Alternative Imaging Techniques


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Alternative Imaging Techniques

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Alternative Imaging Techniques

  1. 1. EQUINE MEDICINE Alternative Imaging Techniques: Ultrasound, MRI, CT Scan
  2. 2. Ultrasound Evaluation of soft tissue Transducer- Probe that uses sound waves to image tissues Echo-Sound waves that bounce off tissues and travel back to the transducer Converted by a computer into a gray scale image
  3. 3. Transducers Sector Scan-Pie-shaped image Phased Array-Crystals pulsed sequentially Delay between pulses Annular Array-Crystals in ring Pulse directed through crystals Use: Limited access areas
  4. 4. Transducers Linear Array Scan-Rectangular-shaped image Alternate pulse on groups of crystals Use: Unrestricted areas Equine tendons Transrectal imaging
  5. 5. Patient Preparation Clip or shave area Scrub area with shampoo & rinse thoroughly Wipe area with alcohol Use acoustic coupling gel to eliminate air
  6. 6. Imaging
  7. 7. Digital Radiography Basis for all digital images is the DICOM file format
  8. 8. Digital Radiography DICOM: Digital Imaging & Communications in Medicine Standard: Secure standardized images Reliable accurate images Hold up under legal scrutiny Other formats: jpeg, tiff, gif, png, psg Need viewing program to use!!!!
  9. 9. Digital Radiography Image Quality: Hardware & software used Imagine detector Image processing Monitor
  10. 10. Computed Radiography Replaces film, intensifying screen & cassette with an imaging plate Processor is replaced with a digital imaging reader Advantages: Digital imaging Retrofit of equipment Mobile Relatively inexpensive Disadvantages: Imaging plate needed Single plate development Image reader needed
  11. 11. Direct Digital Radiography Radiographic film & cassette are replaced with an imaging sensor Advantages: Digital imaging Partial retrofit of equipment Immediate image generation No processing No imaging plate Image quailty Disadvantages: Cost Sensor attachment by wire
  12. 12. Computed Axial Tomography Produces cross-sectional imaging X-ray beam is highly collimated, & rotates around animal to obtain image
  13. 13. Computed Axial Tomography Voxel-Density of a small volume within a patient Projected onto screen or film to produce image Advantages: Detects small tissue density differences Highly detailed image produced Ability to see deep/small changes Disadvantages: Cost Requires general anesthesia Gantry opening may limit patient access
  14. 14. Magnetic Resonance Imaging Uses hydrogen protons in the body to produce a detailed image Animal placed in a magnetic field Magnet aligns hydrogen protons in the same direction Pulse of high energy radio frequency disrupts alignment Radiofrequency is released as atoms realign-imaged produced
  15. 15. Magnetic Resonance Imaging System Types: High Field System 1.0 T magnetic field Higher detail image Fast image production General anesthesia required Low Field System <0.5 T Lower image quality Longer acquisition times Animal may be standing
  16. 16. Magnetic Resonance Imaging Imaging Protocols Proton Density-Clear anatomic structure T2 Weighting-High fluid contrast T1 Weighting-Good bone definition Variations Short Tau Inversion Recovery (STIR) Fat Suppression (FS) Water-Excitation (WE)
  17. 17. Imaging
  18. 18. Nuclear Scintigraphy Radioactive substance injected into the body & traced as it interacts with tissues May localize problem area, will not determine cause Advantages: May be performed in a standing animal Single injection used to image entire animal Image Production: Gamma rays are acquired through a collimator Computer uses information to produce an image
  19. 19. Nuclear Scintigraphy Phases of Distribution: Vascular Phase: Immediately after injection Represents vascular blood flow Early Pool Phase: Soft tissue phase Lasts 15 min Diffusion from blood vessels to tissues Late Pool Phase: Bone phase 2-3 hr post injection up to 24 hrs