VTNE Diagnostic Imaging Techniques 4 — Questions and Answers
Question 1: Which contrast medium is typically used for a positive-contrast cystogram in small animals?
- Barium sulfate suspension
- Iodinated water-soluble contrast agent (Correct answer)
- Carbon dioxide gas
- Saline solution
Correct answer: Iodinated water-soluble contrast agent
Iodinated water-soluble contrast agents (e.g., iohexol) are used for cystography because barium is contraindicated if bladder rupture is possible and would be hazardous in the peritoneal cavity.
Question 2: On thoracic radiographs, which cardiac measurement is used to objectively assess heart size in dogs?
- Cardiothoracic ratio
- Vertebral heart score (VHS) (Correct answer)
- Left atrial to aortic root ratio
- Pulmonary vein diameter
Correct answer: Vertebral heart score (VHS)
The vertebral heart score (VHS) measures cardiac long and short axes and compares their sum to thoracic vertebral body lengths, providing a breed-adjusted assessment of heart size.
Question 3: A radiograph of a cat's abdomen reveals a 'string of pearls' pattern in the small intestine. This finding suggests:
- Normal gas distribution
- Mechanical ileus with gas trapped in mucosal folds (Correct answer)
- Functional ileus
- Intussusception
Correct answer: Mechanical ileus with gas trapped in mucosal folds
A 'string of pearls' pattern describes small oval gas bubbles trapped between mucosal folds, a classic sign of mechanical small intestinal obstruction.
Question 4: Which statement about nuclear scintigraphy (gamma scintigraphy) is CORRECT?
- It provides superior anatomical detail compared to MRI
- It uses radioactive tracers to evaluate physiologic function (Correct answer)
- It is primarily used for soft tissue mass biopsy guidance
- It does not produce ionizing radiation
Correct answer: It uses radioactive tracers to evaluate physiologic function
Nuclear scintigraphy uses radiopharmaceuticals (radioactive tracers) that localize to specific tissues or organs, allowing functional assessment such as thyroid activity or bone metabolism.
Question 5: When taking a radiograph of a rabbit's skull, which positioning is MOST important for a true lateral view?
- Ensuring both tympanic bullae are superimposed (Correct answer)
- Placing the rabbit in sternal recumbency
- Angling the beam 20° caudally
- Using high kVp to penetrate the dense skull
Correct answer: Ensuring both tympanic bullae are superimposed
True lateral skull positioning requires both tympanic bullae to be superimposed; any rotation will separate them and distort assessment of the nasal passages, teeth, and bullae.
Question 6: During ultrasound-guided fine-needle aspiration, the needle appears as a bright hyperechoic line because of:
- The needle's high water content
- Specular reflection of sound waves off the metal surface (Correct answer)
- Acoustic enhancement distal to the needle
- Refraction artifact
Correct answer: Specular reflection of sound waves off the metal surface
The smooth metal surface of the needle acts as a specular reflector, returning nearly all ultrasound energy back to the transducer, creating a bright hyperechoic appearance.
Question 7: What is the recommended minimum distance a non-PPE-wearing person should stand from the primary X-ray beam during a radiographic exposure in a clinical setting?
- 1 meter
- 2 meters
- 3 meters (Correct answer)
- 6 feet
Correct answer: 3 meters
NCRP guidelines recommend non-PPE personnel stand at least 2 meters (approximately 6 feet) from the X-ray tube and the primary beam during an exposure.
VTNE Diagnostic Imaging Techniques 4
Which contrast medium is typically used for a positive-contrast cystogram in small animals?