title: Impact of filter convolution and displayed field of view on estimation of coronary Agatston scores in low-dose lung computed tomography.
abstract: BACKGROUND
  Coronary artery calcification (CAC) may be quantified on low-dose computed tomography (CT) of the lung (LDCT). This study aims to evaluate the effects of filter convolution (FC) and displayed field of view (dFOV) in a Toshiba 320-row CT scanner in quantifying CAC, and to compare the CAC scores obtained by LDCT with standard cardiac CT.
  
  
  METHODS
  Fifty subjects (52 to 85years, mean 68.5, 36 males) with visible CAC underwent both standard cardiac CT and LDCT. CAC scores were obtained from standard cardiac CT using conventional FC12(22) (FC12 with 22-cm dFOV) and four different LDCT protocols: FC02(22), FC02(40), FC08(22), and FC08(40). CAC scores obtained by each LDCT protocol were compared with those obtained by standard cardiac CT.
  
  
  RESULTS
  CAC scores obtained by all four LDCT protocols were well correlated with those by standard protocol (Pearson's coefficient=0.978 to 0.987, p<0.001; kappa=0.731 to 0.836, p<0.001). CAC scores obtained by FC08(22) showed the best agreement with standard cardiac CT (kappa=0.836, p<0.001). Under fixed dFOV, CAC scores in FC08 were significantly higher than in FC02 (p<0.001). Under fixed FC, CAC scores were significantly higher in 22-cm dFOV than in 40-cm dFOV (p≤0.006).
  
  
  CONCLUSIONS
  Both FC and dFOV have significant impact on CAC scoring. To obtain reliable data, consistent parameters should be employed when quantifying CAC using LDCT. In a Toshiba 320-row CT scanner, CAC scores obtained by FC08(22) agree well with standard cardiac CT.
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Institute for Radiological Research, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan. Electronic address: ylw0518@cgmh.org.tw.
authors.forename: Yung-Liang
authors.initials: YL
authors.lastname: Wan
authors.affiliation: Department of Public Health and Center of Biostatistics, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Pei-Kwei
authors.initials: PK
authors.lastname: Tsay
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Institute for Radiological Research, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Patricia Wanping
authors.initials: PW
authors.lastname: Wu
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Institute for Radiological Research, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Yu-Hsiang
authors.initials: YH
authors.lastname: Juan
authors.affiliation: Institute for Radiological Research, Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Hui-Yu
authors.initials: HY
authors.lastname: Tsai
authors.affiliation: Institute for Radiological Research, Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Chung-Yin
authors.initials: CY
authors.lastname: Lin
authors.affiliation: Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Institute for Radiological Research, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Chih-Sheng
authors.initials: CS
authors.lastname: Yeh
authors.affiliation: Section of Pulmonary Medicine, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wang
authors.affiliation: Section of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, College of Medicine, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Chen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards; D061205:Vascular Calcification / Q000000981:diagnostic imaging / Q000503:physiopathology
keywords: Computed tomography; Coronary calcification; Displayed field of view; Filter convolution; Low-dose lung CT