¹⁸F-FDG-PET/CT findings in pancreatic metastasis

This study aimed to evaluate the fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) findings and pattern of FDG uptake in pancreatic metastases.

A total of 19 consecutive patients (26 lesions) with histologically or clinically confirmed pancreatic metastases who had undergone ¹⁸F-FDG-PET/CT were enrolled in this retrospective study. Among the 19 patients, 14 patients underwent abdominal contrast-enhanced CT (ceCT). The location, size and FDG uptake patterns of the pancreatic lesions were recorded. Metabolic activity by means of maximum standardised uptake value (SUV_max) was measured by drawing regions of interest at the site of pancreatic lesions. Twenty pancreatic cancer patients were included in this study as comparative data analysis. The difference of SUV_max between pancreatic metastases and primary pancreatic cancer were compared using the Mann–Whitney U test. P < 0.05 was considered significant.

Three different patterns of FDG uptake could be distinguished in the pancreatic metastatic lesions, including focal nodule or mass, multiple foci and segmental lesion with high FDG uptake. The average SUV_max in pancreatic metastases was 7.8 ± 6.9 versus 7.4 ± 3.9 in primary pancreatic cancer (P = 0.987 > 0.05). Four intrapancreatic isodense nodules in three patients were undetected on ceCT.

The described patterns of FDG uptake findings may be helpful for a better characterisation of pancreatic metastases although semiquantitative analysis using SUV_max could not be used as a criterion for differentiating pancreatic metastases from primary pancreatic cancer. FDG-PET/CT has also an advantage in detecting unsuspected pancreatic metastases which cannot be detected by ceCT imaging. Thus, it is a useful adjunct to the described features on CT.