706 Dinosaur Egg Structure Investigated Using MRI M. McJury, N.D.L. Clark",J.Liston', B. Condon- Dept. Clinical Physics, Western Infirmary, Glasgow: 'Hunterian Museum.University of Glasgow, -MRI Unit, Southern General Hospital, Glasgow. Introduction The Hunterian Museum at the University of Glasgow recently acquired a number of 80 million year old fossilised dinosaur eggs from Hunan Province, China. A number of analytical techniques, including CT and MRI, were used to investigate the internal structure of the eggs. The 1 mm thick eggshell is composed mainly of calcium carbonate surrounded by a medium grained sandy matrix rich in quartz, mica, feldspar, clays, and iron-oxide cemented by micritic calcium carbonate. The egg-shell has been compacted by the weight of the overburden and, as a result, cracked allowing the free movement of fluids into the shell structure. At first sight it would appear that the subject is unsuited to analysis by MRI, as a reasonable amount of mobile NMR-sensitive protons are necessary to produce images with acceptable signal-to-noise. Due to the nature of the egg- shell, however, trapped moisture allows it to be successfully imaged as distinct from the rest of the egg structure. Methods The eggs, including their matrix, were placed in the head coil of a Siemens 1T Impact. The coil was loaded with the standard coil loader and a saline phantom. Images were obtained using an SE1000/10 which collected 50 averages over 106 minutes. The matrix was 128x256 with slice widths of 1 and 20cm. Results The thin shells of the dinosaur eggs were clearly delineated on the images produced. A number of other imaging sequences were run, including FLASH sequences, but the spin echo sequence yielded artefact-free images of the highest signal-to-noise. The imaging sequence was altered to excite a 20cm slice, producing a projection of the entire shell. By calibrating with respect to phantoms(1) the water content of the shell was measured. Conclusion MRI was used to generate images of fossilised dinosaur eggs. The images show a shell structure distinct from the rest of the egg. By acquiring a projection of the entire egg, the water content of the shell was measured. These results are complimentary to the results from CT and other analytical techniques used in the investigation of these prehistoric specimens. References 1. 6. Condon et al. J.Comput. Assist. Tomogr 1986;10:784-792