Interpretation of 99 mTc-pertechnetate scintigraphy after irradiation of brain tumours

Abstract

99 m Tc-pertechnetate scintigraphy was performed on 31 patients with cerebral tumours both before and after radiotherapy. As a complementary examination 75Se-sodium selenite scintigraphy was performed in 25 of these cases. After radiation therapy the 99 m Tc accumulation increased or remained unchanged in 81 per cent and diminished in 19 per cent of the cases. In 9 of the 18 patients scanned three months after irradiation the 99mTc uptake was still as large as in the previous examination. In the 9 cases the uptake had diminished. After 6 months, 7 of the 14 patients examined still showed some accumulation. After 12 months, 6 of the 13 scanned cases showed accumulation but no signs or symptoms of recurrent brain tumour. 99mTc pertechnetate scintigraphy seems unreliable after radiotherapy in diagnosing brain tumour recurrences. In 76 per cent of the cases the 75Se-sodium selenite accumulation disappeared immediately after irradiation. After three months only one case showed any sign of uptake.