Ultrasonographic imaging of vomiting cats (Proceedings)
Why do they vomit? Because they can! What organ is the cause? What do we know about pancreatitis, inflammatory bowel disease and hepatobiliary conditions? This session will present a spectrum of cases, each providing a significant radiographic or ultrasound learning point.
The strengths of radiology include the evaluation of gas-filled structures, detection of mineralization and the assessment of liver size. Radiographs provide a global view of the abdomen and often provide a perspective unavailable from ultrasound.Ultrasound
The strengths of radiology include the evaluation the internal architecture of intra-abdominal organs. As a real-time modality, ultrasound often gives instant gratification of mass lesions for organ or origin and key metastatic manifestations.
In cats we want to work as quickly as possible to expedite an answer before the cat tells us that "time is up"! I do almost all exams without sedation, because many of these patients are quite ill. Sedating a patient prolongs the imaging usually resulting in better quality imaging.
We always want to do a complete job and see everything. Keeping track of the "most important sites" helps prioritize a fast efficient examination. Don't dwell on a normal appearing liver at the expense of an incomplete study of the GI tract and pancreas.
Is there free peritoneal fluid? Maybe perform an abdominocentesis now to maximize efficiency. Is there concurrent pleural free fluid...this would be a bad sign! Bicavitary free fluid is a very poor prognosticator and strongly associated with bad diseases; FIP, bad cancer, severe heart failure. Concurrent pericardial free fluid (tricavitary free fluid) is highly associated with cardiomyopathy in its most severe manifestation.
Hyperechoic peritoneal fat is often associated with free peritoneal fluid. Lacking free fluid, finding a site of hyperechoic peritoneal fat is a very important localizer for disease. Is the fat adjacent to a small intestinal bowel loop, pancreas or liver? This helps focus your examination towards a "more important" region or organ. On the other hand, not all-important lesions have an associated surrounding region of hyperechoic peritoneal fat.
Look for diffuse changes such as enlargement, changes in echogenicity and irregular shape. Cholangiohepatitis is very common and quite often occult. Elevated liver enzymes are enough clinical justification to perform a liver fna for cytology. The most common manifestation of cholangiohepatitis is a diffuse hypoechogenicity.
Clinical pathologists use the same term (hepatic lipidosis) to describe any fat infiltration in hepatocytes. All fat cats have a hyperechoic liver characterized by mild fat infiltration. This is a variation of normal and of no clinical concern. The clinical disease "hepatic lipidosis", with severe fat infiltration, is much more attenuating than the fat infiltration associated with normal obese cats. Make sure you read the cytology report carefully to find the "degree" of hepatic lipidosis. "Mild" is a normal variant, whilst severe is associated with liver failure, hyperbilirubinemia and clinical signs.
Dogs regenerate the liver with nodular changes. Benign nodular regeneration is very unusual in cats. Seeing nodules in the liver of cats is much more commonly associated with primary and metastatic cancer and demands additional testing, such as a fna of the nodule. An exception is the very characteristic echo pattern associated with biliary cyst adenoma. This lesion is both hyperechoic and hypoattenuating. The distal enhancement (=through transmission) artifact associated with a hyperechoic lesion is unique. This lesion is benign, although may continue to grow and have a mass-effect on the surrounding liver parenchyma.