CT appearances and dynamic changes in severe acute respiratory syndrome

Objective: To study the CT appearances and dynamic imaging changes in clinically diagnosed severe acute respiratory syndrome (SARS). Methods: Sequential HRCT examinations at a 4-6 day interval were performed in 60 patients with SARS. The findings on CT images were analyzed. Results: HRCT was performed in 25 cases within 3 days after onset when the disease was at the initial stage. The small focal patchy opacity was found in 22 cases (88.0%, 22/25), and oval small ground-glass opacities in 20 cases (80.0%, 20/25) were among those cases. In another 35 cases, the first HRCT scans were performed 3 days later after onset when the disease was at the progressive stage. Multiple larger opacities were visualized in all cases at the progressive stage, they included the pure ground-glass opacities in 10 cases (16.7%, 10/60), ground-glass opacities accompanied by consolidation in 45 (75.0%, 45/60), prominent consolidations in 5 (8.3%, 5/60). The lesions strongly progressed in 50 cases (83.3%, 50/60) and distinctly resolved in 10 cases (16.7%, 10/60) within 10-14 days after admission. The pulmonary interstitial hyperplasia was found in 4 cases (6.7%, 4/60). Conclusion: HRCT was able to distinctly demonstrate the density, shape, and range of pulmonary lesions of SARS, and reflect the alternation due to the interstitial hyperplasia of the lungs. HRCT can be used to display the early abnormalities and dynamic changes of SARS