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Thin-section CT of severe acute respiratory syndrome: evaluation of 73 patients exposed to or with the disease.

PURPOSE
To retrospectively analyze the thin-section computed tomographic (CT) features in patients with severe acute respiratory syndrome (SARS) at the authors' institution.


MATERIALS AND METHODS
From March 11, 2003, to April 2, 2003, 74 patients with symptoms and signs suggestive of SARS underwent CT of the thorax; all underwent thin-section CT except for one patient who underwent conventional CT. Group 1 (n = 23) patients had symptoms of SARS in keeping with criteria from the Centers for Disease Control and Prevention and a positive chest radiograph. Group 2 (n = 17) patients had a high clinical suspicion of SARS but a normal radiograph. Group 3 (n = 34) patients had minor symptoms and a normal chest radiograph. The thin-section CT images were analyzed for ground-glass opacification or consolidation, lesion size in each lung segment, peripheral or central location, interstitial thickening, and other abnormalities.


RESULTS
Thin-section CT scans were abnormal only for patients in groups 1 and 2. The patient with only conventional CT scans was in group 3; scans for group 3 patients were normal. Affected segments were predominantly in the lower lobes (91 of 149 affected segments). Common findings included ground-glass opacification, sometimes with consolidation, and interlobular septal and intralobular interstitial thickening. The size of each lesion and the total number of segments involved were smaller in group 2 patients. A majority of patients in group 1 (14 of 23) had mixed central and peripheral lesions. In group 2, however, peripheral lesions were more common (10 of 17). In both groups, a purely central lesion was uncommon (one of 23 in group 1 and two of 17 in group 2).


CONCLUSION
Common thin-section CT features of SARS are ground-glass opacification and lower lobe and peripheral distribution.