Specific indications for pancreatic ultrasonography include:<\/span>\u00a0<\/span><\/p>\n The pancreas is a thin, elongated organ consisting of lobules of glandular tissue surrounded by connective tissue. It can be subdivided into 3 parts: the left lobe, body, and right lobe.<\/span>\u00a0<\/span><\/p>\n \u00a0 An illustration of the pancreatic position and surrounding anatomy in the dog and cat.<\/span><\/i>\u00a0<\/span><\/p>\n The anatomy of the ductal system varies between species. In dogs, the pancreatic duct joins the duodenum at the major duodenal papilla, adjacent to the common bile duct. With most, an accessory pancreatic duct joins the duodenum at the minor papilla though anatomic variation exists. In cats, the common bile duct fuses with the pancreatic duct before entering the major papilla. Only 20% of cats are estimated to have an accessory pancreatic duct<\/span>1<\/span>.<\/span>\u00a0<\/span><\/p>\n Due to the proximity of gastrointestinal structures, intraluminal gas will create reverberation artefacts which can obscure the adjacent pancreas. The presence of gas can be reduced through fasting the patient; where possible, a minimum of 12 hours fasting is recommended prior to an ultrasound examination of the pancreas.<\/span>\u00a0<\/span><\/p>\n Because the right lobe of the pancreas sits adjacent to the descending duodenum in the right cranial abdomen, it is important to include the last 3-4 intercostal spaces in the clipped area. It may be necessary to use the intercostal windows to view parts of the pancreas in this area, especially in deep chested dogs.<\/span>\u00a0<\/span><\/p>\n The highest frequency setting that gives adequate depth of penetration to view the area of the pancreas being examined should be used in order to maximise axial resolution. In most patients, a transducer with a frequency range of 8-15Mhz is ideal. However, in larger dogs, transducers with a lower frequency range (5-8Mhz) may be necessary to ensure adequate ultrasound penetration. Either a micro-convex or linear transducer can be used for the examination. Linear transducers are capable of higher frequency settings and are ideal for smaller patients and superficial areas of the abdomen. However, their larger footprint makes them harder to manoeuvre around the body. In comparison, micro-convex transducers produce a lower frequency range though their smaller, curved surface make them ideal in larger patients and for imaging using the intercostal spaces.<\/span>\u00a0<\/span><\/p>\n The normal pancreas has an inconspicuous, poorly marginated appearance. Therefore, the use of anatomic landmarks to guide an examination of the pancreas is essential.<\/span><\/strong>\u00a0<\/span><\/p>\n The patient is positioned in right or left lateral recumbency depending on the area of the pancreas to be examined.<\/span>\u00a0<\/span><\/p>\n With the transducer in sagittal orientation, the probe can be slid up the costal arch to roughly mid abdomen level.\u00a0 Identify the <\/span>spleen <\/span><\/strong>and the <\/span>splenic vein <\/span><\/strong>which is visible in the far field, deep to the body of the spleen.\u00a0<\/span>\u00a0<\/span><\/p>\n The left lobe of the pancreas lies immediately caudal to the greater curvature of the stomach and follows the course of the splenic vein as it runs to join the cranial mesenteric vein forming the <\/span>portal vein<\/span><\/strong>. By sliding the probe, you can follow the course of the splenic vein towards the portal vein. The area of the left lobe of the pancreas is between the splenic vein and portal vein at the level where both are visible.\u00a0<\/span>\u00a0<\/span><\/p>\n Bordering the area of the left lobe of the pancreas the greater curvature of the <\/span>stomach<\/span><\/strong> lies immediately cranially, the <\/span>transverse colon<\/span><\/strong> is caudal, and the <\/span>spleen<\/span><\/strong> lies laterally. These structures can be identified as boundaries to mark the area where the left pancreatic lobe can be seen.<\/span>\u00a0<\/span><\/p>\n Place the transducer caudal to the xiphisternum with the probe marker orientated cranially. Identify the <\/span>stomach<\/span><\/strong> caudal to the liver and fan the transducer towards the patient\u2019s right side to the point where the stomach just disappears from the image. This is the level of the pylorus. Fan the probe back towards the patient\u2019s left until the image of the pyloric area of the stomach just appears again and then rock the probe to angle slightly caudally. Fanning the probe dorsally and ventrally from this point, the <\/span>portal vein<\/span><\/strong> should be identified. The portal vein is the largest ventral vessel and should be visible on the right-hand side of the screen as a tubular, anechoic structure. The area of the body of the pancreas is visible between the portal vein and pyloric area of the stomach at this level.