Nilsson BW, Rikner G, Wolgast M. The validity of an intravenous isotope method for cerebral blood flow measurements. An experimental study.
Scand J Clin Lab Invest 1977;
37:201-8. [PMID:
356173 DOI:
10.3109/00365517709091483]
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Abstract
The intravenous isotope method has been examined. The method uses 99Tc as the indicator with recording of the radioactivity with two gamma-dectors placed bilaterally over the skull and oriented over the bifurcation of the middle cerebral artery. 65% of the total curve obtained was found to be generated by activity passing in the ipsilateral internal carotid artery, 25% in the contralateral internal carotid artery and less than 10% by activity passing in the two external carotid arteries. The counting rate efficiency for an intracerebral location was 19.4 +/- 1.8 times the count rate from the same activity placed at 1 m distance in air which in turn was 5 cps/muCi. The variability in efficiency from patient to patient was thus estimated at +/- 9%. The duration of the input bolus had a marked influence on the vurve, which will be of importance since it showed a rather large variability from patient. Using the peak activity as an index of the cerebral blood flow the intravenous method showed a surprisingly good correlation with the 133Xe wash-out method; the correlation coefficient was 0.93 and the variability at slightly subnormal values estimated at +/- 15%. It is concluded that the method can be used in the case of limited demands on the accuracy of the cerebral blood flow determinations.
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