What effect does smaller slice thickness tend to have on SNR?

• A. Increases SNR
• B. Decreases SNR
• C. No effect on SNR
• D. Has a variable effect on SNR

Answer: (B)

Smaller slice thickness tends to decrease the signal-to-noise ratio (SNR) in magnetic resonance imaging. This occurs because thinner slices capture less signal from the tissue being imaged. Since the SNR is a measure of the desired signal strength relative to background noise, a reduction in the volume of tissue sampled results in less signal being received. Consequently, the inherent noise relative to the smaller signal becomes more pronounced, leading to a lower SNR.

This relationship highlights a trade-off in imaging techniques where thinner slices improve spatial resolution at the cost of SNR. Therefore, while thinner slices can yield more detailed images, they may also result in noise that obscures the quality and clarity of the final image, depending on the specific imaging parameters and the type of scan being performed.