Which of the following is NOT a sign of cardiac decompensation on radiography?

The narrowing of the space between the ribs is not typically a sign of cardiac decompensation seen on radiographic studies. Instead, signs of cardiac decompensation are more commonly associated with observable changes in the heart and lung fields.

Cephalization of pulmonary blood vessels, enlargement of the heart, and pleural effusions are all significant indicators of heart failure on imaging studies. Cephalization refers to the redistribution of blood flow in the lungs due to increased pressure in the pulmonary circulation, which is often a result of left heart failure. Heart enlargement, or cardiomegaly, signifies volume overload or heart strain. Pleural effusions are fluid collections that can occur due to increased hydrostatic pressure from heart failure, indicating worsening cardiac function.

The space between the ribs, or the intercostal space, is influenced by various factors including lung volume and body posture, but it does not specifically indicate cardiac dysfunction. It may change for other reasons unrelated to heart failure, which is why narrowing in this area is not a recognized sign of decompensation in the context of radiographic assessment.