ultrasound and imaging

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  1. 1. 16- Dec - 201416- Dec - 2014 UltrasoundUltrasound Arsalan KhanArsalan Khan MPhil (Clinical Medicine & Surgery)MPhil (Clinical Medicine & Surgery) 2014-ag-14512014-ag-1451 University of Agriculture, FaisalabadUniversity of Agriculture, Faisalabad PakistanPakistan
  2. 2. UltrasoundUltrasound
  3. 3. UltrasoundUltrasound The sound waves of frequency higher thanThe sound waves of frequency higher than 20KHz used for diagnostic and therapeutic20KHz used for diagnostic and therapeutic purpose and imaging are calledpurpose and imaging are called ultrasoundultrasound Sound waves are measured in Hertz (Hz)Sound waves are measured in Hertz (Hz) Diagnostic Ultrasound = 1-20 MHzDiagnostic Ultrasound = 1-20 MHz Sound waves are produced by aSound waves are produced by a transducertransducer
  4. 4. Principle: Pulse echo principlePrinciple: Pulse echo principle Ultrasound waves not heard becauseUltrasound waves not heard because human middle ear (eardrum) cant vibratehuman middle ear (eardrum) cant vibrate at such frequency.at such frequency. Frequency: 3.5 (intestines and U.Frequency: 3.5 (intestines and U. bladder), 5 (liver, pancreas and spleen),bladder), 5 (liver, pancreas and spleen), 7.5 (Rectum and testicles) and7.5 (Rectum and testicles) and 10MHz (Superficial organs).10MHz (Superficial organs). www.dvmdocs.webs.comwww.dvmdocs.webs.com
  5. 5. Transducer (probe)Transducer (probe) It consists of ; Piezoelectric crystalIt consists of ; Piezoelectric crystal When electric charge is applied it emits soundWhen electric charge is applied it emits sound waveswaves Sound is reflected from patientSound is reflected from patient Returning echo is converted to electric signalReturning echo is converted to electric signal grayscale image on monitor is formedgrayscale image on monitor is formed Echo may be reflected, transmitted or refractedEcho may be reflected, transmitted or refracted This probe has dual function that is it producesThis probe has dual function that is it produces as well as receive the sound wavesas well as receive the sound waves The monitor converts these signals to imageThe monitor converts these signals to image
  6. 6. As frequency increases, resolution improvesAs frequency increases, resolution improves As frequency increases, depth of penetrationAs frequency increases, depth of penetration decreasesdecreases Use higher frequency transducers to image moreUse higher frequency transducers to image more superficial structuressuperficial structures Velocities:Velocities: Soft tissues = 1400-1600m/secSoft tissues = 1400-1600m/sec Bone = 4080 m/secBone = 4080 m/sec Air = 330 m/secAir = 330 m/sec
  7. 7. WorkingWorking A sound wave is produced by the vibration of PiezoA sound wave is produced by the vibration of Piezo electric crystals in the transducer and focused by theelectric crystals in the transducer and focused by the transducer or lens in front of transducertransducer or lens in front of transducer Water based gel is placed between the patient body andWater based gel is placed between the patient body and probeprobe These waves return in the same manner and areThese waves return in the same manner and are received by the transducerreceived by the transducer These waves are processed and are transformed intoThese waves are processed and are transformed into digital image on the monitordigital image on the monitor
  8. 8. Modes of SonographyModes of Sonography A-modeA-mode: A-mode (amplitude mode) is the: A-mode (amplitude mode) is the simplest type of ultrasound.; signals aresimplest type of ultrasound.; signals are recorded as spikes on a graph. Therecorded as spikes on a graph. The vertical (Y) axis of the display shows thevertical (Y) axis of the display shows the echo amplitude, and the horizontal (X)echo amplitude, and the horizontal (X) axis shows depth or distance into theaxis shows depth or distance into the patient. This type of ultrasonography ispatient. This type of ultrasonography is used for ophthalmologic scanning.used for ophthalmologic scanning. It is single dimension and represented inIt is single dimension and represented in the form of spikes and peaks.the form of spikes and peaks.
