Final answer:
PET scans are a non-invasive tool for brain functionality and mapping. They use radioactive tracers to monitor blood flow and map active regions of the brain, and are useful for examining brain function, but ultrasounds are the safest imaging technique during pregnancy.
Step-by-step explanation:
Positron Emission Tomography (PET) scans are a non‐invasive way to examine brain functionality and physiology, and to map brain function. During a PET scan, an individual drinks or is injected with a mildly radioactive substance, called a tracer. This tracer allows for the monitoring of blood flow to active areas of the brain, helping to create a map of active and inactive regions during certain behaviors. Although PET scans expose the brain to radiation and have limitations in detailing the precise timing of brain events, they are particularly useful in examining the anatomy and function of the brain. PET scans are adept at monitoring the brain's use of oxygen and water, identifying regions of decreased metabolism such as those linked to Alzheimer's disease, and locating brain areas responsible for specific functions like sight, speech, and fine motor activities.
Ultrasound technology, on the other hand, is the least invasive of imaging techniques and uses no electromagnetic radiation, making it the safest option for monitoring pregnancies. The MRI and fMRI are other techniques that can provide detailed images of brain structures and activity over time, as these use a strong magnetic field and do not involve radioactive tracers.