Magnetic Resonance Imaging (MRI) Practice Test

What is the effect of reducing the FOV in an MRI scan?

1. Increased signal to noise

2. Decreased signal to noise

3. No effect on image quality

4. Increased scan time

The correct answer is: Decreased signal to noise

Reducing the Field of View (FOV) in an MRI scan has a significant impact on the signal-to-noise ratio (SNR). A smaller FOV concentrates the area of interest, which in turn increases the amount of signal received from that specific area relative to the noise present in the system. However, a reduced FOV can also lead to changes in how the data is collected and processed. Typically, when the FOV is decreased, the same number of data points are collected over a smaller physical area. This may increase the relative strength of the signal coming from the region of interest, but it can also inadvertently increase the system noise, as there is less signal collection possible from the peripheral areas that contribute to the overall noise. When considering all these factors, the increase in noise—which may occur if the area being examined is not densely populated with signal—compared to the signal effectively results in a decreased SNR. Therefore, while a smaller FOV does create a condition for more focused imaging, the specific dynamics often lead to a decrease in the SNR, justified by looking at the relationship between spatial resolution and noise distribution. Thus, the effect of reducing the FOV in an MRI scan is characterized by a decrease in the