Which aspect does not improve with smaller voxel size?

• A. Spatial resolution
• B. Image clarity
• C. Scan time
• D. Contrast

Answer: (C)

Smaller voxel size does indeed improve several aspects of MRI imaging, such as spatial resolution, image clarity, and contrast. Spatial resolution relates to the ability to distinguish between two closely positioned objects, and smaller voxels allow for finer differentiation, enhancing image detail. Image clarity benefits from reduced voxel size because it minimizes the partial volume effects, meaning that structures within the voxel are less likely to blend together, resulting in clearer images.

Contrast in MRI pertains to the differences in signal intensity between various tissues; smaller voxel sizes can help distinguish these differences more effectively. This increased resolution can help reveal subtle differences in tissue characteristics.

However, while smaller voxel sizes enhance these aspects of imaging, they often lead to increased scan times. This is due to the need for more data points to reconstruct the images, as well as potential changes needed in parameters like the signal-to-noise ratio (SNR) to maintain image quality. Therefore, smaller voxel sizes do not improve scan time and can actually extend it, making this choice the correct answer.