The C¹⁵O₂ Build-up Technique to Measure Regional Cerebral Blood Flow and Volume of Distribution of Water

Abstract

Summary:A new method to measure regional CBF (rCBF) and volume of distribution of water is presented. It centres on recording the tissue build-up and retention of ISO-labelled water during the continuous inhalation of ISO-labelled carbon dioxide. Simultaneously, the arterial concentration is continuously monitored, and corrections for delay and dispersion in the recorded response are made by curve fitting. The values for the volume of disSeveral tracers have been proposed for the mea surement of regional CBF (rCBF) with positron emission tomography (PET). However, in practice most clinical applications have used H2150 as a flow tracer (Lammert sma and Frackowiak, \985). H2150 has been administered intravenously or by inhala tion of C1502. In the latter case the ISO label is rapidly transferred to the water pool in the lung capillary bed (West and Dollery, 1962).The preference for H21S0 as a flow tracer is based on a number of advantages: (a) the relative simplic ity of producing both H21S0 and CIS02 (Clark and Buckingham, 1975); (b) the short half-life of ISO (2.05 min), allowing for repeat measurements dur ing one scanning session and/or combination of rCBF measurements with any other (metabolic, re ceptor, etc.) study; (c) the partition coefficient of

Functional neuroanatomy of antisaccade eye movements investigated with positron emission tomography.

“…The C1502 buildup technique has been studied by Lammertsma et al (25). Unpublished work in the Massachusetts General Hospital PET laboratory has confirmed that the integrated counts over inhalation periods up to 90 sec is a linear function of the flow over the expected range; that is, the amount of radiation that gets into tissue is proportional to blood flow.…”

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

“…Errors due to tissue heterogeneity are small (less than 10%) in these methods (Herholz and Pat lak, 1987); as for errors due to time shifts and dis persion of input functions, only limited data are available, but in theory they can be modeled and accounted for (Lammertsma et a!. , 1986(Lammertsma et a!. , , 1987c.…”

In vivo Measurement of the Volume of Distribution of Water in Cerebral Grey Matter: Effects on the Calculation of Regional Cerebral Blood Flow

“…In contrast to the Recently, a new method has been described for the measurement of CBF using inhalation of C1502 and positron emission tomography (PET) (Lam mertsma et aI., 1990). This method involves two separate steps in generating reproducible functional CBF images, which are required in the analysis of activation or stimulation studies.First, the dynamic PET frames collected during and after inhalation of C1502 are analyzed using a nonlinear regression technique to obtain accurate estimates of delay and dispersion of the arterial blood curve (Lammertsma et al, 1989). Second, us ing these values of delay and dispersion, a pixel-by pixel integral analysis is then applied to the inhala tion (buildup) phase.…”

“…First, the dynamic PET frames collected during and after inhalation of C1502 are analyzed using a nonlinear regression technique to obtain accurate estimates of delay and dispersion of the arterial blood curve (Lammertsma et al, 1989). Second, us ing these values of delay and dispersion, a pixel-by pixel integral analysis is then applied to the inhala tion (buildup) phase.…”