Which of the following parameters would NOT increase SNR?

Increasing the receiver bandwidth does not enhance signal-to-noise ratio (SNR) and, in fact, can decrease it. SNR in MRI is influenced by the amount of noise in the system versus the amount of signal received. When you increase the receiver bandwidth, you actually capture a broader range of frequencies, which allows for more noise to enter the system without a corresponding increase in the signal from the region of interest. This broader range leads to a higher noise level compared to the signal, ultimately resulting in a lower SNR.

In contrast, decreasing slice thickness concentrates the signal within a smaller volume, which can improve SNR since there’s less tissue volume contributing to the noise. Increasing the number of excitations (NEX/NSA) allows for more signal acquisition over time, enhancing the overall signal relative to the noise and improving SNR. Decreasing receiver noise directly enhances the SNR since SNR is a ratio of signal strength to noise strength; with less noise present, the SNR increases. Thus, only an increase in receiver bandwidth fails to improve SNR.