**Core Concept**
PET (Positron Emission Tomography) scan is a type of imaging test that uses small amounts of radioactive materials to visualize metabolic processes in the body. This technique relies on the detection of positron emissions from the radioactive tracer, which are then converted into gamma rays that are used to create detailed images of the body's internal structures.

**Why the Correct Answer is Right**
The correct answer is related to the principles of PET scan technology. PET scans are highly sensitive to changes in glucose metabolism, which makes them particularly useful for detecting cancer, neurodegenerative diseases, and other conditions. The radioactive tracer used in PET scans is typically a glucose molecule with a radioactive isotope, such as fluorine-18, which is taken up by cells and then emits positrons as it decays. This process allows for the creation of detailed images of glucose metabolism in the body.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because PET scans do not primarily use magnetic fields to create images, unlike MRI scans. While some PET-MRI hybrid scanners exist, PET scans themselves rely on the detection of positron emissions.
**Option B:** This option is incorrect because PET scans are not primarily used for detecting structural abnormalities in the body, such as fractures or tumors. While they can provide some information about anatomical structures, their primary use is in visualizing metabolic processes.
**Option C:** This option is incorrect because PET scans are not typically used for detecting genetic mutations or abnormalities in DNA. While some PET tracers may be used to study specific biological pathways, PET scans themselves are not a direct measure of genetic information.

**Clinical Pearl / High-Yield Fact**
It's worth noting that PET scans are highly dependent on the quality of the radioactive tracer used, and small variations in the tracer's preparation or administration can significantly impact image quality and diagnostic accuracy.

**Correct Answer: C. PET scans are used to visualize metabolic processes in the body, making option C the correct answer.**