Examination of the Tissue Water in Cucumber Fruit by Small Dedicated Magnetic Resonance Imaging with a 1-T Permanent Magnet

Abstract

The morphology and physical state of tissue water of cucumber fruit were examined by magnetic resonance imaging (MRI) and compared using a 1-Tesla (T) permanent magnet that was devised for food research and a 7-T high-resolution magnet. Then, the distribution and mobility of water were analyzed between tissues by the relaxation time-weighted imaging methods. Sarcocarp, placentas, seeds and vascular bundles of the fruits in different physiological conditions were distinguishable by 1-T small MRI, while clear morphology was observed by 7-T high-resolution MRI. However, while low mobility of water in the tissues of low water content, such as the placentas, was not detected due to the fast T₂ decay of the signals in the high magnetic field of 7-T MRI, it was detected by 1-T MRI, which had slower T₂ decay of the signals. Moreover, the T₁ signal recovery was faster in the 1-T MRI than in the 7-T MRI. These results indicate that the small 1-T MRI is suitable for analyzing the physical conditions of water in respect to the detection of the low mobility of water and also for obtaining a strong T₁ contrast of morphology despite the lower quality of the images compared to the high-resolution images. The 1-T small MRI is therefore an effective method for studying the properties of food materials with a wide range in the amount and mobility of water.