Which parameter combination would most likely yield a low signal-to-noise ratio (SNR)?

In the context of magnetic resonance imaging (MRI), the signal-to-noise ratio (SNR) is influenced significantly by both the repetition time (TR) and the echo time (TE). A low SNR indicates that the signal from the tissue being imaged is weak compared to the background noise, which can degrade image quality.

The first choice indicates a relatively long TR of 2200 milliseconds and a TE of 90 milliseconds. In MRI, longer TR values generally allow for more complete T1 relaxation of the tissues between excitations, resulting in higher SNR. However, a longer TE, especially beyond the T2 relaxation time of the tissues being imaged, can lead to a greater loss of signal due to T2 decay, which results in decreased SNR.

The combination of a long TR and a relatively long TE (90 milliseconds) can lead to a lower SNR because while the TR allows for some signal recovery, the TE causes significant signal loss, particularly for tissues with relatively short T2 values. This results in a weaker signal being detected when compared to the noise level.

In contrast, the other combinations usually involve shorter TEs or more optimal TR values that would support better signal recovery and less signal loss due to T2 decay