Studies of the chemical and biological properties of the liver-imaging agent 99mTc-phytate.

The correlation between chemical formulation and biodistribution of 99mTc-phytate solutions was examined. On the basis of radiochemical analyses and biological experiments, the following optimum parameters were found: weight ratio of the anhydrous sodium phytate to SnCl2 18:1; concentration of phytate 5-6 g/l, pH of the injection solution 6-7. Maximum uptakes in rat organs were in the liver 95.8 +/- 3.26 at 15-20 min p.i., and in the spleen 3.98 +/- 0.79% 3 hours p.i. Two new methods for radiochemical analysis enabling the separation of three peaks were used: ITLC-SG Gelman chromatography and molecular sieving through Sephadex G-25. The bench-life of the injection solution was also checked during a 5-h period, as well as its shelf-life which was at least 6 months. Clinical examinations showed excellent visualization of the normal liver with discrete radiocolloid uptake in the spleen and no uptake in other tissues. With SPECT a more precise and clear localization of liver lesions was achieved especially due to the low uptake of 99mTc-phytate in the spleen.