211 Visualization of soft tissue sarcomas (STS) and melanoma and quantitation of the protein synthesis rate with L-1-[C-11]-tyrosine positron emission tomography (PET)

Abstract

<h3>Introduction</h3> Malignant tumor cells have an increased proliferation rate and increased demand for amino acids. This physiochemical phenomenon can be visualized by PET. The potential of L-l-[C-11]tyrosine (TYR) to visualize STS or melanoma and quantify the protein synthesis rate (PSR) was investigated <h3>Methods</h3> 12 patients (pts) with a tumor were studied, mean age 50 (range 24–74) yrs received 296±92 MBq TYR IV. All pts were studied in a dynamic mode, images were corrected for attenuation with a transmission scan. Arterial blood samples were taken for measurement of the tyrosine input function, and the assessment of tyrosine metabolites ([C-11]CO₂, [C-11]) proteins. Region of interest was placed over the tumor and PSR of the tumor was calculated with the use of computer analysis (Patlak). Histology was obtained after PET. <h3>Results</h3> All malignant and benign lesions were correctly identified with TYR-PET. The malignant lesions depicted as a hot spot, the benign lesions as a cold spot. The mean PSR's (nmol/ml/min) and Tumor-to-Muscle ratio (TM ratio) are statistically significant between malignant and benign lesions (P=0.03). <h3>Condusion</h3> TYR is applicable for the visualization of STS and melanoma, PSR may allow future use in the evaluation of chemotherapy or radiotherapy.