title: Impact of scar on water-perfusable tissue index in chronic ischemic heart disease: Evaluation with PET and contrast-enhanced MRI.
abstract: BACKGROUND
  The water-perfusable tissue index (PTI) is assumed to differentiate viable myocardium from scar tissue, but histological comparisons in humans are lacking. The present study compares PTI with delayed contrast-enhanced magnetic resonance imaging (DCE-MRI), a validated marker of fibrotic tissue, in patients with ischemic left ventricular (LV) dysfunction. In addition, the optimal PTI threshold for detection of myocardial viability was defined when DCE-MRI was taken as a reference.
  
  
  METHODS
  Twenty patients with ischemic LV dysfunction were studied with positron emission tomography, using oxygen-15-labeled water and carbon monoxide as tracers, and DCE-MRI.
  
  
  RESULTS
  Of the 200 analyzed segments, 112 demonstrated DCE and were subsequently divided in three subgroups according to the severity of enhancement. PTI was 1.04 +/- 0.21 in control segments and gradually decreased with increasing extent of DCE to 0.77 +/- 0.31 for segments with transmural enhancement (p < 0.001). However, PTI progressively underestimated infarct size with increasing quantities of scar tissue (r = 0.61, p < 0.01). A PTI cutoff value of 0.89 yielded the best diagnostic accuracy for detection of myocardial viability with sensitivity and specificity values of 75 and 77%, respectively.
  
  
  CONCLUSIONS
  PTI is inversely related to the extent of scar tissue estimated by DCE-MRI in patients with chronic ischemic heart disease and LV dysfunction. However, with increasing quantities of scar tissue, PTI overestimates the extent of residual viable tissue. A PTI threshold of 0.89 yields the best diagnostic accuracy for viability detection.
authors.affiliation: Department of Cardiology, 6D 120, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. p.knaapen@vumc.nl
authors.forename: Paul
authors.initials: P
authors.lastname: Knaapen
authors.forename: Olga
authors.initials: O
authors.lastname: Bondarenko
authors.forename: Aernout M
authors.initials: AM
authors.lastname: Beek
authors.forename: Marco J W
authors.initials: MJ
authors.lastname: Götte
authors.forename: Ronald
authors.initials: R
authors.lastname: Boellaard
authors.forename: Arno P
authors.initials: AP
authors.lastname: van der Weerdt
authors.forename: Cees A
authors.initials: CA
authors.lastname: Visser
authors.forename: Albert C
authors.initials: AC
authors.lastname: van Rossum
authors.forename: Adriaan A
authors.initials: AA
authors.lastname: Lammertsma
authors.forename: Frans C
authors.initials: FC
authors.lastname: Visser
mesh_terms: D000368:Aged; D002908:Chronic Disease; D002921:Cicatrix / Q000175:diagnosis*; D003326:Coronary Circulation; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000473:pathology*; D015425:Myocardial Reperfusion; D049268:Positron-Emission Tomography; D014022:Tissue Survival; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water