In B-mode imaging, where is amplitude located on the image?

• A. X axis
• B. Y axis
• C. Z axis
• D. C axis

Answer: (C)

In B-mode imaging, commonly used in ultrasound, the amplitude of the returning echoes is represented on the brightness of the pixels in the image. Although the term "axes" can be somewhat specific, in the context of three-dimensional imaging, the brightness or amplitude information is interpreted along the Z-axis, which is typically associated with the intensity of the echo signals.

The Z-axis in B-mode imaging represents the amplitude of the returning signals which is converted into varying shades of gray on the image. Higher amplitude signals appear brighter, while lower amplitude signals appear darker. This representation allows clinicians to differentiate between different tissues or structures based on their echogenicity.

The other axes typically denote spatial dimensions: the X-axis represents lateral positions while the Y-axis denotes depth or distance from the transducer. Therefore, since amplitude or brightness of the signal is indicative of the intensity of returning signals, it is appropriately positioned along the Z-axis in B-mode imaging.