Ultrasound knobology

ultrasound in musculoskeletal pain management

1. Ultrasound Knobology Dr. Darendrajit MD, FIPM Department of Physical Medicine and Rehabilitation All India Institute of Medical Sciences, Bhubaneswar

2. ULTRASOUND KNOBOLOGY Human ear can hear sound from 20-20000 Hz Ultrasound: >20 kHz R everse piezoelectric effect i.e , electricity application to the quartz resulting in quartz vibration Medical ultrasound: 1 to 20 MHz

3. Absorption Refraction Reflection/scattering

4. Ultrasonographic terms Probe Depth Focus Gain Time Gain Compensation (TGC) Anisotropy

5. Linear 10+ MHz Curvilinear 5-2 MHz Compact linear 10+ MHz

6. Coupling medium Gel Standoff pad

7. Heel-toe maneuver Toggle maneuver Gel stand-off positioning

8. Depth The depth setting must be adjusted so that the structures of interest fall within the field of view The objective is to set the depth to just below the desired target

9. Focus Allows to adjust the focal zone to various depths in the field By positioning the focus at the same level as the target(s) of interest , the amount of beam divergence can be limited and lateral resolution maximized accordingly

10. Gain D ictates how bright ( hyperechoic ) or dark ( hypoechoic ) the image appears Increasing the gain amplifies the electrical signal produced by all returning echoes which in turn increases the brightness of the entire image, including background noise

11. Time Gain Compensation(TGC) Similar to the gain dial TGC differs by allowing the operator to adjust the brightness independently at specific depths in the field

12. In-plane method Out of plane method

13. Needle insertion point

14. Anisotropy A rtefact encountered in muscles and tendons during a musculoskeletal ultrasound examination Change in appearance from light to dark as the transducer is tipped back and forth

15. Acoustic Shadowing

16. Acoustic Enhancement

17. Reverberation Artifact

18. Reverberation Artifact

19. Color Doppler Color flow imaging shows colored blood flow superimposed on a gray-scale image , in which two colors such as red and blue represent flow toward and away from the transducer, respectively

20. Advantages of US Low cost and portability No contraindications, orthopedic hardware not a problem Ability to visualize structures not limited by orthogonal planes Continuous modification of imaging based on findings Palpation, stress, testing, and application of resistance while imaging Muscles: Architecture; imaging while testing with resistance Tendons: Fiber structure, degenerative changes, longitudinal tears Ligaments: Fiber structure, ability to stress test while imaging Cysts and bursae : Septations , debris not seen on MRI

21. Disadvantages M ore operator-dependent than other imaging methods D oes not penetrate bone, so structures deep to bone, such as intra-articular ligaments, are not visualized Does not cross air interfaces; on imaging structures obscured by the lungs or by gas in the intestine Obese patients are not imaged well; by loss of acoustic energy and by difficulty in obtaining the correct focal length

22. Thank You