Dual isotope single-photon emission computerized tomography used for prediction of histology and survival in patients after high-dose radiotherapy for malignant astrocytoma

This study was conducted to determine the sensitivity of dual-isotope single-photon emission computerized tomography (SPECT) in predicting tumor recurrence and survival in patients treated with high-dose radiotherapy for malignant gliomas. Studies using SPECT with thallium-201 (Tl-201) and technetium-99m (Tc-99m) hexamethypropyleneamine oxime (HMPAO) in 50 consecutive patients with malignant astrocytomas treated by surgery and high-dose radiotherapy were performed 1 day before reoperation. Maximum uptake of Tl-201 in the lesion was expressed as a ratio to that of the contralateral scalp, and uptake of Tc-99m HMPAO was expressed as a ratio to that of the cerebellar cortex. Patients were stratified into groups based on maximum radioisotope uptake values in their tumor beds. Differences in tumor histopathology at reoperation and 1-year survival between SPECT groups were determined by using chi-square analysis. The majority of patients in Group IA (Tl-201 ratio less than 2 or Tc-99m HMPAO ratio less than 0.5)...