title: Characterization of normal and infarcted rat myocardium using a combination of small-animal PET and clinical MRI.
abstract: The combination of small-animal PET and MRI data provides quantitative in vivo insights into cardiac pathophysiology, integrating information on biology and morphology. We sought to determine the feasibility of PET and MRI for the quantification of ischemic injury in the rat model.
  
  
  METHODS
  Fourteen healthy male Wistar rats were studied with 18F-FDG PET and cine MRI. Myocardial viability was determined in a transmural myocardial infarction model in 12 additional rats, using 18F-FDG PET and delayed-enhancement MRI with gadolinium-diethylenetriaminepentaacetic acid. All PET was acquired with a dedicated small-animal PET system. MRI was performed on a 1.5-T clinical tomograph with a dedicated small-animal electrocardiographic triggering device and a small surface coil.
  
  
  RESULTS
  In normal rats, 18F-FDG uptake was homogeneous throughout the left ventricle. The lowest mean uptake of the 18F-FDG was found in the apical regions (79% +/- 6.0% of maximum) and the highest uptake was in the anterior wall (93% +/- 4.3 % of maximum). Myocardial infarct size as determined by histology correlated well with defects of glucose metabolism obtained with 18F-FDG PET (r = 0.89) and also with delayed-enhancement MRI (r = 0.91). Left ventricular ejection fraction in normal rats measured by cine MRI was 57% +/- 5.4% and decreased to 38% +/- 12.9% (P < 0.001) in the myocardial infarction model.
  
  
  CONCLUSIONS
  Integrating information from small-animal PET and clinical MRI instrumentation allows for the quantitative assessment of cardiac function and infarct size in the rat model. The MRI measurements of scar can be complemented by metabolic imaging, addressing the extent and severity of ischemic injury and providing endpoints for therapeutic interventions.
authors.affiliation: Nuklearmedizinische Klinik und Poliklinik der Technischen Universität München, Klinikum rechts der Isar, Munich, Germany. higuchi@po2.nsknet.or.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Higuchi
authors.forename: Stephan G
authors.initials: SG
authors.lastname: Nekolla
authors.forename: Antanas
authors.initials: A
authors.lastname: Jankaukas
authors.forename: Axel W
authors.initials: AW
authors.lastname: Weber
authors.forename: Marc C
authors.initials: MC
authors.lastname: Huisman
authors.forename: Sybille
authors.initials: S
authors.lastname: Reder
authors.forename: Sibylle I
authors.initials: SI
authors.lastname: Ziegler
authors.forename: Markus
authors.initials: M
authors.lastname: Schwaiger
authors.forename: Frank M
authors.initials: FM
authors.lastname: Bengel
mesh_terms: D000818:Animals; D004562:Electrocardiography; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism; D006321:Heart / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D051381:Rats; D017208:Rats, Wistar; D015899:Tomography, Emission-Computed, Single-Photon; D016277:Ventricular Function, Left
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose