[en] Marked hypointensity on the second echo of long repetition time (TR) pulse sequences at 1.5 T has been noted in colloid cysts of the third ventricle and mucous retention cysts of the sinuses. Both are lesions containing a large quantity of material that stains positive for polysaccharide. In an attempt to explain these findings, polysaccharide materials (potato starch) were prepared at 1%, 3%, and 7% (liquid) and 10% (gel) concentrations in distilled deionized water, .01 and .1m mM FeCl3. Imaging at 1.5 T and measurements of T1 and T2 at 1.9 T were performed. Relaxation rates of 10% dextran solutions with average molecular weights of 17,000, 40,000, 70,000, 150,000 and 450,0000 were measured at 1.9 T. The addition of 1% - 10% starch to water shortened T1 and increased the brightness of images obtained at short TR/TE. The addition of FeCl3 increased T1 shortening and image brightness with T1 weighting. T2 was minimally affected by the soluble polysaccharide, but somewhat more decreased in the gelatinous material