Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Left cranial lung lobe pulmonary artery is more easily visualized in the lateral thoracic radiographs, as compared to the right cranial lung lobe pulmonary artery.
Reason (R) : The left cranial lung lobe pulmonary artery is located more dorsally in the thorax and is usually superimposed on other vessels or the thicker dorsal part of the mediastinum.
In light of the above statements, choose the correct answer from the options given below

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

On a lateral thoracic radiograph, the cranial lobar vessels follow a standard ventral-to-dorsal relationship: "Artery - Bronchus - Vein" (ABV) from dorsal to ventral.
The right cranial lobar vessels are always positioned more cranially than the left, making the right vessels easier to evaluate.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
In veterinary thoracic radiology, interpreting lateral radiographs requires a detailed understanding of the anatomical positioning of the lobar pulmonary vessels and bronchi, along with how they superimpose on other structures.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Assertion (A):
On a lateral thoracic radiograph of a dog or cat, the right cranial lobar pulmonary vessels are located ventral and cranial to the left cranial lobar vessels.
Because the right cranial lobar pulmonary artery is situated further cranially and has minimal overlying structures, it is typically much easier to identify and visualize clearly compared to the left cranial lobar artery.
The left cranial lobar artery is often partially obscured by surrounding tissues.
Therefore, Assertion (A) is incorrect (false).
- Reason (R):
The left cranial lung lobe pulmonary artery is positioned more dorsally and caudally relative to the right cranial lobar artery.
Due to this dorsal position, it is frequently superimposed on the cranial vena cava, the trachea, or the thick soft-tissues of the cranial mediastinum, which makes it harder to visualize clearly on lateral radiographs.
Therefore, Reason (R) is correct (true).
Thus, Assertion (A) is false, but Reason (R) is true.

Step 3: Final Answer:
The correct option is (D).