title: Duplex ultrasound and contrast-enhanced ultrasound versus computed tomography for the detection of endoleak after EVAR: systematic review and bivariate meta-analysis.
abstract: BACKGROUND
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Cambridge Vascular Unit, Cambridge University Hospitals NHS Foundation Trust, UK.
authors.forename: T A
authors.initials: TA
authors.lastname: Mirza
authors.forename: A
authors.initials: A
authors.lastname: Karthikesalingam
authors.forename: D
authors.initials: D
authors.lastname: Jackson
authors.forename: S R
authors.initials: SR
authors.lastname: Walsh
authors.forename: P J
authors.initials: PJ
authors.lastname: Holt
authors.forename: P D
authors.initials: PD
authors.lastname: Hayes
authors.forename: J R
authors.initials: JR
authors.lastname: Boyle
mesh_terms: D000783:Aneurysm / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects / Q000295:instrumentation*; D003287:Contrast Media; D019317:Evidence-Based Medicine; D006801:Humans; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000209:etiology; D011237:Predictive Value of Tests; D011475:Prosthesis Failure; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure; D018616:Ultrasonography, Doppler, Duplex
chemical_list: D003287:Contrast Media