High field NMR microscopic imaging of cultivated strawberry fruit

The experimental conditions required for discrimination of various types of tissue in fruits of cultivated strawberry (Fragaria X Ananassa) at high fields (ca. 7 T) have been investigated, In marked contrast to soft fruits of other species, from which informative images have been derived at high fields using a variety of pulse sequences and acquisition parameters, appreciable image intensities from parenchymal and vascular tissues in healthy strawberry fruits were obtained only with a spin-echo imaging sequence using large sweep widths (ca, 100,000 Hz), and consequently small values for TE (<5 ms), indicating predominantly short T-2 values for these tissues, Damage caused by infection by the fungal pathogen Botrytis cinerea is readily seen as a result of a large increase in T-2 in the infected tissue, whereas ripening processes appear to be characterized primarily by small variations in the T-2-weighted contrast and in the relative magnitudes of T-1 between vascular and parenchymal tissue, In addition, it was possible selectively to enhance the contributions to images from the achenes (''seeds'') by using very short relaxation delays, thereby enhancing T-1-dominated contrast mechanisms.