CORRELATION BETWEEN GADOLINIUM-DIETHYLENE-TRIAMINEPENTAACETIC ACID CONTRAST ENHANCEMENT AND TL-201 CHLORIDE UPTAKE IN PEDIATRIC BRAIN-STEM GLIOMA

We previously showed that thallium-201 (Tl-201) chloride is accumulate d in over 75% of brain tumors, including brainstem gliomas. The imagin g of Tl-201 with Single photon emission computed tomography (SPECT) ma y require an abnormal increase in permeability of tumor vessels to all ow penetration of the blood-brain barrier. To test this hypothesis, we evaluated the correlation between gadolinium enhancement and the degr ee of Tl-201 uptake on SPECT and the contributions of either gadoliniu m enhancement or Tl-201 uptake to the prognosis in children with brain stem gliomas. Forty-two sets of paired SPECT scans and magnetic resona nce imaging (MRI) scans were obtained longitudinally in 13 cases. Alto gether, 31 of 42 pairs (74%) of scans showed concordance between the p resence of gadolinium enhancement and Tl-201 uptake. There were no cas es that demonstrated Tl-201 uptake but lacked gadolinium enhancement. The results indicate that Tl-201 SPECT is Of value primarily when brai nstem tumors have vessels that are demonstrably permeable to gadoliniu m, prior to or as a result of radiotherapy.