What is a potential downside of reducing the slice thickness in MRI?

Reducing the slice thickness in MRI indeed leads to decreased signal-to-noise ratio (SNR). This occurs because a thinner slice captures less total signal from the tissue being imaged. Since SNR is directly related to the volume of tissue sampled, thinner slices draw from smaller volumes, resulting in a lower overall signal for reconstruction. A compromised SNR can make it difficult to distinguish between different tissues or pathologies in the final images, potentially impacting the diagnostic quality.

In contrast, improved spatial resolution is generally a benefit of thinner slices, as they can provide more detailed images; however, this is often a trade-off with SNR. Increased scan time is also a common result of decreasing slice thickness, as more slices may be needed to cover the same area, but this does not directly relate to SNR. Likewise, increasing motion artifacts can arise from longer scan times, but the primary reason that decreased slice thickness impacts SNR is the smaller volume of signal contributing to each pixel. Thus, the correct understanding of the relationship between slice thickness and SNR is crucial for optimizing MRI parameters for effective imaging.