Chest x-ray is the go-to exam for patients presenting in the emergency room with lung conditions such as pneumonia or other lower respiratory tract infections. But CT produces better chest images, and improvements in the technology now allow for its use at a radiation dose comparable to x-ray, according to a team led by presenter Dr. Maadrika Kanglie.
Since the effectiveness of ultralow-dose CT in the emergency department isn't clear, Kanglie and colleagues conducted a study to compare diagnostic accuracy of low-dose CT and chest x-ray for lung diseases. The research included 2,312 patients randomized into either a CT group or an x-ray group between January 2017 and May 2018; the investigators tracked measures such as true and false positives.
The group found that ultralow-dose CT identified more pneumonia compared with chest x-ray and that the proportion of true positives for pneumonia was higher for CT than for x-ray. However, CT produced more false positives for pneumonia than chest x-ray.
CT identified more cases of lower respiratory tract infections than x-ray, and the proportion of true positives for this condition was higher. There were fewer false negatives and more false positives compared with x-ray, however.
Finally, the researchers also discovered that CT was less effective than x-ray for identifying pulmonary congestion.
"The lower accuracy of ultralow-dose CT for pulmonary congestion in our study might be related to the relative unfamiliarity of radiologists to identify [it on CT], as until now CT is seldom used for this indication," Kanglie and colleagues noted.