title: Hypodense regions in unenhanced CT identify nonviable myocardium: validation versus 18F-FDG PET.
abstract: OBJECTIVE
  The aim of the present study was to evaluate the accuracy of hypodense regions in non-contrast-enhanced cardiac computed tomography (unenhanced CT) to identify nonviable myocardial scar tissue.
  
  
  METHODS
  Hypodense areas were visually identified in unenhanced CT of 80 patients in the left ventricular anterior, apical, septal, lateral and inferior myocardium and CT density was measured in Hounsfield units (HU). Findings were compared to (18)F-fluorodeoxyglucose uptake by positron emission tomography (FDG PET), which served as the standard of reference to distinguish scar (<50 % FDG uptake) from viable tissue (≥50 % uptake).
  
  
  RESULTS
  Visually detected hypodense regions demonstrated a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 74, 97, 84 and 94 %, respectively. A receiver-operating characteristic (ROC) curve analysis revealed a cutoff value of mean HU at <28.8 for predicting scar tissue with an area under the curve of 0.93 yielding a sensitivity, specificity, PPV and NPV of 94, 90, 67 and 99 %, respectively.
  
  
  CONCLUSIONS
  Hypodense regions in unenhanced cardiac CT scans allow accurate identification of nonviable myocardial scar tissue.
authors.affiliation: Department of Radiology, Cardiac Imaging, University Hospital Zurich, Switzerland.
authors.forename: Tobias A
authors.initials: TA
authors.lastname: Fuchs
authors.forename: Jelena R
authors.initials: JR
authors.lastname: Ghadri
authors.forename: Julia
authors.initials: J
authors.lastname: Stehli
authors.forename: Catherine
authors.initials: C
authors.lastname: Gebhard
authors.forename: Egle
authors.initials: E
authors.lastname: Kazakauskaite
authors.forename: Bernd
authors.initials: B
authors.lastname: Klaeser
authors.forename: Oliver
authors.initials: O
authors.lastname: Gaemperli
authors.forename: Michael
authors.initials: M
authors.lastname: Fiechter
authors.forename: Philipp A
authors.initials: PA
authors.lastname: Kaufmann
mesh_terms: D000368:Aged; D002921:Cicatrix / Q000000981:diagnostic imaging*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D005260:Female; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18