Podcast
Questions and Answers
What is the main purpose of A-mode in ultrasound imaging?
What is the main purpose of A-mode in ultrasound imaging?
In A-mode, what is the depth of an interface proportional to?
In A-mode, what is the depth of an interface proportional to?
What is the average sound velocity used in soft tissue for A-mode calculations?
What is the average sound velocity used in soft tissue for A-mode calculations?
What application is related to A-mode in detecting brain tumors?
What application is related to A-mode in detecting brain tumors?
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What is considered abnormal for a shift in the middle structure using Echo encephalography in adults?
What is considered abnormal for a shift in the middle structure using Echo encephalography in adults?
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In the field of ophthalmology, what is not measured using A-mode biometry?
In the field of ophthalmology, what is not measured using A-mode biometry?
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Why do higher ultrasound frequencies up to 20 MHz provide better resolution in eye examinations?
Why do higher ultrasound frequencies up to 20 MHz provide better resolution in eye examinations?
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Which ultrasound mode is used to obtain 2D images of the body?
Which ultrasound mode is used to obtain 2D images of the body?
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What distinguishes B-mode from A-mode in ultrasound imaging?
What distinguishes B-mode from A-mode in ultrasound imaging?
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Which of the following structures is not directly examined using B-mode ultrasound?
Which of the following structures is not directly examined using B-mode ultrasound?
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Study Notes
US Image Modes
A-Mode (1D)
- Used to obtain diagnostic information about the depth of structures (image with 1 dimension)
- US waves sent into the body, measuring time required to receive reflected sound (echoes) from interfaces between different tissues
- Depth of interface recorded is proportional to time it takes for echo to return: Depth = Velocity × time
- In average soft tissue, sound velocity is 1540 m/sec, and echo takes 13 µsec at a depth of 1 cm
- Applications: detection of brain tumors and eye diseases
Applications of A-Mode Scan
Echo Encephalography
- Used to detect brain tumors
- Pulses of ultrasound sent to a thin region of the skull above the ear
- Echoes from different structures displayed on oscilloscope
- Compare echoes from left and right sides of head to find shift in middle structure:
- Shift > 3 mm for an adult (abnormal)
- Shift > 2 mm for a child (abnormal)
Ophthalmology
- Used in diagnosis of eye diseases and biometry (measuring distances in the eye)
- Ultrasound frequencies up to 20 MHz used for better resolution and minimal absorption
US Image Modes
B-Mode (2D)
- Used to obtain 2D images of the body
- Principle same as A-Mode, but transducer moves, and storage oscilloscope forms the image
- Provides information about internal structures of the body (size, location, and change over time)
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Description
Learn about different modes of ultrasound imaging, including A-Mode, used to obtain diagnostic information about the depth of structures in the body. Understand how it works and its applications.
