Thallium-201 SPECT in Brain Gliomas

OBJECTIVE: To compare various published thallium-201 uptake indexes in the differential diagnosis in recurrent brain gliomas. MATERIAL AND METHODS: Thallium-201 SPECT studies were performed in 79 patients previously treated for glial tumor with clinical or radiologic suspicion of recurrence. Regions of interest were established in the tumor area and in other sites with normal uptake. RESULTS: A high linear correlation was found among indices, with significant differences between all index pairs. Logistic regression analysis confirmed high colinearity among indexes, with index 3 (mean counts in tumor/mean counts in contralateral hemisphere) showing a slightly superior predictive power to differentiate tumor absence from tumor presence and tumor absence from low-grade recurrence. These findings were supported by analysis of areas under the ROC curve. CONCLUSIONS: The uptake indices studied behave similarly in the evaluation of a possible recurrence of a glial brain lesion and should be considered complementary to visual evaluation as a semi-objective tool.