SingJ・Phys.，Vol、１８，Ｎｏ．１，２００２，１７－２２1７

ＳＥＮＴＩＮＥＬＩｊＹＭＰＨＮＯＤＥＢＩＯＰＳＹＢＹＡＨＩＧＨＴｃＳＱＵＩＤ

SaburoTanakaHajimeOta,YCichiKondoandYUkikoMatsuzawa
EcoIO9ical助ginee7m9,⑰"ohcBshMﾉmue7s伽qf71echM叩",Ｌ１Ｈ伽ｒｉ９ａｏｈＧＺ１ＢｍｐａＡ抄cho
TbyohashiAdchiイイル8580,兆pα〃

YasuhiroTamakiandShinzaburoNoguchi
Depa7me汎tqfSwpicalO〃colM/,B2omedicGlReseamchＯｅｍｅ７０ｓａｋａｕ脚ers鋤Ｇ７皿泌GteSchool
QfMeclicme,2-2-ＥＺＯＹｔＢｍＭＧｏＡＤｃＬ,Ｓｕ伽，Ｏｓａｋａ565-0871,Ｊ〃α〃

TheperfOrmanceofalymphnodedetectionsystemusedwithahighTcsuper-conductingquantuminterfCrencedevice(SQUID)wasinvestigatedThesignal

fromtheparticleswasdependentonthefrequencyofthemagneticfieldThis
resultsuggestedthatthepolarizatioｎｉｓｄｕｅｔｏｎｏｔｏｎｌｙｔｈｅａｌｉｇｎｍｅｎｔｏｆｔｈｅ
ｄｉｐｏｌｅｍｏｍｅｎｔｓｂｕｔａｌｓｏｔｈｅｐｈｙｓicalrotationoftheparticles．
ｌＮＴＲＯＤＵＣＴＩＯＮ

Ｗｅｈａｖｅｒｅｃｅｎｔｌｙｐｒｏｐosedtheapplicationofahigh-Tcsuperconductingquantum
interferencedevice(SQUID）tothenewlydevelopedsurgicaltechniqueofsentmel
lymphnodebiopsy・Axillarylymph-nodedissectionisanimportantprocedureinthe
surgicaltreatmentofbreastcancer・Ｈowever,intheearlydiagnosisstage,thenumber
ofdissectionsinwhichaxillarynOdesarefreeofdiseaseisapttobeincreasedThesetreatmentｓｌｅａｄｔｏｓｏｍｅｐｒｏｂｌｅｍｓｓｕｃｈａｓａｌｙｍｐhedemaandasensoryneuropa房

thyinthepatient・Ｔｈｅｓｅｎｔｉｎｅｌｎｏｄｅｂｉｏｐｓｙｉｓａｋｉｎｄｏｆtesttoinvestigatewhether
thesentinelnode，whichinitiallyreceivesmalignantcellsfromabreastcarcinomais
disease-freeornot・Ｉｆｔｈｅｓｅｎｔｉｎｅｌｎｏｄｅｉｓｆｒｅｅｏｆdisease，ｙｏｕｃａｎｌｅａｖｅｔｈｅｒｅｓｔｏｆ
ｔｈｅｌｙｍｐｈ－nodesbecauseofnoconcernfbrprogressionThisbiopsyisbasedonthe
hypothesisthatifthefirstlymphnode(sentinelnode)isfreeofdisease,thesecond
andtherestofthenodesmustbenegativeTwomethodswhichdetectthesentinel

nodehavebeendevelopedandreportedtodate1-3・Ｏｎｅｉｓａｋｉｎｄｏｆｒａｄｉｏｇｕｉｄｅ，

ｗｈｉｃｈｕｓｅｓａｇａｍｍａｄｅｔｅｃｔｏｒａｎｄａｒａｄioisotopesuchastechnetiumlabeledsulfilr
colloidAfterinjectingtheisotopeintoabreastlesion,thesentinellymphnodewillbe
identifiedbythegammadetector・ThenthesentinelnodeisexcisedandexaminedIn

thismethodthesentinellymph-nodeissuccessfilllyidentifiedwith94.4％accuracy1・Thoughthepredictabilityofthismethodisextremelyhigh，radiationexposureisinevitablefbrmedicalstafT・Theothermethodusesabluedye;asurgeonidentifiesthesentinellymph-nodewithhisnakedeyeWiththismethodthepredictabilityisstill
70％accurate2，

