Which of the following is NOT affected by changing the slice thickness?

Changing the slice thickness in MRI scans has various effects on different aspects of the acquired images. The correct answer is that T2 contrast remains unaffected by changes in slice thickness.

This is because T2 contrast relates to the intrinsic properties of the tissues being imaged, specifically how quickly proton spins lose coherence after the initial excitation pulse. T2 values are inherent to the tissues and are dependent on the molecular environment and the type of tissue being imaged, not on the slice thickness itself.

In contrast, image resolution can be impacted by slice thickness. Thinner slices generally produce images with finer detail, leading to higher resolution. The signal-to-noise ratio is also influenced by slice thickness; thicker slices will typically accumulate more signal due to greater volume elements being sampled, thereby improving the signal-to-noise ratio. Additionally, anatomical coverage is directly affected, as increasing slice thickness allows for more anatomy to be included within a single image slice, thereby increasing coverage. However, all these factors—resolution, signal-to-noise ratio, and anatomical coverage—are subject to change with varying slice thickness, while T2 contrast remains constant.