The researchers analyzed 4,369 chest radiographs from 313 SARS patients from the time of their admission into the hospital until death (in 48 of the patients) or discharge from the hospital. The researchers found that by looking at the amount of lung opacification (white shadows in the lungs on the radiographs where black areas denoting air should be), they could predict with a reasonable degree of accuracy whether the case of SARS in the patient was a potentially fatal one.
"SARS usually presents as a chest infection. Similar to other types of chest infections, the lungs may show areas of opaqueness when a chest radiograph is performed," said Gregory E. Antonio, MD, of the Chinese University of Hong Kong and lead author of the study. More than half of the patients who died from the disease had greater than 20% lung opacification on the seventh day, whereas 86% of those who survived had less than 10% lung opacification on the seventh day.
According to the study authors, speed is of great importance in an epidemic like SARS, both in terms of diagnosis and of assessing progress during treatment. "Our findings could help decide on a change in the treatment for a patient, such as introducing new drugs, using more aggressive treatment or transferring the patient to a specialized unit. They also might help in establishing measures that could reduce the mortality rate of the disease," said Dr. Antonio.
The study appears in the March 2005 issue of the American Journal of Roentgenology.