Therefbreweproposealocalizationsystemcombinedwithahigllsensitivity

superconductingqUantuminterferencedevice(SQUID)magnetometerandultrasmall

1８

SaburoTanakaHajimeOta,YbichiKondoet.aﾉ．

ironoxideparticles・ＴｈｅｓｙｓｔｅｍｗｅａｒｅｐｒｏｐｏｓｉｎｇｉｓｓｈｏｗｎｉｎＦｉｇ・LTheparticles
wouldbeinjectedintothebreast;andthehigh-TcSQUIDisusedasasensingdetector
fbrtheparticles・Thismethodhassomeadvantages：noradiationexposureandan
accurateidentificationbecauseofthevisiblecoloroftheparticlesthemselves・For
thisapplication,theSQUIDmagneticsensorshouldidentifj/thelocationofthesmall
quantityofparticlesunderthesensor・A1thoughaSQUIDbiosusceptometrysystemhasbeenreported4，ｉｔｉｓｖｅｒｙｄｉＨｉｃｕｌｔｔｏｄｅｔｅｃｔｔｈｅｌｏｃationbecauseofthesmall

quantity・DetectionmethodsofsmallmagneticparticleswithaSQUIDimmunoassay，ｗｈｉｃｈｃａｎｂｅａｌｓｏａｐｐｌｉｅｄｔｏｏｕｒｄｅｔｅctionsystem，havebeenproposedinseveral

groups5-7.Eveniftheparticlesaremadeofironoxide,iftheirsizebecomestoosmall，

theyshowsuperparamagneticproperties・Therefbre，somemagneticfieldshouldbe
appliedtotheparticlesfbrdetectionbecausetheyhavealmostnopermanentmagnetic
dipoleatroomtemperature・Koetitzet・aLappliedapulsefieldtotheparticlesandthen
measuredthefielddecayfromtheparticlesintherangeofｍｓ・Enpukuetal・measured
thefieldfromtheparticlesunderaDCmagneticfieldFbrtheworkdescribedhere，
wemeasuredthefieldfromtheparticlesunderanACmagneticfield．
Lymphnode■■■■■■■■巴_)K三国
鴫

ｅｎｓｏｒ

Lymphnode(containsIronoxideparticIes）
Fig.１．Thesystemdiagramofthesentinel-nodebiopsyusinghighTcSQUID,whichweareproposingTheparticleswouldbeinjectedintothebreast；ａｎｄｔｈｅｈｉｇｈ－ＴｃＳＱＵＩＤｉｓｕｓｅｄａｓａｓｅｎsing
detectorfbrtheparticles､Ｔｈｉｓｍｅｔｈｏｄｈａｓａｎａｄｖａｎｔａｇｅｏｆｎｏｒａdiationexposure．

Wehavealreadyreportedtheresultsofpreliminarystudyusingparticlesdis-

persedliquidinatube8・Inthispaper，wediscussaboutamagneticfieldfrequency
dependenceoftheSQUIDsignal．

ＥＸＰＥＲＩＭＥＮＴＡＬＳＥＴＵＰ

ＴｈｅｓｃｈｅｍａｔｉｃｄiagramofthesystemisshowninFig2、ＴｈｅＳＱＵＩＤｉｓｍａｄｅｏｆ

Ｙ１Ｂａ２Ｃｕ３０７－gthinfilm・ThejunctionsutilizedintheSQUIDareofthestep-edge
type・ThewashersizeoftheSQUIDisabout２．５x25mm2andtheefTectiveareais
０．１１ｍｍ2.TheSQUIDwasoperatedinaHux-lockedloopThemagneticfluxnoisein

thewhitenoiseregionwasabout30〃o/Hz1/2．

!’

ＳＥＮＴＩＮＥＬＬＹＭＰＨＮＯＤＥＢＩＯＰＳＹＢＹＡＨＩＧＨＴｃＳＱＵＩＤ

1９

ThecryostatwasspeciallydesignedfbraSQUIDmicroscope・TheSQUIDwas
locatedinsideavacuuｍａｎｄｓｅｐａｒａｔｅｄｂｙａ５０〃mthickquartzwindow・Ａｍｏｒｅｄｅ‐taileddescriptioncanbefbundelsewhere9Twocoils(Helmholtztype)weremounted
justabovetheSQUIDmicroscope1o''1.AfinepOlytetrafluoroethylenetubewithan
innerdimensionoｆ0.85-0.95ｍｍｄｉａ.，whichconveyssmallparticles，wasthreaded
intothecoils・Amotordrivensyringepumpwasemployedtoconveytheparticlesby
pushingairinsidethetubeAsinusoidalACcurrentwithafrequencyof5Hｚ－１００Ｈｚ
ｗａｓｄｉｒｅｃｔｅｄｔｏｔｈｅｃｏｉｌｓ；themagneticfieldgeneratedfromthecoilwasmodulated

bythefrequency・Ｔｈｅmodulatedsignalassociatedwiththeparticlemotionwasthen
demodulatedbythelock-in-amplifier・Thelock-in-amplifierconsistsofaphasesensitivedetector，aphaseshifterandalow-passfilter12Theuseofthelock-in-amp1ifierisacrucialpointtoobtainagoodresolutioninthesystem・TheSQUIDposition
wascarefilllyadjustedbefbremeasurement,sothattheSQUIDoutputsignalwithout
particlesbecamezero．

」ｎｕＢ「】･「Ｉ【】皿-ﾛ雷Ｘ＝･川ge川トノ、ａ(Ｌ二二11二」ト田【】ｎ－ｕＩ【：【】岳ピノｗ●●」Ⅱ、ｌＯＣＫ

Ｄｒｄｅｒａｒｎに】、Ⅲ【Ⅲ｡”

ＪＵＩＤｍａｏｎｅｔｃ

ｅ「Fig.２．Schematicdiagramofthesystemfbrthefeasibilitytest・Apairofcoilsweremountedjust

abovetheSQUIDcryostat・ExternalacmagneticfieldwasappliedbythecoilsAmotordriven
syrinｇｅｐｕｍｐｗａｓｅｍｐｌｏｙｅｄｔｏｐｕｓｈｔｈｅｍａｇneticparticlesampleinsideathinｔｕｂｅ・Themodulated

signalassociatedwiththeparticlemotionwasdemodulatedbythelock-inamplifier．

AfteraJjustingtheSQUID,thesystemwasreadytomeasuremagneticfield
fromtheparticles・Weusedultra-smallparticlesfromMeitoSangyoCo.,LtdSimilar
particlesareusedasamagneticresonanceimaging(MRI)contrastagentThecore
oftheparticleisironoxidem304(magnetite)whichiscoatedwithanalkali-treateddextran・Theaveragecorediameterwasllnm，whichwasmeasuredfromtheX-ray
difIractionpatternusingScherrer，sequation13・TheaverageddiameterofthecoatedparticleswaslOOnmTheparticleshadsuperparamagneticproperties、Theparticles
weresuppliedinthefOｒｍｏfanaqueousmagneticHuidTheoriginalfluidcontained
5.9ｍｇ/mlofironlfwesuppose52g/cm3asthespecificgravityofthecore,ｗｅｃａｎｅｓｔｉｍａｔｅｔｈｅｗｅｉｇｈｔｏｆｔｈｅｍｏｎo-particleas3,6ｘｌＯ－１８ｇａｎｄｔｈｅｔｏｔａｌｎｕｍｂｅｒｏｆ
ｐａｒticlesintheoriginalsolutionas1.5xlO16/mLTheoriginalfluidwasdilutedwith
distilledwatertohavethedesiredconcentrations・ThenthefluidwassweptinthefineSaburoTanakaHajimeOta,YbichiKondoet.aﾉ．

2０

tubewiththescanspeedofO､33-1.1ｍｍ/secunderanACmagneticfieldof9xlO-5
to7xlO-4T(peaktopeakvalue)．

ＲＥＳＵｍｒＡＮＤＤＩＳＣｕＳＳＩＯＮｓ

Weperfbrmedallofthemeasurementsinamagneticallyshieldedroomwithashielding

factorof-50dBat０．１Ｈｚ・Weinvestigatedthedetectableweightsoftheiron・The

SQUIDsignalwasproportionaltotheweightoftheironinthefluid・Atadistanceof
40mm,ｔｈｅｍinimumdetectableweightwasL6似9.Ｗｈｅｎｔhedistancewasdecreased
tolmm,thisdecreasedto360pg8．

==Ｔ=TWTV7麟一

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Frequency［Ｈz】

Ｆｉｇ．３．FYequencydependenceoftheoutputsignaLThemodulationfrequencyoftheHelmholtzcoil
waschangedfroｍ５ＨｚｔｏｌＯＯＨｚ・Closedcirclesshowtheresultsfromliquidsample、Opencircles
showtheresultsfromliquidwithapieceofcotton．

