In vivo venous blood T1 measurement using inversion recovery true‐FISP in children and adults

Abstract

A time‐efficient method is described for in vivo venous blood T₁ measurement using multiphase inversion‐recovery‐prepared balanced steady‐state free precession imaging. Computer simulations and validation experiments using a flow phantom were carried out to demonstrate the accuracy of the proposed method for measuring blood T₁ by taking advantage of the continuous inflow of fresh blood with longitudinal magnetization undisturbed by previous radiofrequency pulses. In vivo measurement of venous blood T₁ in the sagittal sinus was carried out in 26 healthy children and adults aged 7–39 years. The measured venous blood T₁ values decreased with age as a whole (P = 0.006) and were higher in females than males (P = 0.013), matching the expected developmental changes and gender differences in human hematocrit level. The estimated mean blood T₁ values were highly correlated with normal hematocrit levels across age and gender groups (Spearman's r = 0.93, P = 0.008). The longitudinal repeatability of this technique was 4.0% as measured by the within‐subject coefficient of variation. The proposed multiphase inversion recovery‐prepared balanced steady‐state free precession imaging method is a feasible technique for fast (T₁ measurement and may serve as an index of hematocrit level in individual subjects. Magn Reson Med, 2010.