title: Calf muscle perfusion at peak exercise in peripheral arterial disease: measurement by first-pass contrast-enhanced magnetic resonance imaging.
abstract: OBJECTIVE
  To develop a contrast-enhanced magnetic resonance (MR) technique to measure skeletal muscle perfusion in peripheral arterial disease (PAD).
  
  
  METHODS
  A total of 11 patients (age = 61 +/- 11 years) with mild to moderate symptomatic PAD (ankle-brachial index [ABI] = 0.75 +/- 0.08) and 22 normals were studied using an MR-compatible ergometer. PAD and normal(max) (Nl(max); N = 11) exercised to exhaustion. Nl(low) (N = 11) exercised to the same workload achieved by PAD. At peak exercise, 0.1 mm/kg of gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) was infused at 3-4 cm(3)/second followed by a saline flush at the same rate. A dual-contrast gradient echo (GRE) sequence enabled simultaneous acquisition of muscle perfusion and arterial input function (AIF). The perfusion index (PI) was defined as the slope of the time-intensity curve (TIC) in muscle divided by the arterial TIC slope.
  
  
  RESULTS
  Median workload was 120 Joules in PAD, 210 Joules in Nl(low), and 698 Joules in Nl(max) (P < 0.001 vs. Nl(low) and PAD). Median PI was 0.29 in PAD (25th and 75th percentiles [%] = 0.20, 0.40), 0.48 in Nl(low) (25th, 75th % = 0.36, 0.62; P < 0.02 vs. PAD), and 0.69 in Nl(max) (25th, 75th % = 0.5, 0.77; P < 0.001 vs. PAD). Area under the ROC-curve for PI differentiating patients from Nl(max) was 0.95 (95% confidence interval [CI] = 0.77-0.99).
  
  
  CONCLUSIONS
  Peak-exercise measurement of lower limb perfusion with dual-contrast, first-pass MR distinguishes PAD from normals. This method may be useful in the study of novel therapies for PAD.
authors.affiliation: Department of Medicine, University of Virginia Health System, University of Virginia, Lee Street, Charlottesville, VA 22908, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Isbell
authors.forename: Frederick H
authors.initials: FH
authors.lastname: Epstein
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhong
authors.forename: Joseph M
authors.initials: JM
authors.lastname: DiMaria
authors.forename: Stuart S
authors.initials: SS
authors.lastname: Berr
authors.forename: Craig H
authors.initials: CH
authors.lastname: Meyer
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Rogers
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Harthun
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Hagspiel
authors.forename: Arthur
authors.initials: A
authors.lastname: Weltman
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Kramer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003287:Contrast Media; D015444:Exercise; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007383:Intermittent Claudication / Q000503:physiopathology*; D007866:Leg / Q000098:blood supply; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply*; D012372:ROC Curve; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA