Background and purpose: Pulsatility index (PI) in the middle cerebral artery (MCA) is considered a measure of peripheral vascular resistance. Several established cardiovascular risk factors are common for both MCA PI and carotid atherosclerosis. Accordingly, in the present study we hypothesized an association between ultrasound-derived indices of carotid atherosclerosis and MCA PI.
Methods: All residents in Akershus County, born in 1950, were invited to a cardiovascular examination, The Akershus Cardiac Examination (ACE) 1950 Study (2012-2015). A thorough ultrasound examination was performed to assess indices of atherosclerosis in the carotid arteries, and PI in the MCAs. In all, 3154 (85.1%) had adequate transcranial and carotid data. Associations between indices of carotid atherosclerosis and MCA PI were assessed by regression analyses adjusted for established cardiovascular risk factors.
Results: Mean age was 64 (standard deviation [SD]: .6) years, and 1,357 (43%) were women. Mean MCA PI was .97 (SD: .17). Participants in the upper quartile of MCA PI had higher pulse pressure, more frequently hypertension, diabetes mellitus, and a history of coronary artery disease. Both carotid plaque score (B .007 [95% CI: .003-.010]) and carotid intimamedia thickness (B .173 [95% CI: .120-.226]) were significantly associated with MCA PI in adjusted analysis. The model R2 was .055.
Conclusion: In a population-based sample of middle-aged adults, ultrasound-derived indices of carotid atherosclerosis were independently associated with MCA PI. However, the overall explained variance of MCA PI was low, suggesting other factors than atherosclerosis and cardiovascular risk factors to play an important role for MCA PI.
Keywords: Carotid atherosclerosis; middle cerebral artery; pulsatility index; transcranial Doppler; ultrasound.
© 2019 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.