Temperature measurement of foods using chemical shift magnetic resonance imaging as compared with T1-weighted temperature mapping

A method based on change in proton precession frequency with temperature was compared with temperature measurement by T1-weighted imaging. Temperature maps of a gel, and of cooked and raw red potatoes were developed during heating from 20 to 60°C. To measure change in proton precession frequency, a steady state free precession sequence allowed 2-dimensional acquisitions in 8 sec with spatial resolution of 0.88 mm². Temperature resolution with chemical shift imaging, ranged from 0.3 to 3°C, decreasing with increasing temperature due to a decrease in signal to noise ratio. The difference by this method and thermocouples was < 5°C. T1-weighted spin-echo images showed artifacts due to an inhomogeneous T1 distribution within the potatoes, indicating chemical shift was more reliable for inhomogeneous foods.