Abdomen and Oncology

Key images Findings

69-year-old male presented with abdominal pain. Dual-energy CT images from the IQon Spectral CT showed a hypervascular pancreatic tumor consistent with a possible neuroendocrine tumor.

Virtual monoenergetic images at lower keV increases the mean attenuation values of vascularized tumors, making the diagnosis of hypervascular small lesions possible through a single CT acquisition obtained during the venous phase. Volume rendering (VR) reconstructions obtained from the data sets provide an opportunity to enhance the clinician’s ability to visualize the lesion that is being studied.

Axial and VR images

On the conventional CT axial image obtained during the venous phase after 70 ml of contrast (iodine concentration 350 mg/ml), the tumor present in the head of the pancreas was not clearly visualized. There was an obvious hypervascular tumor in the corresponding virtual monoenergetic axial image at 50 keV. Only the VR reconstructions generated from the low monoenergetic data sets could depict the tumor and stage it, excluding the presence of vascular invasion. A cephalic pancreaticoduodenectomy was performed and histological results revealed a neuroendrocrine tumor (pT1 N0 R0).

Discussion

There is an obvious advantage of dual-energy CT for detection and staging of pancreatic tumors using low monoenergetic data sets. This improvement in the clinician’s ability to visualize the pathology in question also leads to an opportunity to reduce CT examinations to a single post-contrast acquisition, which also means a reduced radiation dose to the patient in daily clinical practice.

Conventional CT with contrast, venous phase, axial image: The cephalic pancreatic tumor (white arrow) tends to blend into normal parenchyma.

Virtual monoenergetic axial image at 50 keV shows a hypervascular tumor in the head of the pancreas (white arrow).

VR reconstructions obtained from conventional CT images do not show the tumor.

Multiplanar VR reconstructions obtained from virtual monoenergetic at 50 keV show the tumor and rule out invasion of superior mesenteric-portal vein confluence (blue arrows).

Macroscopic specimens of cephalic pancreaticoduodenectomy reveals a tumor without vascular invasion.

Histopathological findings (HE x 0.25, HE x 20, synaptophysin x 0.25) characteristic of a neuroendocrine tumor. Proliferation index through ki-67 expression (ki-67 x 20).

History Benefits or pitfalls of dual-energy CT