**10. Conclusion**

As the search continues for new products and newer areas of applications, 12jI compounds would provide the vital bridge between truly biological PET tracers based on nC/18F labeled compounds and the much more easily accessible SPECT tracers based on "Tcm and inIn products, thereby rendering a transition from PET to SPECT, that is from medical research to clinical utility, a reality. products would provide a fine complement to "Tcm compounds, especially for imaging process(es) involving slower kinetics of tracer and in the cases where conjugation of In-BCA with the bio-active substrate causes less alterations of the biological activity. Though the question "After 99Tcm, what next?" is posed time and again,

the well-known attractive advantages of 99Tcm are not likely to be matched by any other tracer in the foreseeable future and consequently the impetus to develop 99Tcra based radiopharmaceuticals will continue. It could be safely predicted that the future of radiopharmaceuticals and in turn, clinical nuclear medicine, will continue to be dominated by "Tcm products, as has been the case in the past.
