DIAMAGNETIC SUSCEPTIBILITY CHANGES IN APPLE TISSUE AFTER BRUISING

In nuclear magnetic resonance images of bruised apples, the bruised ti ssue regions appear brighter than intact tissue regions. The cause for the contrast was investigated. The spin-spin relaxation rates (1/T-2) of the bruised regions were found to be greater than those of firm ti ssue regions ruling out this mechanism as a cause for the contrast. By comparing spin-echo images (with echo delays of 14 ms and 50 ms) with gradient-recalled-echo images (with echo delay of 5.5 ms) it was conc luded that the contrast may be attributed to the decrease in the diama gnetic susceptibility variations within the bruised regions as a resul t of the partial destruction of the cellular structure caused by bruis ing. Images of a bruised apple were acquired before bruising, immediat ely after bruising and approximately every 4 h thereafter, and showed that the contrast between bruised and non-bruised regions increased wi th time.