医学超声影像学的基础与应用

BasisandClinicApplicationofUltrasound

医学超声影像学的基础和应用

1ContentsBasicconceptions（Keywords)UltrasoundInstrumentsPrinciplesandapplicationofultrasoundtechniquesNewdevelopmentofultrasoundtechniques

2ContentsBasicconceptions（Keywords)UltrasoundInstrumentsPrinciplesandapplicationofultrasoundtechniquesNewdevelopmentofultrasoundtechniques

3Basicconceptions(keywords)Audiblesound:frequence20-20000Hz超声波（Ultrasound）frequence>20KHzsound频率（Frenquency，f)cyclespersecond.unit:Hz速度（Velocity，C)unit:m/s,variesdependingonthetypeoftissue(elasticity,density).Air330m/sWater1480m/s,Softtissue1540m/s,Bone3500m/s波长（Wavelength，λ)

distancetransmittedwithin1cycleunit:m

频率：单位时间内声源振动的次数声速：声波在介质中传播的速度,单位m/s波长：声波在振动一个周期时间内所传播的距离c=f,λ=c/f例：3.5MHz声波在软组织中的波长（穿透的深度）0.44mm4Basicconceptions(keywords)

c=λfQ1:What’sthewavelength(transmitdepth)ofa3.5MHzprobewhentransmittinginhumansofttissues?Answer:

0.44mm5反射(Reflection):声波入射到介质界面,部分声波返回原介质折射(Refraction)：介质声速变化引起的声传播方向发生改变散射(Scattering)：声波遇到介质后向多个方向传播的现象

Basicconceptions(keywords)Medium1Medium2IncidenceReflectionRefractionIncidenceScattering1)2((6吸收(Absorption)：声波传导过程中部分声能转变为热能或其他分子能量的过程。衰减（Attenuation):

声波在介质中传播时，其强度随传播距离的增加而逐渐减弱的现象。Q2:Whythetransmitdepthisstilllimitedandthetissuefarawayfromtheprobeisnotclearevenusinglowfrequencyprobe?Answer:AttenuationBasicconceptions(keywords)7BiologicaleffectsofUltrasound

超声的生物学效应空化效应（Cavitationeffect）高强度超声使组织液化,产生微泡的现象机械效应（mechanicaleffect）使介质产生位移、速度改变、加速度、切应力变化等…

评价参数是机械指数（MI）定义：具有一定声强的超声波在生物介质中传播，引起介质结构、功能或形态学变化。热效应（thermaleffect)声波传导过程中使介质温度升高的现象

评价参数是热指数（TI）8超声医学(UltrasonicMedicine)定义:

超声波与计算机技术结合用于临床诊断和治疗的一门学科。临床应用:诊断(Diagnosis):useofreflection,refractionandscatteringofultrasoundtoevaluatetissuemorphology,characteristicsandfunctions治疗(Treatment):ultrasoundhighenergy,intensity超声理疗Physicaltherapy

低剂量连续波超声射频消融Radiofrequencyablation(RFA)

中等剂量肿瘤高强度聚焦（High-intensityfocusedultrasound

HIFU刀)肿瘤体外超声碎石invitroultrasoniclithotripsy9Clinicalapplication

实质脏器

(solidviscera)liver、spleen、pancreas、kidneys

含液性器官

(fluid-filled

organs)gallbladder,urinarybladder

心脏结构

(cardiacstructure)

血管结构(vascularstructures)carotidartery,IJV,cerebralvessels,limbvessels,aorta,renalvessels,inferiorvenacave,hepaticvein,portalveins

小器官

(smallpart)breast,scrotum,thyroid

妇科、产科

(gynecologyandobstetric)

10ContentsBasicconceptions（Keywords)UltrasoundInstrumentsPrinciplesandapplicationofultrasoundtechniquesNewdevelopmentofultrasoundtechniques

11CompositionsofultrasoundinstrumentPower（电源）Emittercircuit（发射电路）Transducer（Probe）换能器（探头）SignalAmplifier（信号放大器）DisplayScreen（显示器）12超声探头(Probe,Transducer)1.定义:发射并接受超声的装置。电能与声能互相转换

emitandreceiveultrasoundsignal

electricenergy

soundenergy

由晶片、吸收（声）模块、匹配层及导线组成。

132.

探头类型（ProbesTypes）单晶片或多晶片笔式探头（pentypeprobe)：A超M超临床应用于经颅多普勒超声和胎儿监护仪机械扫描探头(mechanicscanningprobe)：机械传动方式带动传感器往复摇摆或连续旋转来实现扇形扫描过程。14电子扫描探头(electronicscanningprobes)：

线阵探头相控阵探头凸阵探头

三维容积探头(3-DVolumetransducer):

用于三维超声成像(电子探头聚集与机械扫描集成探头)LinearprobePhasedarrayprobeConvexprobe153.探头频率（Probefrequency）单频探头:标称频率为发散时振幅最强的频率变频探头:同一探头可选择2-3种频率,频率可变宽频探头:发射时有一很宽的频带范围高频探头:血管内及浅表器官成像Medicalultrasoundfrequencyrange:1-20MHZ164.分辨力Resolution定义:Theabilitytodifferentiatetwodifferentobjects.纵向分辨力(Axialresolution)Itistheminimumreflectorseparationalongthesoundpath.横向分辨力(Lateralresolution)

Itistheminimumreflectorseparationverticaltothesoundpath.17Highfrequencytransducer:betteraxialresolutionbutlowerpenetration(穿透力）.Lowfrequencytransducer:lessaxialresolutionbutbetterpenetration.Superficialtissue:highfrequencyprobe.e.g.thyroid,carotidarteryDeeptissue:lowfrequencyprobe.e.g.abdomen4.分辨力Resolution185.声场UltrasonicField定义：spacefullofultrasoundenergy

