NAVLE Small Animal Diagnostic Imaging 5 — Questions and Answers
Question 1: On abdominal radiographs, a 'gravel sign' (multiple small mineral opacities) within a bowel loop is most suggestive of:
- Urolithiasis with passed stones
- Small intestinal foreign body obstruction (Correct answer)
- Feline hyperthyroidism-related GI changes
- Chronic pancreatitis with calcification
Correct answer: Small intestinal foreign body obstruction
The 'gravel sign' represents accumulation of mineral debris proximal to a small intestinal obstruction where normal transit is blocked, concentrating ingested minerals.
Question 2: Which Doppler modality provides a color-coded two-dimensional map of blood flow direction and velocity within a vessel or cardiac chamber?
- Pulsed wave Doppler
- Continuous wave Doppler
- Color flow Doppler (Correct answer)
- Power Doppler
Correct answer: Color flow Doppler
Color flow Doppler superimposes a color-coded map of mean flow velocity and direction over the B-mode image, using red/blue by convention for flow toward/away from the transducer.
Question 3: A dog has a myelogram that shows a contrast column that is deviated to one side and compressed at a single level but does not completely stop. This pattern is most consistent with:
- Extradural compression (disc herniation) (Correct answer)
- Intradural-extramedullary mass
- Intramedullary lesion (tumor/edema)
- Normal variant
Correct answer: Extradural compression (disc herniation)
Extradural lesions (such as disc material or vertebral bone) deviate and compress the contrast column from the outside without interrupting the intrathecal flow completely.
Question 4: On ultrasound of the urinary bladder, a dependent hyperechoic layer with acoustic shadowing that moves when the patient is repositioned most likely represents:
- Bladder wall thickening
- Transitional cell carcinoma
- Uroliths (bladder stones) (Correct answer)
- Blood clots
Correct answer: Uroliths (bladder stones)
Uroliths are hyperechoic foci with acoustic shadowing that are gravity-dependent and shift position when the patient moves, distinguishing them from wall masses.
Question 5: Which MRI finding is characteristic of syringomyelia (syrinx) in a Cavalier King Charles Spaniel with Chiari-like malformation?
- T1 hyperintense intramedullary lesion
- T2 hyperintense fluid-filled cavity within the spinal cord (Correct answer)
- Contrast-enhancing ring lesion within the cord
- T2 hypointense lesion in the dorsal columns
Correct answer: T2 hyperintense fluid-filled cavity within the spinal cord
A syrinx appears as a T2 hyperintense (fluid signal) cavity within the spinal cord parenchyma on MRI, reflecting the accumulation of CSF-like fluid.
Question 6: On abdominal radiographs, which finding is MOST consistent with a congenital portosystemic shunt in a young dog?
- Splenomegaly with portal vein dilation
- Microhepatica (small liver) with renomegaly (Correct answer)
- Hepatomegaly with ascites
- Normal liver size with splenic mineralization
Correct answer: Microhepatica (small liver) with renomegaly
Congenital portosystemic shunts divert hepatotrophic factors away from the liver, causing microhepatica; compensatory renal hypertrophy often produces concurrent renomegaly.
Question 7: A cat's thoracic CT shows a pulmonary mass with a 'halo sign' (ground-glass opacity surrounding a solid nodule). This finding in cats is most associated with:
- Primary lung adenocarcinoma
- Pulmonary lymphoma
- Fungal pneumonia (cryptococcosis) (Correct answer)
- Feline asthma
Correct answer: Fungal pneumonia (cryptococcosis)
The CT halo sign represents hemorrhage or inflammatory infiltrate surrounding a fungal nodule and is classically associated with angioinvasive fungal infections including Cryptococcus in cats.
NAVLE Small Animal Diagnostic Imaging 5
On abdominal radiographs, a 'gravel sign' (multiple small mineral opacities) within a bowel loop is most suggestive of: