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CBF and transcranial Doppler sonography during vasodilatory stress tests in patients with common carotid artery
S Vorstrup1, V Zbornikova, H Sjöholm
1Department of Neurology, Rigshospitalet, Copenhagen, Denmark.
Insights
Transcsranial Doppler (TCD) does not predict cerebral blood flow (CBF) in patients with carotid artery occlusion. Combining TCD with CBF measurements provides complementary information on cerebrovascular reserve and flow distribution.
Area of Science:
- Neurology
- Vascular Medicine
- Medical Imaging
Background:
- Cerebrovascular disease, particularly common carotid artery (CCA) occlusion, impairs cerebral blood flow (CBF).
- Assessing cerebral vasoreactivity is crucial for understanding collateral circulation and stroke risk.
Purpose of the Study:
- To evaluate the correlation between transcranial Doppler (TCD) measurements and regional CBF in patients with CCA occlusion.
- To determine if TCD can predict regional CBF and assess cerebrovascular reserve.
Main Methods:
- CBF was measured using xenon-133 inhalation and SPECT imaging.
- Cerebral vasoreactivity was assessed using 6% CO2 inhalation and acetazolamide administration.
- TCD measurements of the middle cerebral artery (MCA) were performed at baseline and during vasodilatory challenges.
Main Results:
- Patients with CCA occlusion exhibited significantly lower global CBF compared to healthy controls.
- CBF increased substantially during CO2 inhalation and acetazolamide administration, indicating collateral compensation.
- Correlations between MCA TCD velocity and regional CBF were statistically significant only when data from all conditions were pooled.
Conclusions:
- TCD velocity measurements alone are insufficient to predict regional CBF in patients with CCA occlusion.
- TCD and CBF measurements offer complementary information, with TCD reflecting collateral pathways (Circle of Willis) and CBF studies detailing flow distribution.
Abstract:
Cerebral blood flow (CBF) and the cerebral vasoreactivity was measured in patients with cerebrovascular disease and longstanding occlusion of the common carotid artery (CCA). In addition, regional CBF was correlated with transcranial doppler (TCD) measurements at baseline and during 6% CO2 inhalation and after intravenous administration of 1 g of acetazolamide. Twelve patients with a mean age of 62 years (range 45 to 71 years) were included, and the data compared to age-matched healthy controls. CBF was measured by intravenous injection of xenon-133 and SPECT (Tomomatic 564). TCD of the middle cerebral artery (MCA) was done by EME TC-64B. A very low global CBF value of 28 +/- 5 (SD) ml 100 g-1 min-1 was found at baseline as compared to 55 +/- 5 ml 100 g-1 min-1 in the normal controls. During 6% CO2-inhalation and after acetazolamide administration, CBF increased by 58 +/- 24% and 51 +/- 21%, respectively, indicating substantial collateral supply. Correlative analysis of CBF in the MCA territory and TCD in the MCA showed statistical significance only for the pooled data, i.e. compiling the data obtained during baseline and the two vasodilatory tests, and then only for the mean and peak TCD velocity (e.g. r = 0.59, p less than 0.002, n = 35, mean velocity, right side). We conclude that TCD measurements do not predict regional CBF in patients with CCA occlusion. The study emphasizes that these two methods yield supplementary information, with TCD measurements providing information of the circle of Willis and CBF studies of the flow distribution.