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Dynamic Cerebral Autoregulation Assessment Using Extracranial Internal Carotid Artery Doppler Ultrasonography
Nai-Fang Chi1, Hsiao-Lun Ku2, Chen-Yen Wang3
1Department of Neurology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Neurology, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan.
Ultrasound in Medicine & Biology
|April 17, 2017
Summary
Dynamic cerebral autoregulation (dCA) assessed via the extracranial internal carotid artery (ICA) shows agreement with middle cerebral artery (MCA) measurements. While effective, ICA and MCA results for dCA are not interchangeable.
Area of Science:
- Neuroscience
- Medical Imaging
- Cardiovascular Physiology
Background:
- Transcranial Doppler ultrasonography of the middle cerebral artery (MCA) is standard for assessing dynamic cerebral autoregulation (dCA).
- Poor temporal bone windows limit MCA-based dCA assessment in some patients.
Purpose of the Study:
- To investigate the agreement and sensitivity of dCA indices derived from the extracranial internal carotid artery (ICA) compared to the MCA.
- To evaluate the utility of ICA-derived dCA indices for stroke diagnosis.
Main Methods:
- Simultaneous measurement of dCA indices, including mean flow correlation index (Mx) and transfer function analysis, from both ICA and MCA in 32 stroke patients and 59 controls.
- Analysis of spontaneous blood pressure fluctuations to determine dCA parameters.
Main Results:
- Mean values for Mx and phase shift were comparable between ICA and MCA.
- Significantly lower gains in very low frequency (VLF) and low frequency (LF) bands were observed for ICA compared to MCA.
- Favorable intra-class correlation coefficients were found for Mx (0.76) and VLF phase shift (0.72) between ICA and MCA.
- No significant difference in the area under the receiver operating characteristic curve for stroke diagnosis was found among dCA indices.
Conclusions:
- Dynamic cerebral autoregulation assessment using the extracranial ICA is a viable alternative when MCA assessment is challenging.
- While ICA-derived dCA indices show good agreement with MCA, the results are not directly interchangeable due to differences in gain parameters.