title: Estimation of myocardial extracellular volume fraction with cardiac CT in subjects without clinical coronary artery disease: A feasibility study.
abstract: BACKGROUND
  Use of CT for assessment of extracellular volume fraction (ECV) is a new approach toward the evaluation of diffuse and focal myocardial fibrosis. It has recently been demonstrated that a hybrid algorithm of half- and full-scan reconstruction can improve image quality of delayed-phase CT.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate reproducibility of CT measurement of ECV of the myocardium using pre-contrast and delayed-phase CT, and to investigate the association between ECV and location, age and gender in subjects without clinical coronary artery disease.
  
  
  METHODS
  Thirty-eight subjects (ages 45-78, mean 65 years, 14 females) without coronary artery stenosis, stress perfusion deficits or myocardial delayed enhancement on comprehensive cardiac CT comprise the study population. Delayed-phase CT was reconstructed with the hybrid algorithm. ECV was calculated as a ratio of the change in Hounsfield unit of the myocardium and the left ventricular (LV) blood before and after contrast administration, multiplied by (1-hematocrit).
  
  
  RESULTS
  Good inter- and intra-observer agreement was observed in CT measurement of ECV (intraclass correlation coefficient: 0.968 and 0.971, respectively). Mean ECV was 26.1 ± 2.0% (range 22.6-30.0%), and was positively related to age (r = 0.46, p = 0.003). Mean ECV in males was lower compared with females (25.5 ± 2.0% vs. 27.1 ± 1.8%, p = 0.02). There was no statistically significant difference in ECV between anterior, septal, inferior, and lateral segments.
  
  
  CONCLUSIONS
  CT measurement of myocardial ECV showed high inter- and intra-observer reproducibility, and age-related increase and gender-related difference of ECV were demonstrated. This might enable additional CT evaluation of diffuse and focal myocardial fibrosis in various pathological conditions as part of a comprehensive cardiac CT examination.
authors.affiliation: Department of Radiology, Mie University Hospital, Tsu, Japan.
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Kurita
authors.affiliation: Department of Radiology, Mie University Hospital, Tsu, Japan. Electronic address: kakuya@clin.medic.mie-u.ac.jp.
authors.forename: Kakuya
authors.initials: K
authors.lastname: Kitagawa
authors.affiliation: Department of Radiology, Mie University Hospital, Tsu, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kurobe
authors.affiliation: Department of Cardiology, Mie University Hospital, Tsu, Japan.
authors.forename: Shiro
authors.initials: S
authors.lastname: Nakamori
authors.affiliation: Department of Cardiology, Mie University Hospital, Tsu, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakajima
authors.affiliation: Department of Cardiology, Mie University Hospital, Tsu, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Dohi
authors.affiliation: Department of Cardiology, Mie University Hospital, Tsu, Japan.
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ito
authors.affiliation: Department of Radiology, Mie University Hospital, Tsu, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Sakuma
mesh_terms: D000367:Age Factors; D000368:Aged; D000465:Algorithms; D009202:Cardiomyopathies / Q000000981:diagnostic imaging*; D000072226:Computed Tomography Angiography / Q000379:methods; D005109:Extracellular Matrix / Q000473:pathology*; D005240:Feasibility Studies; D005260:Female; D005355:Fibrosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods; D009206:Myocardium / Q000473:pathology*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011857:Radiographic Image Interpretation, Computer-Assisted; D015203:Reproducibility of Results; D012737:Sex Factors; D014057:Tomography, X-Ray Computed
keywords: CT delayed enhancement; Computed tomography; Extracellular matrix; Myocardial extracellular volume fraction; Myocardial fibrosis