Magnetic Resonance Imaging (MRI) Practice Test

If the field of view (FOV) is reduced by a factor of 2, how does the voxel volume change?

1. It remains the same

2. It doubles

3. It is reduced by a factor of 4

4. It increases by a factor of 4

The correct answer is: It is reduced by a factor of 4

When the field of view (FOV) is reduced by a factor of 2, it directly affects the dimensions of the voxel. Voxel volume is calculated as the product of its width, height, and depth. Reducing the FOV by a factor of 2 means each linear dimension (width, height, and depth) of the voxel will also be halved. Therefore, if you have a voxel with dimensions of, for example, \(x \times y \times z\), reducing each dimension by half results in new dimensions of \((\frac{x}{2}) \times (\frac{y}{2}) \times (\frac{z}{2})\). To find the change in volume, you can calculate the original volume as \(V = x \cdot y \cdot z\). After reducing each dimension, the new volume becomes \((\frac{x}{2}) \cdot (\frac{y}{2}) \cdot (\frac{z}{2}) = \frac{x \cdot y \cdot z}{8}\), which shows that the volume has been reduced by a factor of 8. Given that the volume reduction also relates to the overall total decrease in the voxel