title: Optimized energy of spectral CT for infarct imaging: Experimental validation with human validation.
abstract: OBJECTIVE
  Late contrast enhancement visualizes myocardial infarction, but the contrast to noise ratio (CNR) is low using conventional CT. The aim of this study was to determine if spectral CT can improve imaging of myocardial infarction.
  
  
  METHODS
  A canine model of myocardial infarction was produced in 8 animals (90-min occlusion, reperfusion). Later, imaging was performed after contrast injection using CT at 90 kVp/150 kVpSn. The following reconstructions were evaluated: Single energy 90 kVp, mixed, iodine map, multiple monoenergetic conventional and monoenergetic noise optimized reconstructions. Regions of interest were measured in infarct and remote regions to calculate contrast to noise ratio (CNR) and Bhattacharya distance (a metric of the differentiation between regions). Blinded assessment of image quality was performed. The same reconstruction methods were applied to CT scans of four patients with known infarcts.
  
  
  RESULTS
  For animal studies, the highest CNR for infarct vs. myocardium was achieved in the lowest keV (40 keV) VMo images (CNR 4.42, IQR 3.64-5.53), which was superior to 90 kVp, mixed and iodine map (p = 0.008, p = 0.002, p < 0.001, respectively). Compared to 90 kVp and iodine map, the 40 keV VMo reconstructions showed significantly higher histogram separation (p = 0.042 and p < 0.0001, respectively). The VMo reconstructions showed the highest rate of excellent quality scores. A similar pattern was seen in human studies, with CNRs for infarct maximized at the lowest keV optimized reconstruction (CNR 4.44, IQR 2.86-5.94).
  
  
  CONCLUSIONS
  Dual energy in conjunction with noise-optimized monoenergetic post-processing improves CNR of myocardial infarct delineation by approximately 20-25%.
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Veit
authors.initials: V
authors.lastname: Sandfort
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Palanisamy
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Rolf
authors.initials: R
authors.lastname: Symons
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Pourmorteza
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Ahlman
authors.affiliation: ORS Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Rice
authors.affiliation: ORS Division of Veterinary Resources, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Thomas
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Davies-Venn
authors.affiliation: Siemens AG, Healthcare Sector, Forchheim, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Kwan
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Ankur
authors.initials: A
authors.lastname: Pandey
authors.affiliation: Johns Hopkins University, Baltimore, MD, USA.
authors.forename: Stefan L
authors.initials: SL
authors.lastname: Zimmerman
authors.affiliation: Radiology and Imaging Sciences - National Institutes of Health Clinical Center, Bethesda, MD, USA. Electronic address: bluemked@cc.nih.gov.
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Delayed iodine CT; Dual energy CT; Infarct; Virtual monoenergetic