Prediction of survival in patients with suspected recurrent cerebral tumors by quantitative thallium-201 single photon emission computed tomography.

Abstract

To assess whether quantitative 201Tl single photon emission computed tomography (SPECT) can be used as a prognostic test in patients with suspected recurrent cerebral tumor, regardless of various combined therapies given. The study population consisted of 22 patients with grade 4, 3, or 2 glioma and 7 patients with solitary cerebral metastasis. All patients had undergone combined radiotherapy and chemotherapy after or during surgical debulking. Each patient underwent 201Tl brain SPECT to differentiate recurrent tumor from cerebral radiation necrosis, because the prior computed tomography and/or magnetic resonance imaging showed a mass lesion with an irregularly enhanced rim in the irradiation field. Higher values of 201Tl index (L/N ratio) showed a tendency for shorter survival (r = -0.502, p < 0.05). In patients with grade 3 glioma or solitary cerebral metastasis, survival time was definitely dependent upon 201Tl index values, that is, above or below the baseline index of 2.5. Grade 4 glioma patients, however, had a very short-term survival independent of 201Tl index values. Quantitative 201Tl SPECT may be a useful tool for predicting survival of patients with suspected recurrent cerebral tumor and may be used in place of fluorine-18-2-deoxy-2-fluoro-D-glucose (18F-FDG) scan.