Page 561 - Atlas of Small Animal CT and MRI

5.5

Pancreas

The canine and feline pancreas is readily visible on Inflammatory disorders
unenhanced and contrast‐enhanced CT images and on
MR images. CT is preferred because of faster scanning Acute pancreatitis has been diagnosed using CT imag­
times and the ability to eliminate motion artifact when ing in dogs and cats (Figures 5.5.4, 5.5.5). The pancreas
viewing the thin tissue of the pancreas. However, MR is enlarged with irregular borders and is intensely con­
has increased contrast resolution and provides excellent trast enhancing. Regions of hypoattenuation may be
information in inflammatory diseases, such as chronic present in necrotic regions. The surrounding mesentery
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pancreatitis. 1 has fat stranding secondary to local inflammation.
The normal feline pancreatic thickness on T1 images is Chronic pancreatitis resulting in fibrosis and fat replace­
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9.5 ± 1.2 mm, and pancreatic duct size is 1.65 ± 0.05 mm. ment may be hypoattenuating and poorly contrast
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The pancreas is T1 hyperintense and T2 hypointense enhancing (Figures 5.5.6, 5.5.7). Nodular regions and
compared to the liver, with a uniform architecture. The mild enlargement without surrounding mesenteric
feline pancreatic duct is oriented in the long axis of each inflammation are characteristic of chronic pancreatitis.
lobe and may be visualized as a hypoattenuating (CT), Pancreatitis is a challenging disease to diagnose in cats
hypointense (T1), or hyperintense (T2, FSE) linear struc­ using ultrasound and CT. MR imaging shows promise in
ture. The feline pancreas is hypoattenuating to liver on detecting these changes with increased tissue contrast
unenhanced CT images, with rapid contrast enhance­ and 3D volume imaging. Pancreatitis appears as T1
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ment and gradual washout (Figure 5.5.1). CT imaging hypointensity and T2 hyperintensity with pancreatic
features of the canine pancreas are similar (Figure 5.5.2). duct dilation. The signal intensity changes are likely
Multiphase CT angiography allows the evaluation of caused by edema and fibrosis. Administration of secretin
pancreatic tissues in the native, arterial, portal, and can be used to dilate the pancreatic duct. This improves
delayed phases of contrast enhancement. The canine visualization of the pancreatic duct in normal cats; how­
pancreas is isoattenuating to liver on unenhanced images, ever, in those with pancreatitis, it causes only minimal
1
hyperattenuating on arterial phase images, and hypoat­ change to ducts that are already dilated. Unenhanced
tenuating on portal and delayed phase images. The atten­ and contrast‐enhanced CT images cannot consistently
uation differences are due to the purely arterial blood differentiate normal cats from those with pancreatitis
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supply of the pancreas, which results in rapid enhance­ unless there is marked pancreatic enlargement.
ment following injection of contrast medium, compared Complications of pancreatitis in both species
to the predominantly portal enhancement of the liver. include formation of pseudocysts, abscesses, and
The pancreaticoduodenal artery is visible during the necrosis. Pancreatic cysts and pseudocysts can also
arterial phase, and the pancreaticoduodenal vein opaci­ occur as incidental findings (Figure 5.5.8). On CT
fies during the portal and delayed phases (Figure 5.5.3). 4 images, pseudocysts and abscesses appear fluid

Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
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