Correlation between postoperative 3-[I-123]iodo-L-alpha-methyltyrosine uptake and survival in patients with gliomas

The aim of this study was to evaluate the prognostic value of SPELT imaging using the amino acid analog 3-[I-123]iodo-L-alpha -methyltyrosine (IMT) in patients with gliomas. Methods: One hundred fourteen consecutive patients with newly diagnosed gliomas were examined by IMT SPELT (low-grade glioma, n = 12; anaplastic astrocytoma or oligodendroglioma, n = 46; glioblastoma, n = 56). Seventy-one of these patients had undergone tumor resection 4-6 wk before SPELT imaging (group A). Forty-three patients with unresectable tum ors were examined after stereotactic biopsy (group B). IMT uptake at the si te of the tumor was assessed visually and quantified relative to a contrala teral reference region (IMT uptake ratio). After IMT SPELT, all patients we re treated with conformal radiotherapy. The median follow-up time was 27 mo . Results: In group A, focal IMT uptake at the resection site was visible i n 52 of 71 patients (73%). Median survival was only 13 mo in these patients , whereas median survival was reached in patients without focal IMT uptake (P = 0.02). Furthermore, the intensity of IMT uptake significantly correlat ed with survival: patients with an IMT uptake ratio >1.7 were at a 4.6 time s higher risk of death than were patients with a lower IMT uptake (P<0.001) . The IMT uptake ratio remained a significant prognostic factor when age an d grading were included in a multivariate model. In contrast, IMT uptake di d not correlate with survival in group B (P = 0.95). Conclusion: In patient s with unresectable high-grade gliomas, IMT uptake appears not to correlate with the biologic aggressiveness of tumor cells. Nevertheless, the clear a ssociation between focal IMT uptake after tumor resection and poor survival suggests that IMT is a specific marker for residual tumor tissue. Therefor e, IMT SPELT is expected to become a valuable tool for the planning and mon itoring of local therapeutic modalities.