Diagnostic Accuracy of Dual-Time-Point Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography in Verification Local Recurrence in Pancreatic Cancer Patients

PURPOSE: The aim of this study was to evaluate the accuracy of dual-time point in differentiating benign from malignant local recurrent lesions in pancreatic cancer. PATIENTS AND METHODS: Thirty-four patients with pancreatic cancer (22 males and 12 females, mean age: 58.3 ± 10.3) who presented with soft-tissue lesions at the operative bed. Early whole-body positron emission tomography/computed tomography (PET/CT) and delayed imaging on the abdomen were performed. The maximum standardized uptake value (SUVmax) of the initial image (SUVmax E) and the delayed image (SUVmax D) were determined. A Retention Index (RI) was also calculated. These indices were correlated with histopathology and follow-up as reference criteria. RESULTS: No significant statistical difference in SUVmaxE was found between benign and malignant lesions, while SUVmaxD and RI of the malignant lesions (mean 8.6 ± 2.7 and 35.8 ± 18.3, respectively) were significantly higher than those of benign ones (mean 3.3 ± 1.4 and-6.2 ± 15.2, respectively) (P < 0.005). With SUVmaxD 4.9, malignancy could be predicted with the highest sensitivity (95.8%) and accuracy (94.1%) between the whole parameters. The estimated negative and positive predictive values (PPVs) were 90.0% and 95.8%, respectively. A cutoff point 16 for RI showed higher specificity and PPV (100% and 100%, respectively). Forty-seven total (11 benign and 36 malignant) lesions were identified. Increased SUVmax is noted on delayed images in most of malignant lesions, except for two that maintained stationary. CONCLUSION: Dual-time-point 18F fluorodeoxyglucose-PET/CT seems to be a reliable additional method to differentiate between malignant and benign postoperative local soft-tissue lesions in patients with pancreatic cancer.