Medical Imaging and Doppler Ultrasound

Questions and Answers

What does a sound wave transport through a medium?

Information

Energy (correct)

Mass

Sound

Which of the following units measures power associated with sound?

Watts (W) (correct)

Joules (J)

Decibels (dB)

Pascals (Pa)

What term describes the weakening of an ultrasound beam as it penetrates the body?

Reflection

Attenuation (correct)

Refraction

Scattering

Intensity, associated with a sound wave, is defined as what?

The power per unit area Signup and view all the answers

Who described the detection of fetal heart movement using Doppler ultrasound?

Callagan Signup and view all the answers

What does hypo-echoic refer to in ultrasound imaging?

An area with decreased brightness of echoes Signup and view all the answers

Which system was introduced in the mid-1970s to combine imaging and Doppler techniques?

Duplex system Signup and view all the answers

How is intensity measured in acoustics?

Watts per meter squared (W/m²) Signup and view all the answers

What is the frequency range considered safe for diagnostic ultrasound?

2 MHz to 10 MHz Signup and view all the answers

Which parameter affects both power and intensity in a sound wave?

Pressure amplitude Signup and view all the answers

What major problem did the imaging system developed in the early 1970s experience?

Slow image production Signup and view all the answers

What is the wavelength in the context of sound waves?

The distance between consecutive peaks of the wave Signup and view all the answers

What did Luksell apply to detect cerebral midline echoes?

The principle of an industrial flaw detector Signup and view all the answers

In what year did Wild and Reid publish their work on the direct contact scanner?

1964 Signup and view all the answers

What is the frequency range for audible sound?

20 Hz to 20,000 Hz Signup and view all the answers

Which scanner was developed by Baun in the early 1970s?

Ophthalmic scanner Signup and view all the answers

What type of image does a curved transducer face produce?

Sector or pie-shaped image Signup and view all the answers

Which display mode corresponds to the amplitude of returning echoes?

B-mode Signup and view all the answers

In ultrasound imaging, what does TGC stand for?

Time Gain Compensation Signup and view all the answers

What is the effect of aliasing in Doppler ultrasound?

It creates false Doppler shift indicators Signup and view all the answers

How is the time for one frame of an ultrasound image determined?

2ND divided by speed of sound Signup and view all the answers

What typically generates a linear field of view (FOV) in ultrasound applications?

Linear arrays Signup and view all the answers

What is the primary function of the additional interpolated lines in ultrasound imaging?

To enhance image quality Signup and view all the answers

Which transducer type is typically used for abdominal applications?

Curved array Signup and view all the answers

What is a disadvantage of using Pulse Wave Mode in Doppler ultrasound?

It lacks directional information and accurate velocity data. Signup and view all the answers

What factor does not influence the Doppler shift?

Distance from the transducer Signup and view all the answers

What should the angle between the sound beam and the direction of blood flow be to optimize Doppler ultrasound accuracy?

Less than 60 degrees Signup and view all the answers

How does the sample volume affect Doppler frequency detection?

Larger sample volumes detect more Doppler frequencies. Signup and view all the answers

What is the main benefit of using Power Doppler?

It allows for detection of a larger range of Doppler shifts. Signup and view all the answers

Which of the following statements about the Doppler shift is incorrect?

It solely depends on the speed of the moving blood. Signup and view all the answers

Which material has the highest speed of sound based on the given data?

Bone Signup and view all the answers

Which characteristic describes how sound waves transfer energy?

They require an elastic medium to transfer energy. Signup and view all the answers

What happens to the wavelength of a sound wave when it travels from a less compressible medium to a more compressible medium?

The wavelength increases. Signup and view all the answers

Which statement about frequency and speed of sound is correct?

Frequency is unaffected by changes in speed of sound waves. Signup and view all the answers

In which medium does sound travel the slowest according to the data provided?

Air Signup and view all the answers

What is the primary function of focus in ultrasound imaging?

To concentrate the sound beam for better imaging. Signup and view all the answers

What characterizes higher frequency sound waves?

They have shorter wavelengths. Signup and view all the answers

Which of the following statements about the materials listed is true?

Bone has the highest speed of sound of all materials listed. Signup and view all the answers

Study Notes

Historical Development of Ultrasound Technology

1964: Callagan pioneered detection of fetal heart movement using Doppler ultrasound.
Wild and Reid developed direct contact scanners, enabling images of forearm muscles and breast tissue.
Baun introduced an ophthalmic scanner, enhancing imaging techniques.
Luksell utilized industrial flaw detection principles on human skulls, identifying cerebral midline echoes.
Early 1970s: A duplex system linked a high-resolution real-time imaging scanner with a pulsed Doppler device for carotid circulation evaluation.
Late 1980s: Advancements in Doppler ultrasound techniques improved imaging time and efficiency.

Sound Classification

Infrasound: Sound waves below 16 Hz.
Audible Sound: Frequencies between 20 Hz to 20,000 Hz.
Diagnostic Ultrasound: Operates between 2 MHz to 10 MHz for safe medical imaging.

Fundamental Principles of Ultrasound

Sound waves transfer energy through a medium; energy is measured in joules (J).
Power (P) indicates the energy production rate, expressed in watts (W); 1 W equals 1 J/s.
Intensity (I) measures power per unit area, expressed in W/m².
Ultrasound beam experiences attenuation due to absorption, scattering, and beam spread as it penetrates tissues.

Wave Characteristics

Waves exhibit properties like wavelength, frequency, and speed.
Wavelength (λ): Distance between consecutive peaks; changes with media density.
Speed of sound varies across materials, influenced by density:
- Air: 330 m/s
- Fat: 1,450 m/s
- Water: 1,480 m/s
- Kidney: 1,556 m/s
- Average Tissue: 1,540 m/s
- Muscle: 1,600 m/s
- Bone: 4,080 m/s

Imaging Principles

Focusing concentrates the sound beam into a smaller area, leading to clearer images.
B-mode (Brightness mode): Displays echoes on a monitor as shades of gray, correlating intensity levels with brightness.
Sector Field of View (FOV): Generated using oscillating, rotating, and phased array transducers for abdominal applications.
Linear FOV: Generated by linear arrays, suitable for superficial imaging.

Time Gain Compensation (TGC) and Signal Processing

TGC compensates for echo intensity loss due to depth, enhancing image clarity.
Aliasing occurs from exceeding the Doppler shift threshold, leading to inaccurate blood velocity readings.
Power Doppler allows visualization of small vessels but sacrifices directional and velocity info.

Doppler Effect and Blood Flow

Doppler Shift: Dependent on frequency, blood velocity, and the angle of the sound beam; optimal angle is less than 60 degrees.
Sample Volume: The region selected for doppler shifts impacts the quality of spectral display, with larger volumes detecting a wider frequency range.

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Description

This quiz explores the developments in medical imaging, specifically focusing on Doppler ultrasound and its applications in detecting fetal heart movement and blood flow. Key contributions from Callagan, Wild, and Reid are highlighted, showcasing advancements in the field. Test your knowledge on these crucial medical technologies and their evolution.