In a retrospective analysis of patients from the Community-Acquired Pneumonia Organization international cohort study, PA and lateral radiographs had a sensitivity of 83.9% versus 67.3% for AP radiographs when using CT as the reference standard [29]. Single-view PA, single lateral view, or single-view AP radiographs have been shown to have statistically equivalent sensitivities for detection of parapneumonic effusions [30], with most missed parapneumonic effusions occurring in patients with coexistent lower lobe consolidation [30]. The specificity of chest radiography for the detection of complicated parapneumonic effusions, defined as those requiring thoracentesis, is modest. For example, in a retrospective study of 66 patients undergoing thoracentesis for parapneumonic effusions, chest radiography had a specificity of 60% for the detection of complicated parapneumonic effusions [31]. US Chest Identification of a pleural effusion for possible US-guided thoracentesis is currently the primary reason for chest US [32]. Current American Association for Thoracic Surgery consensus guidelines recommend thoracic US for the diagnostic evaluation of pleural space infection (class I), typically occurring in patients with prior imaging documenting the presence of a pleural effusion [13]. US findings of septations [33,34], increased echogenicity of the pleural effusion [31,35], pleural thickening [36], and microbubbles [37] are associated with parapneumonic effusion/empyema. A retrospective study of 66 patients with suspected parapneumonic effusion found that US chest had a significantly higher specificity (90%, 95% CI, 76.3%-97.2%) and a nonsignificant difference in sensitivity (69.2%, 95% CI, 48.2%-87.7%) compared with CT chest for the diagnosis of complicated parapneumonic effusion [31]. A retrospective comparison of US chest and CT chest in pediatric patients found similar accuracy for the detection of parapneumonic effusion [38].
Workup of Pleural Effusion or Pleural Disease. In a retrospective analysis of patients from the Community-Acquired Pneumonia Organization international cohort study, PA and lateral radiographs had a sensitivity of 83.9% versus 67.3% for AP radiographs when using CT as the reference standard [29]. Single-view PA, single lateral view, or single-view AP radiographs have been shown to have statistically equivalent sensitivities for detection of parapneumonic effusions [30], with most missed parapneumonic effusions occurring in patients with coexistent lower lobe consolidation [30]. The specificity of chest radiography for the detection of complicated parapneumonic effusions, defined as those requiring thoracentesis, is modest. For example, in a retrospective study of 66 patients undergoing thoracentesis for parapneumonic effusions, chest radiography had a specificity of 60% for the detection of complicated parapneumonic effusions [31]. US Chest Identification of a pleural effusion for possible US-guided thoracentesis is currently the primary reason for chest US [32]. Current American Association for Thoracic Surgery consensus guidelines recommend thoracic US for the diagnostic evaluation of pleural space infection (class I), typically occurring in patients with prior imaging documenting the presence of a pleural effusion [13]. US findings of septations [33,34], increased echogenicity of the pleural effusion [31,35], pleural thickening [36], and microbubbles [37] are associated with parapneumonic effusion/empyema. A retrospective study of 66 patients with suspected parapneumonic effusion found that US chest had a significantly higher specificity (90%, 95% CI, 76.3%-97.2%) and a nonsignificant difference in sensitivity (69.2%, 95% CI, 48.2%-87.7%) compared with CT chest for the diagnosis of complicated parapneumonic effusion [31]. A retrospective comparison of US chest and CT chest in pediatric patients found similar accuracy for the detection of parapneumonic effusion [38].