Fig 1.
Flow diagram of patient inclusion.
PNET, pancreatic neuroendocrine tumor; PDAC, pancreatic ductal adenocarcinoma.
Table 1.
Demographic characteristics of patients with hypovascular pancreatic neuroendocrine tumors (hypo-PNETs) and those with pancreatic ductal adenocarcinoma.
Fig 2.
A 51-year-old woman with pancreatic neuroendocrine carcinoma.
(a) Unenhanced image shows an isodense mass (arrow) located in the head of the pancreas. (b, c) Arterial (b) and portal venous (c) phase images show a well circumscribed mass (arrows) with a hypovascular enhancement pattern. (d) There was neither upstream pancreatic parenchymal atrophy nor pancreatic duct dilatation (arrowheads).
Fig 3.
A 60-year-old man with pancreatic ductal adenocarcinoma.
(a) Unenhanced image shows an isoattenuation mass (arrow) located in the head of the pancreas. (b, c) Arterial (b) and portal venous (c) phase images show an ill-defined mass (arrows) with a hypovascular enhancement pattern. (d) Pancreatic parenchymal atrophy and pancreatic duct dilatation were observed (arrowheads).
Fig 4.
A 42-year-old man with pancreatic neuroendocrine carcinoma.
(a—c) Unenhanced (a), arterial (b), and portal venous phase (c) images show a well-defined mass (arrows) in the body of the pancreas. The CT attenuation was 38 HU at the unenhanced phase, 52 HU at the arterial phase, and 75 HU at the portal venous phase. A 60-year-old man with pancreatic ductal adenocarcinoma. (d—f) Unenhanced (d), arterial (e), and portal venous phase (f) images show an ill-defined mass (arrows) in the body of the pancreas. The CT attenuation was 38 HU at the unenhanced phase, 43 HU at the arterial phase, and 55 HU at the portal venous phase. The dialated pancreatic duct is noted (arrowheads).
Table 2.
CT findings in hypovascular pancreatic neuroendocrine tumors (hypo-PNETs) and pancreatic ductal adenocarcinoma (PDAC).
Fig 5.
The dynamic contrast-enhanced curves in hypo-PNETs and PDAC.
The CT attenuation of hypo-PNETs and PDAC was 33.4 ± 4.9 and 34.0 ± 5.2 Hounsfield units at the unenhanced CT images, respectively. The CT attenuation of hypo-PNETs was higher than that of PDAC in the arterial phase (p<0.001) and portal venous phases (p = 0.003). hypo-PNET, hypovascular pancreatic neuroendocrine tumor; PDAC, pancreatic ductal adenocarcinoma.
Fig 6.
Box-and-whisker plots of the tumor-to-pancreas enhancement ratio in hypo-PNETs and PDAC in the arterial, portal venous, and delayed phase.
The tumor-to-pancreas enhancement ratios in hypo-PNETs were higher than those of PDAC in the arterial phase (p<0.001) and portal venous phase (p = 0.01). hypo-PNET, hypovascular pancreatic neuroendocrine tumor; PDAC, pancreatic ductal adenocarcinoma.
Fig 7.
Receiver operating characteristic curves of quantitative computed tomography imaging findings in the differentiation of hypo-PNETs from PDAC.
The area under the curves ranged from 0.693–0.888. hypo-PNET, hypovascular pancreatic neuroendocrine tumor; PDAC, pancreatic ductal adenocarcinoma; ACE, contrast enhancement in the arterial phases; PCE, contrast enhancement in the portal venous phases; AER, the tumor-to-pancreas enhancement ratio in the arterial phase; PER, the tumor-to-pancreas enhancement ratio in the portal venous phases.
Table 3.
The receiver operating characteristic analysis of CT findings in differentiating hypovascular pancreatic neuroendocrine tumors (hypo-PNETs) from pancreatic ductal adenocarcinoma (PDAC).