title: Assessment of minimally invasive direct coronary artery bypass grafting of the left internal thoracic artery by means of magnetic resonance imaging.
abstract: OBJECTIVE
  We sought to evaluate graft patency, flow, and flow reserve in patients with minimally invasive direct coronary artery bypass surgery of internal thoracic artery grafts by a combined magnetic resonance protocol with a phase-contrast technique and magnetic resonance angiography.
  
  
  METHODS
  At 1.5 T (Magnetom Sonata, Siemens), 30 symptomatic patients with 30 left internal thoracic artery grafts were examined 6 years after minimally invasive surgical intervention. Navigator-gated magnetic resonance angiography and contrast-enhanced FLASH-3D magnetic resonance angiography (0.2 mmol gadopentate-diethylene triamine pentetic acid [Gd-DTPA]/kg body weight) was used to assess bypass patency. Phase-contrast flow measurements with retrospective gating were performed in the internal thoracic artery grafts at rest and after stress induction with dipyridamole (0.57 mg/kg body weight). Graft patency was evaluated by means of multidetector computed tomography (Sensation 16, Siemens).
  
  
  RESULTS
  Internal thoracic artery grafts were occluded in 5 of 30 patients. In 6 patients the anastomosis to the left anterior descending artery was highly stenotic (>70 % ) at multidetector computed tomography. In patients with regular grafts (multidetector computed tomography), a significant improvement of graft flow ( P < .001) and diastolic/systolic peak velocity ratio ( P < .001) after stress induction was detected. Magnetic resonance angiography combined with flow reserve measurements could differentiate between occluded-stenotic and regular minimally invasive direct coronary artery bypass grafts.
  
  
  CONCLUSIONS
  Magnetic resonance imaging allows a combined assessment of bypass patency and flow with flow reserve in patients after the minimally invasive direct coronary artery bypass operation. The protocol of this study might be applicable for the evaluation of graft status in symptomatic patients after revascularization.
authors.affiliation: Department of Diagnostic Radiology, Eberhard-Karls-University, Tuebingen, Germany. norbert.stauder@med.uni-tuebingen.de
authors.forename: Norbert I
authors.initials: NI
authors.lastname: Stauder
authors.forename: Michael
authors.initials: M
authors.lastname: Fenchel
authors.forename: Heidrun
authors.initials: H
authors.lastname: Stauder
authors.forename: Axel
authors.initials: A
authors.lastname: Küttner
authors.forename: Albertus M
authors.initials: AM
authors.lastname: Scheule
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kramer
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Stephan
authors.initials: S
authors.lastname: Miller
mesh_terms: D000368:Aged; D003251:Constriction, Pathologic; D001026:Coronary Artery Bypass / Q000379:methods*; D006083:Graft Occlusion, Vascular / Q000175:diagnosis*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008323:Mammary Arteries / Q000473:pathology / Q000637:transplantation*; D008875:Middle Aged; D012039:Regional Blood Flow; D012680:Sensitivity and Specificity; D014654:Vascular Patency