MRI

Scanning Using MRI Machine

 Nuclear magnetic resonance imaging (MRI) is a relatively new technology first developed by the Dr. Raymond Damadian, a Physician and scientist at the University of Nottingham, England in 1973. In clinical practice MRI is used to distinguish pathologic tissue from normal tissue. It uses strong magnetic fields and non ionizing radiation in the radio frequency range unlike CT scan and traditional X-rays which use ionizing radiation so MRI is more harmless to the patient.

MRI Scan of Human Brain

        While forming the 3-D image of internal body structure the damaged tissue tends to develop edema which makes a T₂  weighted sequence sensitive for pathology, and generally able to distinguish pathologic tissue from normal tissue. A common MRI test consists of 5-20 sequences, each of which are chosen to provide a particular information about the subject tissue. This causes the nuclei to produce a rotating magnetic field detectable by the scanner and the information is recorded to construct an image of the scanned area of the body. 3-D spatial information is obtained by providing magnetic field gradients in each direction. MRI provides good contrast between the different soft tissues of the body, due to which MRI technology is more useful in imaging the brain, muscles, heart and cancers. When a person is inside the MRI scanner the body becomes aligned with the direction of field. At the same time a radio frequency transmitter is turned on which produces more varying electromagnetic field. After the field is turned off, those protons which absorbed energy revert back to the original lower energy spin down state. As hydrogen dipole has two spins they release the difference in energy as photon which is detected by the scanner electromagnetic signals and in this way nuclear magnetic resonance (NMR) is used for imaging.

        In just a few decades the use of MRI scanners has grown tremendously. Now the doctors may order MRi scan to help diagnose multiple sclerosis, brain tumors, torn ligaments, tendonitis and many other disorders. An MRI scan is the best way to see inside the human body without cutting it open.