title: Assessment of carotid plaque composition using fast-kV switching dual-energy CT with gemstone detector: comparison with extracorporeal and virtual histology-intravascular ultrasound.
abstract: BACKGROUND
  The present study compares the applicability of CT carotid plaque imaging using effective Z maps using gemstone spectral imaging (GSI) with that of conventional extracorporeal carotid ultrasound (US) and virtual histology-intravascular ultrasound (VH-IVUS).
  
  
  METHODS
  We assessed stenosis in 31 carotid arteries of 30 patients. All patients underwent carotid CTA using GSI (Discovery CT750 HD, GE Healthcare). US and IVUS were examined with 25 and 8 vessels, respectively. We compared the effective Z values at noncalcified carotid plaque with the plaque components identified by US. We defined the plaque with low or low to iso intensity on US as vulnerable plaque and the plaque with iso, iso to high, and high intensity on US as stable plaque. We also performed visual assessment of color-coded effective Z maps in comparison with VH-IVUS and compared effective Z values with plaque components generated by VH-IVUS.
  
  
  RESULTS
  The effective Z values at noncalcified carotid plaque were significantly lower for a group with vulnerable plaque, than with stable plaque on US (p < 0.05). Receiver operating curve analysis showed that AUC of effective Z values was 0.882 concerning the differentiation of these two groups on US. The interpretation of color-coded effective Z maps was essentially compatible with that of VH-IVUS for carotid plaque in all vessels. Effective Z values at noncalcified plaque showed significant negative correlation with the areas of fibro-fatty components generated by VH-IVUS (ρ = -0.874, p < 0.05).
  
  
  CONCLUSIONS
  Effective Z maps generated by GSI can detect vulnerable carotid plaque materials.
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishi-cho, Yonago, 683-8504, Japan. shino-y@olive.plala.or.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shinohara
authors.affiliation: Division of Neurosurgery, Department of Neurological Sciences, Faculty of Medicine, Tottori University, Yonago, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sakamoto
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishi-cho, Yonago, 683-8504, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Kuya
authors.affiliation: Division of Clinical Radiology, Tottori University Hospital, Yonago, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Kishimoto
authors.affiliation: Division of Clinical Radiology, Tottori University Hospital, Yonago, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Iwata
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishi-cho, Yonago, 683-8504, Japan.
authors.forename: Yasutoshi
authors.initials: Y
authors.lastname: Ohta
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishi-cho, Yonago, 683-8504, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Fujii
authors.affiliation: Division of Neurosurgery, Department of Neurological Sciences, Faculty of Medicine, Tottori University, Yonago, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Division of Radiology, Department of Pathophysiological and Therapeutic Science, Faculty of Medicine, Tottori University, 36-1, Nishi-cho, Yonago, 683-8504, Japan.
authors.forename: Toshihide
authors.initials: T
authors.lastname: Ogawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007472:Iohexol; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D018084:Ultrasonography, Interventional / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol
keywords: CT angiography; Carotid plaque; Effective Z; Gemstone spectral imaging; Virtual histology-intravascular ultrasound