Contrast‐enhanced Ultrasonographic Findings in Three Dogs With Pancreatic Insulinoma

Abstract

Abdominal ultrasonography is one of the most common diagnostic imaging modalities used for dogs with suspected insulinoma; however, pancreatic masses are clearly identified in fewer than half of affected dogs and benign pancreatic nodules can be difficult to differentiate from malignant ones. The purpose of this prospective study was to describe contrast-enhanced ultrasonography (CEUS) characteristics of confirmed pancreatic insulinoma in a group of dogs. Inclusion criteria were as follows: (1) repeated hypoglycemia (blood glucose levels <60 mg/dl, twice or more); (2) elevated blood insulin levels with hypoglycemia; (3) pancreatic nodules detected with conventional ultrasonography; and (4) histological confirmation of pancreatic islet cell carcinoma. Immediately following conventional ultrasonography of the entire abdomen, CEUS of the pancreatic nodule and adjacent parenchyma was performed using contrast-specific technology pulse inversion imaging and perflubutane microbubble contrast agent. Three dogs met inclusion criteria. Pancreatic nodules in all the three dogs became more clearly demarcated after injection of the contrast agent. Each nodule showed different enhancement patterns: markedly hyperechoic for 5 s, slightly hyperechoic for 1 s, and clearly hypoechoic for over 30 s. These results were not in complete agreement with previously reported CEUS findings in human patients with insulinoma. All nodules were surgically resected and histopathologically confirmed as malignant insulinomas. Findings from the current study indicated that contrast-enhanced ultrasound may help to increase conspicuity of pancreatic insulinomas in dogs and that enhancement characteristics may be more variable in dogs than in humans.

Contrast-Enhanced Ultrasonographic Detection and Dual-Phase Computed Tomographic Angiography in a 5-Year-Old Boxer with Pancreatic Insulinoma&lt;br/&gt;—Case Report

“…Previous canine studies have shown an increased number of nodules in the pancreas and improved anatomic localization with CEUS (contrast-enhanced ultrasound) compared with conventional ultrasound [4]. In addition, the nodule margins have been better demarcated with CEUS [4] [6]. However, in a recent case series of three dogs with pancreatic nodules with histologically confirmed insulinoma the nodules were visible using both conventional and CEUS [6].…”

Canine insulinomas appear hyperintense on MRI T2‐weighted images and isointense on T1‐weighted images

“…A study in dogs on contrast‐enhanced ultrasound demonstrated a difference in enhancement patterns of insulinomas and pancreatic adenocarcinomas . Meanwhile, another study on contrast‐enhanced ultrasound suggested that this modality may help to increase the conspicuity of canine insulinomas; however, enhancement characteristics in the examined patients were variable . Computed tomography, including dynamic CT, dual‐phase CT angiography, and triple‐phase CT, has appeared promising for identification of pancreatic insulinomas and their metastases in both canines and humans, but the enhancement pattern of canine insulinomas on CT remains to some extent inconsistent .…”

Quantitative Contrast‐enhanced Ultrasonographic Assessment of Naturally Occurring Pancreatitis in Dogs

“…In 4 dogs, nonenhancing pancreatic parenchymal lesions were identified on CEUS. The enhancement characteristics of these lesions (nonenhancement) on CEUS suggest areas of pancreatic ischemia or necrosis instead of neoplasia such as pancreatic insulinoma (hypo‐enhancement or hyper‐enhancement) or adenocarcinoma (hypo‐enhancement) . However, histopathologic confirmation was not available in this study.…”

“…Perfusion of various abdominal organs such as the liver, spleen, pancreas, kidney, and adrenal glands can be studied noninvasively using CEUS . Applications of CEUS in the diagnosis of pancreatic neoplasia also have been reported in veterinary medicine . CEUS utilizes microbubble (MB) contrast agents that remain entirely intravascular when administered IV, with no extravasation into surrounding tissue .…”