Among pancreatic neuroendocrine tumors (PNETs), pancreatic insulinomas are often particularly
difficult to detect by imaging studies, making localization diagnosis difficult [1]
[2]. Recently, the new technique of detective flow imaging endoscopic ultrasound (DFI-EUS),
which is capable of displaying minute blood flow in the entire pancreas without contrast
medium, has been introduced. We report a pancreatic insulinoma that was difficult
to detect with other imaging tests, and for which DFI-EUS was useful for tumor detection.
A 40-year-old woman presented with a chief complaint of dizziness. She had recurrent
hypoglycemic attacks. Contrast-enhanced dynamic computed tomography, magnetic resonance
imaging, fluorodeoxyglucose-positron emission tomography, and somatostatin receptor
scintigraphy did not detect any lesions. EUS was performed using an ultrasound scanning
system (ARIETTA 850; FUJIFILM Medical Co., Ltd., Tokyo, Japan) and convex-type endoscope
(GF-UCT260; Olympus, Tokyo, Japan). B-mode EUS showed a 9-mm pale tumor with slightly
higher echogenicity than the surrounding area ([Fig. 1], [Video 1]). DFI-EUS detected a distinct multivessel tumor in the body of the pancreas ([Fig. 2]). Contrast-enhanced EUS by Sonazoid (Daiichi-Sankyo, Tokyo, Japan) revealed a hypervascularized
tumor ([Fig. 3]). EUS-guided fine-needle aspiration was not performed because of the high risk of
complications due to the main pancreatic duct interposition in the puncture line;
selective arterial secretagogue injection test was positive in the body of the pancreas.
The clinical diagnosis was insulinoma and a distal pancreatic body resection was performed.
The final pathological diagnosis was PNET G1, insulinoma.
Fig. 1 B-mode endoscopic ultrasound showed a 9-mm pale tumor (arrows) with slightly higher
echogenicity than the surrounding area.
Fig. 2 Detective flow imaging endoscopic ultrasound (DFI-EUS) detected a distinct hypervascular
tumor (arrows). Strong blood flow effect was observed on the tumor surface and small
vascular blood flow was observed in the interior. a B-mode image. b DFI-EUS.
Fig. 3 Contrast-enhanced endoscopic ultrasound depicted a mildly hypervascularized tumor
(arrows), although the boundary with the surrounding area was somewhat difficult to
discern. a B-mode image. b Contrast-enhanced endoscopic ultrasound.
Imaging findings of B-mode endoscopic ultrasound (EUS), detective flow imaging endoscopic
ultrasound (DFI-EUS), and contrast-enhanced EUS in pancreatic insulinoma. DFI-EUS
clearly delineated a tumor with more vascularity than contrast EUS.Video 1
DFI-EUS is a new method for imaging and detecting small vessels and low-velocity blood
flow without the use of ultrasound contrast agents. A previous study reported the
utility of DFI-EUS for pancreaticobiliary lesions [3]. In this case, DFI-EUS clearly delineated a tumor with more vascularity than contrast
EUS and was useful in the diagnosis of insulinoma. DFI-EUS is useful in the evaluation
of tumor blood flow in pancreatic insulinomas. While Sonazoid contrast can only adequately
observe the field of view at the time of contrast injection, DFI-EUS can screen the
entire pancreas. DFI-EUS may be useful for screening and localizing the entire pancreas
for insulinomas and other PNETs.
Endoscopy_UCTN_Code_CCL_1AF_2AZ
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