Biology and Technology

CT
A CT scanner produces images known as tomography  which offer a much more detailed image than X-rays and permit doctors to see images of the interior organs and structures of the body. IT is a ring-shaped and has a motorized bed that moves through it slowly. The generated images will ultimately be sent to a computer for analysis. The X-ray revolves around the patient, scanning and creating images of different areas of the body. This forms a complete picture of the body, which shows a cross-section of the inside of the body that many people refer to as 'slices.' The cross-sectional images enable doctors to diagnose a number of different conditions and diseases. They can also show inflammation, bleeding, damage to internal organs and abnormal structures, such as tumors. The images are generated by X-ray scanners, which capture images as the motorized bed moves through the scanner. A radiographer operates the scanner and they will ensure that the bed is in the correct position. Different parts of the body can be scanned, and the bed moves slowly to allow many diverse images to be taken. The radiographer may ask the patient to breathe in or hold their breath at certain points during the scan.

CT scans provide very detailed images of the internal structures in the body. This allows doctors to spot things that would be missed with other types of scans, and quicker than MRI scans and be used on different parts of the body, and also for diagnostic processes. CT scans are a very effective means of checking for damage following an accident or severe injury, as the images enable doctors to detect damage, bleeding or inflammation. They can then decide on a course of treatment very quickly. Scans can also be used to test for damage following a stroke or hearth attack.

The amount of radiation a person receives during a CT scan is minimal. In men and non-pregnant women it has not been shown to produce any adverse effects. However, doing a CAT test hides some risks. If the subject or the patient is pregnant it maybe recommended to do another type of exam to reduce the possible risk of exposing her fetus to radiation. Also in cases of asthma or allergies it is also recommended to avoid this type of scanning. Since the CT scan requires a contrasts medium, there's a slight risk of an allergic reaction to the contrast medium. Having certain medical conditions; Diabetes, asthma, heart disease, kidney problems or thyroid conditions also increases the risk of a reaction to contrast medium.

PET

A PET scan uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. PET stands for positron emission tomography. The machine detects pairs of gamma rays which are emitted indirectly by a tracer (positron-emitting radionuclide) which is placed in the body on a biologically active molecule. The images are reconstructed by computer analysis. Modern machines often use a CT X-ray scan which is performed on the patient at the same time in the same machine. 

PET scans can be used to diagnose a health condition, as well as for finding out how an existing condition is developing. PET scans are often used to see how effective an ongoing treatment is.

Radiotracer - Before carrying out a PET scan, a radioactive medicine is produced in a cyclotron (a type of machine). The radioactive medicine is then tagged to a natural chemical. This natural chemical could be glucose, water, or ammonia. The tagged natural chemical is known as a radiotracer. The radiotracer is then inserted into the human body. 

When it is inside the radiotracer will go to areas inside the body that use the natural chemical. For example, FDG (fluorodeoxyglucose - a radioactive drug) is tagged to glucose to make a radiotracer. The glucose goes into those parts of the body that use glucose for energy.Cancers, for example, use glucose differently from normal tissue - so, FDG can show up cancers. 

Detecting positrons - A PET scan detects the energy emitted by positively-charge particles (positrons). As the radiotracer is broken down inside the patient's body positrons are made. This energy appears as a 3-dimensional image on a computer monitor. 
The image - The image reveals how parts of the patients body function by the way they break down the radiotracer. A PET image will display different levels of positrons according to brightness and color. 

When the image is complete it will be examined by a radiologist who reports his/her findings to a doctor. A radiologist is a doctor who specializes in interpreting these types of images, as well as MRI scan, CT scan, Ultrasound and X-ray images.

• Epilepsy - it can reveal which part of the patient's brain is being affected by epilepsy. This helps doctors decide on the most suitable treatments.MRI and/or CT scans are recommended for people after a first seizure, this study explains.


• Alzheimer's disease - it is very useful in helping the doctor diagnose Alzheimer's disease. A PET scan that measures uptake of sugar in the brain significantly improves the accuracy of diagnosing a type of dementia often mistaken for Alzheimer's disease, a study revealed.


• Cancer - PET scans can show up a cancer, reveal the stage of the cancer, show whether the cancer has spread, help doctors decide on the most appropriate cancer treatment, and give doctors an indication on the effectiveness of ongoing chemotherapy. A PET scan several weeks after starting radiation treatment for lung cancer can indicate whether the tumor will respond to the treatment, a study showed. This article looks at whether PET scans are beneficial during cancer diagnosis, staging and monitoring.


• Heart disease - a PET scan helps detect which specific parts of the heart have been damaged or scarred. Any faults in the working of the heart are more likely to be revealed with the help of a PET scan. A study revealed how comprehensive diagnosis of heart disease based on a single CT scan is possible.


• Medical research - researchers, especially those involved in how the brain functions get a great deal of vital data from PET scans.

fMRI

Functional magnetic resonance imaging, or FMRI, works by detecting the changes in blood oxygenation and flow that occur in response to neural activity – when a brain area is more active it consumes more oxygen and to meet this increased demand blood flow increases to the active area. FMRI can be used to produce activation maps showing which parts of the brain are involved in a particular mental process.

fMRI helps to explain what the brain does and which brain regions are involved in what types of processes. While fMRI and other imaging methods cannot tell us whether a region is definitely involved in a specific process (patients with lesions and the use of transmagnetic stimulation are the only techniques so far which can suggest causation), it can still help us understand what functions are carried out by which regions. Knowing which regions engage in which processes aids in understanding variations between individuals as well as complementing data from patient studies.