MRI (Magnetic Resonance Imaging) functions properly when using a strong magnetic field and radio waves to make detailed images of the body’s internal structure. The major process is accomplished by using the magnetic field to orient the hydrogen atoms in the body, then the same magnetic energy is used to create a radio wave exciting the hydrogen atoms, finally as the hydrogen atoms relax back to their original position, energy is sensed and used to produce an image.
Basic Principles Are-
We are all composed of cells that contain water, which contains hydrogen ions (H2O). The magnetic field’s strength and polarity can be changed, therefore it can effectively restrict a change in the proton’s “spin” during which we can construct layers of information. Precession describes the way protons will return to their initial state when the magnet is turned off. Put simply, different tissue types in our bodies will recover at different conditions, and that’s how we see or differentiate the different tissues in the body.
Reclamation and Signal Detection:
When magnetic radio waves are turned off the protons will relax back to their inherent state while releasing energy in the form of radio waves. The MRI machine detects this energy and sends the signals to a computer where they are interpreted.
Image Generation:
The nature and state of the proton environment and type of tissue determine the nature and intensity of the signals we observe. Each of the numerous tissues and structures within the body has a different relaxation time, the MRI machine will generate complex images of each distinct tissue because of its ability to separate the various tissues.
Computer Processing:
The received signals are converted into digital signals in the form of an image that can be displayed on a computer monitor, or printed. The computer will then use advanced algorithms, synthesize the data, reconstruct an image, and the image is dished up to the user to examine and interpret the internal organs and internal tissue of the patient.
Essentially, MRI exploits the natural magnetic properties of the body to produce a diagnostic image with a whole lot of ease and detail, and without any use of ionizing radiation as with X-ray imaging.
Strong Magnetic Fields:
MRI machines generate a strong magnet, creating a very strong magnetic field.
This magnetic field aligns the magnet moments of hydrogen atoms (protons) in your body which causes those protons to spin in an aligned manner.
Radio Frequency Pulses:
The MRI machine next sends radio waves which excitates or gives energy to the protons. The radio waves are at the correct frequency to flip the aligned protons out of equilibrium.
Conclusion
The magnetic field acts on the probe or protons when they are at the equilibrium condition. Is then delivered to the patient to disrupt or perturb the equilibrium condition with a highly controlled energy called a radio frequency pulse. The radio frequency pulse will excite the protons into another orientation that is not aligned with the magnetic field direction. The radio frequency pulse is very short, and there is then a time interval for the protons to relax back to equilibrium.
When proton relaxation brings them back to homeostasis (in a direction aligned with the magnetic field) the protons will emit signals which can be detected by computational coils producing an analogue signal. These analogue signals are then put through A/D (analogue/digital) converters sending digital data to the computers.
Since all tissues in the body have unique properties about returning to homeostasis, MRI can be used to distinguish between tissue types.
MRI can program changes in magnetic field strength ,and radio frequency pulse sequence to produce images either T1 contrast or T2 contrast based.
Frequently Asked Questions
Q. What is the mechanism of the MRI?
Most protons, which are typically randomly aligned in the nuclei of water in biological tissue, are aligned by a strong, stable external magnetic field.
Q. Why is MRI so loud?
Most of the characteristic sound heard from an MRI scan is caused by the changes of the magnetic fields of the gradient coils at high rate.
Q. Why can’t you drink water before an MRI?
Water is usually permitted before MRI scan but please follow the instructions.
Q. What is not allowed during MRI?
An MRI has a large magnetic field that will not allow the following items into the room: the vast majority of metal objects such as jewelry, watches, credit cards, etc; electronic devices such as cell phones, hearing aids, and other devices.
Q. How to pass time during MRI?
To help make the time go more lickety-split in an MRI, you might want to think about relaxing, distraction, and focusing on positive things. You might want to think about guided meditation, happy music, or letting your mind wander to positive images or stories.
