Magnetic resonance imaging (MRI )

Magnetic resonance imaging (MRI )

Magnetic resonance imaging (MRI)is noninvasive method of mapping the internal structure and certain aspects of function within the body. hazard .

It uses nonionizing electromagnetic radiation and appears to be without exposure-related

HISTORICAL PERSPECTIVEName of MRI previously is nuclear magnetic resonance (NMR),first described by Bloch and Purcell in 1946
In applications to medicine, it is now commonly referred to as magnetic resonance (MR).

Application for human study between 1973-1977

MR describes the phenomenon whereby the nuclei of certain atoms, when placed in a magnetic field, absorb and emit energy of a specific or resonant frequency.

Mean that the nuclei of certain elements align with the magnetic force when placed in astrong magnetic field .

At the field strengths currently used in medical imaging ,hydrogen nuclei (protons ) in water molecules and lipids are responsible for producing anatomical imaging .

If radiofrequency of hydrogen is applied ,aproportion of the protons change alignment ,flipping through apreset angle , rotate in phase with one another.fallowing this radiofrequency pulse,the protons return (realign )to their original postion .