<\/span>\u00a0<\/span><\/p>\n With the probe in a sagittal orientation, identify the <\/span>right kidney<\/span><\/strong>. From this point slide the probe ventrally. The duodenum is positioned laterally, immediately deep to the right body wall and is usually the first loop of small intestine visualised in the ultrasound image. In some patients the ascending colon will be visible between the kidney and the duodenum. The duodenum is identifiable by its lateral position and the straight course it travels in the right abdomen. It has larger wall thickness compared to other parts of the small intestine due to a prominent mucosal layer. With the <\/span>duodenum<\/span><\/strong> visualised in a sagittal plane make small fanning movements dorsally to identify the area of the right lobe of the pancreas, which is dorsomedial to the descending duodenum. In canine patients, the pancreaticoduodenal vein can help to identify the area of the right pancreatic lobe. It is visualised as an anechoic tubular structure within the pancreas. Rotating the probe through 90 degrees to achieve a transverse image of the duodenum, the pancreas can sometimes be visualised as an irregular triangular area adjacent to the dorsomedial border of the duodenum.<\/span>\u00a0<\/span><\/p>\n Normal pancreatic tissue is thin and appears isoechoic to the surrounding mesenteric tissue and fat, making it indistinct. It is hypoechoic relative to the spleen and iso- to hyperechoic relative to the liver.<\/span>\u00a0<\/span><\/p>\n In dogs, the body and left lobe are harder to visualise in comparison to the right lobe. Whereas in cats, the right lobe is harder to visualise in comparison to the body and left lobe.<\/span>\u00a0<\/span><\/p>\n \u00a0 Right lobe of the pancreas in a dog.<\/span><\/i><\/strong> This image shows a transverse plane image of the right lobe adjacent to the dorsomedial border of the descending duodenum. The borders of the pancreas are marked with the dotted yellow line and the pancreaticoduodenal vein can be seen as a central round anechoic (black) area within the pancreatic tissue.<\/span><\/i>\u00a0<\/span><\/p>\n \u00a0 Body of the pancreas in a cat. <\/span><\/i><\/strong>In this sagittal plane image, the body of the pancreas is visible as a roughly triangular area of tissue (red arrow) caudal to the pylorus (blue arrow) and ventral to the portal vein (green arrow).<\/span><\/i>\u00a0<\/span><\/p>\n \u00a0 Left lobe of the pancreas in a dog. <\/span><\/i><\/strong>This sagittal plane image of the left cranial abdomen shows the left lobe of the pancreas as a roughly triangular area of tissue. The digital callipers are placed on the image to measure the pancreas width. The stomach, filled with intraluminal gas, is visible cranially (blue arrow), the transverse colon caudally (red arrow) and the spleen occupies the near field (green arrow). The splenic vein is visible as a circular anechoic area between the spleen and pancreas.<\/span><\/i>\u00a0<\/span><\/p>\n Normal ranges are available for measuring the thickness of the pancreas in cats and dogs:<\/span>\u00a0<\/span><\/p>\n Dog<\/span><\/strong>2<\/span><\/strong>:<\/span><\/strong> Right lobe \u2013 Normal width: 0.39-1.6cm, mean= 0.81cm\u00a0<\/span>\u00a0<\/span><\/p>\n Left lobe \u2013 Normal width: 0.36-1.4cm, mean= 0.65cm\u00a0<\/span>\u00a0<\/span><\/p>\n Body \u2013 Normal width: 0.35-1.1cm, mean= 0.63cm\u00a0<\/span>\u00a0<\/span><\/p>\n Cat<\/span><\/strong>3<\/span><\/strong>: <\/span><\/strong>Right lobe \u2013 Normal width: 0.3-0.57cm, mean 0.43cm<\/span>\u00a0<\/span><\/p>\n Left lobe \u2013 Normal width: 0.46-1.03cm, mean= 0.65cm\u00a0<\/span>\u00a0<\/span><\/p>\n Body \u2013 Normal width: 0.46-0.9cm, mean= 0.64cm<\/span>\u00a0<\/span><\/p>\n The pancreatic duct can be differentiated from any vessels using Doppler ultrasound. The duct is not readily identifiable in dogs but is more frequently identifiable in cats as a central anechoic area within the pancreas, most easily identifiable within the left lobe. In cats the duct diameter increases with age: mean duct diameter in cats \u226510 years 1.3mm (range 0.6-2.4mm)<\/span>3<\/span>.<\/span>\u00a0<\/span><\/p>\n \u00a0<\/span><\/p>\n It is important to recognise that the pancreas can appear ultrasonographically normal despite the presence of pathology.\u00a0<\/span>\u00a0<\/span><\/p>\n The diagnosis of pancreatitis requires a multimodal approach, and it is important to interpret ultrasound findings along with history, physical exam findings and the results of serum assays such as the specific canine pancreatic lipase assay<\/span>4<\/span>.<\/span>\u00a0<\/span><\/p>\n Ultrasonographic changes seen in acute pancreatitis include:<\/span>\u00a0<\/span><\/p>\n\n
Normal Anatomy\u00a0<\/span><\/h3>\n
![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%201%20Pancreatic%20anatomy.png\")
<\/span><\/p>\n\n
Examination Technique\u00a0<\/span><\/h3>\n
![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%202%20Left%20Lobe%20of%20the%20Pancreas%20Position.jpg\")
Left Lobe of Pancreas\u00a0<\/span><\/strong>\u00a0<\/span><\/h4>\nBody of Pancreas<\/span><\/strong>\u00a0<\/span><\/h4>\n
![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%203%20Body%20of%20the%20Pancreas%20Position.jpg\")
<\/span><\/p>\nRight Lobe of Pancreas\u00a0<\/span><\/strong>\u00a0<\/span><\/h4>\n
![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%204%20Right%20Lobe%20of%20the%20Pancreas%20Position.png\")
<\/span><\/p>\nNormal appearance\u00a0<\/span><\/h3>\n
![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%207%20Right%20lobe%20pancreas%20dog%20transverse.jpg\")
<\/span><\/p>\n![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%206%20Body%20of%20the%20pancreas%20cat.jpg\")
<\/span><\/p>\n![\"IMAGE](\"https:\/\/7971300.fs1.hubspotusercontent-na1.net\/hubfs\/7971300\/IMAGE%205%20Left%20lobe%20pancreas%20dog.jpg\")
<\/span><\/p>\nUltrasonographic appearance of pancreatic pathology\u00a0<\/span><\/h3>\n
Pancreatitis<\/span><\/strong>\u00a0<\/span><\/h3>\n
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