ULTRASONOGRAPHIC OBSERVATION OF SECRETIN-INDUCED PANCREATIC DUCT DILATION IN HEALTHY CATS

Cholangiopancreatography in cats: a post-mortem comparison of MRI with fluoroscopy, corrosion casting and histopathology

In human medicine, magnetic resonance cholangiopancreatography (MRCP) is a valuable diagnostic tool for hepatobiliary and pancreatic diseases. In veterinary medicine, however, data evaluating the diagnostic value of MRCP are limited. The primary objectives of this prospective, observational, analytical investigation were to assess whether MRCP reliably visualizes the biliary tract and pancreatic ducts in cats without and with related disorders, and whether MRCP images and measurements of the ducts agree with those of fluoroscopic retrograde cholangiopancreatography (FRCP), corrosion casting and histopathology. A secondary objective was to provide MRCP reference diameters for bile ducts, GB, and pancreatic ducts. Donated bodies of 12 euthanized adult cats underwent MRCP, FRCP, and autopsy with corrosion casting of the biliary tract and pancreatic ducts using vinyl polysiloxane. Diameters of the biliary ducts, gallbladder (GB), and pancreatic ducts were measured using MRCP, FRCP, corrosion casts and histopathologic slides. There was an agreement between MRCP and FRCP in measuring diameters of the GB body, GB neck, cystic duct, and common bile duct (CBD) at papilla. Strong positive correlations existed between MRCP and corrosion casting for measuring GB body and neck, cystic duct, and CBD at the extrahepatic ducts' junction. In contrast to the reference methods, post-mortem MRCP did not visualize right and left extrahepatic ducts, and pancreatic ducts in most cats. Based on this study, MRCP with 1.5 Tesla can be regarded as a contributory method to improve the assessment of feline biliary tract and pancreatic ducts when their diameter is >1 mm.

Feline abdominal ultrasonography: What's normal? What's abnormal? The pancreas

PRACTICAL RELEVANCE

Abdominal ultrasound plays a vital role in the diagnostic work-up of many cats presenting to general and specialist practitioners. Ultrasound examination of the pancreas is a vital part of the investigation into feline pancreatic disease.

CLINICAL CHALLENGES

Despite ultrasonography being a commonly used modality, many practitioners are not comfortable performing an ultrasound examination or interpreting the resulting images. Even for the experienced ultrasonographer, differentiating between incidental findings such as nodular hyperplasia and pathological changes such as neoplasia can be challenging.

AIM

This review, part of an occasional series on feline abdominal ultrasonography, discusses the ultrasonographic examination and appearance of the normal and diseased pancreas. Aimed at general practitioners who wish to improve their knowledge of and confidence in feline abdominal ultrasound, this review is accompanied by high-resolution images and videos available online as supplementary material.

EQUIPMENT

Ultrasound facilities are readily available to most practitioners, although use of ultrasonography as a diagnostic tool is highly dependent on operator experience.

EVIDENCE BASE

Information provided in this article is drawn from the published literature and the author's own clinical experience.

Feline pancreatic ducts are consistently identified on CT and more likely to be dilated in the body of pancreas in cats with elevated feline pancreatic lipase immunoreactivity

Feline pancreatitis is a challenge to diagnose and no previously published study has described the CT characteristics of the pancreatic duct (PD) in cats. The current prospective analytical study was performed to identify and describe the CT characteristics of the PD in normal cats and to compare that to those cats with an elevated feline pancreatic lipase immunoreactivity (fPLI). Contrast-enhanced CT was performed in 16 normal cats and 13 cats with an elevated fPLI. Two ACVR-certified radiologists blinded to the fPLI status assessed whether or not the PD could be identified, contrast phase during which the PD was most conspicuous, and PD shape in the body, right and left lobes. A second-year radiology resident blinded to the fPLI status measured maximum PD diameter and PD:parenchyma. The PD was identified in 84 of 87 pancreatic segments, which was most conspicuous in the portal phase in 28 of 29 cats. The PD shape was tubular (48/84), tapered (34/84), or beaded (2/84) with no significant difference (P = 1.0 to .1615) between groups. Mean maximal PD diameters of normal cats were 1.5-1.7 mm, which was significantly larger in the body of the pancreas in cats with an elevated fPLI (2.4 mm, P = .0313). Mean PD:parenchyma was not significantly different between groups (P = .2001 to .949). In conclusion, the feline PD can be consistently identified on CT, for which the portal phase is preferred. Cats with an elevated fPLI are more likely to exhibit dilation of the PD in the body of the pancreas on CT.

Magnetic resonance (MR) imaging and MR cholangiopancreatography findings in cats with cholangitis and pancreatitis

Cholangiohepatitis/cholangitis is second only to hepatic lipidosis as the most common liver disease in cats and is often associated with concurrent pancreatitis. Magnetic resonance imaging (MRI) and MR cholangiopancreatography (MRCP) have developed into an accurate, highly sensitive and specific imaging tool for the diagnosis of biliary and pancreatic duct disorders in humans. In this prospective case series, 10 cats with suspected cholangitis and/or pancreatitis were enrolled based on clinical history, physical examination and appropriate diagnostic test results. MRI and MRCP sequences with secretin stimulation of the cranial abdomen were performed, and sonography and laparoscopic biopsies for histologic diagnosis were obtained for comparison. MRI detected pancreatic abnormalities in cats suspected of pancreatitis, including T1 pre-contrast hypointense and T2 hyperintense pancreatic parenchyma and a dilated pancreatic duct. The MRI findings of the liver were non-specific. Nine of 10 cats had biliary abnormalities, including gall bladder wall thickening, gall bladder wall moderate contrast enhancement and/or gall bladder debris. Eight of 10 cats had histologic evidence of pancreatitis, as well as hepatitis or cholangitis, with one cat diagnosed with hepatic lymphoma. The advantages of MRI/MRCP over sonography of these cats included the striking pancreatic signal changes associated with pancreatitis and the ability to comprehensibly assess and measure the pancreas and hepatobiliary structures without operator dependence or interference from bowel gas. MRI/MRCP imaging of the feline abdomen may be beneficial in cases with equivocal ultrasound imaging findings.

Hepatic and pancreaticobiliary MRI and mr cholangiopancreatography with and without secretin stimulation in normal cats

Magnetic resonance (MR) cholangiopancreatography is useful in humans to diagnose biliary and pancreatic diseases. Some of these protocols incorporate the use of secretin, which stimulates the exocrine pancreas to release bicarbonate with secondary dilation of the pancreatic duct. We compared the utility and quality of multiple hepatic-pancreaticobiliary MR imaging sequences before and after secretin stimulation of the pancreatic duct in five healthy cats. Multiple MR sequences were evaluated, including fast Spoiled Gradient Recalled in- and out-of-phase, Single Shot Fast Spin Echo (SSFSE), T2 Fast Spin Echo, MR cholangiopancreatography (pre- and postsecretin administration), and Fast Acquisition with Multiphase Efgre (FAME) (postsecretin and before and after gadolinium administration). The MR cholangiopancreatography protocol with secretin stimulation was feasible and yielded high-contrast maps of the biliary ductal anatomy but the pancreactic duct was seen inconsistently. The FAME series most consistently provided visualization of biliary and postsecretin pancreatic ductal anatomy, combined with very good depiction of the liver and pancreas. The remaining sequences each had satisfactory utility and diagnostic quality, with the exception of the SSFSE sequences. Secretin improved the conspicuity of the pancreatic duct.