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A 34-year-old man presented to the ED with a persistent nonproductive cough, myalgias, coryza, and a low-grade fever that he had had for three days.

He was otherwise healthy, smoked half a pack of cigarettes per day, and had no history of asthma, pneumonia, or HIV risk factors.

On examination, he appeared well, and his vital signs were normal aside from a temperature of 100.4°F. He had a slight end-expiratory wheeze on lung auscultation. He was treated with an inhaled bronchodilator. His chest radiograph showed increased opacity in the lower portions of both lungs and indistinct lung markings (Figure 1). The lateral portion of the left heart border was obscured.

The radiograph was interpreted as showing bibasilar infiltrates.

  • Do you agree with this interpretation?

Subtle radiographic signs of pneumonia (focal airspace filling) include indistinct pulmonary vascular markings and obliteration of a normal lung/soft tissue interface (the silhouette sign). Such findings seemed to be present in this patient. At the right base, there is increased opacity and indistinct lung marking. On the left, there is partial obliteration of the left heart border (Figure 1A).

However, the patient’s clinical presentation was more consistent with an upper respiratory tract infection or bronchitis than a multilobar pneumonia. Furthermore, on the lateral view, there are no corresponding areas of increased lung opacity either overlying the heart in the lingula or right middle lobe, or behind the heart in the right or left lower lobes (Figure 1B). An additional finding on the PA view is an abnormally increased cardiothoracic ratio—the width of the heart is greater than half the width of the thorax, suggesting that the patient has an enlarged heart (Figure 1A).

The disparities between the patient’s clinical and radiographic findings and between findings on the PA and lateral radiographs serve as a reminder that a systematic approach to radiograph interpretation should begin with an assessment of the technical adequacy of the radiographs. In this case, the x-ray penetration is correct (thoracic vertebral bodies are visible behind the heart) and the patient has been correctly positioned without rotation. However, the level of inspiration is inadequate—only the 9th rib is visible at the right cardiophrenic sulcus, whereas with a full inspiration, the 10th or 11th rib should be seen in this location (Figure 2).

Figure 2

Initial PA view—Patient 3.

The vascular markings at both lung bases are crowded and indistinct. The left heart border is indistinct. The heart appears enlarged and has a horizontal orientation. These findings are due to the patient’s incomplete inspiration—the ninth ...

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