title: Can the inflammatory response be evaluated using 18F-FDG within zones of microvascular obstruction after myocardial infarction?
abstract: Inflammation that occurs after acute myocardial infarction plays a pivotal role in healing by facilitating the creation of a supportive scar. (18)F-FDG, which is taken up avidly by macrophages, has been proposed as a marker of cell-based inflammation. However, its reliability as an accurate indicator of inflammation has not been established, particularly in the early postinfarction period when regional myocardial perfusion is often severely compromised.
  
  
  METHODS
  Nine adult dogs underwent left anterior descending coronary occlusion with or without reperfusion. Animals were imaged between 7 and 21 d after infarction with PET/MR imaging after bolus injection of gadolinium-diethylenetriaminepentaacetic acid (DTPA), bolus injection of (18)F-FDG, bolus injection of (99)Tc-DTPA to simulate the distribution of gadolinium-DTPA (which represents its partition coefficient in well-perfused tissue), and injection of (111)In-labeled white blood cells 24 h earlier. After sacrifice, myocardial tissue concentrations of (18)F, (111)In, and (99)Tc were determined in a well counter. Linear regression analysis evaluated the relationships between the concentrations of (111)In and (18)F and the dependence of the ratio of (111)In/(18)F to the apparent distribution volume of (99m)Tc-DTPA.
  
  
  RESULTS
  In 7 of 9 animals, (111)In increased as (18)F increased with the other 2 animals, showing weak negative slopes. With respect to the dependence of (111)In/(18)F with partition coefficient, 4 animals showed no dependence and 4 showed a weak positive slope, with 1 animal showing a negative slope. Further, in regions of extensive microvascular obstruction, (18)F significantly underestimated the extent of the presence of (111)In.
  
  
  CONCLUSIONS
  In the early post-myocardial infarction period, (18)F-FDG PET imaging after a single bolus administration may underestimate the extent and degree of inflammation within regions of microvascular obstruction.
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada Medical Imaging, University of Western Ontario, London, Ontario, Canada frank.prato@lawsonimaging.ca.
authors.forename: Frank S
authors.initials: FS
authors.lastname: Prato
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Butler
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: Jane
authors.initials: J
authors.lastname: Sykes
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada.
authors.forename: Lynn
authors.initials: L
authors.lastname: Keenliside
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada Medical Imaging, University of Western Ontario, London, Ontario, Canada Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada; and Division of Cardiology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.
authors.forename: Kimberley J
authors.initials: KJ
authors.lastname: Blackwood
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada Medical Imaging, University of Western Ontario, London, Ontario, Canada.
authors.forename: R Terry
authors.initials: RT
authors.lastname: Thompson
authors.affiliation: Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada; and.
authors.forename: James A
authors.initials: JA
authors.lastname: White
authors.affiliation: Stephenson Cardiovascular MR Centre, Libin Cardiovascular Institute, University of Calgary, Alberta, Canada; and.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Mikami
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Thiessen
authors.affiliation: Lawson Health Research Institute, London, Ontario, Canada Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada Division of Cardiology, Department of Medicine, University of Western Ontario, London, Ontario, Canada.
authors.forename: Gerald
authors.initials: G
authors.lastname: Wisenberg
mesh_terms: D000818:Animals; D003326:Coronary Circulation; D054059:Coronary Occlusion / Q000473:pathology; D003331:Coronary Vessels / Q000473:pathology; D004285:Dogs; D005260:Female; D019788:Fluorodeoxyglucose F18; D019786:Gadolinium DTPA / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D007249:Inflammation / Q000000981:diagnostic imaging*; D008264:Macrophages / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008833:Microcirculation; D064847:Multimodal Imaging; D009203:Myocardial Infarction / Q000473:pathology*; D004369:Pentetic Acid / Q000737:chemistry; D049268:Positron-Emission Tomography; D015203:Reproducibility of Results; D013667:Technetium / Q000737:chemistry; D013997:Time Factors
chemical_list: D019788:Fluorodeoxyglucose F18; D013667:Technetium; D004369:Pentetic Acid; D019786:Gadolinium DTPA
keywords: 111In-labeled white blood cells; 18F-FDG; PET/MRI; late gadolinium enhancement (LGE); myocardial infarction; myocardial inflammation