金真-北師大講課北師大ERP課程課件

磁共振腦功能成像系列講座

腦血流與BOLDfMRI

HemodynamicActivity

&BOLDfMRI

306醫(yī)院MR中心暨“認(rèn)知神經(jīng)科學(xué)與學(xué)習(xí)”國家重點(diǎn)實(shí)驗(yàn)室腦功能成像中心金真mdjinzhen@163.com

PartI

BrainNeuronVesselHemoglobin腦的外觀viewofthebrainSagital矢狀位（左右）Axial

軸位（上下）Coronal

冠狀位（前后）brain

大腦的分葉

cerebrallobesbrain體積：額葉最大,枕葉最小(代謝最高)大腦的分區(qū)

Brainareas

Brodmann(1909)分為52區(qū)(根據(jù)神經(jīng)細(xì)胞的結(jié)構(gòu)劃分)

分區(qū)20-200

brain

灰質(zhì)和白質(zhì)Gray&whitematterbrain

皮層和神經(jīng)元

Cortex&NeuronsNeuron皮質(zhì)厚約1.5～4.5mm,總面積約2200cm2功能柱：直徑300～500um貫穿皮層的垂直細(xì)胞柱神經(jīng)元的定義和結(jié)構(gòu)

神經(jīng)元:神經(jīng)系統(tǒng)的結(jié)構(gòu)和功能單位(人腦約有1000億個(gè))神經(jīng)元構(gòu)成:細(xì)胞體(核、質(zhì)、膜)突起(樹突、軸突)Neuron樹突&軸突(Dendrites&axon)Neuron樹突:神經(jīng)元的天線

軸突:傳出/傳出神經(jīng)元間的連接軸-樹(51%),軸-棘(47%),軸-體,軸-軸樹-樹,樹-體,體-體,體-軸Neuron

突觸synapse構(gòu)成:突觸前膜(5~7nm)

間隙(25~30nm)

后膜(50~60nm)突觸：神經(jīng)元間的接觸點(diǎn)（數(shù)百～上千個(gè)/神經(jīng)元,人腦100trill.)分類:化學(xué)性傳遞,電傳遞;興奮性突觸,抑制性突觸線粒體突觸小泡突觸前膜神經(jīng)介質(zhì)神經(jīng)受體高等動(dòng)物點(diǎn)對(duì)點(diǎn),快速準(zhǔn)確的傳遞方式Neuron

離子通道Ionchannel

NeuronGlu.:Na+NMDA:Ca++

GABA:Ch-&K+腦血管:

cerebralvesselsvessel腦重約1300-1400克（腦：體＝1/40）

腦血流量80ml/min/100g（腦：體＝1/5）皮層80ml/min/100g；白質(zhì)21ml/min/100g動(dòng)脈和靜脈(artery&vein)vessel動(dòng)脈：離心方向,口徑粗-細(xì),3cm-30um靜脈:回心方向,Stroke

男，46，右肢不利1天Perfusion(stroke)

TTP

MTT

rCBFrCBVMRSCSI毛細(xì)血管capillary

vessel毛細(xì)血管：

直徑5～10um300mm/m3白質(zhì)1000mm/m3

皮層；血紅蛋白hemoglobin

-4個(gè)球蛋白-每個(gè)球蛋白包含一個(gè)血紅素-每個(gè)血紅素中心有一個(gè)鐵原子(Fe)-每個(gè)血紅素可以結(jié)合一個(gè)氧分子(O2)

Hb血紅蛋白的磁敏感性

Oxyhemoglobin(Hb)Deoxyhemoglobin(dHb)

Diamagneticparamagnetic

氧合血紅蛋白磁化率低，具抗磁性(磁場－）

去氧血紅蛋白磁化率高,具順磁性

(磁場＋）

HbLinusPauling

(1901-1994)AmericanchemistNobellaureate

Hbv.sdHb

20%difference!

