Quantitative Analysis of ¹¹C-acetate in Nasopharyngeal Carcinoma with Positron Emission Tomography

Although several kinetic models have been proposed for myocardium ¹¹C-acetate PET quantitative studies, currently there are no reports applying them to tumor diagnosis. In this study, we adopted one of the existing models for performing quantitative analysis on nasopharynx carcinoma (NPC) patients. Ten patients were included, with five NPC and five control subjects. For each subject, one ROI of nasopharynx area and one ROI of muscle area were drawn on PET images. Four rate constants were then estimated using the non-linear least squares method. The extraction fraction K was calculated from these estimated parameters. We found K showed significant difference in the two groups, while the average K of nasopharynx areas was 0.2675 ± 0.1562 in NPC and 0.0763 ± 0.0425 in control patients. In addition, a higher ¹¹C-acetate inflow rate constant from plasma was observed in the NPC nasopharynx area, while the clearance rate was lower. Meanwhile, the rate constants of muscle area in the two groups showed no significant difference. These results indicate that, for tumors, those estimated parameters will be significantly different due to the characteristics of ¹¹C-acetate uptake. In conclusion, our results proved the portability of applying kinetic model analysis in ¹¹C-acetate tumor studies. Such an analysis can provide physicians with objective reference for clinical diagnosis.