Objective: This study aimed to evaluate the role of ascites metabolism measurement in (18)F-fluorodeoxyglucose ((18)F-FDG) PET/computed tomography (CT) for auxiliary diagnosis and prognostic evaluation of malignant ascites.
Materials and methods: This was a retrospective study on 55 patients, including 36 with malignant ascites and 19 with benign ascites of undetermined origin, before they underwent their first (18)F-FDG PET/CT scan. The χ(2) -test was used to compare the diagnostic efficiencies among (18)F-FDG PET/CT ascites metabolism measurement, tumor localization, and ascites cytology examination. The standard uptake values of ascites and of the normal liver were measured, respectively, and their ratio, denoted as T/NT, was calculated for each patient. The receiver-operating characteristic curve was used to analyze the diagnostic efficiency of the ascites T/NT, ascites carcinoembryonic antigen, ascites CA1(25), and ascites CA(199), and the linear regression was used to analyze the relationship between the ascites T/NT and the survival time of patients.
Results: The metabolic level of malignant ascites was high. The sensitivity and accuracy of ascites metabolism measurement were higher than those of ascites cytology examination (χ(2) =6.98, 4.58; all P's<0.05). The specificity of ascites metabolism measurement was higher than that of (18)F-FDG PET/CT tumor localization (χ(2) =5.70, P<0.05). The T/NT value of malignant ascites (0.68 ± 0.17) was higher than that of benign ascites (0.38 ± 0.10) (t=7.21, P<0.05). The area under the receiver-operating characteristic curve of ascites T/NT was larger than those of ascites carcinoembryonic antigen, CA(125), and CA(199). There was a negative correlation between the ascites T/NT and the survival of patients with malignant ascites (r=-0.647, P<0.01).
Conclusion: Ascites metabolism measurement has an important auxiliary diagnostic value in (18)F-FDG PET/CT for ascites patients. The ascites T/NT may be a good index for prognostic evaluation of malignant ascites.