V. Brain Tumour Detection using Radioactive Arsenic

Although brain tumours can often be fairly accurately localised, the conventional procedures which are used, such as arteriography and air studies, are not entirely devoid of risk. Therefore an additional technique which is simple and which does not involve such risks can very often be of value. We wish to report on one of the latest radioisotope techniques, one which employs radioactive arsenic. Sweet, Mealey, Brownell and Aronow (1959) at Boston, have examined over 3,000 patients using an earlier version of this technique, and have reported very good results. Our modification of the technique consists in using arsenic 72, which emits more positrons per disintegration than arsenic 74, and in using colour scintiscanning instead of black and white scanning to enhance the contrast. The rationale is that certain chemical substances, in particular phosphorus, potassium, arsenic, and some other chemicals, including rubidium, gallium, copper versenate, and some dyes or proteins which can be labelled with 131I, or 203Hg, occur in higher concentration in brain tumours than in normal brain tissue. Figure 1 shows the relative uptake of 74As in four types of brain tumour as determined at autopsy by Mealey, Brownell and Sweet (1959) in more than 100 patients. Each of the four sections of this figure shows specimen uptake within two days after injection of the isotope. We are most concerned with uptake in the first few hours, i.e. the points close to the left-hand margin of each of the four diagrams.