title: Variability and accuracy of coronary CT angiography including use of iterative reconstruction algorithms for plaque burden assessment as compared with intravascular ultrasound-an ex vivo study.
abstract: OBJECTIVE
  To systematically assess inter-technique and inter-/intra-reader variability of coronary CT angiography (CTA) to measure plaque burden compared with intravascular ultrasound (IVUS) and to determine whether iterative reconstruction algorithms affect variability.
  
  
  METHODS
  IVUS and CTA data were acquired from nine human coronary arteries ex vivo. CT images were reconstructed using filtered back projection (FBPR) and iterative reconstruction algorithms: adaptive-statistical (ASIR) and model-based (MBIR). After co-registration of 284 cross-sections between IVUS and CTA, two readers manually delineated the cross-sectional plaque area in all images presented in random order.
  
  
  RESULTS
  Average plaque burden by IVUS was 63.7 ± 10.7% and correlated significantly with all CTA measurements (r = 0.45-0.52; P < 0.001), while CTA overestimated the burden by 10 ± 10%. There were no significant differences among FBPR, ASIR and MBIR (P > 0.05). Increased overestimation was associated with smaller plaques, eccentricity and calcification (P < 0.001). Reproducibility of plaque burden by CTA and IVUS datasets was excellent with a low mean intra-/inter-reader variability of <1/<4% for CTA and <0.5/<1% for IVUS respectively (P < 0.05) with no significant difference between CT reconstruction algorithms (P > 0.05).
  
  
  CONCLUSIONS
  In ex vivo coronary arteries, plaque burden by coronary CTA had extremely low inter-/intra-reader variability and correlated significantly with IVUS measurements. Accuracy as well as reader reliability were independent of CT image reconstruction algorithm.
  
  
  CONCLUSIONS
  • IVUS is deemed the gold standard in-vivo coronary plaque assessment                                                                              • But coronary CT angiography findings correlate strongly with IVUS results                                                                              • Coronary CT angiography now allows plaque quantification close to IVUS                                                                              • Iterative image reconstruction algorithms do not alter accuracy or reproducibility                                                                              • Plaque quantification is more challenging in smaller eccentric calcified lesions.
authors.affiliation: Cardiac MR PET CT Program, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Stolzmann
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Schlett
authors.forename: Pal
authors.initials: P
authors.lastname: Maurovich-Horvat
authors.forename: Akiko
authors.initials: A
authors.lastname: Maehara
authors.forename: Shixin
authors.initials: S
authors.lastname: Ma
authors.forename: Hans
authors.initials: H
authors.lastname: Scheffel
authors.forename: Leif-Christopher
authors.initials: LC
authors.lastname: Engel
authors.forename: Mihály
authors.initials: M
authors.lastname: Károlyi
authors.forename: Gary S
authors.initials: GS
authors.lastname: Mintz
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
mesh_terms: D000465:Algorithms; D017023:Coronary Angiography / Q000592:standards*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D018084:Ultrasonography, Interventional