title: Fractal analysis of the ischemic transition region in chronic ischemic heart disease using magnetic resonance imaging.
abstract: OBJECTIVE
  To introduce a novel hypothesis and method to characterise pathomechanisms underlying myocardial ischemia in chronic ischemic heart disease by local fractal analysis (FA) of the ischemic myocardial transition region in perfusion imaging.
  
  
  METHODS
  Vascular mechanisms to compensate ischemia are regulated at various vascular scales with their superimposed perfusion pattern being hypothetically self-similar. Dedicated FA software ("FraktalWandler") has been developed. Fractal dimensions during first-pass (FDfirst-pass) and recirculation (FDrecirculation) are hypothesised to indicate the predominating pathomechanism and ischemic severity, respectively.
  
  
  RESULTS
  Twenty-six patients with evidence of myocardial ischemia in 108 ischemic myocardial segments on magnetic resonance imaging (MRI) were analysed. The 40th and 60th percentiles of FDfirst-passwere used for pathomechanical classification, assigning lesions with FDfirst-pass≤ 2.335 to predominating coronary microvascular dysfunction (CMD) and ≥2.387 to predominating coronary artery disease (CAD). Optimal classification point in ROC analysis was FDfirst-pass= 2.358. FDrecirculationcorrelated moderately with per cent diameter stenosis in invasive coronary angiography in lesions classified CAD (r = 0.472, p = 0.001) but not CMD (r = 0.082, p = 0.600).
  
  
  CONCLUSIONS
  The ischemic transition region may provide information on pathomechanical composition and severity of myocardial ischemia. FA of this region is feasible and may improve diagnosis compared to traditional noninvasive myocardial perfusion analysis.
  
  
  CONCLUSIONS
  • A novel hypothesis and method is introduced to pathophysiologically characterise myocardial ischemia. • The ischemic transition region appears a meaningful diagnostic target in perfusion imaging. • Fractal analysis may characterise pathomechanical composition and severity of myocardial ischemia.
authors.affiliation: Charité - Universitätsmedizin Berlin, Institut für Radiologie, Charitéplatz 1, 10117, Berlin, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Michallek
authors.affiliation: Charité - Universitätsmedizin Berlin, Institut für Radiologie, Charitéplatz 1, 10117, Berlin, Germany. dewey@charite.de.
authors.forename: Marc
authors.initials: M
authors.lastname: Dewey
mesh_terms: D000368:Aged; D002908:Chronic Disease; D005260:Female; D017709:Fractals; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results
keywords: Coronary artery disease; Fractals; Microvessels; Myocardial ischemia; Perfusion imaging