1、to display tissue structureB mode is also called 2D mode.,B-Mode,ppt课件,8,B-Mode,HP 70020A,1981,TOSHIBA SDS-10A,1981,ppt课件,9,Doppler-Mode,Christian Andreas Doppler AustriaPhysicist and mathematician Born in 1803 in SalzburgFound Doppler Principle in 1842 Died in 1853 in Venice,ppt课件,10,Doppler-Mode,S
2、ound source:NOT moving,Sound source:moving,ppt课件,11,Doppler-Mode,ppt课件,12,Doppler-Mode,Blood cell NOT moving,Blood cell moving,forward/backward,ppt课件,13,Doppler-Mode,v,f+fD,ppt课件,14,fD:Doppler shift of the frequencyf:Transmitted frequencyv:Velocity of the blood:Angle of incidence betweenthe ultrasou
3、nd beam and the direction of the flowc:speed of sound in tissue,PW Mode（Pulse-Wave）,PW:Pulse-Wave Doppler,Function:to measure velocity of blood flow,VelocityTime,1959,ppt课件,15,PW Mode,Sample VolumeAngle Correction,Sample Line,Gray scale stands for:the amount of all objects in that velocityin the sam
4、ple volume.,ppt课件,16,Principle of PW,Elements are both transmitting and receiving sound waves.The transmitting and receiving of sound waves are NOT in the same time.There is a Sample Volume.,PRF:Pulse Repetition Frequency,Transmit,Receive,Transmit,Receive,ppt课件,17,CW Mode（continuous wave）,Function:t
5、o measure velocity of blood flow,especially in heart,CW:Continuous-Wave Dopplerspeed of blood cells displayed on a time/velocity graphTime,ppt课件,18,Velocity,1956,CW Mode,Sensitive RegionAngle Correction,Sample Line,Gray scale stands for:the amount of all objects in that velocityalong the sample line
6、.,ppt课件,19,Principle of CW,Some elements are transmitting sound waves.The others are receiving.The transmitting and receiving of sound waves are JUST in the same time.,ppt课件,20,There is NO Sample Volume.But there is a sensitive region.,Color Mode,Color Doppler:Pixels assigned color based on mean vel
7、ocity,Function:to display direction of blood flow,Color mode is also called CDFI mode（Color Doppler Flow Imaging）or CFM（color flow mapping）,Red towards probe Blue away from probe,ppt课件,21,1983,Power Mode,Power Doppler:Pixels assigned color based on mean power,ppt课件,22,Power mode is also called CPA m
8、ode.（Color Power Angio）Function:to display volume of blood flow,especially at low velocity,DirPower Mode,ppt课件,23,Color Maps,Gray Scale,ppt课件,24,Velocity,Power,Directional Power,B mode,Color mode,Power mode,Difference-Color&colorize,B mode-colorizedWhole image is colorized.,ppt课件,25,Color modeOnly b
9、lood flow is colorized.Tissue is monochrome.,Difference-Color&Power,Power Doppler displays amplitude of signal（how much）Color Doppler displays velocity（how fast）,ppt课件,26,Angle Dependent,Color mode,vertical,ppt课件,27,oblique,Power mode,Angle Dependent,Yes,No,At perpendicular angle,No flow displayed,D
10、isplayed normally,Difference-PW&CW,Velocit,Locat Applicatio,ransmitting,und waves.,yLoweSample volume nAll,Sample line Cardiology,Continuous wave,PW modePrinciplePulsed-waveAll elements are t and receiving soProbeAll,CW mode,Sample Volume,Angle Correction,Sample Line,Some elements are transmitting s
11、SoeunnsditiwveavReesg.ion The others are receiving.,Phased arrayA,npgelencCilo,rortehcetrionHigh,Sample Line,ppt课件,28,Image Performance Knowledge,ppt课件,29,How to define a good B-mode imageHow to define a goodColor image How to define a goodPW/CW image,B-Mode Image,Ultrasound Wave DemonstrationT,Obje
