Magnetic Resonance Imaging (MRI) Practice Test

What role does a steep slice selection gradient play in MRI?

1. Increases scan time

2. Enhances image quality

3. Generates thin slices

4. Improves the magnetic field uniformity

The correct answer is: Generates thin slices

A steep slice selection gradient in MRI is critical for generating thin slices. The gradient defines the magnetic field strength and, by extension, the frequency of the precessing spins in the selected slice. When the gradient is steep, it creates a rapid change in the magnetic field over a short distance, allowing for a more precise selection of the area being imaged. This precision helps to isolate thinner sections of the anatomical structure being examined, which can improve spatial resolution. In contrast, a shallow gradient results in a broader range of frequencies being accepted, leading to thicker slices that may encompass more surrounding tissue. Therefore, utilizing a steep slice selection gradient is essential when aiming to achieve thin slices that enhance the clarity of the image by reducing partial volume effects from adjacent structures.