title: Importance of Reference Muscle Selection in Quantitative Signal Intensity Analysis of T2-Weighted Images of Myocardial Edema Using a T2 Ratio Method.
abstract: OBJECTIVE
  The purpose of our study was to identify the suitability of various skeletal muscles as reference regions for calculating the T2 SI ratio for a semiautomated quantification of the extent of myocardial edema with T2-weighted images.
  
  
  METHODS
  Thirty-four patients with acute myocardial infarction (MI) were enrolled. The extent of myocardial edema was determined by T2 SI ratio map, using 4 different muscles as reference: major and minor pectoralis, serratus anterior, teres minor-infraspinatus, and subscapularis. The size of myocardial edema as visually quantified was used as the standard of truth. The control group consisted of 15 patients with chronic MI. Intra- and interobserver variability were assessed.
  
  
  RESULTS
  Due to poor image quality four patients were excluded from the analysis. In acute MI patients, serratus anterior muscle showed the strongest correlation with the visual analysis (r = 0.799; P < 0.001) and low inter- and intraobserver variability, while the other muscles resulted in a significant interobserver variability. In contrast, the use of other muscles as a reference led to overestimating edema size.
  
  
  CONCLUSIONS
  In acute MI patients, serratus anterior resulted to be the most reliable and reproducible muscle for measuring the extent of myocardial edema.
authors.affiliation: CMR Centre, Montreal Heart Institute, University of Montreal, Montreal, QC, Canada H1T 1C8 ; Department of Radiological, Onchological and Pathological Sciences, Sapienza, University of Rome, 00161 Rome, Italy ; Stephenson CMR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada T2N 2T9.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Carbone
authors.affiliation: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada S7N 5B4.
authors.forename: Helene
authors.initials: H
authors.lastname: Childs
authors.affiliation: King Abdulaziz Cardiac Center, Riyadh 11426, Saudi Arabia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Aljizeeri
authors.affiliation: Stephenson CMR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada T2N 2T9 ; Department of Diagnostic Imaging, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada T2N 2T9.
authors.forename: Naeem
authors.initials: N
authors.lastname: Merchant
authors.affiliation: CMR Centre, Montreal Heart Institute, University of Montreal, Montreal, QC, Canada H1T 1C8 ; Stephenson CMR Centre, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada T2N 2T9.
authors.forename: Matthias G
authors.initials: MG
authors.lastname: Friedrich
mesh_terms: D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D004489:Edema, Cardiac / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods* / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000592:standards