FDG PET/CT findings of solid pseudopapillary tumor of the pancreas with CT and MRI correlation.

PURPOSE

The aim of this study was to evaluate retrospectively (18)F-FDG PET/CT findings of solid pseudopapillary tumor of the pancreas (SPTP).

PATIENTS AND METHODS

FDG PET/CT findings were reviewed in 8 patients with SPTP confirmed by pathology. Early PET/CT scans were performed 1 hour after FDG injection in all 8 patients. After an interval of 1 hour, delayed PET/CT scans were performed in 6 patients. All patients underwent enhanced CT and 4 patients underwent MRI.

RESULTS

A total of 8 tumors were detected in all 8 patients. CT and MRI findings included encapsulation (n = 2), solid and cystic components (n = 4), focal calcification (n = 7), and weak enhancement during the arterial phase on enhanced CT or MRI and increasing enhancement during the portal venous phase (n = 8). All the tumors showed increased FDG uptake. The mean SUVmax of all tumors was 8.9, with a high variability of SUVmax among lesions ranging from 2.5 to 29.1. The tumors (n = 6) with high cellularity had stronger FDG uptake, whereas the tumors (n = 2) with low cellularity had relatively low FDG uptake. The tumors (n = 6) with pancreatic parenchymal, vascular, or perineural invasions had intense FDG uptake, whereas the tumors (n = 2) without invasions had slight-to-moderate FDG uptake. Two tumors with relatively high proliferative index had very strong FDG uptake, whereas those (n = 6) with low proliferative index or negative Ki-67 staining result had relatively lower FDG uptake. On delayed FDG PET/CT images, The SUVmax of SPTP increased in 4 patients and slightly decreased in 2 patients.

CONCLUSIONS

CT or MRI demonstrated morphological features of SPTP and FDG PET/CT that reflected the histopathological composition of the tumors. FDG uptake of SPTP may be related to tumor cellularity, proliferative index, or histological malignancy. Familiarity with the morphological and functional imaging findings of SPTP may be helpful for correct diagnosis and appropriate treatment.