This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Xray chest shows ground glass opacity in all of the following conditions, EXCEPT: 
Select and explain. 
A. Pneumonia, B. Hyaline membrane disease, C. Left to right cardiac shunt, D. Obstructive TAPVC
C: Left to right cardiac shunt
Answer: C: Left to right cardiac shunt 
Explanation: In the left to right cardiac shunt the flow of pulmonary and systemic circulation is balanced and hence there is no pulmonary oedema or hypeension. So, ground glass opacity is not found on Xray. Left to right shunts are the most common type of congenital hea defect and feature shunting of blood from the oxygenated higher pressure left side to the lower pressure right side. 3 main types of left to right shunts are ASD, VSD AND Patent ductus aeriosus. Uncorrected left to right shunt leads to pulmonary hypeension, right hea failure and death. Ref: Radiologic-Pathologic Correlations from Head to Toe: Understanding the Manifestations of Disease By Nicholas C. Gousoyiannis, Pablo R. Ros, 2005, Pages 137-139; The Nature Of Disease: Pathology for The Health Professions By Thomas H. McConnell, Page 316.