Tl-201 SPECT Compared with Histopathologic Grade in the Prognostic Assessment of Cerebral Gliomas

Abstract

Purpose Although Tl-201 SPECT has been used to evaluate the malignant grade of cerebral gliomas, the gold standard continues to be histopathologic examination. The authors assessed and compared the prognostic abilities of the two studies using survival analysis. Materials and Methods Twenty-nine patients underwent 34 sessions of Tl-201 SPECT plus surgery for primary or recurrent cerebral gliomas 12 to 78 months before this analysis. Using conventional survival analyses, such as the log-rank test, Cox regression, and the Akaike cross-tab method, the authors evaluated the prognostic significance of 10 variables: histopathologic grade, Tl-201 SPECT, Tc-99m HMPAO SPECT, tumor cell viability, radionecrosis, neurologic defects, clinical improvement, surgery, chemotherapy, and external beam radiotherapy. Results Tl-201 SPECT was most strongly related to prognosis, followed by histopathologic grade. The other variables had little prognostic value. The Cox stepwise selection procedure indicated that Tl-201 SPECT was the only independent predictor of outcome, whereas histopathologic analysis was eliminated from the prognostic model. However, the Kaplan-Meier survival curve and the Akaike method indicated that histopathologically low-grade tumors were more closely associated with longer-term survival than were Tl-201 low uptake tumors. Conclusions Tl-201 SPECT is not only closely correlated with the histopathologic grade of tumor but is a significantly better predictor of outcome than histopathologic grade. However, histopathologic examination may provide additional information on longer-term survival. Tl-201 SPECT is a valuable procedure, especially in patients in whom a histologic diagnosis of possible glioma cannot be made.