Which adjustments reduce the overall signal-to-noise ratio (SNR) in an MR image?

The overall signal-to-noise ratio (SNR) in an MRI image is influenced by several factors related to imaging parameters. When considering adjustments that can lead to a reduction in SNR, it’s important to understand how each parameter impacts the acquisition of signal.

Decreasing the repetition time (TR) typically leads to less time for longitudinal relaxation to occur, which can result in a lower signal. Additionally, reducing the phase matrix decreases the number of phase encodings, which can inadvertently reduce the amount of signal obtained from the tissue being imaged, further decreasing SNR. Likewise, decreasing the field of view (FOV) can lead to a smaller area being imaged, resulting in a lack of adequate signal over that region compared to a larger FOV. These combined adjustments – decreasing TR, reducing the phase matrix, and decreasing the FOV – would collectively reduce the overall SNR in the image.

Understanding how each of these adjustments works within the MRI framework is essential for proper imaging technique. The correct response reflects a scenario where each chosen adjustment contributes to a decrease in SNR, making it vital for students to grasp how each setting interacts with the fundamental concepts of magnetic resonance imaging.