what is mri measured in
MRI measures the water content in tissues â both normal tissue and abnormal. MRI uses a powerful magnetic field that: 1  Makes the hydrogen protons in water molecules line up in the direction of the magnetic field.2  Once the hydrogen protons have been lined up, radio waves are used to knock them out of line.he strength of the magnet used in the MRI machine is important to the quality of the images. Magnet strength is measured in Tesla (T). 1  Most conventional MRI machines are 1.5T or 2.0T.