ttk 4165
DESCRIPTION
Hans Torp NTNU, Norway. TTK 4165. Signalbehandlingsteknikker i medisinsk bildediagnostikk Signal Processing in Medical Imaging Faglærer: Hans Torp Institutt for sirkulasjon og bildediagnostikk. Hans Torp NTNU, Norway. Introduksjon. Litt ultralydfysikk og historisk tilbakeblikk - PowerPoint PPT PresentationTRANSCRIPT
TTK 4165
Signalbehandlingsteknikker i
medisinsk bildediagnostikk
Signal Processing in Medical Imaging
Faglærer: Hans TorpInstitutt for sirkulasjon og bildediagnostikk
Hans TorpNTNU, Norway
Introduksjon Introduksjon
• Litt ultralydfysikk og historisk tilbakeblikkLitt ultralydfysikk og historisk tilbakeblikk
• Ultralyd avbildningUltralyd avbildning
• Ultralyd Doppler for måling/avbildning av hastighetUltralyd Doppler for måling/avbildning av hastighet
• Oversikt over faget TTK4165Oversikt over faget TTK4165
Hans TorpNTNU, Norway
lecture overview
• Physical principles of ultrasoundPhysical principles of ultrasound
• Ultrasound imagingUltrasound imaging
• Ultrasound Doppler and flow imagingUltrasound Doppler and flow imaging
• Overview TTK4165Overview TTK4165
Hans TorpNTNU, Norway
Sound field depends on source size and Sound field depends on source size and wavelengthwavelength
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Ultrasonic M-Mode (Motion Mode)Ultrasonic M-Mode (Motion Mode)
Hans TorpNTNU, Norway
Echoes from tissue structures are received and displayed
First Cardiac trials by Edler and Hertz in 1953
Real-time Ultrasound B-mode Real-time Ultrasound B-mode 19741974
N. Bom & al. “Multiscan EchoCardiograph” Ultrasound in Medicine aug. 74
Hans TorpNTNU, Norway
Vis film
Doppler blood flow meter Pedof 1976Doppler blood flow meter Pedof 1976Blood velocity Mitral inflow
Normal relaxation
Delayed relaxation
• Fourier transform - measure bloodflowFourier transform - measure bloodflow
• Gaussian Random process Gaussian Random process - ultrasound signal- ultrasound signal
• Analog computer diff. equation solverAnalog computer diff. equation solver- model of the cardiovascular system - model of the cardiovascular system
• Bernouli equationBernouli equation- from blood velocity to pressure- from blood velocity to pressure
Ultrasound probeUltrasound probe
Fokus
Focusing Steering and Focusing
50-200 elements 50-200 elements
Received Echoes Received Echoes from close objectsfrom close objects
probeelements
Objects
1
2
Digital Beam FormerDigital Beam Former
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#Channels:128
# samples per channel: 10.000
•Data per scanline: 2*10.000*128 = 2.5 Mb •Data per image: 2.5*100 = 250 Mb•Data per second: 40* 250 Mb = 10 Gb
1986CFM 700 5 channelsMekanisk scanning
1996System Five 128 channelsElektronic scanningMekanisk scanning
2000Vivid 7 128 kanalerElektronisk scanning
Real-time 2D B-modeReal-time 2D B-modeWall motion assessmentWall motion assessment
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Hans TorpNTNU, Norway
Ultrasound ProbesUltrasound Probes
Linear arrayHigh resolutionLimited width
Curve-linear arrayLarge image widthLarge near field
Phased arraySmall footprint90 deg. sector format
Hans TorpNTNU, Norway
Ultrasound imaging can be applied Ultrasound imaging can be applied to almost all human organsto almost all human organs
Liver Fetus 3 ½ mnd
Kidney
Twin fetus
Ultrasound imaging:Measure dimensions, areas, volumesStudy anatomical detailsAssessment of muscle contractionHeart-valve function
Heart, 4 chamber view
Image resolutionImage resolution
Daperture
F:
Foc
al d
epth
F-number f# = F/D
Wavelength: L
”Dot-size”: f# L
Camera exampleL = 0.9 e-3 mmf# = 5.6Resolution: 0.005 mm ~ 50000 dpiInfrared camera gives lower resolution
Ultrasound exampleL = 0.5 mm (3 MHz)f# = 8cm/2cm= 4 Resolution: 2 mm ~ 125 dpi
Larger probe -> improved resolutionHigher frequency -> improved resolution
Probe-diameterD
F:
Foc
al d
epth
L
•Computer-simulated ultrasound image•Higher frequency -> better resolution
Embryo 7 weeks. Ca 13 mm length
3D Transvaginal ultrasound3D Transvaginal ultrasoundThe Lancet:
In-vivo three-dimensional ultrasound reconstructions in the embryonic and early fetal period
Harm-Gerd Blaas 1, Sturla H. Eik-Nes 1, Sevald Berg 2, Hans Torp 2;
Limb development in Norway 20Limb development in Norway 20thth century century
12 weeks 18 weeks
Color Doppler velocity imagingColor Doppler velocity imaging
PW Doppler: Velocity from one point
Color flow imaging:Velocities in the whole image
Color M-mode: Velocities along a line
Tissue Velocity ImagingTissue Velocity Imaging
Moving upwardMoving downward
SystoleEarlyrelax.
Atrialsystole
Curved M-mode
Hans TorpNTNU, Norway
Strain rateStrain rate
Lvv
SR 12
Lv1v2
Tissue velocity Strain rate
SR
Adapted from J-U. Voigt and A. Heimdal
ShorteningNo changeElongation
Wall motion quantification
SystoleEarlyrelax.
Atrialsystole
Curved M-mode
Real-time 3D imagingReal-time 3D imaging2D matrix array2D matrix array
• 32-192 elements in a 1D 32-192 elements in a 1D arrayarray
• 32*32 ... 96*96 elements 32*32 ... 96*96 elements in a 2D arrayin a 2D array
• 1000 - 10000 elements1000 - 10000 elements
• CableCable
• ElectronicsElectronics
• BeamformerBeamformer
50 x 1elements
50 x 50=2500elements
Sanntid 3DSanntid 3D
Azimuth
Elevation
4D Volume Imaging4D Volume Imaging
• No ECG gatingNo ECG gating
• Volume rendering / orthogonal Volume rendering / orthogonal slicingslicing
• Volume size: Volume size: ~20 x 80º / ~35 x 45º~20 x 80º / ~35 x 45º
• Volume rate: 17-25Volume rate: 17-25
Standard setup Increased elevation width
4D Color Imaging (ECG Gated)4D Color Imaging (ECG Gated)
• Gated from 7 heart Gated from 7 heart beatsbeats
• High frame rates High frame rates (17-35 frames / (17-35 frames / second)second)
• High Color sensitivityHigh Color sensitivity
• High Color resolutionHigh Color resolution
TTK4165 OverviewTTK4165 Overview
• Pulse Echo principlePulse Echo principle
• Ultrasound beamformingUltrasound beamforming
• General imaging system General imaging system
• Ultrasound imaging system Ultrasound imaging system
• Doppler – blood velocity measurement and imagingDoppler – blood velocity measurement and imaging
• Patient safety issuesPatient safety issues
• Ultrasound contrast imagingUltrasound contrast imaging
• 3D imaging3D imaging