[18 F-fluorodeoxyglucose positron emission tomography for characterization and initial staging of pancreatic tumors]

Abstract

Aim: To evaluate positron emission tomography (PET) with (18)F-fluorodeoxyglucose (FDG) for characterizing and initial staging of pancreatic tumors and to determine its impact on therapeutic strategy.

Patients and methods: This study included 24 patients with pancreatic tumor who underwent PET before treatment. Twenty-two patients had a malignant tumor and two had a benign tumor. The PET scan was performed after intravenous injection of FDG with a gamma camera. PET findings were compared with histology of the pancreatic tumor (n=24), liver metastases (n=5), peritoneal metastases (n=5), and lymph node metastases (n=5). Absence of metastasis or lymph node involvement was determined by surgery or by CT scan, ultrasonography, magnetic resonance imaging and at least two months follow-up.

Results: The sensitivity of the PET scans to identify pancreatic carcinoma was 64% (95% confidence interval 44-84%). PET scans could not be interpreted for lymph node involvement adjacent to the tumor. For liver metastases, the PET scan was positive in 3 out of 5 patients. For peritoneal metastases, the PET scan was positive in 4 out of 5 patients but was doubtful in one. There were two false positives. Among the 4 cystic tumors, the PET scan was positive for 2 malignant tumors and negative for 2 benign tumors. Surgical strategy was modified in only one of the 24 patients on the basis of PET findings.

Conclusion: The sensitivity of PET for the diagnosis of primary malignant pancreatic tumor was found to be low. The contribution of FDG-PET to the surgical decision appears to be limited to the detection of metastases or lymph node involvement distant from the tumor, contraindicating surgery. Nevertheless, the sensitivity of FDG-PET is lower than that of laparoscopy for peritoneal metastases. Indications for PET should be included in an evaluation of therapeutic decision making and cost analysis.