1、 Ultrasound Imaging and Its ApplicationsMingyue DingDepartment of Bio-medical Engineering“Image Processing and Intelligent control” Key Laboratory of Education Ministry2022/10/22OUTLINES1. What is ultrasound?2. History of the development of ultrasound imaging technique3. 2D ultrasound imaging4. 3D u

2、ltrasound imaging5. 3D ultrasound imaging applications3What is SOUND?Sound is a mechanical wave that we can hear A mechanical wave can be described by:Amplitude: aWavelength: Frequency: fSound speed: Ca4Sound Propagation SpeedSound can be transmitted through any medium- gas, liquid, or solid.Sound s

3、peed through the medium depends on the compressibility of the medium. The speeds of some materials are shown in the table below. Sound speed in different materials (m/s)AluminiumBoneLiverKidneyBloodFatWaterLungAir64003500157015601570146014936503325Properties of Sound PropagationSound at different fr

4、equency can be transmitted in the same medium at the same speed.The different medium has different speed for sound transmission with the same frequency. 7Principle of Ultrasound Imaging8Principle of Ultrasound ImagingA pulse is propagated and its reflection is received, both by the transducer.Key as

5、sumption: - Sound waves have a nearly constant velocity of 1500 m/s in H2O.- Sound wave velocity in H2O is similar to that in soft tissue.Thus, echo time maps to depth.10Ultrasound Image (Embryo)11Ultrasound: Resolution and Transmission FrequencyTradeoff between resolution and attenuation - higher f

6、requency shorter wavelength higher attenuationPower loss:Typical Ultrasound Frequencies: Deep Body 1.5 to 3.0 MHzSuperficial Structures 5.0 to 10.0 MHze.g. 15 cm depth, 2 MHz, 60 dB round tripWhy not use a very strong pulse?Ultrasound at high energy can be used to ablate (kill) tissue.Cavitation (bu

7、bble formation)Temperature increase is limited to 1 C for safety.12Frequency Used in US ImagingTo have enough resolution for the observation of human organs, a frequency higher than 0.15 MHz , a wavelength less than 1.0cm, has to be used.Also the frequency will determine the depth of imaging, the lo

8、wer the frequency, the big the depth will be.For abdominal imaging, a frequency between 1.0-3.0MHz has to be used.For eye examination, a frequency as high as 20 MHz is used.For IVUS imaging, 40 MHz is used. 14History of the Development of Ultrasound (II)Systematic investigations into using ultrasoun

9、d as a diagnostic tool was made by George Ludwig, a physician at the Naval Research Institute in Bethseda, Maryland in the experiments on animal tissues using pulse-echo ultrasound. “SONICS-techniques for the use of sound and ultrasound in engineering and science” (Theodore Hueter, Richard Bolt) boo

10、k published in 1954.15History of the Development of Ultrasound (III)After the Korean war, John Julian Wild and John Reid built a linear hand-held B-mode instrument and become the first publication on intensity-modulated cross-section ultrasound imaging.They also invented A-mode trans-vaginal and tra

11、ns-rectal scanning transducers in 1955.17History of the Development of Ultrasound (V)In 1962, the first commercially available , hand-held articulated arm compound contact scanner was produced by engineers William Wright and Edward Meyerdink in USA.The work of Howry and his team is the most importan

12、t pioneering work in B-mode ultrasound imaging and contact scanning that we have today. 18Pulse-echo RangingApplications:BatsSonar system Detects submarinesSONAR-Sound Navigation And Ranging.192D Ultrasound ImagingA-mode ultrasoundHorizontal axis is used to represent time while the vertical axis of

13、the signal is to represent the amplitude of the signal. 202D Ultrasound ImagingB-model ultrasound To use the brightness of the screen to display the amplitude of the signal. The greater the amplitude, the greater the brightness of the spot. 212D Ultrasound ImagingB-model ultrasound scan: Sector scan

14、Linear scanPPI (plan position indicator) SectorLinearPPI222D Ultrasound ImagingM-mode ultrasoundAlso called Motion ultrasound 24Ultrasound Doppler Transducer25Ultrasound Doppler Principle272D Ultrasound Machine28Ultrasound ImagingWhy use ultrasound? Low cost and portable system Safest imaging modali

15、ty Fast, real-time imaging Suitability for viewing the soft tissues and organs such as prostate, liver, heart, lung 29Limitations of 2D Ultrasound Imaging2D technique must build the 3D image mentally leads to inaccuracy & variability leads to long proceduresSpatially flexible technique difficulties

16、in reproducing same view difficulties in patient follow-up difficulties in interventional procedures303D Ultrasound: Side-fire scan3D Reconstruction3D MotorizedScan (uniform)31Rotational Mover (Side-Fire)32Parallel Scanning333D Carotid US: Freehand scan34Scanning mode in 3D ultrasound Mechanical sca

17、nning Parallel scanning Rotational scanning Fan scanning Random scanning, free hand scanning Real time 3D volume probe: 2D array transducer volume probe 35Parallel scanning36Side-fire Scanning37Random scanning with a localization system38Intravascular Ultrasound Imaging39IVUS Catheter Configuration4

18、0The Analysis of IVUS Image41Angiography VS IVUS42Disease can only be identified by IVUS43The IVUS Catheter Usage in USA and World44IVUS Applications45Measurement of Plaque464D IVUS473D US application: fetus defect detectionBorn infant3D fetus image48493D Prostate Ultrasound Image by using transrect