近场(nearfield):closetothetransducer

声束比较平行远场(farfield):farawayfromtheprobe，声束扩散、声束宽随检测距离增加而不断增宽近场长度L=r2/λ=d2×f/4cd探头晶片直径，C声速，r组织密度，λ波长近场远场196.超声仪器功能键

Keysontheultrasoundinstrument增益(Gain):

调整图像灵敏度聚焦(Focus):

可选择聚焦区数目，以取得观察区清晰图像深度(Depth):

增加或减小深度，使图像增大或缩小20帧频:(FR):

每秒内成像的数量重复脉冲频率(PRF):

每秒内发射脉冲群的次数速度标尺(Scale):

指彩色标图所能显示的速度范围取样容积(SV):

沿超声束的不同深度对某一区域的多普勒信号进行定位探测,该区域即取样容积6.超声仪器功能键

Keysontheultrasoundinstrument21Keysparametersdisplayedontheimages22Howtoobtainhighqualityultrasoundimages?Q3:WhatfactorsdoHighqualityimagesdependon?Answer:1)Instrumentqualityandprobeselection2)Instrumentadjustment3)Operator’sexperienceandskills23ContentsBasicconceptions（Keywords)UltrasoundInstrumentsPrinciplesandapplicationofultrasoundtechniquesNewdevelopmentofultrasoundtechniques

24Historyofmedicalultrasoundtechniques1942，GermanyDr.DussikAmodeultrasound1949，Dr.Howry2-Dultrasoundinclinic1954，Dr.EdlerMmodeultrasound1973，Dr.JohnsonusedpulsedDopplertodiagnoseventricularseptaldefect1980s，ColorDopplerultrasoundinclinic1982，Aaslid,Transcranialdoppler(TCD)

25UltrasoundinstrumentsinWorldWarII坦克式双探头旋转式（腹部）潜水镜式（产科胎儿）26ThebasicultrasoundexaminationsmodesA-ModeB-ModeD-ModeM-modeA

BestMedicalDoctor(ABMD)27A超（AmplitudeModulation）原理：幅度调制型，以超声的传播和反射时间为横坐标，以反射波幅为纵坐标。反射强，波幅高。反射弱，波幅低。

one-dimensionalsystem,representthetimeanddistancetheamplitudeofthespikeisrelatedtothereflectedenergymeasuredistancealongthepathofsoundtransmission&reflection28应用：脑中线探测；眼球探测；胸腔积液探测；心包积液探测；肝脓肿探测。现已基本淘汰A超（AmplitudeModulation）29B-mode（Brightnessmode）B-modeisthebasisofultrasoundtechniques原理：辉度调制型，以不同辉度光点代表反射信号的强弱。反射强则亮，反射弱则暗。为二维切面图。Two-dimensionalsystemdotsofvaryingbrightnessarerelatedtothereflectedenergy应用：组织结构形态学、病变性质诊断

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无回声区

echofreearea

低回声区

hypoechoicarea

等回声区

isoechoicarea

高回声区

hyperechoicarea透声区sonolucent声影

acousticshadow

声像图描述关键词—组织回声(echo)31无回声低回声不均回声、实性强回声、声影32无回声型

液性无回声胆汁衰减性无回声骨骼后方均质性无回声淋巴结低回声型皮下脂肪组织等回声型肝、脾实质强回声型包膜正常人体组织的回声强度类型33Orientationoftheimages

超声影像定位Superficial-frontHead-proximalFoot-distalDeep-backLongitudinalView(纵向)TransversionalView(横向)LeftexternalRightinteranaldeepsuperficialLongitudinal(纵向)viewlefttowardheadrighttowardfootTransverse(横向)view

leftshowingrightside,rightshowingleftsideUpshowingsuperficialDownshowingdeeper34Descriptionofultrasoundimages

声像图描述Location位置Size大小Shape形态Boarder边界Innerechocharacteristics内部回声特征Surroundingcharacteristics周围回声及毗邻关系Activity活动度QuantitativeAnalysis定量分析35M-mode（MotionMode）原理：采用灰度调制，在水平偏转板上加入一对慢扫描锯齿波，横坐标表示时间，纵坐标表示距离。time-sequencerecordingTimealongthehorizontalaxisDepthalongtheverticalaxis应用：多用于心脏检查城墙样二尖瓣狭窄36DopplerModeconstantspeed(equal)Higherpitch(dis)normal

pitchLowerpitch多普勒效应(Dopplereffect):(physicistDoppler1842)声源与接受物体间存在运动时,接受的频率发生改变的现象。objectstravellingtowardsthelistenerproduceapositivefrequencyshift.相对运动时，频率增高objectstravellingawayproduceanegativefrequencyshift.背向运动时，频率减低37多普勒效应

DopplerEffect

多普勒公式:v=fdc/2f0cosθ

应用：检测血管腔内红细胞的运动速度，评价血流动力学，血管狭窄、闭塞等38

脉冲波：间断发射、接收声波连续波：连续发射、接收声波连续波多普勒(CW)：两组换能器，不受深度限制，测高速血流脉冲波多普勒(PW)：单个换能器，有距离选通能力，受PRF限制39彩色多普勒

CDFI能量多普勒

CPA血管结构、运动速度、方向红细胞散射的能量积分－能量大小

频谱多普勒SpecturalForm速度、方向、声频异常DopplerDisplaymodes40ContentsBasicconceptions（Keywords)UltrasoundInstrumentsPrinciplesandapplicationofultrasoundtechniquesNewdevelopmentofultrasoundtechniques

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三维超声

Three-dimensionalUltrasoundImagingareacquiredontheirX、YandZaxis,manuallyrealigned,andthereconstruc