Pleural fluid: accuracy of computed tomography in differentiating exudates from transudates

To determine the accuracy of computed tomography in differentiating pleural exudates from transudates when reviewed subjectively by two experienced radiologists in a community hospital.

Computed tomography scans of 55 consecutive patients who had a thoracenteses within 10 days of the study were retrospectively reviewed independently by two experienced staff radiologists. They were asked to evaluate subjectively parietal pleural thickness (anterior, lateral, posterior), attenuation of extra-pleural fat, and categorize pleural fluid as loculated or free flowing. Radiographic findings were correlated with biochemical results of thoracentesis (Light's criteria) to assess the accuracy of computed tomography in differentiating pleural exudates from transudates.

For the diagnosis of an exudate, pleural thickening alone had the best sensitivity and specificity (50%, 100%, respectively) with an accuracy of 55%.

Subjective evaluations for increased pleural thickness have a high accuracy for diagnosing pleural exudates.