Magnetic Resonance Imaging (MRI) Practice Test

Which parameter combination produces the best spatial resolution in MRI?

1. 5mm slice thickness, 128 x 128 matrix

2. 3mm slice thickness, 256 x 256 matrix

3. 2mm slice thickness, 512 x 512 matrix

4. 4mm slice thickness, 256 x 256 matrix

The correct answer is: 3mm slice thickness, 256 x 256 matrix

To understand why this combination produces the best spatial resolution in MRI, it's important to consider the components that contribute to spatial resolution: slice thickness and matrix size. A thinner slice thickness reduces partial volume effects, allowing for better differentiation of structures that are close together in the depth dimension. Therefore, a slice thickness of 3mm is beneficial as it provides finer detail than thicker slices. The matrix size also plays a critical role in resolution. A higher matrix size indicates a greater number of pixels used to represent an image—thus providing more detailed information in the same field of view. In this case, a 256 x 256 matrix means more data points are sampled, resulting in higher resolution images compared to smaller matrix sizes. When these factors are analyzed together, the 3mm slice thickness combined with a 256 x 256 matrix provides a strong balance between minimizing slice thickness to capture finer details while maximizing the number of pixels to interpret the available data comprehensively. This combination results in improved spatial resolution, making it easier to visualize and distinguish between closely positioned anatomical structures.