PURPOSE: Cardiac CT achieves its high temporal resolution by lowering the scan range from 2pi to pi plus fan angle (partial scan). This, however, introduces CT-value variations, depending on the angular position of the pi range. These partial scan artifacts are of the order of a few HU and prevent the quantitative evaluation of perfusion measurements. The authors present the new algorithm partial scan artifact reduction (PSAR) that corrects a dynamic phase-correlated scan without a priori information. METHODS: In general, a full scan does not suffer from partial scan artifacts since all projections in [0, 2pi] contribute to the data. To maintain the optimum temporal resolution and the phase correlation, PSAR creates an artificial full scan pn(AF) by projectionwise averaging a set of neighboring partial scans pn(P) from the same perfusion examination (typically N approximately 30 phase-correlated partial scans distributed over 20 s and n = 1, ..., N). Corresponding to the angular range of each partial scan, the authors extract virtual partial scans pn(V) from the artificial full scan pn(AF). A standard reconstruction yields the corresponding images fn(P), fn(AF), and fn(V). Subtracting the virtual partial scan image fn(V) from the artificial full scan image fn(AF) yields an artifact image that can be used to correct the original partial scan image: fn(C) = fn(P) - fn(V) + fn(AF), where fn(C) is the corrected image. RESULTS: The authors evaluated the effects of scattered radiation on the partial scan artifacts using simulated and measured water phantoms and found a strong correlation. The PSAR algorithm has been validated with a simulated semianthropomorphic heart phantom and with measurements of a dynamic biological perfusion phantom. For the stationary phantoms, real full scans have been performed to provide theoretical reference values. The improvement in the root mean square errors between the full and the partial scans with respect to the errors between the full and the corrected scans is up to 54% for the simulations and 90% for the measurements. CONCLUSIONS: The phase-correlated data now appear accurate enough for a quantitative analysis of cardiac perfusion.
PURPOSE: Cardiac CT achieves its high temporal resolution by lowering the scan range from 2pi to pi plus fan angle (partial scan). This, however, introduces CT-value variations, depending on the angular position of the pi range. These partial scan artifacts are of the order of a few HU and prevent the quantitative evaluation of perfusion measurements. The authors present the new algorithm partial scan artifact reduction (PSAR) that corrects a dynamic phase-correlated scan without a priori information. METHODS: In general, a full scan does not suffer from partial scan artifacts since all projections in [0, 2pi] contribute to the data. To maintain the optimum temporal resolution and the phase correlation, PSAR creates an artificial full scan pn(AF) by projectionwise averaging a set of neighboring partial scans pn(P) from the same perfusion examination (typically N approximately 30 phase-correlated partial scans distributed over 20 s and n = 1, ..., N). Corresponding to the angular range of each partial scan, the authors extract virtual partial scans pn(V) from the artificial full scan pn(AF). A standard reconstruction yields the corresponding images fn(P), fn(AF), and fn(V). Subtracting the virtual partial scan image fn(V) from the artificial full scan image fn(AF) yields an artifact image that can be used to correct the original partial scan image: fn(C) = fn(P) - fn(V) + fn(AF), where fn(C) is the corrected image. RESULTS: The authors evaluated the effects of scattered radiation on the partial scan artifacts using simulated and measured water phantoms and found a strong correlation. The PSAR algorithm has been validated with a simulated semianthropomorphic heart phantom and with measurements of a dynamic biological perfusion phantom. For the stationary phantoms, real full scans have been performed to provide theoretical reference values. The improvement in the root mean square errors between the full and the partial scans with respect to the errors between the full and the corrected scans is up to 54% for the simulations and 90% for the measurements. CONCLUSIONS: The phase-correlated data now appear accurate enough for a quantitative analysis of cardiac perfusion.
Authors: Michael A Speidel; Courtney L Bateman; Yinghua Tao; Amish N Raval; Timothy A Hacker; Scott B Reeder; Michael S Van Lysel Journal: Med Phys Date: 2013-01 Impact factor: 4.071
Authors: A M Bucher; C N De Cecco; U J Schoepf; R Wang; F G Meinel; S R Binukrishnan; J V Spearman; T J Vogl; B Ruzsics Journal: Br J Radiol Date: 2014-08-19 Impact factor: 3.039
Authors: Yinghua Tao; Guang-Hong Chen; Timothy A Hacker; Amish N Raval; Michael S Van Lysel; Michael A Speidel Journal: Med Phys Date: 2014-07 Impact factor: 4.071
Authors: A Sisniega; W Zbijewski; J W Stayman; J Xu; K Taguchi; E Fredenberg; Mats Lundqvist; J H Siewerdsen Journal: Phys Med Biol Date: 2015-11-27 Impact factor: 3.609
Authors: Marc Dewey; Maria Siebes; Marc Kachelrieß; Klaus F Kofoed; Pál Maurovich-Horvat; Konstantin Nikolaou; Wenjia Bai; Andreas Kofler; Robert Manka; Sebastian Kozerke; Amedeo Chiribiri; Tobias Schaeffter; Florian Michallek; Frank Bengel; Stephan Nekolla; Paul Knaapen; Mark Lubberink; Roxy Senior; Meng-Xing Tang; Jan J Piek; Tim van de Hoef; Johannes Martens; Laura Schreiber Journal: Nat Rev Cardiol Date: 2020-02-24 Impact factor: 32.419