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Limited Ultrasound Training Developed by: Dr. David Ying, Radiologist Michelle Zehr, RN, BSN © CompassCare Pregnancy Services The following information.

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Presentation on theme: "Limited Ultrasound Training Developed by: Dr. David Ying, Radiologist Michelle Zehr, RN, BSN © CompassCare Pregnancy Services The following information."— Presentation transcript:

1 Limited Ultrasound Training Developed by: Dr. David Ying, Radiologist Michelle Zehr, RN, BSN © CompassCare Pregnancy Services The following information is the copyrighted intellectual property of CompassCare Pregnancy Services, and may not be used by any party without the expressed written permission of CompassCare.

2 Objectives Describe indications for limited ultrasound exams Understand and apply the basic principles of ultrasound physics and instrumentation Understand the implications for patient care from ultrasound findings © CompassCare Pregnancy Services

3 Ultrasound Physics and Instrumentation © CompassCare Pregnancy Services

4 Sound Wave Propagation © CompassCare Pregnancy Services

5 Electromagnetic Wave: Radio Wave, Light Wave Does not require medium for transmission and is measured in wavelength (distance between two adjacent vibrations) © CompassCare Pregnancy Services

6 Mechanical Wave: Sound Wave Transmitted through a medium such as air, water, solid and is measured in frequency (vibrations per second), or hertz (Hz=1 vibration/second) © CompassCare Pregnancy Services

7 Waveforms Compared Light 370 trillion to 750 trillion Hz Spectrum of visible light ranges from 780nm to 380nm (Nanometer=I billionth of a meter) Ultraviolet, X-ray and gamma rays have progressively shorter wavelengths Infrared and radio microwave have progressively longer wavelengths Sound spectrum ranges from ,000 Hz. Ultrasound is in the range higher than 20,000 Hz Medical ultrasound is in the range of 2-7 megahertz ( MHz = 1,000,000 Hz) © CompassCare Pregnancy Services

8 Useful terms: Attenuation: Weakening of sound as it propagates through a medium Causes: Absorption, reflection, and scattering Decibels (dB): units used to relatively quantify intensity of sound for comparison purposes © CompassCare Pregnancy Services

9 Frequency: cycle/vibrations per second expressed in hertz (Hz) 1 Hz=1 vibration/second Intensity: Power (energy/time)/area= Watts/area © CompassCare Pregnancy Services

10 Incidence: Direction of sound wave travel to the boundary between 2 media e.g. perpendicular, oblique angle Impedance: = density of medium X propagation speed © CompassCare Pregnancy Services

11 Inverse square law: intensity of sound varies inversely with the square of the distance from the source Speed of propagation: depends on the medium. The more solid (high elasticity or stiffness) medium allows faster speed. Decreasing speed in solids, water, air. © CompassCare Pregnancy Services

12 Boundary behavior: (interface between media) Reflection: bouncing back from the boundary Specular: when the boundary is smooth and flat Scattering: when the boundary is rough and uneven Refraction: crossing the boundary with change in direction Transmission: going through the boundary © CompassCare Pregnancy Services

13 Transducer Functions A transducer converts one form of energy to another. An ultrasound transducer converts sound wave energy to electric energy and vice versa. © CompassCare Pregnancy Services

14 Composition of an U/S Probe Piezoelectric element: Material that is capable to convert pressure and electricity, such as ceramic or quartz Element (crystal) in linear, curved (sector) and phased array Damping/matching, material: To improve transmission © CompassCare Pregnancy Services

15 Operating Frequency The higher the operating frequency, the thinner the transducer element, the greater the attenuation (or the lesser the depth penetration) 3.5 or 5.0 MHz for the abdominal probe 5.0 or 7.5 MHz for the internal/vaginal probe © CompassCare Pregnancy Services

16 Beam Focusing: Focusing electronically to improve resolution at various depths Coupling Medium: Gel that is used to eliminate air at transducer-skin interface to maximize ultrasound transmission © CompassCare Pregnancy Services

17 Types of transducers External: Linear array Flat top, curved top, pointed top Sector Flat top, curved top, pointed top Internal (endo-): Rectal, vaginal, esophageal, vascular, etc. © CompassCare Pregnancy Services

18 Penetration: Depth of images obtained is directly related to: Attenuation by the medium Power of the beam Frequency (Hz), inverse relationship © CompassCare Pregnancy Services

19 Time-Gain Compensation To provide a more uniform image by compensating the weaker signals from deeper (further from the transducer) tissue as a result of longer time and greater attenuation © CompassCare Pregnancy Services

20 Resolution Detail Contrast Temporal © CompassCare Pregnancy Services

21 Detail: Degree of separation of structure echoes or signals Axial resolution: along the beam direction Lateral resolution: perpendicular to the beam direction Increased frequency means increased resolution but decreased penetration (useful U/S frequency is 2-15mHz) © CompassCare Pregnancy Services

22 Contrast: Improves with: Greater gray scale (U/S signal strength vs. B-W scale) Color display © CompassCare Pregnancy Services

23 Temporal: Improves with higher frame rate © CompassCare Pregnancy Services

24 Artifacts Types: False (erroneous) signals or images Missing signals or structures Wrong locations Incorrect sizes © CompassCare Pregnancy Services

