Question

Explain at least three of the following techniques used to study the brain: EEG, CT scan, MRI, PET scan, fMRI. What is the significance of these brain-imaging techniques?

Answer 1

1. EEG: Electroencephalography is an electrophysiological method to record the electrical patterns inside the brain. It measures the electrical activity generated by neurons via electrodes placed on the scalp surface. It is mainly used to daignose conditions like:

• Epilepsy
• Head injuries
• Dizziness
• Brain tumors
• Sleeping problems and disorders
• Brain death etc
• Coma
• Mental retardation
• Cognitive impairments etc.

The neurons in the brain produce electrical signals that form brain waves. The macroelectrodes are attached to the scalp that transfer signals to the EEG. It allows to record the impulses across the surface of brain the changes across those impulses. Continue recoding with sleep second accuracy is the main feature of EEG. It detects conscious state of a person i.e, sleep awake unanaeisthetic etc. There are no risks from EEG.

Procedure: The technician attaches 20 small electrodes to your brain with washable glue. You will be asked to

• Open and close your eyes
• Breath deeply
• Breathe rapidly
• Keep looking at flash light
• Lie down with eye closed.
• After the test the technician will remove the electrodes and you may concern neurologist who will interpret your result to you.

2. MRI (MAGNETIC RESONANCE IMAGING) :

MRI is a painless procedure. It allows the patient to slide in and uses magnetic and radio waves, and a computer for creating detailed images of brain and brain stem. These machines are kept in hospitals and radiology centres.

It is useful in detection of

• Cyst
• Tumors
• Swelling
• Headches
• Blurry visions of seizures
• Damage to brain caused by stroke
• Structural abormalities
• Multiple sclerosis

Electronic devices are not allowed in the MRI room. If wearing any king of metals you will be asked to remove it. In case of children going through MRI Scan sedation medicine is given so that he/she is asleep.

Procedure: time:30-45 minutes

The patient is asked to lie on the movable scanning table and a coil is placed over the head. The table then slides in the tunnel and the technician takes the images of the brain. In case of any specific problem a contrast solution will be given via a vein. This solution highlights blood vessels and other areas making it clear for the doctors to understand the problem in detail.

After the procedure the patient can come off the moving table and the results will be interpreted by radiologist to the doctors whom you can visit later and discuss with.

3. PET scan : position emission tomography shows how the brain is functioning. It is an imaging test which uses tracer (radioactive substance) to detect disease or any kind of injury in the brain. It can detect very early changes at cellular level which cannot be revealed via CT Scans and MRI. It is most commonly used in cancer and cardiology treatments.

Procedure: The tracers are swallowed, inhaled, or injected in the arm. After sometime certain organs and tissues absorb the tracers which helps the doctors to see how the organ and tissues are working. The tracers travels to cells which uses glucose for energy the more energy cells need the more radio tracer will built in that position. These activities will be shown as "HOT SPOTS" bright areas where activity of cell is high.

Or "COLD SPOTS" where activity is less in the cells and it is less bright.

Normal cells ause very less glucose than cancer cells this a radio tracer made with glucose will light up in areas of cancer.

PET Scan is used for detection of

• Depression
• Head trauma
• Alziemer's disease
• Parkinson's disease
• Brain disorders
• Heart problems
• Detecting cancer
• Seeing if cancer has spread
• Seeing if cancer treatment is working
• Cancer recurrence
• Memory disorders
• Seizures disorders