Quantitative 99mTechnetium cerebral circulation time in brain infarction. Its relation to clinical findings, electroencephalograms and conventional radionuclide studies.

Four circulation time parameters were measured by intravenously injected 99mTechnetium and a gamma camera in 183 patients displaying a unilateral supratentorial brain infarction. The mean values of all the calculated circulation time parameters in the infarcted hemisphere were significantly slower than those of the contralateral hemispheres. The difference between the hemispheres proved a more sensitive parameter than absolute values. Both the quantitative circulation time differences between the hemispheres and the absolute circulation time values showed significant correlations with several clinical findings, e.g. severity of infarction, recovery from infarction, and patient's age. However, quantification gave only a minor addition to the number of the patients with abnormalities detected by routine static and dynamic brain scintigrams. Though the value of the quantitative intravenous 99mTechnetium method in routine clinical work is limited, it provides valuable information on the haemodynamics in brain infarction, e.g. the persistence of measurable asymmetry suggesting decreased function even of non-infarcted parts of the affected hemisphere ("deafferentiation").