The results revealed that high IDO activity could be identified by [11C]AMT.331 In 2012, Juhász et al. performed a dynamic PET/CT scan with [11C]AMT in nine women with BC (stages II-IV); the results revealed that IDO-positive BC (stages II-IV) exhibited rapid [11C]AMT uptake within 20 min post-injection.332 In 2016, Xin et al. synthesized two radiopharmaceuticals, namely 1-L-[18F]FETrp and 1-D-[18F]FETrp, for evaluating tryptophan metabolism mediated by the IDO-KP in tumours. This evidence concerns the gene IDO1 and breast cancer.