Volumetric thermometry with proton resonance

Proton resonance frequency (PRF), by which it precesses in the magnetic field, alters due to change in temperature, which can be detected with magnetic resonance imaging (MRI). MRI scanner uses protons’ nuclear magnetic resonance phenomenon. The target is first excited with a radio frequency pulse, then it’s relaxation to initial stage is observed. Parts with different temperatures can be mapped according to the characteristics of the signal they emit during relaxation. PRF thermometry is recognized as the best method to study in vivo temperature distribution with MRI scanner. PRF thermometry is favored due to a good large scale linearity and tissue independence. When tissue containing water is heated, the hydrogen bonds between water molecules are soften as a result of increased Brownian motion. When hydrogen bonds are weaker, the magnetic shielding from electron cloud around proton is stronger. Now that the magnetic shielding is stronger, the local magnetic field of that proton is weakened. Lower magnetic field leads to lower proton nuclear magnetic resonance. Change in nuclear magnetic resonance can be detected with phase difference mapping as a phase shift in phase images with MRI scanner. Noninvasiveness is universally justified in clinical medicine. Diseases and tumors in living tissues can be noninvasively treated with hyperor hypothermia. Abnormal situations can be detected by observing the temperature changes in the body. MRI scanner can be used to examine tissue temperatures during temperature treatments. Temperature mapping can also be used to monitor unwanted tissue heating related to MRI examinations. The purpose of this thesis is to produce volumetric thermometry data with proton resonance, and to optimize the imaging parameters in order to achieve the best signal-tonoise ratio for magnetic resonance thermometry.