rCBF measurements by 133Xe inhalation: recent methodological advances.

Some recent methodological improvements of the 133Xe-inhalation method for determination of the rCBF are reviewed. Improvements of the classical (Obrist) method of analysis involving routines for correction of background, remaining activity and contamination from 133Xe in the air passages are described. Advantages and limitations of the ISI as compared to the bi-exponential flow parameters are discussed as well as different ways to determine technical quality and reliability of the flow calculations. Finally, a new method of curve analysis based on Fourier transforms is described. This method allows use of the full curve from start of 133Xe breathing and offers improved methods for correction of influence from air passages and arteries. Its advantages in terms of greater sensitivity and validity are discussed.