Is Positron Emission Tomography Using 18 F-Fluorodeoxyglucose and 11 C-Acetate Valuable in Diagnosing Indeterminate Pancreatic Masses?

Abstract

Background:

It can be impossible to differentiate a mass forming chronic pancreatitis from adenocarcinoma of the pancreas using standard anatomical imaging. Positron emission tomography using 2-[¹⁸F] fluoro-2deoxy-D-glucose (¹⁸FDG-PET) and 1-[¹¹C]-acetate (¹¹C-acetate-PET) are methods taking advantage of the metabolic differences between benign and malignant tissues.

Aims:

To determine the diagnostic accuracy of ¹⁸FDG-PET and ¹¹C-acetate-PET in indeterminate pancreatic masses.

Methods:

Twenty patients with an indeterminate mass of the head of the pancreas were prospectively studied. All patients underwent ¹⁸FDG-PET and eighteen of them ¹¹C-acetate-PET. Scans were evaluated qualitatively and quantitatively; the later by using regional standardised uptake value (SUV). Final diagnosis was established using histopathologic evaluation of resected specimen or biopsy.

Results:

Adenocarcinoma was diagnosed in twelve patients and chronic pancreatitis in eight. Qualitative evaluation of ¹⁸FDG-PET imaging revealed three false negative and one false-positive results. The sensitivity, specificity, and diagnostic accuracy were 75 %, 88 %, and 80 %, respectively. The cut-off SUV to differentiate malignant from benign disease was 3,5 demonstrating a sensitivity of 91.7 % and a specificity of 75 %.

Conclusion:

¹⁸FDG-PET imaging could not confirm or exclude malignancy in indeterminate masses of the head of the pancreas with high sensitivity and diagnostic accuracy. ¹¹C-acetate-PET provided no additional diagnostic benefits.