Duplex ultrasound and contrast-enhanced ultrasound versus computed tomography for the detection of endoleak after EVAR: systematic review and bivariate meta-analysis.

INTRODUCTION Contrast-enhanced computed tomography (CT) has become the 'gold-standard' imaging modality for surveillance following EVAR. However repeated CT causes cumulative contrast related renal injury. Duplex ultrasound (USS) and contrast-enhanced (non-nephrotoxic) duplex scanning (CEUS) are less invasive but considered less accurate than CT. The aim of this study was to determine the diagnostic accuracy of imaging modalities used to detect endoleak. Accordingly, we undertook a systematic review and meta-analysis of the evidence base for USS and CEUS compared to CT following EVAR. METHODS Medline, Embase, trial registries, conference proceedings and article reference lists were searched to identify trials comparing USS or CEUS with CT following EVAR. Contrast-enhanced computed tomography was taken as the 'gold-standard' investigation. USS and CEUS were compared to CT in separate meta-analyses. RESULTS Twenty-one studies in 2601 patients compared USS with CT. The sensitivity of USS at detecting endoleak was 0.77 (95% CI 0.64-0.86; I(2)=0.82) and pooled specificity 0.94 (95% CI 0.88-0.97; I(2)=0.90). Seven studies (288 patients) compared CEUS vs CT. The pooled sensitivity was 0.98 (95% CI 0.90-0.99; I(2)=0.32) and specificity 0.88 (95% CI 0.78-0.94; I(2)=0.67). CONCLUSION This study confirms that unenhanced USS has poor sensitivity for endoleak detection; however CEUS is a highly sensitive modality. These results should be interpreted with some caution due to heterogeneity in analysed trials and further research is needed to evaluate the efficacy of CEUS before it can be utilised as the primary imaging modality for EVAR surveillance.