NAVLE Diagnostic Imaging Interpretation 4 — Questions and Answers
Question 1: Which finding on thoracic radiographs of a cat is MOST suggestive of hypertrophic cardiomyopathy (HCM)?
- Valentine-shaped heart on VD view with left atrial enlargement (Correct answer)
- Globoid cardiac silhouette with loss of cardiac waist
- Right-sided cardiomegaly with increased sternal contact
- Microcardia with retraction of lung lobes
Correct answer: Valentine-shaped heart on VD view with left atrial enlargement
HCM in cats classically produces a Valentine or bivalve-shaped cardiac silhouette on the VD view due to biatrial enlargement.
Question 2: On abdominal radiographs, retroperitoneal effusion is BEST identified by:
- Loss of renal and sublumbar muscle detail with preserved peritoneal serosal detail (Correct answer)
- Loss of all serosal detail including the bladder and intestines
- Gas accumulation dorsal to the kidneys
- Displacement of the colon ventrally
Correct answer: Loss of renal and sublumbar muscle detail with preserved peritoneal serosal detail
Retroperitoneal effusion selectively obliterates retroperitoneal structures (kidneys, sublumbar muscles) while intraperitoneal serosal detail (bladder, gut) may remain visible.
Question 3: What is the significance of 'air bronchograms' on thoracic radiographs?
- Air-filled bronchi are visible because surrounding alveoli are fluid-filled, indicating alveolar disease (Correct answer)
- The bronchi contain fluid while the alveoli are normally aerated
- Gas is present within the bronchial walls
- Pleural air outlines the bronchi from the outside
Correct answer: Air-filled bronchi are visible because surrounding alveoli are fluid-filled, indicating alveolar disease
Air bronchograms occur when alveolar consolidation or fluid makes normally invisible air-filled bronchi visible by contrast.
Question 4: On ultrasound of the urinary bladder, a non-shadowing, gravity-dependent echogenic material that shifts with patient repositioning is MOST consistent with:
- Cystic calculi too small to shadow (sludge/crystalluria) (Correct answer)
- Transitional cell carcinoma
- Blood clot
- Polypoid cystitis
Correct answer: Cystic calculi too small to shadow (sludge/crystalluria)
Fine echogenic material that is gravity-dependent and moves freely with repositioning but does not shadow is consistent with fine crystalluria or bladder sludge.
Question 5: In nuclear scintigraphy, a 'cold spot' on a thyroid scan in a dog MOST likely represents:
- Nonfunctional or necrotic tissue within the thyroid (Correct answer)
- Hyperfunctional adenoma
- Normal thyroid tissue
- Ectopic thyroid tissue
Correct answer: Nonfunctional or necrotic tissue within the thyroid
A cold (photopenic) area on thyroid scintigraphy indicates reduced radionuclide uptake, consistent with nonfunctional, necrotic, or cystic tissue.
Question 6: On orthogonal radiographs of a long bone, periosteal new bone with a 'sunburst' pattern is MOST characteristic of:
- Primary bone tumor (osteosarcoma) (Correct answer)
- Nutritional secondary hyperparathyroidism
- Hypertrophic osteopathy
- Septic osteomyelitis
Correct answer: Primary bone tumor (osteosarcoma)
A sunburst or spiculated periosteal reaction radiating perpendicular to the cortex is a classic aggressive pattern associated with osteosarcoma.
Question 7: Which imaging modality is BEST for evaluating the extent of soft tissue masses adjacent to bone in a dog?
- MRI (Correct answer)
- Plain radiography
- Nuclear scintigraphy
- Fluoroscopy
Correct answer: MRI
MRI provides superior soft tissue contrast resolution compared to CT, radiography, and scintigraphy, making it the modality of choice for soft tissue mass characterization.
NAVLE Diagnostic Imaging Interpretation 4
Which finding on thoracic radiographs of a cat is MOST suggestive of hypertrophic cardiomyopathy (HCM)?