HbRTThulborn

1T12T

43T8Hb血紅蛋白與MR信號(hào)

HbBrainThelastfrontierof20thcenturyPartIIBOLDfMRIAngeloMosso

1890ThemostwidelyusedfMRImethod,to“see”howthebrainisworking

BOLDfMRIArteryVeinArteriolesVenulesCapillaryBedNeurons血氧水平依賴對(duì)比

BloodOxygenationLevelDependentcontrast

OxyhemoglobinDeoxyhemoglobin

Diamagneticparamagnetic

氧合血紅蛋白磁化率低，具抗磁性去氧血紅蛋白磁化率高,具順磁性SeijiOgawa1934-1990discoveredBOLDinBelllab.HbdHbSEGEGE7T血流↑↑↑(ca.50％)氧耗↑（ca.5％）血氧水平↑,順磁性去氧

HB↓,形成局部梯度磁場,T2*WI局域性信號(hào)強(qiáng)度↑(BOLD效應(yīng))。腦區(qū)激活時(shí)血流動(dòng)力學(xué)變化mismatchBOLDfMRIcontrastisacomplexphenomenonwhichdependson

CMRO2氧耗

CBF血流量

CBV血容積

腦血流動(dòng)力學(xué)反應(yīng)曲線LargeandsmallvesselresponseLargevesselcontributions?DoestheratioofnegativetopositiveBOLDcontrastchangewithB0insuchamannerastosuggestmoreofasmallervesselcontributiontothenegativeresponserelativetothepositiveresponse?DIP&Undershoot-2%-0.5%1%5%Huetal，MRM37,877-84,1997EarlynegativeBOLD(3-4sec.)LatepositiveBOLD(8-9sec.)ObservedsiteofBOLDeffectSiteofelevatedneuronalactivity“...highlylocalizedtoindividualcorticalcolumns.However,thelatephaseofthevascularresponseislesslocalized,spreadingoverdistancesof3to5millimeters.”

Malonek&Grinvald,Science,272,551,1996.

BOLDfMRI

信號(hào)判讀

Datapost-processingSPMAFNI咬肌運(yùn)動(dòng)及運(yùn)動(dòng)障礙研究

BOLDsignal

size&location

BOLDsignal

size&location

BOLDsignal

location

ADHD

BOLDsignal

size

BOLDsignal

negative

M，1，無小腦畸形

M，1.7，病腦后遺癥ContralteralHippocampus(R-Hi)IpsilateralHippocampus(L-Hi)BOLDsignal

negative

BOLDsignal

where&when

fMRI

進(jìn)展

NeuronalcurrentMRI(ncMRI)

Lorentzeffect

DiffusionfMRI新的成像方法

fMRI

BesidesBOLD神經(jīng)（元）電流成像

NeuronalcurrentMRI(ncMRI)

Directmagneticresonancedetectionofneuronalelectricalactivity

PetridouN

PNAS2006Oct24;103

神經(jīng)元興奮電流磁場信號(hào)(相位15,幅度5%)

Lorentz

力成像

LorentzeffectimagingFindingneuroelectricactivityundermagnetic-fieldoscillations(NAMO)withmagneticresonanceimaginginvivo

Trong-KhaTruong

PNAS2006Aug15;103(33):12598-601彌散腦功能成像

DiffusionfMRIDirectandfastdetectionofneuronalactivationinthehumanbrainwithdiffusionMRI.LeBihan

PNAS2006May23;103(21):8263-8

KeyPoint：“cellswelling”2.4searlierthanBOLDsignalsignalchange1.7%

RestingStagefMRI

realtimefMRIBOLDfMRI的新方法

Restingstatecorrelation0.550.75ccRLM1S1PSAApSMACMAdPMdPMd:dorsalpremotor CMAd:dorsalcingulatemotorareaM1:primarymotorarea SMA:supplementarymotorareaS1:primarysomato- PSAAp:posteriorparietalsensoryarea somatosensoryassociationareaRightHandmovementEffectiveConnectivity(Task-drivencovariance)2.55.0t“True”Connectivity(Task-independentcovariance)PaincontroltaskdeCharmsR.C.et.al.PNAS2005;102:18626-18631Copyright?2005,TheNationalAcademyofSciencesControloverbrainactivationandpainlearnedbyusingreal-timefunctionalMRIVolumetricanalysisofthespatialpatternoflearnedcontroloveractivationConclusionofBOLDfMRI

首選的無創(chuàng)性腦科學(xué)研究功能影像學(xué)方法具有較高的時(shí)間和最好的空間分辨率

信號(hào)源于神經(jīng)元興奮時(shí)毛細(xì)血管和小靜脈內(nèi)氧合和脫氧血紅蛋白比例的變化信號(hào)范圍和位置與實(shí)際興奮腦區(qū)有差異信號(hào)變化有3-6秒的延遲BOLDfMRI

v.sPET放射性：無有空間分辨率：高低信號(hào)源：血氧水平葡萄糖代謝率費(fèi)用：低高重復(fù)性：易難受體：不能可以BOLDsignal=neuronactivity?

no&yesSignal=BOLDeffect?

yes&nolargeBOLDsignal=betterbrainfunction?

yes&noPositivesign