title: Evaluation of the Effect of Intracoronary Attenuation on Coronary Plaque Measurements Using a Dual-phase Coronary CT Angiography Technique on a 320-row CT Scanner--In Vivo Validation Study.
abstract: OBJECTIVE
  The characterization of plaques based on their computed tomography (CT) number is important for the detection of vulnerable atherosclerotic plaques. An earlier in vitro study showed that intravascular attenuation affected the attenuation of coronary atherosclerotic plaques. We attempted to validate this finding in vivo and here we introduce a dual-phase coronary CT angiography (CCTA) technique to address this issue.
  
  
  METHODS
  Institutional ethics committee approval and informed consent were obtained. Thirty patients (30 noncalcified plaques) underwent dual-phase CCTA. Two CT datasets were obtained, one with coronary artery enhancement and the other without coronary artery enhancement. The CT number of the plaque and the adjacent vessel lumen was measured in a circular region of interest on curved planar reconstruction images. The region of interest setting was consistent between the two CT datasets. We performed linear regression analysis of the changes in the CT numbers (ΔHounsfield unit), calculated by subtracting the two CT datasets, for the lumen and for the plaque. We also evaluated the relationship between plaque attenuation on nonenhanced coronary artery images and luminal attenuation with and without contrast enhancement.
  
  
  RESULTS
  The ΔHounsfield unit for the plaque and the lumen showed a strong correlation (r = 0.61). There was no significant correlation between plaque attenuation on nonenhanced coronary artery images and luminal attenuation with and without contrast enhancement (r = 0.23 and 0.24, respectively).
  
  
  CONCLUSIONS
  Intravascular attenuation changed the attenuation of coronary atherosclerotic plaques. Using the copy-paste technique, the CT number of identical plaques can be measured in registered dual-phase CCTA images for the evaluation of coronary plaques.
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan. Electronic address: masafkidoh@yahoo.co.jp.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Kidoh
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.affiliation: Medical Physics, Kumamoto University, Kumamoto, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Funama
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Yuki
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Hirata
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Namimoto
authors.affiliation: Department of Diagnostic Radiology, Kumamoto University, 1-1-1, Honjo, Kumamoto 860-8556, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007479:Iopamidol; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000295:instrumentation / Q000379:methods*; D009140:Musculoskeletal Diseases; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D015900:Radiography, Dual-Energy Scanned Projection / Q000379:methods*; D015898:Tomography Scanners, X-Ray Computed
chemical_list: D003287:Contrast Media; D007479:Iopamidol
keywords: Computed tomography (CT); Contrast media; Coronary CT angiography; Diagnosis