Cross-modality image fusion of FDG PET and contrast-enhanced CT for the diagnoses of pancreatic lesions and staging of pancreatic cancer

Abstract

Objective To explore the value of the cross-modality fusion images provided by PET/CT and contrast-enhanced CT (CECT) in differentiating malignant from benign pancreatic lesions and evaluating staging for pancreatic cancer.Methods Data from 70 patients with pancreatic lesions who had undergone CECT and PET/CT examinations in our hospital from September 2010 to October 2013 were analyzed.Of these 70 patients,45 were males and 25 females; the median age was 57 years old.Fifty patients had malignant lesions,and 20 patients had benign lesions.Cross-modality image fusion (PET/CECT) was obtained using Multimodality Workplace Ture D software (Siemens Ltd).The pathological and imaging follow-up were used as gold standard,then the value of PET/CT,CECT and PET/CECT in differentiating malignant from benign pancreatic lesions and evaluating staging for pancreatic cancer was determined.Results The sensitivity,specificity,positive predictive value (PPV),negative predictive value (NPV),accuracy and Kappa value of CECT,PET/CT and PET/CECT the 3 methods in differentiating benign from malignant pancreatic lesions were 82.0％,65.0％,85.4％,59.1％,77.1％ and 0.465; 92.0％,65.0％,86.8％,76.5％,84.2％ and 0.597 ; 96.0％,90.0％,96.0％,90.0％,94.3％ and 0.860,and the difference of sensitivity,NPV,and accuracy between CECT and PET/CECT was statistically significant (P ＜ 0.05).In 15 of 31 patients who were confirmed to have malignant tumor after surgery,peripancreatic vessel invasion was verified.The sensitivity,specificity,PPV,NPV,accuracy of the 3 methods in diagnosing peripancreatic vessel invasion were 93.3％,93.7％,93.3％,93.8％,and 93.5％; 26.7％,75％,50.0％,52.2％ and 51.6％; 93.3％,93.7％,93.3％,93.8％ and 93.5％,and the difference of sensitivity,NPV,and accuracy between CECT and PET/CECT was statistically significant (P＜0.05).In 19 of 31 patients who were confirmed to have malignant tumor after surgery,regional lymph node metastasis was histologically detected.The sensitivity,specificity,PPV,NPV,accuracy of 3 methods in detecting regional lymph node metastasis were 63.2％,91.7％,92.3％,61.1％ and 74.2％; 78.9％,83.3％,88.2％,71.4％ and 80.6％; 89.5％,91.7％,94.4％,84.6％ and 90.3％,and there were no statistically significant differences.In 17 of 50 patients with malignant tumor,distant metastasis was confirmed after biopsy or follow-up.The sensitivity,specificity,PPV,NPV and accuracy of 3 methods in detecting distant metastasis were 58.8％,100％,100％,82.5％ and 86％ ;82.4％,91.0％,82.4％,90.9％ and 88％; 94.1％,97.0％,94.1％,97.0％ and 96.0％,and the difference of sensitivity and NPV between CECT and PET/CECT was statistically significant (P ＜ 0.05).Conclusions Cross-modality image fusion of PET/CT and CECT is a convenient and effective method that can be used to compensate for some limitations of PET/CT and CECT in differential diagnosis of pancreatic lesions and staging assessments of pancreatic cancer,and to improve the diagnostic efficacy. Key words: Pancreatic neoplasms ; Positron-emission tomography ; Tomography, X-ray computed; Contrastenhancement; Diagnostic, differential; Neoplasm staging