Measurement of local cerebral blood flow by computerized tomography with inhalation of stable xenon and curve-fitting method

Non-invasive methods are described for estimating local cerebal blood flows (LCBF) and local partition coefficients (Lλ) during inhalation of 30 % stable xenon gas (Xe) in oxygen during CT scanning. After the denitrogenation with pure oxygen breathing, 30 % Xe is inhaled for four minutes to minimize subanesthetic effects with a rubber facemask and the delivery system of Xe. Local time-Δ Hounsfield units curve during the Xe wash-in and wash-out phase is utilized in order to calculate Lλ and LCBF using a least squares curve fitting analysis. Calculated Lλ and LCBF with the new method manifested reasonable distribution between the grey and white matters, and reproducibility was excellent in our study. Several case studies of patients with cerebral infarction are presented to demonstrate the characterization of Lλ and LCBF patterns in various tissues and theoretical grounds underlying the new method of curve fitting analysis are discussed. (author)