DUAL-ISOTOPE SINGLE-PROTON EMISSION COMPUTERIZED-TOMOGRAPHY SCANNING IN PATIENTS WITH GLIOBLASTOMA-MULTIFORME - ASSOCIATION WITH PATIENT SURVIVAL AND HISTOPATHOLOGICAL CHARACTERISTICS OF TUMOR AFTER HIGH-DOSE RADIOTHERAPY

Object. The study was conducted to determine the association between d ual-isotope single-photon emission computerized tomography (SPECT) sca nning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multi forme. Methods. Studies in which SPECT with Tl-201 and Tc-99m-hexameth ypropyleneamine oxime (HMPAO) were used were performed 1 day before re operation in 47 patients with glioblastoma multiforme who had previous ly been treated by surgery and high-dose radiotherapy. Maximum uptake of Tl-201 in the lesion was expressed as a ratio to that in the contra lateral scalp, and uptake of Tc-99m-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups ba sed on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological character istics of tissue at reoperation, and SPECT uptake group with respect t o 1-year survival was elucidated by using the chi-square statistic. Co mparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year w ere presented according to the Kaplan-Meier method, and the significan ce of potential differences was evaluated using the log-rank method. T he effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox propor tional models that controlled for age and gender. All patients in Grou p I (Tl-201 ratio < 2 and Tc-99m-HMPAO ratio < 0.5) showed radiation c hanges in their biopsy specimens: they had an 83.3% 1-year survival ra te. Group II patients (Tl-201 ratio < 2 and Tc-99m-HMPaO ratio of grea ter than or equal to 0.5 or Tl-201 ratio between 2 and 3.5 regardless of Tc-99m-HMPAO ratio) had predominantly infiltrating tumor (66.6%); t hey had a 29.2% 1-year survival rate. Almost all of the patients in Gr oup III (Tl-201 ratio > 3.5 and Tc-99m-HMPAO ratio greater than or equ al to 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.0 1); however, SPECT grouping was more closely associated with 1-year su rvival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). Conclusions. Dual-isotope SPECT d ata correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and hi gh-dose radiation therapy.