title: Lower extremity stepping-table magnetic resonance angiography with multilevel contrast timing and segmented contrast infusion.
abstract: OBJECTIVE
  Standard lower extremity contrast-enhanced magnetic resonance angiography (LE-CEMRA) with single injection bolus-chase methods on the basis of a single pelvis timing run can be accurate for depicting most vascular occlusive lesions but may fall short of catheter-based angiography when imaging tibial and pedal vessels. Magnetic resonance angiography techniques with a second contrast timing bolus and separate acquisitions for the calves and the pelvis greatly improve reliability and reduce venous contamination to levels that may render conventional angiography obsolete.
  
  
  METHODS
  From July to December 2001, 60 consecutive patients underwent LE-CEMRA of the calves with separate stepping-table acquisitions of the pelvis and thighs. Forty-five (75%) had complete or partial angiographic correlation during an endoluminal intervention or operative completion study. Lower extremity vessels were divided into anatomic segments (aortoiliac, femoropopliteal, tibial-pedal) for review. Three blinded observers assessed magnetic resonance source partitions, maximum-intensity projections, and volume-rendered images. Disease per segment was graded from insignificant (<20%) to occluded (100%) in 10% increments. Segments were also scored for venous contamination (scale, 0 to 3) and diagnostic quality (scale, 1 to 5). Digital subtraction angiograms were assessed similarly but separately.
  
  
  RESULTS
  The combination dual-timing/dual-injection technique had an overall sensitivity, specificity, and accuracy of 99%, 97%, and 98%. Venous contamination and artifact were virtually eliminated with combined technique LE-CEMRA. Diagnostic quality of calf and foot vessels was significantly superior to conventional bolus-chase magnetic resonance techniques (P <.01).
  
  
  CONCLUSIONS
  Hybrid dual-acquisition LE-CEMRA allows complete timing specification that consistently produces high-quality, artifact-free images of the calf and pedal vessels. These techniques may be accurate enough to replace conventional digital subtraction angiogram for evaluation of lower extremity vascular occlusive disease.
authors.affiliation: Division of Vascular Surgery and the Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. mmorasch@nmh.org
authors.forename: Mark D
authors.initials: MD
authors.lastname: Morasch
authors.forename: Jeremy
authors.initials: J
authors.lastname: Collins
authors.forename: F Scott
authors.initials: FS
authors.lastname: Pereles
authors.forename: James C
authors.initials: JC
authors.lastname: Carr
authors.forename: Mark K
authors.initials: MK
authors.lastname: Eskandari
authors.forename: William H
authors.initials: WH
authors.lastname: Pearce
authors.forename: J Paul
authors.initials: JP
authors.lastname: Finn
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007866:Leg / Q000098:blood supply*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media