The Role of CT Pulmonary Angiography in the Investigation of Unilateral Pleural Effusions

Abstract

Background: Pulmonary embolism (PE) is frequently cited as a common primary cause of unilateral pleural effusion, but in clinical practice appears to be uncommon. Objectives: In order to evaluate this observation, CT pulmonary angiography (CTPA) was performed in consecutive patients presenting to a single centre with a new uninvestigated unilateral pleural effusion and no clear cause and was supplemented by delayed-phase thoracic CT, optimized for visualization of the pleura. Methods: All patients underwent standard clinical assessment and pleural investigations in line with recent national guidelines and were followed up for a minimum of 1 year or until histological/microbiological diagnosis. Results: One hundred and fifty patients were recruited, and of these, 141 had a CTPA. PEs were detected in 9/141 (6.4%) patients, and of these, 8/9 were subsequently diagnosed with pleural malignancy. In only 1 case was PE clinically suspected and in no case was PE the primary cause of effusion; 9.8% (8/82) of patients who were ultimately diagnosed with pleural malignancy had PE at presentation. Conclusions: This study indicates that PE is a frequent concomitant finding in patients with malignant effusions but uncommon as a primary cause of unilateral effusion. In addition, it highlights the known difficulty of clinical diagnosis of PE in the context of malignancy. In view of this, we recommend that CTPA combined with pleural-phase thoracic CT should be considered at presentation when investigating patients with suspected malignant pleural effusion.

The diagnostic performance of routinely acquired and reported computed tomography imaging in patients presenting with suspected pleural malignancy

“…In a previous prospective study Hooper et al performed CTPA and late arterial phase CT (optimised for pleural imaging) in 141 patients with suspected PM. However the primary objective of this study was to assess the incidence of pulmonary emboli [7] and the diagnostic performance of CTPA for PM was not reported. In a small randomised study, Raj et al previously demonstrated better enhancement of the pleura utilising delayed phase (at 60–90 s post-contrast) CT acquisition [8], Therefore venous-phase CT should be requested in all patients with suspected PM, and this may have been used more frequently in the Hallifax study.…”

Identification and management of pleural effusions of multiple aetiologies

“…Malignancy is an independent risk factors for venous thromboembolic disease(VTE) (36), increasing the overall risk 7-fold in patients with cancer, and 22 fold in patients with lung cancer (37). This study demonstrates that PEs are uncommon in unilateral effusions, however if it does occur, it is frequently associated with malignancy (35).…”

“…The clinical diagnosis of pulmonary embolism (PE), particularly in the presence of a pleural effusion, can be difficult (35). A prospective trial investigating the incidence of PEs in consecutive patient with a unilateral effusions, with a dual phase CTPA (35), found the incidence of concurrent PEs was low (6.4%) and in no cases was it felt to be the leading cause of the effusion. PE was only clinically suspected in one case.…”

Evaluation of the patient with pleural effusion

“…29 However, a prospective study in which CT pulmonary angiography was performed in 141 consecutive patients with an undiagnosed effusion showed a pulmonary embolism in only nine patients (6.4%). 30 In no patient was the embolism thought to have caused the effusion. Thus, whether a pulmonary CT angiogram is warranted in all patients with an undiagnosed effusion remains to be determined.…”