title: Fast measurement of blood T1in the human carotid artery at 3T: Accuracy, precision, and reproducibility.
abstract: To develop a fast protocol for measuring T1values in the internal carotid artery (ICA), to validate this technique with in vitro measurements, and to evaluate its reproducibility.
  
  
  
  A modified Look-Locker sequence was optimized to enable rapid determination of T1in the ICA at 3T. T1values from the ICA were compared with in vitro measurements on individually sampled venous blood oxygenated to arterial levels. A test-retest reproducibility study was also conducted.
  
  
  
  The group-averaged arterial blood T1value was 1908 ± 77 ms for six women (hematocrit = 0.39 ± 0.03) and 1785 ± 55 ms for seven men (hematocrit = 0.45 ± 0.02), which is 100-200 ms longer than the widely adopted value obtained from bovine blood experiments. The arterial T1value per subject correlated significantly with individual hematocrit values. The intrasession and intersession coefficients of variation were 1.1% and 2.1%, respectively, indicating good precision and reproducibility of our method. Reasonable agreement was observed between the in vivo and in vitro results with a correlation coefficient of 0.78.
  
  
  
  The proposed method can provide fast arterial T1measurement on individual subjects. When not performing such a subject-specific measurement, we recommend the use of 1908 ms and 1785 ms for healthy women and men, respectively, or 1841 ms for adults in general. Magn Reson Med 77:2296-2302, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Wenbo
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Peiying
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: Hanzhang
authors.initials: H
authors.lastname: Lu
authors.affiliation: Division of Pediatric Hematology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Strouse
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Peter C M
authors.initials: PCM
authors.lastname: van Zijl
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.|F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Qin
authors.initials: Q
authors.lastname: Qin
mesh_terms: D000328:Adult; D000465:Algorithms; D001769:Blood / Q000000981:diagnostic imaging*; D001783:Blood Flow Velocity / Q000502:physiology*; D002339:Carotid Arteries / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
keywords: in vivo blood T1; internal carotid artery; inversion recovery