A new method for simultaneous measurement of temperature and velocity maps by magnetic resonance imaging

Magnetic resonance imaging (MRI) has the advantage of internal observation of complex materials over optical measurement. The reason is that MRI can measure not only the complex geometry, but also the spatially resolved temperature and velocity distributions of interstitial fluid flow. In the present paper, the accuracy of temperature measurement using the conventional Inversion Recovery (IR) method, which is based on temperature dependence of spin-lattice relaxation of water proton in a fluid, has been evaluated by measuring temperature maps of stagnant doped water in a differentially heated cell. The accuracy was within 10% of the temperature difference, δT = 17.2°C and the measurable temperature resolution was within ±0.5°C. A new method using a set of tagging pulses for simultaneous measurement of temperature and velocity maps of flowing fluid has been developed by being extended the conventional IR method. This method can compensate the reduction of the NMR signal intensity due to flow motion so that it can maintain the high accuracy of temperature measurement. Temperature and velocity maps of the doped water flowing through a cooled pipe were measured and the accuracy of temperature measurement was evaluated. The accuracy obtained using the present method was within 15% of the temperature difference, δT = 15°C.