PET with 1-[1-carbon-11]-tyrosine to visualize tumors and measure protein synthesis rates

We studied the potential of PET with L-[1-C-11]-tyrosine (TYR) to visualize tumors outside the central nervous system and to quantify their protein synthesis rates (PSRs). Methods: Twenty-two patients suspected of having a malignant tumor underwent a PET study with TYR before biopsy, The PSR in nanomoles per milliliter tumor tissue per minute as well as the PSR in contralateral normal tissue, standardized uptake values (SUVs) and tumor-to-nontumor-ratios (T/N ratios) were calculated. Results: Fifteen of the 16 malignancies (94%) were correctly visualized as a hot spot. A chondrosarcoma of the sacrum was not visualized. Of the six patients with benign lesions, cold spots were correctly identified in four (67%), A benign schwannoma and an intramuscular hemangioma of the forearm were visualized as hot spots. PSR in tumor tissue was higher than in the corresponding contralateral normal tissues. PSR and SUV in malignant tumors were higher than in benign tumors. Conclusion: TYR appears to be a good tracer for imaging malignancies. The PSR, which was higher in malignant tumors than in normal tissue and the studied benign lesions, could be quantified and correlated with the SUV.