A comparison of phosphate bone-scanning agents in normal subjects and patients with malignant disease

Abstract

None of the established bone-scanning compounds 85Sr, 87Srm nor 18F is entirely satisfactory and because of this the place of skeletal scanning is not clearly defined. 18F is the most effective of the available bone-scanning compounds but its 100 minute half-life makes distribution difficult and restricts its use in Britain to the Greater London Area. There has recently been considerable interest in certain compounds of phosphate which show great promise as bone scanning agents (Subramanian et al., 1972; Yano et al., 1973; Hosain, 1973; Citrin et al., 1974). The phosphate compounds polyphosphate, pyrophosphate and ethane hydroxy diphosphonate, are readily labelled with 99Tcm in the presence of the reducing agent stannous chloride. 99Tcm is one of the standard isotopes used in nuclear medicine. Its physical characteristics are ideal and it is produced from a simple generator on site. If Tc-labelled phosphates are shown to be effective and safe then bone scanning will be routinely available in hospitals with even the most limited isotope facilities. It is clearly important to know which of the currently available phosphate compounds, polyphosphate, pyrophosphate and ethane hydroxy diphosphonate (EHDP)* is the most effective agent. We have compared these three agents in 29 patients with known malignant disease of the skeleton to compare their relative efficiency in demonstrating bony metastases. We have also measured serial blood and whole-body levels in a number of normal subjects to establish which compound gives lowest blood activity and lowest whole-body radiation dose.