Acute respiratory distress syndrome caused by pulmonary and extrapulmonary injury: a comparative CT study.
OBJECTIVE
To determine computed tomographic (CT) differences between acute respiratory distress syndrome (ARDS) due to pulmonary injury (ARDS(p)) and extrapulmonary injury (ARDS(ex)).


METHODS
CT appearances in 41 patients (27 male, 14 female; mean age, 47.1 years +/- 17.1 [SD]; age range, 17-79 years; those with ARDS(p), n = 16; those with ARDS(ex), n = 25) were categorized as typical or atypical of ARDS by two observers. The extent of individual CT patterns was also quantified.


RESULTS
Typical CT appearances were more frequent in ARDS(ex) than ARDS(p) (18 [72%] of 25 vs five [31%] of 16 patients, respectively; P <.01). Sensitivity, specificity, and accuracy of a typical CT pattern for the diagnosis of ARDS(ex) were 72%, 69%, and 71%, respectively. Atypical appearances were characterized by more extensive nondependent intense parenchymal opacification (IPO) (P =.03) and cysts (P =.05), whereas typical CT appearances had more extensive dependent IPO (P =.01). Typical appearances at CT were independently related to the cause of ARDS (odds ratio, 8.9; 95% CI: 1.8, 44.2; P <.01) but were independent of the time from intubation. Foci of nondependent IPO were more extensive in ARDS(p) (P =.05) than ARDS(ex), but this finding was ascribable to differences in time to CT (after intubation) between ARDS(p) and ARDS(ex).


CONCLUSIONS
The differentiation between ARDS(p) and ARDS(ex) can, with some caveats, be based on whether the CT appearances are typical or atypical of ARDS but not on any individual CT pattern in isolation.
Department of Radiology, Royal Brompton Hospital, Sydney St, London SW3 6NP, England.
S R
SR
Desai
A U
AU
Wells
G
G
Suntharalingam
M B
MB
Rubens
T W
TW
Evans
D M
DM
Hansell
D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008171:Lung Diseases / Q000150:complications* / Q000473:pathology; D055370:Lung Injury; D008297:Male; D008875:Middle Aged; D012128:Respiratory Distress Syndrome / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000473:pathology; D014057:Tomography, X-Ray Computed