Diagnostic performance of ¹⁸F-FDG PET/CT, contrast enhanced CT and MRI in cystic pancreatic tumors

Objectives The diagnostic accuracy of combined ¹⁸F-FDG PET/CT with contrast enhanced CT (ceCT) was prospectively compared to ceCT and magnetic resonance imaging (MRI) with MR cholangiopancreatography in differentiating malignant and benign pancreatic cysts.

Methods Altogether 31 patients with pancreatic cysts were studied. Study protocol included FDG PET/CT, ceCT and MRI combined with magnetic resonance cholangiopancreatography (MRCP). All modalities were evaluated by experienced specialists who were blinded to the clinical history and previous imaging studies. The imaging results were compared to macroscopical findings at operation and/or histopathological analysis (n=22) or follow-up (n=9).

Results 6/31 patients had malignant and 25/31 benign findings. FDG PET/CT differentiated accurately all malignant cystic lesions and was false positive only in two cases. The sensitivity values were 100% , 83% and 83% and specificity values were 92%, 76% and 88% for FDG PET/CT, ceCT and MRI, respectively. The negative predictive value for FDG-PET/CT in differential diagnosis of benign and malignant pancreatic cystic lesion was 100% and PPV was 75%. The diagnostic accuracy was 94%, 77% (p<0.05) and 87% for ¹⁸F-FDG PET/CT, ceCT and MRI, respectively.

Conclusions FDG PET/CT with ceCT was most accurate method to differentiate benign and malignant pancreatic cysts and it had an impact on clinical decision making. These findings highlights the important complementary role of FDG PET/CT in the evaluation of cystic pancreatic lesions. The use of FDG PET/CT is recommended especially in diagnostically challenging cases.