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PEER REVIEWED 82 IMAGING ESSENTIALS REVIEWED PEER LOCALIZATION AND SCANNING TECHNIQUE Typically, an 8 to 10-MHz curved array or 12-MHz linear transducer is used for dogs and cats. Animals are usually scanned in dorsal recumbency; however, right and left lateral recumbency may assist with displacement of gas and fluid in the stomach to better visualize deeper structures. Longitudinal axis and transverse axis views of the different segments of the gastrointestinal tract are necessary for a complete examination. Maintain a consistent sequence when evaluating the complete gastrointestinal tract; preferably, in the following order: all parts of the stomach (fundus, body, pyloric antrum), pyloroduodenal junction (pyloric sphincter), duodenum, jejunum, ileum, ileocecocolic (cat) or ileocolic (dog) junction, cecum, and parts of the colon (ascending, transverse, descending). Stomach The stomach is scanned initially in long axis plane, relative to the patient, which creates a transverse view of the stomach, beginning at the fundic portion located immediately caudal to the left division of the liver. The fundus is located in the left craniolateral quadrant, the body of the stomach is located closer to midline as the transducer is swept to the right of the patient, and the pyloric antrum can extend to the right side of the patient depending on the degree of distension. The pylorus and pyloroduodenal junction is found closer to midline in most cats. In deep chested dogs, a right dorsal intercostal approach may be needed to better visualize the pyloroduodenal junction. Occasionally, the gastroesophageal junction (cardia) may be visualized. Duodenum After imaging the pyloroduodenal junction, the orad portion of the descending duodenum is visualized. The descending duodenum is followed caudally, keeping it in long axis, along the right lateral abdominal body wall in the dog. An intercostal approach may be needed to identify the cranial aspect of the descending duodenum in the dog. When the patient is placed in dorsal recumbency, the right kidney may be used to identify the duodenum as it will be located ventral or ventrolateral to that kidney within the near field of the image. The descending duodenum in the cat will be either in a midline position or just to the right of midline. Ultrasonography of the Gastrointestinal Tract: Stomach, Duodenum, and Jejunum Elizabeth Huynh, DVM, and Clifford R. Berry, DVM, DACVR University of Florida IMAGING ESSENTIALS