Cross-modality PET/CT and contrast-enhanced CT imaging for pancreatic cancer

Abstract

Aim: To explore the diagnostic value of the cross-modality fusion images provided by positron emission tomography/computed tomography (PET/CT) and contrast-enhanced CT (CECT) for pancreatic cancer (PC).

Methods: Data from 70 patients with pancreatic lesions who underwent CECT and PET/CT examinations at our hospital from August 2010 to October 2012 were analyzed. PET/CECT for the cross-modality image fusion was obtained using TureD software. The diagnostic efficiencies of PET/CT, CECT and PET/CECT were calculated and compared with each other using a χ(2) test. P < 0.05 was considered to indicate statistical significance.

Results: Of the total 70 patients, 50 had PC and 20 had benign lesions. The differences in the sensitivity, negative predictive value (NPV), and accuracy between CECT and PET/CECT in detecting PC were statistically significant (P < 0.05 for each). In 15 of the 31 patients with PC who underwent a surgical operation, peripancreatic vessel invasion was verified. The differences in the sensitivity, positive predictive value, NPV, and accuracy of CECT vs PET/CT and PET/CECT vs PET/CT in diagnosing peripancreatic vessel invasion were statistically significant (P < 0.05 for each). In 19 of the 31 patients with PC who underwent a surgical operation, regional lymph node metastasis was verified by postsurgical histology. There was no statistically significant difference among the three methods in detecting regional lymph node metastasis (P > 0.05 for each). In 17 of the 50 patients with PC confirmed by histology or clinical follow-up, distant metastasis was confirmed. The differences in the sensitivity and NPV between CECT and PET/CECT in detecting distant metastasis were statistically significant (P < 0.05 for each).

Conclusion: Cross-modality image fusion of PET/CT and CECT is a convenient and effective method that can be used to diagnose and stage PC, compensating for the defects of PET/CT and CECT when they are conducted individually.

Keywords: Contrast enhancement; Diagnostic imaging; Pancreatic neoplasms; Positron-emission tomography; Staging; Tomography, X-ray computed.

Figure 1

A 46-year-old female patient with repeated upper abdominal pain for 9 mo. A-C: PET/CT image [A: Low density lesion in the pancreatic head (depicted by plain CT scanning); B: Increased FDG uptake at the lesion (SUVmax = 2.93, depicted by PET scanning); C: Pancreatic head cancer suggested by a hypermetabolic lesion at the pancreatic head (depicted by a fusion image of PET/CT)]; D-F: PET/CECT fusion image [D: ischemic lesion at the pancreatic head in the pancreatic parenchymal phase (depicted by CECT scanning); E: Delayed enhancement at the head of the pancreas suggested by a slight high density lesion in the venous and delayed phases (depicted by CECT scanning); F: Increased FDG uptake and delayed enhancement of the lesion at the pancreatic head (depicted by a fusion image)]. As the increased FDG uptake could be induced by pancreatitis, this case was diagnosed as chronic pancreatitis via a PET/CECT fusion image, which was confirmed by postoperative pathology. PET/CT: Positron emission tomography/computed tomography; CECT: Contrast-enhanced CT; FDG: Fluorodeoxyglucose.

Figure 2

A 61-old male patient with upper abdominal pain for more than 3 mo. A-B: PET/CT image [A: Enlargement at the junction of the pancreatic body and tail (depicted by plain CT scanning); B: Increased FDG uptake at the lesion with the SUVmax of 10.6. This disease was diagnosed as pancreatic cancer (depicted by a PET/CT image)]; C-D: CECT and PET/CECT fusion image: splenic artery invasion was clearly displayed; the splenic artery was thinner with irregular vascular edges. This case was pathologically diagnosed as a moderately differentiated pancreatic ductal adenocarcinoma with splenic artery invasion. PET/CT: Positron emission tomography/computed tomography; CECT: Contrast-enhanced CT; FDG: Fluorodeoxyglucose.

Figure 3

A 49-year-old pancreatic cancer patient. A-C: CECT images at the arterial phase, pancreatic parenchymal phase, and delayed phase. A tiny, round, low density, 9 mm lesion was found at the posterior right liver lobe (arrow). This lesion was diagnosed as a hepatic cyst by CECT imaging because no enhancement was found in the lesion; D: A PET/CECT fusion image showed increased FDG uptake at the lesion with an SUVmax of 5.2. This lesion was diagnosed as liver metastasis from pancreatic cancer with PET/CECT fusion images, which was confirmed by biopsy; E: PET image for the entire body. A high metabolic mass was found at the pancreatic head (triangle). PET/CT: Positron emission tomography/computed tomography; CECT: Contrast-enhanced CT; FDG: Fluorodeoxyglucose.