Summary: PET Scan

A fresh human brain does not resemble the stereotypical fixated human brain typically seen in textbooks or diagrams. Instead, a fresh human brain is rich in vasculature, extending across the entire surface of the brain. The brain, in a sense, is greedy, requiring twenty percent of the oxygen coming from the lungs and twenty percent of the blood pumped by the heart. Recently, the brain’s greediness has led to advances in medical brain imaging technology. The PET scan maps the amount blood flow through specific areas of the brain, allowing researchers to localize particular functions to precise areas of the brain. In the TED talk, Dr. Allen explains the function of the cerebellum, temporal cortex, and frontal lobe – areas of the brain whose functions were determined using PET scan.

The photons are then tracked by a tomographic scintillation counter, and the information is processed by a computer to provide both image and data on blood flow and metabolic processes within bodily tissues. PET scans are particularly useful for diagnosing brain tumor and the effects of strokes on the brain, along with various mental illnesses. They are also used in brain research and in mapping of brain functions.

Positron Emission Tomography is a scanning technique that allows us to measure in detail the functioning of distinct areas of the human brain while the patient is comfortable, conscious and alert. PET represents a type of functional imaging, unlike X-rays or CT scans, which show only structural details within the brain. The differences between these types of imaging don’t end there.

Due to this, it has been deemed difficult to determine which deficit is the consequence of which part of a lesion. To overcome this problem, other methods are being used to aid in the visualisation of memory processes in the healthy parts of the brain. These come in the form of functional neuroimaging studies using Positron Emission Tomography (PET) and Functional Magnetic Resonance Imaging (fMRI). These studies have allowed researchers to target specific memory processes using targeted psychological experiments. However, with all psychological experiments, there are limitations to using neuroimaging equipment. PET and fMRI attain their signals from local changes in blood flow or metabolism correlated with neural activity rather than from brain waves (or signals). The local vascular changes affect the distribution of an injected radionuclide (e.g. O15) in PET or magnetic properties that are blood-oxygen level dependent (BOLD) in fMRI. The indirect measure of neural activity limits the temporal and spatial fidelity of activations.

Using Functional MRI helps to visualize the brain functionality through local metabolism. In this technology it allows the researcher to measure and track the brain functions by discovering the correlated changes in blood flow. From this functional Mri when a brain function is acted out the flow of oxygenated rich blood is detected and highlighted on the specific location where the functionality came from on the brain.

Different maps are taken of the brain in order to determine if there are any problems with the brain. An electroencephalogram (EEG) is used an amplified read out of the brain waves. A magnetic resonance imaging scan (MRI) gives a detailed picture of the brain’s soft tissues. It also shows the structure of the brain. A function magnetic resonance imaging scan or function MRI (fMRI) shows the function of parts of the brain as well as the brain’s structure. It also has the ability to show when a person is lying. Scientists also use a neuroimaging technique called a positron emission tomography scan (PET scan) to view the brain. (Barron’s AP Psychology 6th Edition) The PET scan shows each brain area’s consumption of chemical fuel which is glucose. There is a scale for the PET scan to determine activity in the brain when performing a certain action. The colors range from purple to red, purple represents no activity while red represents very high activity. The PET scan can

The PET scan also will show two and three-dimensional images of the brain; however, the PET scan measures brain activity. This is done by injecting radioactive isotopes into the blood stream. The isotopes attach to

Unlike the MRI, the fMRI is used to understand brain activity and function over developmental time and in real time a. Point 2: Which is most used among Psychologists and Neuroscientists - Though these are not the only ways we can study the brain, these are the main ones we use in psychology and neuroscience. - In psychology and neuroscience, not a lot of studies are done using an MRI, because it has limitations and can only really show us the anatomy of the brain and maybe if there is any kind of brain damage. Based on information from Mayo Clinic 2012, the popular method of research involving brain imaging techniques these days is using the EEG, paired with what is called a Brain Computer Interface. Since there are always electrical signals going on in the brain, its really hard to pinpoint a reaction. So computers were coded to give a particular output whenever there is a specific electrical response in the brain.

For instance, testing reflexes, muscle tone, strength, being able to get up from a chair, then walk across the room, vision, sense of hearing, coordination and balance. Blood tests can help doctors rule out other possible causes of disorientation and memory loss, like thyroid disorders or the lack of vitamins. Pictures of the brain are now used to spot out visible distortions related to other conditions such as strokes, a trauma or tumors that may cause emotional changes. New items, used mainly in utmost medical centers or in clinical trials allow doctors to find certain brain changes caused by Alzheimer's. Magnetic Resonance Imaging or MRI uses radio waves and a magnetic field to make detailed pictures of the brain. MRI's are used to rid of other conditions that may account for or be added to emotional symptoms. Computerized Tomography, a CT scan creates cross-sectional pictures of the brain. It's used to rule out tumors, strokes and head traumas. Positron Emission Tomography or a PET scan is where a person is injected with a low-level radioactive tracer into a vein, which is a special type of glucose that shows overall activity in various brain areas. This can show which parts of your brain are not working properly. Under certain conditions, such as increasing dementia

Soft tissue structures such as heart, lungs, liver and other organs are clearer and more detailed with MRI when comparing with the other methods.

fMRI scans were performed by using a complex machine with massive specifications, named 4-T whole-body Varian/ Siemens imaging system. Before they start their imaging, the patient’s heart rate was monitored with a fiber-optic pulse oximeter and placed on their head was a radio frequency coil to capture a map of their brain. Each patient is then instructed to lie calmly, breathe through their nose, and allow themselves to focus on the script that the instructors were about to read. Each script would usually last them about 30 seconds. After the script is read, they are encouraged to recall a memory for about 60 seconds and once they start, so does their measurements of their heartbeats. The script is then repeated again after 120 seconds. This method is repeated 3 times.

Next in this video was the summary of the techniques used for observing the brain. First, the Cat scan was mentioned, which shows actual brain tissue. Second, Pet scan which

There are several technologies to allow researchers to create structural images of the brain. We can use computerised tomography and magnetic resonance imaging to produce a series of X-rays of the brain with the MRI this does produce much higher definition pictures more helpful because it goes beyond just the structural data. Newer techniques like the position emission tomography and functional magnetic resonance imagery. Where the pet requires the participant or patient to ingest a radioactive substance that many if not all participants in a research study may be, are very unwilling do.

2. Functional brain mapping (scanning a person's brain while he or she is performing a certain physical task such as squeezing a ball, or looking at a particular type of picture) is helping researchers better understand how the brain works.

Last of the diagnostic imaging tools is the MRI. MRI, which stands for Magnetic Resonance Imaging, was a technique developed in the 1950?s by Felix Bloch, and is the most versatile, powerful, and sensitive tool in use. The process of MRI was originally called NRI, Nuclear Resonance Imaging, but was found to be to confusing due to the fact that MRI?s don?t use radioactivity and ionizing radiation. The MRI generates a very powerful electromagnetic field, which allows the radiologist to generate thin-section images of any part of the body. Also it can take these images from any direction or angle, and is done without and surgical invasion. Another plus side to the MRI is the time it takes to perform, where as a CAT scan may take 30-60 min. A MRI may only take 15 minutes max. The MRI also creates ?maps? of biochemical compounds within a cross-section of the body. These maps give basic biomedical and anatomical information that provides new knowledge and may allow early diagnosis of many diseases.