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) showed radiation changes in their biopsy specimens (85.7%); they had an 85.7% 1-year survival rate. Group II (Tl-201 ratio between 2 and 3.5) had predominantly infiltrating tumor (78.6%); they had a 42% 1-year survival rate. Almost all of the patients in Group III (Tl-201 ratio greater than 3.5) had solid tumor (93.3%) and they had a 6.7% 1-year survival. Survival and pathological data differed significantly among groups (p less than 0.009).
Dual-isotope SPECT data correlates with histological findings on reoperation and postoperative survival in patients with malignant gliomas.