title: Blood longitudinal (T1) and transverse (T2) relaxation time constants at 11.7 Tesla.
abstract: OBJECTIVE
  The goal of the study was to determine blood T(1) and T(2) values as functions of oxygen saturation (Y), temperature (Temp) and hematocrit (Hct) at an ultrahigh MR field (11.7 T) and explore their impacts on physiological measurements, including cerebral blood flow (CBF), blood volume (CBV) and oxygenation determination.
  
  
  METHODS
  T(1) and T(2) were simultaneously measured. Temperature was adjusted from 25 to 40°C to determine Temp dependence; Hct of 0.17-0.51 to evaluate Hct dependence at 25 and 37°C; and Y of 40-100% to evaluate Y dependence at 25 and 37°C. Comparisons were made with published data obtained at different magnetic field strengths (B(0)).
  
  
  RESULTS
  T(1) was positively correlated with Temp, independent of Y, and negatively correlated with Hct. T(2) was negatively correlated with Temp and Hct, but positively correlated with Y, in a non-linear fashion. T(1) increased linearly with B(0), whereas T(2) decreased exponentially with B(0).
  
  
  CONCLUSIONS
  This study reported blood T(1) and T(2) measurements at 11.7 T for the first time. These blood relaxation data could have implications in numerous functional and physiological MRI studies at 11.7 T.
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA. lina3@uthscsa.edu
authors.forename: Ai-Ling
authors.initials: AL
authors.lastname: Lin
authors.forename: Qin
authors.initials: Q
authors.lastname: Qin
authors.forename: Xia
authors.initials: X
authors.lastname: Zhao
authors.forename: Timothy Q
authors.initials: TQ
authors.lastname: Duong
mesh_terms: D000465:Algorithms; D000818:Animals; D001790:Blood Physiological Phenomena; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
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