Prediction of hemispheric blood flow from carotid velocity measurements. A study with the Doppler and 133Xe inhalation techniques.

Doppler carotid velocity determinations were related to hemispheric blood flow measurements by the 133Xe inhalation method in 28 patients with psychiatric disorders without arterial pathology and in 2 normal subjects. Results from 39 double determinations showed a product-moment correlation of 0.88 (p < 0.001) between right hemispheric blood flow and right internal carotid end-diastolic velocity. The correlation for the left side was slightly lower (r = 0.83), while the common carotid end-diastolic velocity showed a considerably lower correlation of 0.71 (rt) and 0.69 (lt) respectively. The peak-systolic velocity values (internal carotids) showed a less close relationship to hemispheric flow (r = 0.71 (rt) and r = 0.61 (lt)). It is concluded that a fairly accurate (15-20% maximum error) prediction of hemispheric blood flow from Doppler internal carotid end-diastolic velocity values is possible in patients without abnormalities in these arterial systems. The high correlations found, in spite of the fact that arterial diameters were not taken into account, are further proof of the accuracy and validity of both methods.