Comparison of Quantitative Autoradiographic and Xenon-133 Clearance Methods: Correlation of Gray and White Matter Cerebral Blood Flow with Compartmental Blood Flow Indices

Abstract

Summary:The relationships between CBF in gray and white matter to those of the fast and slow components of xenon-133 clearance curves remain uncertain, CBF was measured in 13 anaesthetized baboons under a variety of conditions, using both the xenon-133 clearance technique and [14Cliodoantipyrine quantitative autoradiography. There was a linear relationship between CBF, as deter mined by the stochastic (height/area) analysis of the clearance curve, and mean CBF determined from the au toradiograms (r = 0.94, p < 0.001, slope = 0.86 ± 0.09). There was also a linear correlation between the fast-flow component (measured with xenon-133) and blood flow inThe xenon-133 clearance technique is widely used in both humans and laboratory animals to pro vide a measure of CBF (Hoedt-Rassmussen et aI., 1966;Lassen and Ingvar, 1972; Obrist et aI., 1975; Wyper et aI., 1976; Fitch et aI., 1978; Hetz et aI., 1984; Leli et aI., 1985). A common model of anal ysis of the xenon-133 clearance curves considers the clearances to be the result of the washout of tracer from two parallel compartments. These com partments, which clear at a fast and a slow rate, have been proposed to represent flow in cerebral gray matter and white matter, respectively (Hoedt Rasmussen et aI., 1966; Obrist et aI., 1975). How ever, this interpretation of the clearance curves re mains controversial (Iliff et aI. , 1974; Marcus et aI., 1981). In the present study, the relationship be- tween regional blood flow and the compartmental flow indices was investigated in the baboon using the excellent spatial resolution of quantitative [14C]iodoantipyrine autoradiography. Such a sys tematic investigation of the correlation between CBF measured with autoradiography and that mea sured with xenon-133 clearance has not been re ported previously in the primate. METHODS Animal preparationThe experiments were performed using 13 young, healthy baboons (5-11 kg) prepared in a manner identical to that established in this laboratory (Fitch et a!., 1978).Briefly, the animals were sedated with phencyclidine (10 mg/kg i.m.), anaesthetized with sodium thiopental (7.5 mg/kg), intubated, and connected to a positive-pressure ventilator supplied with a mixture of 70% NP and 30% 02' The ventilation was adjusted such that the animal was normocapnic (Pac02 �40 mm Hg) and normoxic (Pao2 � 100 mm Hg). Phencyclidine (0.01-0.02 mg/kg/min) was infused continuously to maintain anaesthesia, arterial blood pressure was monitored, and a normal body tem-

The hemodynamic effects of internal carotid artery stenosis and occlusion

“…The methodological validation of the '4C-IAP autoradiographic method in baboons has been reported re-cently from this laboratory. 34 The three methods of flow measurement reported in the present study all corresponded well with each other. To eliminate any bias which can be introduced in the interpretation of autoradiographic flow, the flow band analysis method was used here.…”

Cerebral cortical and white matter reactivity to carbon dioxide.

“…15 Slow blood flow is difficult to measure accurately, especially when reduced, because of compartmental slippage, low count rates, contaminating counts from the scalp, and scatter. 18 The paucity of studies of white matter CBF and R, particularly in the white matter of elderly subjects, appears to be the result of these difficulties. Our method avoids the aforementioned limitations.…”