RESEARCH ARTICLE Blood longitudinal (T1) and transverse (T2) relaxation time

Object The goal of the study was to determine blood T1 and T2 values as functions of oxygen saturation (Y), tem-perature (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. Materials and methods T1 and T2 were simultaneously measured. Temperature was adjusted from 25 to 40C to determine Temp dependence; Hct of 0.17–0.51 to evaluate Hct dependence at 25 and 37C; and Y of 40–100 % to evaluate Y dependence at 25 and 37C. Comparisons were made with published data obtained at different magnetic field strengths (B0). Results T1 was positively correlated with Temp, inde-pendent of Y, and negatively correlated with Hct. T2 was negatively correlated with Temp and Hct, but positively correlated with Y, in a non-linear fashion. T1 increased lin-early with B0, whereas T2 decreased exponentially with B0. Conclusion This study reported blood T1 and T2 mea-surements at 11.7 T for the first time. These blood relax-ation data could have implications in numerous functional and physiological MRI studies at 11.7 T