[Clinical usefulness of thallium-201 chloride in the diagnosis of tumors (I)--Evaluation in brain tumors].

Forty-eight patients with suspected brain tumor were studied to evaluate the clinical efficacy of Thallium-201 (201Tl) SPECT. 201Tl scintigrams showed abnormal accumulation in 24/26 (92.3%) and 9/14 (64.3%) of patients with malignant and benign tumors, respectively. 201Tl tended to be retained more prominently in malignant brain tumors than in benign ones. The lesion-to-normal ratios (L/N ratios) of 201Tl demonstrated significant correlation with those of 18F-FDG (n = 5, r = 0.90, p = 0.044). L/N ratios were higher in patients with recurrent tumors than those with necrotic lesions (3.33 +/- 0.81 and 1.73 +/- 0.81, respectively, p = 0.0123). The positive predictive value of L/N ratios > or = 2.5 for diagnosing as recurrence and L/N ratios < 2.5 as necrosis were 83.3% and 100%, respectively. These results suggest that 201Tl scintigraphy may be useful to determine the malignancy of brain tumors and to differentiate recurrence from necrosis after therapeutic procedures.