19、al transducer50Prostate Brachytherpy:Segmented prostate51Continuity Based 3D Prostate Segmentation in US Image 52Needle Detection in 3D53Plaque segmentation:Carotid 3D US image54Volume of plaque: 964 mm3Plaque segmented from the 3D US Carotid image55xnzpxpznyn3D US Guided Breast Biopsy Apparatus56In

20、terface used in our RF Ablation system573D Rotational Scanning Probe 583D US Imaging System based on Rotational Scanning59Reconstruction comparison of pork liver：Sideview Traditional methodOur method60Reconstruction comparison of pork liver：Topview Traditional methodOur method61Water image acquired

21、at three different times62Pin inserted into water at three different times63Pin segmented resultBefore insertionDetected pinAfter insertion643D Ultrasound Application: Prostate BrachytherapyProstate cancer is the second leading cause death of northern American menThe American Cancer Institute estima

22、tes 230,110 new case, 29,900 dead in 2004. Canadian Cancer Society estimates 20,100 new cases, 4,200 dead in 2004.Prostate cancer is curable at early stage.65Standard Treatments of Prostate CancerWatchful waiting:Most patients request or need treatment. Radical prostatecotomy: Gold standard but with

23、 significant morbidity, such as incontinence and impotence. External beam radiation, such as IMRT:Long treatment time, kill the normal tissue.Prostate brachytherapy: Short stay, safe for normal tissue66Brachytherapy Operation67Side-fire Scanned Transrectal Probe 68Needle Tracking and Guidance Under

24、3D Ultrasound ImagingNeed to know where the needle is and where it will go.Determine the tip position of the needle.The processing has to be performed in real-time.69Oblique Needle Insertion70Why is Needle Segmentation in US Images Difficult? Ultrasound image speckle & shadows Large 3D image 357 326

25、 352 1 byte = 40 MBHigh accuracy required Real-time processing (30 fps, or 33 ms per image)71Motivation for Our 3D Needle SegmentationNeedle is conspicuous in a projected image.Line object can be reconstructed from two orthogonal projectionsApproximate needle insertion point and direction is known72

26、Flowchart for our 3D Needle Segmentation Steps 1 & 2Step 3Step 473Step 1: Volume Rendering (Ray Casting)Cast rays through 3D image to image planeVoxelsI n-1 , ,I 074Step 1: Volume RenderingFront-to-back ray tracing equations:Gray level distribution of needle voxels: Gaussian transfer functions:Lumin

27、ance c ( I )Opacity ( I ) 75Example of Volume RenderingWith renderingWithout renderingAgar phantom76Step 2: Volume CroppingComplex background, large volumeEstimate needle position / orientation from a priori knowledge: Manual insertion Motorized mechanical device Localizing system (e.g. magnetic tra

28、cking)Simplifies background, reduces volumeInsertion pointActual needleOriginal volumeCropped volumeNeedle tipApproximate needleThe cropped volume dimensions aredetermined from a priori knowledgeof the approximate insertion point, theapproximate needle direction P, andthe maximum inserted needle len

29、gth78(c) Cropped volume of (a)(b) Rendered result of (a)(d) Rendered result of (c)Effect of Volume Cropping & Rendering(a) Original turkey breast image79Step 3: 2D Needle SegmentationWe used:Global thresholding + flood-filling algorithm for objects with simple echogenicityReal-Time Hough Transform (

30、RTHT) for objects with complex echogenicity80Step 4: 3D Needle Reconstruction3D needle reconstruction is based on two orthogonal projections Both projection directions are chosen to be orthogonal to the approximate needle directionEach projection is orthographic, i.e. the cast rays are parallel813D

31、NEEDLE RECONSTRUCTIONActual needleApproximate needleYXZRQPTwo coordinate systems:(X, Y, Z) : 3D image (P, Q, R) : projectionP P823D Needle ReconstructionPQR2D needle directionP833D Needle Reconstruction Demo84Patient Prostate Needle Segmentation853D Needle Tracking in Agar86Prostate Segmentation in

32、3D Ultrasound Images Motivation:The prostate boundary and volume are needed to assign the patient to the appropriate therapy.The volume of the prostate is required to determine the dosimetry distribution and radioactive seed locations.87Our Approach: Sliced Based3D Prostate SegmentationStep 1Step 3S

33、tep 4yesnoStep 288Step 1: 3D Image Re-slicingParallel re-slicing:Problem: At the ends, only a small portion of the prostate is visible.Rotational re-slicing:The prostate shapes and sizes in the re-sliced images are similar.893D Image Re-slicing(a) Parallel re-slicing(b) Rotational re-slicing90Step 2

34、: Cardinal-Spline Initialization ModelCardinal-spline:Why we chose the Cardinal-spline? No control points are needed, Easy to determine the spline coefficients, Passing through the initial points exactly, and The number of initial points can be varied.91Step 3: Contour DeformationRefine the boundary in the initial 2D slice using DDC method (Lobregt, et al, A Discrete Dynamic Contour Model, IEEE Trans. MI, 14, 12-24, 1995) Extend 2D segmentation to 3D: Propagate the prostate contour in initial slice to an adjacent slice in both directions. Refine the contours and rep