Impact of scar on water-perfusable tissue index in chronic ischemic heart disease: Evaluation with PET and contrast-enhanced MRI

Paul Knaapen, Olga Bondarenko, Aernout M. Beek, Marco J.W. Götte, Ronald Boellaard, Arno P. van Weerdt, Cees A. Visser, Albert C. van Rossum, Adriaan A. Lammertsma, Frans C. Visser

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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. Materials: 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.

Original languageEnglish
Pages (from-to)245-251
Number of pages7
JournalMolecular Imaging and Biology
Issue number4
Publication statusPublished - 1 Jul 2006


  • Delayed contrast-enhanced MRI
  • Ischemic heart disease
  • Perfusable tissue index
  • Positron emission tomography
  • Viability

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