Which of these is a purpose of increasing the NEX in MRI scanning?

Increasing the number of excitations (NEX) in MRI scanning serves several purposes, primarily related to enhancing the signal-to-noise ratio (SNR). When NEX is increased, multiple radio frequency excitations are applied to the same slice of tissue, and the signals from these excitations are averaged together. This averaging effectively reduces the noise present in the image data, as the random noise does not consistently appear in the same way across multiple acquisitions. By averaging, the true signal from the tissue becomes more prominent relative to the background noise, leading to clearer and more defined images.

While increasing NEX can lead to improved SNR, it is important to note that this does not inherently improve image resolution, decrease motion artifacts, or reduce scan time. In fact, increasing NEX typically results in longer scan times because each acquisition requires additional data collection. Thus, enhancing SNR through increased NEX is a critical consideration in MRI protocols where clarity and detail are of utmost importance.