title: Iterative model reconstruction reduces calcified plaque volume in coronary CT angiography.
abstract: OBJECTIVE
  To assess the impact of iterative model reconstruction (IMR) on calcified plaque quantification as compared to filtered back projection reconstruction (FBP) and hybrid iterative reconstruction (HIR) in coronary computed tomography angiography (CTA).
  
  
  METHODS
  Raw image data of 52 patients who underwent 256-slice CTA were reconstructed with IMR, HIR and FBP. We evaluated qualitative, quantitative image quality parameters and quantified calcified and partially calcified plaque volumes using automated software.
  
  
  RESULTS
  Overall qualitative image quality significantly improved with HIR as compared to FBP, and further improved with IMR (p<0.01 all). Contrast-to-noise ratios were improved with IMR, compared to HIR and FBP (51.0 [43.5-59.9], 20.3 [16.2-25.9] and 14.0 [11.2-17.7], respectively, all p<0.01) Overall plaque volumes were lowest with IMR and highest with FBP (121.7 [79.3-168.4], 138.7 [90.6-191.7], 147.0 [100.7-183.6]). Similarly, calcified volumes (>130 HU) were decreased with IMR as compared to HIR and FBP (105.9 [62.1-144.6], 110.2 [63.8-166.6], 115.9 [81.7-164.2], respectively, p<0.05 all). High-attenuation non-calcified volumes (90-129 HU) yielded similar values with FBP and HIR (p=0.81), however it was lower with IMR (p < 0.05 both). Intermediate- (30-89 HU) and low-attenuation (<30 HU) non-calcified volumes showed no significant difference (p=0.22 and p=0.67, respectively).
  
  
  CONCLUSIONS
  IMR improves image quality of coronary CTA and decreases calcified plaque volumes.
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: mihaly.karolyi@cirg.hu.
authors.forename: Mihály
authors.initials: M
authors.lastname: Károlyi
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: szilveszter.balint@gmail.com.
authors.forename: Bálint
authors.initials: B
authors.lastname: Szilveszter
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: martonandko@gmail.com.
authors.forename: Márton
authors.initials: M
authors.lastname: Kolossváry
authors.affiliation: Department of Radiology, University Medical Center Utrecht, 100 Heidelberglaan, 3584, CX Utrecht, The Netherlands. Electronic address: richard.takx@gmail.com.
authors.forename: Richard A P
authors.initials: RA
authors.lastname: Takx
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: celengcsilla@gmail.com.
authors.forename: Csilla
authors.initials: C
authors.lastname: Celeng
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: bartyandi@gmail.com.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bartykowszki
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: adam.jermendy@gmail.com.
authors.forename: Ádám L
authors.initials: ÁL
authors.lastname: Jermendy
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: panajotualexisz@gmail.com.
authors.forename: Alexisz
authors.initials: A
authors.lastname: Panajotu
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: karadyjulia@gmail.com.
authors.forename: Júlia
authors.initials: J
authors.lastname: Karády
authors.affiliation: Philips HealthCare, 4-6 Veenpluis, 5684, Best, The Netherlands. Electronic address: rolf.raaijmakers@philips.com.
authors.forename: Rolf
authors.initials: R
authors.lastname: Raaijmakers
authors.affiliation: Philips HealthCare, 4-6 Veenpluis, 5684, Best, The Netherlands. Electronic address: walter.giepmans@philips.com.
authors.forename: Walter
authors.initials: W
authors.lastname: Giepmans
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: merkely.bela@gmail.com.
authors.forename: Béla
authors.initials: B
authors.lastname: Merkely
authors.affiliation: MTA-SE Cardiovascular Imaging Research Group, Heart and Vascular Center, Semmelweis University, 68. Varosmajor st, 1122, Budapest, Hungary. Electronic address: p.maurovich.horvat@mail.harvard.edu.
authors.forename: Pál
authors.initials: P
authors.lastname: Maurovich-Horvat
mesh_terms: D000368:Aged; D000465:Algorithms; D000072226:Computed Tomography Angiography / Q000379:methods*; D017023:Coronary Angiography / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods
keywords: Atherosclerotic plaque quantification; Cardiac imaging techniques; Coronary CT angiography; Coronary artery disease; Image reconstruction