  9. 9. B-mode or 2D modeB-mode or 2D mode: In B-mode: In B-mode (brightness mode) ultrasound, a linear(brightness mode) ultrasound, a linear array of transducers simultaneously scansarray of transducers simultaneously scans a plane through the body that can bea plane through the body that can be viewed as a two-dimensional image onviewed as a two-dimensional image on screen. B-mode is commonly used toscreen. B-mode is commonly used to evaluate the developing fetus and toevaluate the developing fetus and to evaluate organs, including the liver,evaluate organs, including the liver, spleen, kidneys, thyroid gland, testes,spleen, kidneys, thyroid gland, testes, breasts, and prostate gland.breasts, and prostate gland. Image shown by grey to bright dots.Image shown by grey to bright dots. www.dvmdocs.webs.comwww.dvmdocs.webs.com
  10. 10. M-modeM-mode: In M-mode (motion mode) ultrasound, pulses: In M-mode (motion mode) ultrasound, pulses are emitted in quick succession each time, either an A-are emitted in quick succession each time, either an A- mode or B-mode image is taken. It is used for movingmode or B-mode image is taken. It is used for moving organs and image is shown as oscillations about verticalorgans and image is shown as oscillations about vertical lines. M-mode is used primarily for assessment of fetallines. M-mode is used primarily for assessment of fetal heartbeat and in cardiac imaging, most notably toheartbeat and in cardiac imaging, most notably to evaluate valvular disorders ( Mitral valve regurgitation).evaluate valvular disorders ( Mitral valve regurgitation). Doppler modeDoppler mode: This mode makes use of the Doppler: This mode makes use of the Doppler effect in measuring and visualizing blood flow. In thiseffect in measuring and visualizing blood flow. In this mode, the velocity and direction of blood flows aremode, the velocity and direction of blood flows are depicted in a color map superimposed on the 2-D image.depicted in a color map superimposed on the 2-D image. It evaluates the blood perfusion of the organs.It evaluates the blood perfusion of the organs.
  11. 11. Scanners:Scanners: 1)1)Linear array: It is rectangular. LargeLinear array: It is rectangular. Large number of piezo electric crystals. Used fornumber of piezo electric crystals. Used for superficial organs and rectal examination.superficial organs and rectal examination. It has 64x256 crystals.It has 64x256 crystals. 2)2)Sector array: It is convex probe. It hasSector array: It is convex probe. It has single piezo electric crystal.single piezo electric crystal. www.dvmdocs.webs.comwww.dvmdocs.webs.com
  12. 12. Types of image interpretation:Types of image interpretation: 1)1)Hyper echoic: Returning of echo is veryHyper echoic: Returning of echo is very strong. It is reflecting from very highstrong. It is reflecting from very high density tissue. Bright image is formed.density tissue. Bright image is formed. 2)2)Hypo echoic: Returning echo is weak. LowHypo echoic: Returning echo is weak. Low density tissues. Grey to dark image isdensity tissues. Grey to dark image is formed. E.g. Tumours, abcess,formed. E.g. Tumours, abcess, Hematoma, granulation, inflammation.Hematoma, granulation, inflammation. It is more cellular in nature.It is more cellular in nature. www.dvmdocs.webs.comwww.dvmdocs.webs.com
  13. 13. 3) An echoic: Complete attenuation. No3) An echoic: Complete attenuation. No reflection. From fluid or air. Image is darkreflection. From fluid or air. Image is dark black. E.g. Urinary bladder, lungs, odema,black. E.g. Urinary bladder, lungs, odema, fluid or water accumulation.fluid or water accumulation. 4) Iso echoic: It is normal image. Grey color4) Iso echoic: It is normal image. Grey color image is formed. E.g Liver, spleen,image is formed. E.g Liver, spleen, muscles etc.muscles etc. N.B: Image of ultrasound is cross sectionalN.B: Image of ultrasound is cross sectional www.dvmdocs.webs.comwww.dvmdocs.webs.com
  14. 14. ArtifactsArtifacts Artifacts lead to the improper display of the structures toArtifacts lead to the improper display of the structures to be imagedbe imaged 1) Acoustic shadowing:1) Acoustic shadowing: Ultrasound beam does not pass through an object because ofUltrasound beam does not pass through an object because of reflection or absorption.reflection or absorption. When the reflecting tissue is situated behind the strong reflectingWhen the reflecting tissue is situated behind the strong reflecting tissue. E.g kidney muscles behind the stone. Weak echoes aretissue. E.g kidney muscles behind the stone. Weak echoes are received and the image can misguide for the presence of fluid.received and the image can misguide for the presence of fluid. Black area beyond the surface of the reflectorBlack area beyond the surface of the reflector Examples: cystic calculi, bonesExamples: cystic calculi, bones Acoustic enhancementAcoustic enhancement Hyperintense (bright) regions below objects of lowHyperintense (bright) regions below objects of low Ultrasound beam attenuation. High echo. E.g odemaUltrasound beam attenuation. High echo. E.g odema or fluid behind the muscles.or fluid behind the muscles.
  15. 15. 3)Refraction:3)Refraction: Occurs when the sound wave reaches two tissues ofOccurs when the sound wave reaches two tissues of differing acoustic impedancesdiffering acoustic impedances Ultrasound beam reaching the second tissue changesUltrasound beam reaching the second tissue changes directiondirection May cause an organ to be improperly displayedMay cause an organ to be improperly displayed 4) Reverberation: It is the back and forth motion of4) Reverberation: It

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