NAVLE Small Animal Diagnostic Imaging Questions and Answers

Question 1

A 5-year-old dog presents with acute vomiting and abdominal pain. Abdominal radiographs reveal a segment of small intestine that is severely dilated with gas, proximal to a segment of normal-caliber, empty-appearing small intestine. What is this radiographic finding, often referred to as 'two populations of bowel,' most indicative of?

Accepted Answer

Mechanical obstruction

Answer

The presence of two distinct populations of bowel (one severely dilated and one normal or empty) is a classic radiographic sign of a complete or high-grade mechanical obstruction. The intestine proximal to the blockage becomes distended with gas and fluid, while the intestine distal to the obstruction remains empty. Functional ileus and gastroenteritis typically cause a more generalized, mild to moderate dilation of the intestines without a clear transition point.

Question 2

On abdominal ultrasound of a cat with stranguria, a hyperechoic structure is identified in the center of the urinary bladder. The structure produces a clean, dark vertical band beneath it that obscures deeper tissues. Which of the following best describes this artifact and the most likely identity of the structure?

Accepted Answer

Acoustic shadowing from a urolith

Answer

A urolith (bladder stone) is a mineralized, dense structure that is hyperechoic (bright) on ultrasound. It strongly reflects or attenuates the ultrasound beam, preventing it from passing through to the tissues below. This creates a signal void, or 'acoustic shadow,' which appears as a dark band deep to the stone. A gas bubble would also shadow but typically creates a 'dirty' shadow with reverberation. A blood clot is typically hyperechoic but not dense enough to cause shadowing. A polyp is a soft tissue structure and would not cause shadowing.

Question 3

A 6-year-old Dachshund presents with acute onset of non-ambulatory paraparesis and spinal hyperesthesia localized to the T3-L3 region. Which imaging modality is considered the gold standard for definitively diagnosing intervertebral disc extrusion and assessing the degree of spinal cord compression?

Accepted Answer

Magnetic Resonance Imaging (MRI)

Answer

Magnetic Resonance Imaging (MRI) is the gold standard for imaging the spinal cord and associated soft tissues. It provides excellent detail of the disc material, spinal cord parenchyma, and nerve roots, allowing for precise localization of the extruded disc and evaluation of secondary cord changes like edema or hemorrhage. While CT and myelography can identify cord compression, MRI offers superior soft tissue contrast without the need for intrathecal contrast injection.

Question 4

You are evaluating thoracic radiographs of an older cat with a history of a previously removed mammary carcinoma. The lung fields show multiple, well-defined, variably sized nodules of soft tissue opacity. Which of the following is the most likely interpretation of this pulmonary pattern?

Accepted Answer

Metastatic neoplasia

Answer

The presence of multiple, well-defined, soft tissue nodules (often called a 'cannonball' pattern, though they can be small) throughout the lung fields is the classic radiographic appearance of hematogenous metastatic neoplasia. Fungal pneumonia can also be nodular but is often less defined. Feline asthma typically presents with a bronchial pattern ('donuts' and 'tram lines'). Cardiogenic edema usually appears as an unstructured interstitial to alveolar pattern, often with a patchy distribution.

Question 5

A 4-year-old male Dalmatian has recurrent stranguria. Survey abdominal radiographs are unremarkable. Given this breed's predisposition to radiolucent uroliths, which contrast study is most appropriate to definitively identify their presence within the bladder?

Accepted Answer

Double contrast cystogram

Answer

Dalmatians are prone to forming urate uroliths, which are often radiolucent and not visible on survey radiographs. A double contrast cystogram is the ideal study in this case. This technique uses a small amount of positive contrast medium to coat the bladder wall and any uroliths, followed by distention with negative contrast (gas). The radiolucent uroliths are then outlined by the positive contrast, making them visible against the dark, gas-filled lumen. A positive contrast study alone could obscure the stones.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Small Animal Diagnostic Imaging Questions and Answers