title: Comparison of duplex ultrasound with digital subtraction angiography in the assessment of infra-inguinal autologous vein bypass grafts.
abstract: BACKGROUND
  Postoperative surveillance of infra-inguinal vein grafts has arisen because of the high incidence of vein graft stenoses, which frequently progress to vein graft occlusion. The use of duplex ultrasound as the primary imaging method for graft surveillance is well established. This study aims to compare the accuracy of duplex ultrasound with the reference standard of digital subtraction angiography in the assessment of infra-inguinal vein grafts.
  
  
  METHODS
  Sixty patients underwent routine postoperative duplex ultrasound as part of the local graft surveillance programme. Angiography was subsequently carried out on 18 grafts. Each lower limb arterial tree was divided into three segments (native arteries proximal to the graft, the graft itself and native arteries distal to the graft) resulting in a total of 42 comparisons. Degree of diameter stenosis on ultrasound was compared with angiography findings to determine concordance. Agreement was also expressed as a kappa value.
  
  
  RESULTS
  Overall accuracy of duplex ultrasound was 88% (37/42). A kappa value of 0.80 indicates good agreement. In three of the five discordant cases, ultrasound correctly identified a stenosis, but overestimated the degree of stenosis compared with angiography. In each of the remaining two discordant cases, ultrasound identified a focal stenosis that was not apparent on angiography. In both cases, the area of duplex described abnormality responded to balloon angioplasty.
  
  
  CONCLUSIONS
  Duplex ultrasound as part of the local vein graft surveillance programme is a reliable and accurate method in the detection of failing grafts and in some instances may be more sensitive.
authors.affiliation: Department of Radiology, Christchurch Hospital, Christchurch, New Zealand. nickg@cdhb.govt.nz
authors.forename: Nick M R
authors.initials: NM
authors.lastname: Griffin
authors.forename: Isabel A
authors.initials: IA
authors.lastname: Wright
authors.forename: Tim M
authors.initials: TM
authors.lastname: Buckenham
mesh_terms: D015901:Angiography, Digital Subtraction; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000601:surgery; D019917:Blood Vessel Prosthesis Implantation / Q000379:methods*; D005263:Femoral Artery / Q000601:surgery*; D005500:Follow-Up Studies; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging*; D006801:Humans; D011184:Postoperative Period; D012189:Retrospective Studies; D014182:Transplantation, Autologous; D018616:Ultrasonography, Doppler, Duplex; D014680:Veins / Q000637:transplantation*