NAVLE Small Animal Diagnostic Imaging 2 — Questions and Answers
Question 1: On thoracic radiographs of a dog, which cardiac silhouette finding is most consistent with left atrial enlargement?
- Elevation of the trachea at the carina (Correct answer)
- Rounding of the right heart border
- Loss of the caudal waist on the ventrodorsal view
- Increased sternal contact length
Correct answer: Elevation of the trachea at the carina
Left atrial enlargement causes dorsal displacement and elevation of the trachea at the carina (mainstem bronchi splaying) on lateral radiographs.
Question 2: Which ultrasound artifact appears as hyperechoic lines parallel to a curved reflective surface, such as the near wall of a cystic structure?
- Shadowing
- Reverberation (Correct answer)
- Mirror artifact
- Enhancement
Correct answer: Reverberation
Reverberation artifacts appear as repeating hyperechoic lines at regular intervals deep to a highly reflective surface due to the sound beam bouncing back and forth.
Question 3: A cat presents with pleural effusion. On thoracic radiographs, which finding best differentiates pleural effusion from pulmonary consolidation?
- Air bronchograms within the opacity
- Retraction of lung lobes from the thoracic wall (Correct answer)
- Increased opacity in the perihilar region
- Loss of cardiac silhouette border
Correct answer: Retraction of lung lobes from the thoracic wall
Pleural effusion causes lung lobes to retract away from the thoracic wall, whereas consolidated lung lobes remain in contact with the chest wall.
Question 4: On abdominal radiographs, a 'string of pearls' gas pattern within the bowel wall is most suggestive of which condition?
- Ileus
- Pneumatosis intestinalis (Correct answer)
- Intussusception
- Foreign body obstruction
Correct answer: Pneumatosis intestinalis
Pneumatosis intestinalis (gas within the intestinal wall) produces a 'string of pearls' or bubbly gas pattern and is associated with intestinal necrosis or ischemia.
Question 5: When performing musculoskeletal ultrasound in a dog, a tendon appears hyperechoic with a fibrillar pattern when the beam is perpendicular, but becomes hypoechoic when the transducer is angled. This phenomenon is called:
- Shadowing artifact
- Anisotropy (Correct answer)
- Enhancement
- Refraction
Correct answer: Anisotropy
Anisotropy is the property of tendons and ligaments whereby echogenicity changes dramatically with beam angle relative to fiber orientation.
Question 6: Which radiographic view is most useful for evaluating the dens (odontoid process) of the axis (C2) in a dog for atlantoaxial instability?
- Lateral cervical with flexion
- Open-mouth ventrodorsal (Correct answer)
- Oblique cervical
- Lateral cervical with extension
Correct answer: Open-mouth ventrodorsal
The open-mouth ventrodorsal view projects the dens through the mouth and allows direct visualization of the atlantoaxial articulation and dens morphology.
Question 7: On CT of the nasal cavity in a dog with nasal discharge, which finding most strongly suggests fungal rhinitis (Aspergillus) rather than nasal neoplasia?
- Turbinate destruction with preserved nasal septum (Correct answer)
- Mass with smooth margins crossing the midline
- Fluid-filled nasal cavity with intact turbinates
- Periosteal reaction along the frontal bones
Correct answer: Turbinate destruction with preserved nasal septum
Aspergillus rhinitis typically causes extensive turbinate lysis/destruction while often leaving the nasal septum relatively intact, unlike neoplasia which often crosses the midline.
NAVLE Small Animal Diagnostic Imaging 2
On thoracic radiographs of a dog, which cardiac silhouette finding is most consistent with left atrial enlargement?