Ultrasonography Flashcards

Questions and Answers

What is the technique that sonography is based on?

The sound waves that acquire images in real time without the use of ionizing radiation.

What is the ultrasound periodicity?

The periodicity is greater than 20 kHz, which is greater than the audible range.

What is the vibratory frequency of diagnostic ultrasonography?

It is a range of 1 to 20 MHz.

What is the basic concept of ultrasonography?

The scanner generates electrical impulses that are converted into ultra-high-frequency sound waves by a transducer. Signup and view all the answers

What is the transducer?

It is a device that can convert one form of energy into another; in sonography, it converts electrical energy into sonic energy. Signup and view all the answers

What is the most important component in the transducer?

The thin piezoelectric crystal or metal made up of a great number of dipoles arranged in a geometric pattern. Signup and view all the answers

What is the most widely used piezoelectric material?

Lead zirconate titanate. Signup and view all the answers

How does the transducer generate sound waves?

When the external voltage or electrical impulse generated by the scanner causes the dipoles in the crystal to realign. Signup and view all the answers

How does the transducer receive the sound wave?

The sonic waves that reflect towards the transducer cause a change in the thickness of the piezoelectric crystal. Signup and view all the answers

What is real-time imaging?

It is a technique that permits echoes to be processed rapidly to allow perception of motion. Signup and view all the answers

What is the imaging modality that uses a pulse?

Both A and B Signup and view all the answers

The properties of sound waves when interacting with matter include _____, absorption, reflection, refraction, and scatter.

transmission Signup and view all the answers

The spatial resolution of the ultrasound image depends on _ and the attenuation of the ultrasound beam energy depends on _.

wavelength, frequency Signup and view all the answers

What is the ultrasound frequency choice for greater resolution?

High frequency (5-10 MHz) Signup and view all the answers

What are the factors that affect the fraction of the beam that is reflected to the transducer?

Acoustic impedance of the tissue and the beam's angle of incidence. Signup and view all the answers

What is the acoustic impedance of the tissue?

It is the product of tissue density and the velocity of sound through it. Signup and view all the answers

What are the benefits of the internal echo pattern in ultrasound?

It distinguishes between different tissues and correlates with pathological changes within the tissue. Signup and view all the answers

What are the different echo patterns of the tissue?

Anechoic, hypoechoic, and hyperechoic. Signup and view all the answers

What does the interpretation of sonograms rely on?

It relies on knowledge of both physical properties of ultrasound and anatomy of the tissues being scanned. Signup and view all the answers

What are the applications of ultrasound?

Evaluation of neoplasms, guiding fine-needle aspiration, and 3-D imaging for multiplanar reformatting. Signup and view all the answers

Study Notes

Ultrasonography Basics

Utilizes sound waves to create real-time images without ionizing radiation.
The frequency used in ultrasound is greater than 20 kHz, exceeding the audible range.
Diagnostic ultrasonography typically operates within a frequency range of 1 to 20 MHz.

Transducer Functionality

Converts electrical impulses from the scanner into high-frequency sound waves.
Consists of piezoelectric materials that convert electrical energy into sonic energy.
The most common piezoelectric material is lead zirconate titanate.

Sound Wave Generation

Sound waves are generated when electrical impulses realign dipoles in the crystal, causing rapid changes in thickness that lead to vibrations.
This conversion process transforms electrical energy into sound waves.

Sound Wave Reception

Reflective sonic waves alter the thickness of the piezoelectric crystal, generating electrical signals.
These signals are amplified, processed, and displayed as images on monitors.

Real-Time Imaging

Current technology allows for processing echoes rapidly enough to perceive motion within images.

Imaging Modalities

MRI employs RF pulses while ultrasonography uses sound waves for imaging.

Interaction of Sound Waves with Matter

Sound waves exhibit various properties including transmission, reflection, refraction, absorption, and scattering.

Spatial Resolution & Frequency

Spatial resolution depends on wavelength; higher frequency offers better resolution but less penetration.
High frequency (5-10 MHz) is effective for shallow structures, whereas low frequency (3.5-5 MHz) penetrates deeper but with lower resolution.

Factors Influencing Reflection

The amount of beam reflection is affected by acoustic impedance, related to tissue density and the angle at which the beam hits the tissue.

Acoustic Impedance Defined

Calculated as the product of tissue density and sound velocity, expressed in SI units as rayls (kg/(m²·s)).
Acoustic impedance contributes to the unique internal echo patterns of tissues.

Internal Echo Patterns

Differentiates various tissues based on the reflected sound signals, correlating with pathological changes:
- Anechoic: No signal, appears black (e.g., fluid-filled cysts).
- Hypoechoic: Weak signal, appears gray (e.g., muscle).
- Hyperechoic: Intense signal, appears bright (e.g., bone, ligaments).

Interpretation of Sonograms

Relies on understanding the physical properties of ultrasound and the anatomical characteristics of the scanned tissues.

Applications of Ultrasonography

Used for evaluating neoplasms in various glands and lymph nodes, detecting stones, and guiding fine-needle aspirations.
Supports advanced imaging techniques, including 3-D imaging for better diagnostic evaluation.

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Description

Test your knowledge of ultrasonography with these flashcards. Explore key concepts, techniques, and definitions related to this imaging method. Ideal for students seeking to reinforce their understanding of ultrasound technology.