A REVIEW ON EXPERIMENTAL FINDINGS ON PROTON RELAXATION IN SEVERAL LABORATORY MAGNETIC RESONANCE IMAGING (MRI)

Abstract

Alternative materials that are potentially useful for magnetic resonance imaging (MRI) phantom have been studied to investigate their proton relaxation properties. The laboratory prepared materials should first fulfil characteristics such as inexpensive, non toxic, easy to handle, easily prepared, stable over a long period of time and should possess properties of tissues. Two important quantities of interest that were investigated are the longitudinal (T1) and transversal (T2) relaxation times. In this work, the SNR relaxations of three laboratory-made MRI phantoms which were agar gel, agarose gel and poly[vinyl] alcohol (PVA) slime were measured using a 3-T MRI system. A standard spin-echo pulse sequence was used. The data obtained fulfilled the exponential behaviour of the form SNR a 1 – e^-TR/T1 for T1 curve and of SNR a e^-TE/T2 for T2 curve. By using a curve-fitting method, it was found that the addition of relaxation modifier has significantly shortened the T1 relaxation time of the pure agar, agarose and PVA slime. Their T2 relaxation time was less affected. This indicated the sensitivity of the longitudinal relaxation of the protons to changes in their surroundings (or lattice). The shortening of T1 relaxation time has brought these laboratory-made MRI phantoms closer the properties of a standard MRI water phantom.