Which factor should be decreased to improve signal-to-noise ratio in MRI imaging?

Improving the signal-to-noise ratio (SNR) in MRI is crucial for enhancing image quality, and one effective way to achieve this is by increasing the number of averages. When you acquire multiple images (or averages) of the same section, the signal from the tissue of interest accumulates, while the statistical noise remains constant. This results in a higher SNR because the noise is effectively diluted in relation to the signal as more data is gathered.

The number of averages directly contributes to the SNR, making this method particularly useful in clinical settings where detail and clarity in the images are paramount for accurate diagnosis. Additionally, by increasing the number of averages, the same amount of time is often required, which can be well managed in most MRI protocols.

In contrast, increasing echo time tends to reduce SNR because longer echo times can lead to more signal decay particularly for tissues that have T2 relaxation properties. Decreasing slice thickness can improve spatial resolution but may reduce SNR because the smaller volume of tissue being imaged captures less signal. Similarly, increasing pixel size typically correlates with a trade-off where the SNR might improve due to a larger volume of tissue contributing to the signal, but it also affects spatial resolution and may not be recommended