive mode onlyTransmit/Receive mode only

Initially designed for human skinInitially designed for human skin

4 to 15 x SNR gain / room copper4 to 15 x SNR gain / room copper

Dedicated cryostat 77 KDedicated cryostat 77 K

Desert Cryogenics, CADesert Cryogenics, CA

LN2 +LN2 + SaphireSaphire cold fingercold f inger

GinefriGinefri J.C. et al,J.C. et al, MagnMagn.. ResonReson. Med. 2001. Med. 2001

PoirierPoirier--QuinotQuinot M. et al, ISMRM Berlin 2006M. et al, ISMRM Berlin 2006

capillary tube

3D scan (20 m)3

TR/TE 248/17 ms

scan time 40 min.

SuperconductingSuperconducting surfacesurface coilcoil



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InIn--vivo microvivo micro--MRIMRI histologyhistology(HTS(HTS coilcoil1.5 T)1.5 T)

Comparison of a high-resolution MR slice (a) to the corresponding 3-m-thick

histological slice (b) in a subcutaneously implanted tumor (mouse). The MR image (60

m isotropic resolution) has been acquired an hour after Gd-DOTA injection. The

comparison yields the identification of different tumor components, such as living

tumoral tissue, necrosis, and well-vascularized nontumoral tissue, as a basis of the

structural heterogeneities visible on the MR image.

Poirier-Quinot et al. Performance of a miniature high-temperature superconducting (HTS) surface coil for in vivo microimaging of themouse in a standard 1.5T clinical whole-body scanner 60 (4), 917-927 (2008)



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MicroMicro--IRMIRM1,5 T : tumeur sous1,5 T : tumeur sous--cutancutane (souris in vivo)e (souris in vivo)

M. PoirierM. Poirier--QuinotQuinot et al.,et al.,paraparatre danstre dansMagnMagn..ResonReson. Med.. Med.

antenne IRM supraconductrice 12 mm 80 K :antenne IRM supraconductrice 12 mm 80 K : tude dynamique de latude dynamique de la

permpermabilitabilit tumoraletumorale haute rhaute rsolution spatiale (Gdsolution spatiale (Gd--DOTA)DOTA)

Sequence SPGR 3D

voxel 59x59x300 m3

TR/TE 50/15 msTacq 6.9 min.

Gd-Dota 0.3 mmol/kg

a. avant injection

b. 14 minutes aprs injectionc. 42 minutes aprs injection



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Tumor model: derived from ELTumor model: derived from EL--44Lymphoma expressingLymphoma expressing ovalbuminovalbumin antigenantigen(EG(EG--7 tumors)7 tumors)

Cell model: lymphocytes expressing TCell model: lymphocytes expressing Tcell receptor (TCR) specific forcell receptor (TCR) specific for

ovalbuminovalbumin were obtained from OTwere obtained from OT--11micemice

(OT(OT--1 lymphocytes)1 lymphocytes)

Cell-based anticancer therapy model

TCR antiTCR anti--OVAOVA

OTOT--1 lymphocyte1 lymphocyte

Smirnov P. et al., CMR Evian 2005Smirnov P. et al., CMR Evian 2005



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24 to 7224 to 72 hrhr:: tumortumorinfiltration byinfiltration bylymphocyteslymphocytes

IV injection ofIV injection of labeledlabeled lymphocyteslymphocytes3 103 1066 cellscells 1.51.5 pgpg // cellcell

SpleenSpleenTumorTumor

Up to 24 hr:Up to 24 hr: splenicsplenichoming ofhoming of labeledlabeledlymphocytes,lymphocytes, thenthen

division and maturationdivision and maturation

NegativeNegativeenhancementenhancement of theof thespleenspleen

NegativeNegative enhancementenhancement ofofthethe tumortumor( < 0.2( < 0.2 pgpg // cellcell))

HighlightedHighlightedmechanismsmechanismsby in vivo 7 Tby in vivo 7 T studiesstudies(Smirnov et al., ECR 2005(Smirnov et al., ECR 2005 ((EuropeanEuropean CongressCongress ofof RadiologyRadiology )), Vienna 4, Vienna 4--88 marchmarch2005)2005)



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Control Labeled lymphocytes

ResultsResults: in vivo cellular: in vivo cellular imagingimaging

(voxel size = 59 m3, TE = 14 ms acq. time = 29 min)



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ResultsResults: in vivo cellular: in vivo cellular imagingimaging

Control Labeled lymphocytes



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Ponctuals hyposignal in 3D nanoparticles labeled cells

In vivo cellular imaging / HTS coil 1.5 T

(voxel size = 59 m isotropic 3D, TE = 14 ms acq. time = 29 min)



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Transposition vers la pratique cliniqueTransposition vers la pratique clinique

Animal / Homme

B0

1.5 T

3 T

4.7 T

7 T Preuves de concept

Imagerie molculaire

Application

clinique

transposition

?Opt. Matrielle

Preuves de concept

Imagerie molculaire

Antenne conventionnelle 9 T

( 12 mm)

Antenne supraconductrice 1.5 T

( 12 mm)=

M0

?

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Imageriecellulaire IRM Darrasse Septembre 2010