The role of routine computed tomography in paediatric pleural empyema

Abstract

Background: The incidence of empyema is increasing worldwide in children. While there are emerging data for the best treatment options, there is little evidence to support the imaging modalities used to guide treatment particularly with regard to the role of routine computed tomography (CT). The aims of this study were to develop a radiological scoring system for paediatric empyema and to assess the utility of routine CT scanning in this disease.

Methods: Children with empyema were prospectively enrolled over a 3-year period into a randomised clinical trial of video assisted thoracoscopic surgery versus percutaneous chest drain insertion and urokinase. All children received a pre-operative chest radiograph (CXR), pleural ultrasound scan (USS) and chest CT. In the urokinase arm the clinician inserted the drain with ultrasound evidence only and did not have access to the CT scan at the time of insertion to reflect clinical practice. A scoring system was developed for each individual radiological modality and utilised to compare imaging characteristics of the pleural fluid collection and underlying parenchyma and to assess the utility of USS and CT to predict length of stay post intervention.

Results: Of the 60 subjects recruited, 46 had USS images available for review, 36 had a CT scan meeting inclusion criterion and 31 had all three radiological measurements (CT, USS and CXR) available for analysis. There was substantial inter-observer agreement for USS grades (κ=0.709) and moderate agreement for total CT scores (κ=0.520). There were weak correlations between ultrasound grade and total CT score as well as CT loculation and density scores. Of the 25 CXRs showing simple opacification of the underlying parenchyma only, CT demonstrated simple consolidation (n=14), necrotising pneumonia (n=7), cavitary necrosis (n=3) and pneumatocoeles (n=1). No abnormality was detected on CT scanning which directly altered clinical management. Neither the USS score, nor the CT score, nor a combination of the two, were able to predict length of hospital stay.

Conclusions: CT scanning detects more parenchymal abnormalities than CXR. However, the additional information does not alter management and is unable to predict clinical outcome. This suggests that there is no role for the routine use of CT scanning in children if treated with urokinase and percutaneous chest drain. The omission of routine CT scanning in empyema will reduce the exposure of children to unnecessary radiation and reduce costs.