Early Appearance of Severe Acute Respiratory Syndrome (SARS) on Chest Computed Tomography (CT) and Its Role in Early Diagnosis

摘要

Objective To evaluate the early appearance of severe acute respiratory syndrome (SARS) on chest computed tomography (CT) scan and its role in the early diagnosis. Methods 40 cases of SARS in keeping with criteria from the Chinese Ministry of Health ( equivalent of probable case of WHO criteria) had chest CT scans within 7 days after onset of symptoms, Computerized radiograph (CR) chest X - rays were available as well. These chest X - rays and CT images were retrospectively reviewed to determine if there were any abnormalities on the images. The lesions on the chest CT images were then further analyzed in terms of the number, location, size and density. Results All 40 cases of SARS were positive for abnormalities on chest CT scans, only 25 cases were positive on chest CR, equivocal in 5 and normal in 9 cases. The main abnormalities seen on CT and X- rays were pulmonary infiltrates varied markedly in severity.70% cases had 1 or 2 lesions on chest CT scan, 30% cases had 3 or more lesions. The lesions seen on chest CT scan tended to be ground - glass opacity, sometimes with consolidation. These lesions were very faint and inhomogeneous, easily missed on chest X - rays. Typically the lesions were located in the periphery of the lung, or both central and peripheral, very rare in a purely central location. They were commonly in the shape of patch or ball. Conclusions Chest CT scan is much more sensitive in detecting lesions of the lung in SARS. The early appearance of SARS on chest CT scan is characteristic, but nonspecific. Both indicate that chest CT scan plays a very important role in early diagnosis and differential diagnosis of SARS.