Low tryptophan uptake in contrast-enhancing lesions predicts long-term survival in patients with a previously treated glioblastoma: A pet study

WCN 2013 No: 868 Topic: 36 — Other topic Low tryptophan uptake in contrast-enhancing lesions predicts long-term survival in patients with a previously treated glioblastoma: A pet study C. Juhasz, D.O. Kamson, N.L. Robinette, O. Muzik, P.K. Chakraborty, G.R. Barger, S. Mittal. Neurology and Pediatrics, Wayne State University, USA; PET Center and Translational Imaging Laboratory, Children's Hospital ofMichigan, USA; Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA; Radiology, Wayne State University, Detroit, MI, USA; Neurology,Wayne State University, Detroit, MI, USA; Neurosurgery, Wayne State University, Detroit, MI, USA Background: MRI has limited prognostic value in patients with a previously treated glioblastoma. Positron emission tomography (PET) imaging with alpha[C]methyl-L-tryptophan (AMT), a radiotracer tracking tryptophan transport and metabolism via the immunosuppressive kynurenine pathway, can effectively differentiate glioma recurrence from radiation injury. Objective: To evaluate the prognostic value of AMT uptake measured on post-treatment PET in patients with glioblastoma treated with surgery followed by chemoradiation. Patients and methods: AMT-PET was performed in 32 patients (mean age: 60 years) with a previously treated glioblastoma. The PET scans were done 6–62 months after initial surgery after MRI demonstrated a contrast-enhancing lesion suspicious for tumor progression. AMT uptake values were measured (on summed activity images 30–55 min after tracer injection) in contrast-enhancing regions and contralateral cortex, and correlated with survival after PET. A receiver operating characteristic analysis was performed to determine the optimal cutoff threshold to predict 1-year survival. Results: At the end of follow-up, 23 patients were deceased and 9 alive (for up to 83 months). A cutoff threshold of 1.65 for lesion/cortex AMT uptake ratios provided 82% sensitivity/specificity for 1-year survival after PET. Age-corrected Cox regression analysis showed a strong association between above-threshold AMT uptake ratios and shorter survival (odds-ratio: 4.3 [1.5–12.5], p = 0.005). Below-threshold AMT uptake ratios (n = 13) were associated with an additional year median survival compared to patients with high ratios (618 days vs. 257 days). Conclusion: Low AMT uptake on PET, measured in contrast-enhancing lesions suspicious for tumor progression, predicts long-term survival in patients with a previously treated glioblastoma. doi:10.1016/j.jns.2013.07.2139 Abstract — WCN 2013 No: 1131 Topic: 36 — Other topic Sleep curtailment is associated with altered autonomic tonus in normal-weight individuals W. Moraes, D. Poyares, L. Bittencourt, S. Tufik. Sleep Medicine, Universidade de Sao Paulo, Brazil; Psychobiology, UNIFESP,