Purpose

To prospectively evaluate lung parenchyma on paired inspiration-expiration thin-section computed tomographic (CT) scans in patients recovering from severe acute respiratory syndrome (SARS).

Materials and methods

After the institutional review board approved the study and written consent was obtained from patients, 40 patients (25 female, 15 male; mean age, 42.8 years +/- 12.3 [standard deviation]) underwent thin-section CT at 51.8 days +/- 20.2 after onset of SARS symptoms. Twenty of the 40 patients underwent follow-up thin-section CT at 140.7 days +/- 26.7 after symptom onset. Lung findings were scored according to extent and then grouped in three categories (ground-glass opacity, interstitial opacity, and air trapping) for analysis. Mean CT scores for each finding in the various patient subgroups were compared by using the Mann-Whitney test. Clinical parameters and scores were evaluated for correlation by using Spearman rank correlation analysis. Mean scores for each finding were compared between the two serial examinations by using the Wilcoxon matched-pairs signed rank test.

Results

Air trapping, ground-glass opacity, and reticulation were found in 37 (92%), 36 (90%), and 28 (70%) of 40 patients, respectively, at initial thin-section CT examination and in 16 (80%), 14 (70%), and 10 (50%) of 20 patients, respectively, at follow-up examination. Scans from patients with adult respiratory distress syndrome (ARDS) had a significantly higher score for ground-glass opacity than did those from patients without ARDS (P = .009). A comparison of scores for the serial thin-section CT examinations indicated a significant reduction in the extent of ground-glass opacity (P < .001) and interstitial opacity (P < .001) but not in that of air trapping (P = .38) at follow-up examination. At initial thin-section CT, scores for ground-glass opacity, interstitial opacity, and air trapping correlated with age; those for ground-glass opacity and air trapping, with peak C-reactive protein level. At the second examination, scores for ground-glass opacity and interstitial opacity correlated with peak lactate dehydrogenase level; that for air trapping, with age and peak C-reactive protein level.

Conclusion

Thin-section CT scores correlated with clinical and laboratory parameters in patients after SARS. Although ground-glass opacity and interstitial opacity resolve over time, air trapping persists.