The biological behaviour of technetium complexes with particular reference to brain tumours

Ionic radionuclide complexes and in particular technetium compounds have long been the reagents of choice for the detection of brain tumours. Despite their lack of tumour specificity detection rates in the region of 80% can be routinely achieved. The most widely-used reagent to date has been sodium pertechnetate but recently a number of other technetium complexes such as DTPA, citrate and glucoheptonate with a more rapid blood clearance and better tumour to blood ratios than pertechnetate have been proposed as alternatives. All of these reagents are anionic complexes of reduced technetium which do not bind to any extent to plasma proteins or to enzymes. They do, however, satisfy the requirements of the ionic model proposed by Van der Pompe which has been outlined in the previous chapter. In the study reported here a number of technetium complexes, citrate, glucoheptonate and n-acetyl cysteine have been compared with pertechnetate with regard to their uptake in a transplantable rhabdomyosarcoma in the rat. The results obtained have then been used to provide a possible explanation for observed differences in clinical performance between these reagents. (Auth.)