12、ct,Refraction,Reflection,Scatter,ppt课件,30,B-Mode Image,S/N ratio（Signal/Noise Ratio）信噪比,Much noise in cavity,ppt课件,31,B-Mode Image,Penetration 穿透力,Penetration goes to 17.50cm,Only penetrates at 16.04cm,ppt课件,32,B-Mode Image,Spatial resolution 空间分辨率,Horizontal,ppt课件,33,Logitudinal,B-Mode Image,Contra
13、st resolution 对比分辨率,ppt课件,34,B-Mode Image,Temporal resolution,时间分辨率,ppt课件,35,Color Image,Sensitivity 敏感性,Better sensitivity小血管血流非常丰富,ppt课件,36,Color Image,Spatial Resolution空间分辨率,Right image has better spatial resolution,no obvious color overlay on vessel wall,ppt课件,37,Color Mode,Temporal Resolution
14、时间分辨率也称血流动态感,ppt课件,38,PW Image,Sensitivity,敏感性（低速，深部血流）,ppt课件,39,PW Image,Spectrum,Shape 频谱形态（包络连续性以及声窗）,ppt课件,40,CW Image,Sensitivity 敏感性（在狭窄和返流下的高速血流）,ppt课件,41,Ultrasound Artifacts,ppt课件,42,Side-lobe artifact（旁瓣伪像）Acoustic shadowing（声 影）Acoustic enhancement（回声增强）Slice-thicknessartifact（容积效应）Mirror
15、 image artifact（镜面伪像）Reverberations（混响）Edge shadowing（边界声影）,Side-lobe Artifact,Side-lobe artifact:Intestinalgas（I）is a strong reflector that is projected into the interior of the gallbladder（Gb）.S=side-lobe artifact,T=transducer,ppt课件,43,Side-lobe artifact:The arrowsindicate a side-lobe artifact in
16、a stonefree gallbladder（GB）.The artifact iscaused by gas in the adjacent duodenum（DUO）,Acoustic Shadowing,Acoustic shadowing:A strong acoustic reflector（e.g.,a gallstone=G）casts an acoustic shadow（S）due to reflection and absorption.T=transducer,ppt课件,44,Typical acoustic shadow（S）associated with a ga
17、llstone,Acoustic Enhancement,Acoustic enhancement:Because sound waves are less attenuated in fluid,the echoes behind a fluid-filled structure have greater amplitude.T=transducer,C=cyst,AE=acoustic enhancement,Posterior acoustic enhancement.An area of increased echogenicity（arrows）appears behind the
18、gallbladder（GB）,45,ppt课件,Slice-thicknessArtifact,Slice-thickness artifact:The anterior and posterior cystwalls appear thickened and indistinct.B=beam-width artifact,T=transducer,Beam-widthartifact:Transverse scan through the bladder（B）shows partial thickening and lack of sharpnessof the bladder wall
19、,especially on the farside（arrow）,46,ppt课件,Mirror image Artifact,Mirror image artifact:Schematic representation of sound waves in the liver（L）reflected from the diaphragm（D）,givingrise to a“mirror-image”liver.T=transducer,LS=supraphrenic“mirror-image”liver,Mirror image artifact:Rightsubcostal obliqu
20、e scan demonstrates the liver（L）,the diaphragm（D,or lung entry echo）,a subphrenic hepatic hemangioma,and the reflected hemangioma imaged at a supraphrenic,47,ppt课件location（arrows）,Reverberations,Schematic representation of typical reverberations（R）occurring between strongly reflectiveinterfaces（I）.T
21、=transducer,ppt课件,48,Edge Shadowing,Edge shadowing:When sound waves encounter cyst walls at a tangential angle,they are scattered or refracted.T=transducer,C=cyst,CE=cystic edge shadows,ppt课件,49,Review,ppt课件,50,Ultrasound History:Dimension:Line-Plane-Volume Color:B/W-ColorImage performance:B-mode:Noise,Penetration,Spatial/Contrast/Temporal resolution Color:Sensitivity,Spatial/temporal resolutionPW:Sensitivity,Spectrum shape CW:SensitivityArtifacts:Stone,cyst,needle,gas,
