Radiologists can estimate the risk of death to a SARS patient by the seventh day from the onset of symptoms by using chest radiographs, a new study said Wednesday.

This early determination can allow a physician to better tailor treatment for the SARS patient, researchers in Hong Kong, China, said in a paper appearing in the March 2005 issue of the American Journal of Roentgenology.

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.

They 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, according to Gregory E. Antonio, a researcher at 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 percent lung opacification on the seventh day, whereas 86 percent of those who survived had less than 10 percent lung opacification on the seventh day, data in the research showed.

"The radiographic scores (percentage of lung or the number of zones opacified) obtained by day 7 were the earliest ones with good performance in prognostic prediction, and could be used as fatal prognostic indicators," the researchers concluded in the paper.

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.

The new 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, Antonio said.

(Xinhua News Agency March 3, 2005)