title: Mr flow measurement in the internal mammary artery-to-coronary artery bypass graft: comparison with graft stenosis at radiographic angiography.
abstract: OBJECTIVE
  To evaluate the sensitivity and specificity of breath-hold magnetic resonance (MR) flow measurement for detection of significant stenosis in internal mammary artery bypass grafts.
  
  
  METHODS
  Twenty-six consecutive patients who had undergone coronary artery bypass surgery were examined. Breath-hold velocity-encoded cine MR images were obtained at the midpoint of the internal mammary artery between its origin from the subclavian artery and the distal anastomosis to the left anterior descending artery.
  
  
  RESULTS
  MR images were obtained successfully in 24 patients. At conventional angiography, no significant stenosis was observed in 17 patients (group A), and significant stenosis (diameter > 70%) was observed in seven patients (group B). The mean diastolic-to-systolic peak velocity ratio in group B (0.61 +/- 0.44 [SD]) was significantly lower than that in group A (1.88 +/- 0.96; P <.01). Evaluation of graft stenosis with the diastolic-to-systolic peak velocity ratio revealed a sensitivity of 86% and a specificity of 88%. The mean blood flow rate at baseline in group B (16.9 mL/min +/- 5.5) was significantly lower than that in group A (79.8 mL/min +/- 38.2; P <.01). The sensitivity and specificity of MR blood flow measurement in predicting significant stenosis were 86% and 94%, respectively. The mean pharmacologic flow reserve ratios were 2.00 +/- 1.43 in group A and 1.39 +/- 1.46 in group B (P >.05).
  
  
  CONCLUSIONS
  Fast MR blood flow measurement at baseline is highly useful for predicting significant stenosis in internal mammary arterial grafts.
authors.affiliation: Department of Radiology, Mie University School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan. nanaka@clin.medic.mie-u.ac.jp
authors.forename: N
authors.initials: N
authors.lastname: Ishida
authors.forename: H
authors.initials: H
authors.lastname: Sakuma
authors.forename: B P
authors.initials: BP
authors.lastname: Cruz
authors.forename: T
authors.initials: T
authors.lastname: Shimono
authors.forename: T
authors.initials: T
authors.lastname: Tokui
authors.forename: I
authors.initials: I
authors.lastname: Yada
authors.forename: K
authors.initials: K
authors.lastname: Takeda
authors.forename: C B
authors.initials: CB
authors.lastname: Higgins
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D001026:Coronary Artery Bypass; D003331:Coronary Vessels / Q000473:pathology*; D004176:Dipyridamole; D005260:Female; D006083:Graft Occlusion, Vascular / Q000175:diagnosis*; D006439:Hemodynamics; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008323:Mammary Arteries / Q000473:pathology*; D008875:Middle Aged; D011183:Postoperative Complications; D012680:Sensitivity and Specificity; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D004176:Dipyridamole