Diagnostic Imaging Interpretation Flashcards

A 7-year-old Cavalier King Charles Spaniel with a known history of myxomatous mitral valve disease presents with acute tachypnea. Thoracic radiographs are taken. Which radiographic finding is most characteristic of cardiogenic pulmonary edema in this dog?

Answer: A perihilar to caudodorsal unstructured interstitial to alveolar pattern.

In dogs, left-sided congestive heart failure secondary to mitral valve disease typically leads to cardiogenic pulmonary edema that originates in the perihilar region and extends into the caudodorsal lung fields. This appears as an unstructured interstitial pattern that can progress to an alveolar pattern. A cranioventral pattern is classic for aspiration pneumonia, nodules suggest metastatic disease, and a bronchial pattern indicates chronic airway disease.

A 2-year-old cat is evaluated for acute vomiting and anorexia. On abdominal radiographs, the small intestinal loops appear clustered in the mid-abdomen. Several gas bubbles within the intestines have eccentric, crescent, or triangular shapes. What is the most likely diagnosis?

Answer: Plication of the small intestines due to a linear foreign body.

The radiographic signs described, particularly the bunching or plication of the intestines and the presence of abnormally shaped, eccentric gas bubbles (sometimes called 'tapered enteric gas bubbles' or part of a 'string of pearls' sign), are pathognomonic for a gastrointestinal linear foreign body. The intestines bunch up as they try to move the anchored linear object via peristalsis.

During an abdominal ultrasound of a healthy dog, you identify a structure that appears to be liver parenchyma and a portion of the gallbladder located cranial to the highly echogenic, curvilinear diaphragm. This finding disappears when the transducer is angled differently. What does this represent?

Answer: Mirror image artifact.

This is a classic description of a mirror image artifact. It occurs when the ultrasound beam reflects off a strong, curved specular reflector like the diaphragm-lung interface. The ultrasound machine incorrectly assumes the returning echoes traveled in a straight line and displays a duplicate image of the liver and gallbladder on the far side of the diaphragm. It is a common artifact that should not be mistaken for pathology like a diaphragmatic hernia.

A 12-year-old Quarter Horse is diagnosed with navicular syndrome based on clinical signs and a positive palmar digital nerve block. Which of the following is NOT a classic radiographic finding associated with this condition?

Answer: Widening of the distal interphalangeal (coffin) joint space.

Classic radiographic signs of navicular syndrome involve changes to the navicular bone itself, such as enlarged vascular channels (synovial invaginations), medullary sclerosis, flexor cortex erosions, and enthesophyte formation at ligament attachments. Widening of the coffin joint space is not a feature of navicular syndrome; it would be more indicative of joint effusion, synovitis, or instability unrelated to this specific diagnosis.

A ventrodorsal (VD) thoracic radiograph of a dog shows that the sternum is positioned to the right of the vertebral column. The left lung fields appear larger and more radiolucent than the right. What positioning error most likely occurred?

Answer: The patient's left side was elevated off the table.

When a patient is rotated in a VD view, the side that is elevated (further from the detector) will appear magnified and more radiolucent due to increased air. The sternum will appear shifted towards the side that is down (closer to the detector). In this case, the left side appears larger (elevated) and the sternum is shifted to the right (the 'down' side).

A contrast-enhanced CT scan is performed on an older dog with an ultrasound-identified pancreatic mass. Which finding is most suggestive of a malignant process like pancreatic adenocarcinoma rather than focal pancreatitis?

Answer: A poorly-defined, hypoattenuating mass with evidence of portal vein invasion and enlarged regional lymph nodes.

The most definitive imaging features of malignancy are local invasion of adjacent structures (like the portal vein or duodenum) and evidence of metastasis (such as enlarged regional lymph nodes). While both pancreatitis and neoplasia can cause masses and peripancreatic changes, invasion and metastasis are hallmarks of cancer. Rim enhancement often suggests an abscess, diffuse enhancement suggests pancreatitis, and fat saponification is a classic sign of pancreatitis.