ThenwemeasuredthefrequencydependenceoftheoutputsignaLThesample

consistedofironparticlesof2.4/Lganddistilledwaterof4､4似入Themodulationfre‐

quencyoftheHelmholtzcoilwaschaｎｇｅｄｆｒｏｍ５ＨｚｔｏｌＯＯＨｚ・Theresultsareshown
inFig､３(solidcircles)Thesignalfromthelock-inamplifierdecreasedwiththeincreaseoffrequencyintheregionofmorethanl0Ｈｚ・TheresultssuggestedthatthealigｎｍｅｎｔｏｆｔｈｅｄｉｐｏｌｅｍｏｍｅｎｔｓｏｒｔｈｅｒｏtationoftheparticlesisnotsynchronizedwiththefreqUency・Therefbreweimmersedapieceofcottonwiththeliquidsalnple・Thecontentoftheironandtｈｅｖｏｌｕｍｅｏｆｔｈｅｌｉｑｕｉｄｗｅｒｅａｓｓａｍｅａsthefbrmerexper-

imentlnthissample，therotationoftheparticlesshouldberestrictedbyexistence

ofthecottonthoughitwasnotperfectly・Thefrequencydependencewasmeasured
usingthissampleTheresultswereshowninFi9.3（opencircles)Thesignalwas

oneordersmallerthaｎｔｈａｔｏｆｔｈｅｌｉｑｕｉｄｓａｍｐｌｅｉｎａｌｌｔｈｅfrequency；thisisbecause
oftherestrictionoftheparticle，srotation，AlthoughfUrtherexperimentsareneeded

ＳＥＮＴＩＮＥＬＬＹＭＰＨＮＯＤＥＢＩＯＰＳＹＢＹＡＨＩＧＨＴｃＳＱＵＩＤ

2１

toclarifj/thisphenomenon7,notonlythealignmentofthedipolemomentsbutalso
thephysicalrotationoftheparticlesiscontributedtothepolarization・Therefbrethe
lowerfrequencyshouldbechoseninthesystem．

ＣＯＮＣＬＵＳＩＯＮ

Ｗｅｈａｖｅｄｅｍｏｎｓｔｒａｔｅｄｔｈepossibilityofrealizationofananoparticledetectionsystem
usedwithahigh-TcSQUID,whichisusefillfbrsentinellymphnodebiopsiesTheultra-smallironoxideparticlesof360pginweightofironcouldbedetectedwith
aspaｃｉｎｇｏｆｌｍｍ、Thesignalfromtheparticleswasdependentonthefrequencyof

themagneticfieldThisresultsuggestedthatthepolarizationisｄｕｅｔｏｎｏｔｏｎｌｙｔｈｅａｌｉｇｎｍｅｎｔｏｆｔｈｅｄipolemomentsbutalsothephysicalrotationoftheparticles．
ＡＣＫＮＯＶＶＬＥＤＧＭＥＮＴＳ

Ｔｈｉｓｗｏｒｋｗａｓｐａｒtiallysupportedbyagrant-inAidfbrScienceResearch(B)fromthe
MinistryofEducation，Culture，Sports，ScienceandnchnologyandalSosuppｏｒｔｅｄ

ｂｙＴＨＥＳＡＧＡＷＡＦＯＵＮＤＡＴＩＯＮＦＯＲＰＲＯＭＯＴＩＯＮＯＦＣＡＮＣＥＲＲＥＳＥＡＲＣＨ．

ＲＥＦＥＲＥＮＣＥＳ

１．Ｕ、Veronesi，Ｇ・Paganelli，Ｖ・Galimberti，Ｇ・viale，SZurrida，Ｍ・Bedoni，Ａ・Costa，Ｃ・deCicco，Ｊ、Ｇ・Geraghty,Ａ、Luni，Ｖ・SacchiniandP・Veronesi，TheLancet349，１８６４（1997)．

２．Ａ・EGiuliano，，．Ｍ・Kirgan，Ｊ、Ｍ・GuentherandD．Ｌ・Morton，ＡｎｎＳｕｒｇ２２０，３９８（1994)．

３．Ｃ・ＥＣｏｘ,Ｓ．Ｐ．Pendas,Ｊ・ＭＣｏｘ,Ｅ・Joseph,Ａ・RShons,Ｔ・Yeatman,Ｎ､Ｎ､ＫｕＧ.Ｈ・Lyman,OBerman,FHaddadandD､SReintgen,AnnalsofSurgery227,６４５(1998)．

４．Ｒ・Engelhardt，RFisher，Ｐ・Nielsen，ａｎｄＥ、EGabbe，Proc・ｏｆｌＯｔ九InternationalConfbrenceonBiomagnetism,１８７(1996)．

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Ⅱ１Ⅲ！