Increasing the number of phase encoding steps will produce an image with what characteristic?

• A. Higher brightness
• B. Higher contrast
• C. Higher resolution
• D. Higher noise

Answer: (C)

Increasing the number of phase encoding steps directly contributes to higher resolution in an MRI image. Phase encoding is a key factor in determining the spatial resolution of an image. Each phase encoding step allows for a finer sampling of the data in one direction, improving the ability to distinguish between adjacent objects or structures in that direction.

As the number of phase encoding steps increases, more data points are collected, enhancing the detail and sharpness of the resulting image. This means that smaller structures can be visualized more clearly, which is critical in diagnosing conditions where fine details are essential.

In contrast, increasing phase encoding steps does not inherently increase brightness or contrast. Brightness is influenced by factors such as intensity of the signals and T1 or T2 relaxation times of the tissues, while contrast depends on the differences in signal intensity between various tissues rather than the number of phase encoding steps. Likewise, higher noise levels are often a result of low signal-to-noise ratio (SNR), which is generally not improved simply by increasing phase encoding steps; it is more related to scanner capabilities and techniques used to enhance SNR.