Quantitative PET imaging of tryptophan accumulation in gliomas and remote cortex: Correlation with tumor proliferative activity

PURPOSE Positron emission tomography (PET) studies with α[C-11]methyl-L-tryptophan (AMT) have shown decreased serotonin synthesis based on a decrease of the unidirectional uptake rate (K-complex) in neuropsychiatric conditions such as autism and depression. Increased A M T K-complex in tumors can indicate increased tryptophan metabolism via the immunosuppressive kynurenine pathway. Moreover, apparent AMT volume of distribution (VD’) reflects net tryptophan transport from blood to tissue. We evaluated if kinetic parameters (K-complex, VD’) of AMT, measured by PET, can predict glioma proliferative activity, and if these AMT parameters are altered in remote cortex.