title: Pleural exudates and transudates: diagnosis with contrast-enhanced CT.
abstract: OBJECTIVE
  To determine the accuracy of computed tomography (CT) in enabling differentiation of pleural exudates from transudates.
  
  
  METHODS
  Eighty consecutive patients (86 effusions) underwent contrast-enhanced CT. Thoracentesis was performed to measure pleural and serum total protein and lactate dehydrogenase (LDH) values. Effusions were classified as exudates with accepted criteria. CT scans were evaluated for the presence and appearance of parietal pleural and extrapleural fat thickening.
  
  
  RESULTS
  Fifty-nine effusions were exudates and 27 were transudates. Thirty-six of the 59 exudates (61%) were associated with parietal pleural thickening. All cases of empyema and 56% of the parapneumonic exudative effusions had pleural thickening. The specificity of this finding in diagnosing the presence of an exudate is 96%.
  
  
  CONCLUSIONS
  Parietal pleural thickening at contrast-enhanced CT almost always indicates the presence of a pleural exudate. A pleural exudate in the absence of pleural thickening occurs most frequently in patients with malignancy or uncomplicated parapneumonic effusion.
authors.affiliation: Department of Radiology, University of California, San Francisco 94143-0628.
authors.forename: S L
authors.initials: SL
authors.lastname: Aquino
authors.forename: W R
authors.initials: WR
authors.lastname: Webb
authors.forename: B J
authors.initials: BJ
authors.lastname: Gushiken
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003937:Diagnosis, Differential; D005122:Exudates and Transudates / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D010994:Pleura / Q000000981:diagnostic imaging; D010995:Pleural Diseases / Q000000981:diagnostic imaging*; D010996:Pleural Effusion / Q000000981:diagnostic imaging / Q000209:etiology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed
chemical_list: D007472:Iohexol