Pancreatic neuroendocrine neoplasm: correlation between computed tomography enhancement patterns and prognostic factors of surgical and endoscopic ultrasound-guided fine-needle aspiration biopsy specimens.

PURPOSE

To retrospectively determine whether enhancement patterns in the pancreatic and equilibrium phases of computed tomography (CT) for pancreatic neuroendocrine neoplasms are related to prognostic factors of surgical and endoscopic ultrasound-guided fine-needle aspiration biopsy specimens.

METHODS

Twenty-five pancreatic neuroendocrine neoplasms in 22 patients underwent preoperative dynamic CT. Tumors were classified into two groups by enhancement patterns on preoperative CT. A washout pattern was defined as peak enhancement in the pancreatic phase with washout of at least 60 Hounsfield units in the equilibrium phase. Group 1 comprised tumors showing a washout pattern in more than half of tumor and Group 2 comprised tumors showing a washout pattern in less than half of the tumor. The Ki-67 index and the presence of vascular invasion were evaluated in surgical specimens. The Ki-67 index from biopsy specimens was compared with that from surgical specimens.

RESULTS

There were 12 surgical specimens in Group 1 and 13 in Group 2. Group 2 showed significant correlations with larger Ki-67 indices (p < 0.05) and positive vascular invasion (p < 0.05). The Ki-67 index discrepancy between biopsy and surgical specimens of Group 2 was significantly greater than that of Group 1 (p < 0.05).

CONCLUSIONS

Pancreatic neuroendocrine neoplasms in which less than half of the tumor showed a washout pattern were correlated with poor prognostic factors. Analysis of enhancement patterns may provide predictive information about whether endoscopic ultrasound-guided fine-needle aspiration biopsy is reliable for the assessment of Ki-67 index.