25 Artifact Causes: Section Thickness: Ultrasound beam is 3-D while the displayed image is 2-D © CompassCare Pregnancy Services

26 Artifact Causes: Acoustic speckles: Interference effects of scattered sound beams and echoes from various tissues and directions of the ultrasound beam. © CompassCare Pregnancy Services

27 Artifact Causes: Reverberations: Repeated echoes occur between the transducer and a strong reflector. Mirror image is a form of reverberation artifact and formed with a strong reflector within a tissue. © CompassCare Pregnancy Services

28 Artifact Causes: Refraction: Laterally misplaces or mis-shapens a structure when a beam is refracted in the tissue. e.g. Observed depth of object in water. © CompassCare Pregnancy Services

29 Artifact Causes: Speed error: Axially misplaces a structure when the speed of the ultrasound beam is miscalculated Artifact Causes: © CompassCare Pregnancy Services

30 Artifact Causes: Shadowing: Decrease or loss of ultrasound signal behind a strongly reflecting or attenuating structure, or from the edge of a refracting structure. Artifact Causes: © CompassCare Pregnancy Services

31 Artifact Causes: Enhancement: Increase in echo signals behind a poorly attenuating structure. Artifact Causes: © CompassCare Pregnancy Services

32 Artifact Causes: Grating Lobes: False duplicated and miscalculated images created by side beams in directions different from the primary beam. Artifact Causes: © CompassCare Pregnancy Services

33 Proficiency in imaging technique: Patient Interaction Professional, but friendly Courteous Respectful, esp. in regard to privacy Informative regarding the procedure, but not the diagnosis Proper instrument settings probes and gel. Correct transducer frequency and type. Adjust field size, near and far gain settings Contrast, gain and TGC slope © CompassCare Pregnancy Services

34 Scanning Technique: Patient position: Supine, prone and lateral, to provide shortest distance to the anatomic structure of interest Image: In traditional long (sagittal) and transverse (axial) planes. Also oblique, coronal and angle planes if necessary. Identify anatomic structures and landmarks. Know the pathology (abnormal findings) © CompassCare Pregnancy Services

35 Safety: There is no known risk associated with diagnostic ultrasound since first used in the 70s. The possibility of adverse bio-effects from an even low level, delayed harm of the U/S energy transfer can not be absolutely denied. Minimize use exposure time and intensity of the ultrasound without sacrificing the proper gathering of diagnostic information. © CompassCare Pregnancy Services

36 Patient Education © CompassCare Pregnancy Services

37 Indication for testing: Confirm the viability of pregnancy. visualize your babys heartbeat within the uterus. 31% of all pregnancies are not viable. (it could be miscarriage, ectopic pregnancy, or multiple other reasons why the pregnancy hormone would be in the urine). Confirming how far along she is related to her last menstrual period (LMP). Explain what you anticipate before the exam. © CompassCare Pregnancy Services

38 Gestational Age Gestational Sac (GS) Yolk Sac (YS) Fetal Heart Motion MovementsDevelopment (visualized) 3-4 wks wks +? wks ++? wks wks ++++ arms, legs 9-10 wks ++++ face 11 wks ++++ arms & legs moving, jaw lines, fingers and toes 12 wks ++++ More clarity With each week, size doubles and development is much more defined

39 Scope of Information Provided: © CompassCare Pregnancy Services Ultrasound Exam Results See What You Expect to See Confirm Viability Can not Confirm Viability (Before 6 Weeks) Didnt See What You Expect to See Can not Confirm Viability (After 6 Weeks)

40 See What You Expect To See: Confirm Viability Reiterate what you were able to see. Explain the development that is there that you cant see. Show the model of comparison to where they are, and where theyll be soon. See What You Expect to See Confirm Viability So, Youre Pregnant Brochure Reschedule for Repeat Ultrasound Refer to physician for Prenatal Care Cant Confirm Viability © CompassCare Pregnancy Services

41 Saw What you Expect to See Unable to Confirm Viability: Before 6 Weeks Say, You are __far along and I can not confirm viability. I see ___ and would expect to see that. i.e.: You are 5 weeks today by the measurements, I see the yolk sac (point it out), but can not confirm viability because I can not see the heart beat today. We will need to reschedule you for next week in order to confirm viability. See What You Expect to See Confirm Viability Cant Confirm Viability Give Miscarriage/ Ectopic Pregnancy Brochure Reschedule for repeat ultrasound one week Refer her to physician © CompassCare Pregnancy Services

42 Didnt See What You Expect to See Unable to Confirm: After 6 Weeks Say to the patient, I do not see what I expect to see. Reiterate what you would have expected and explain you are not seeing that today. Follow P&P © CompassCare Pregnancy Services Didnt See What You Expect to See Cant Confirm Viability Symptoms ED No Symptoms Call Patients OB For Plan If no OB, ED

43 What this exam does not include: Sex of the baby Diagnosis of pregnancy from an RN or Sonographer Diagnosis/Opinion of what is wrong if you do not see what you expect to see (to the pt.) © CompassCare Pregnancy Services

44 Criteria for Rescheduling an Ultrasound

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