TCD-profiling. Evaluation beyond the human eye of transcranial Doppler ultrasound flow spectra in subjects with cerebral microangiopathy and controls using AVERAGE

• Published in: Aktuelle Neurologie
• Main Authors: Ritter, M.A., Deppe, M., Püschel, J., Nabavi, D.G., Allroggen, A., Dittrich, R., Ringelstein, E.B.
• Format: Conference Proceeding
• Language: English; German
• Published: 27.09.2006
• ISSN: 0302-4350; 1438-9428
• DOI: 10.1055/s-2006-953366

Aims: Transcranial Doppler ultrasound (TCD) flow spectra of the larger intracranial arteries probably contain relevant information about the microcirculation as shown by increased pulsatility index (PI) or resistance index (RI) in patients with untreated severe cerebral microangiopathy (CM). However, a number of other factors influence flow spectra characteristics. We assume that using analysis of averaged flow spectra could be useful to adjust for a number of confounders. Methods: 12 subjects (aged 63±5 years) with MRI signs of severe CM, but without a history of stroke or vascular dementia and 12 age matched (60±7 years) controls with MRI confirmed absence of CM were examined. Significant stenoses of the input vessels were excluded by extra- and intracranial ultrasound. Blood-pressure, heart rate (HR) and end-tidal CO2 were recorded. The TCD signal of both middle cerebral arteries was recorded for five minutes and 50 cardiac cycles per subject of predefined HR were analysed. Averaged spectra and its first derivation from time (i.e. acceleration, a*) were generated using AVERAGE software. Spectra were normalized according to measured mean flow velocity. Flow velocities were then expressed as percentage values of mean flow velocity [%]. a* was expressed as change of the percentage value over time [%/s] Secondly, length of the systolic part of the cardiac cycle was adjusted for heart rate (HR). The groß morphology of the averaged spectra, conventional indices (PI, RI) and the maximum range of a* (maximum a* – minimum a*) were compared between subjects with and without CM. Results: Blood pressure values, mean heart rate, and end tidal CO2 were not significantly different between subjects with CM and those without. Gross morphology of the spectra was not different between the groups on eyeballing. Pulsatility index (PI: 0.82±0.1 for CM subjects vs. 0.81±0.15 for controls) and resistance index (RI: 0.55±0.05 for CM subjects vs. 0.55±0.06 for controls) were the same in both groups. The range of a* however was 1435 (±253)%/s for controls and 1661 (±215)%/s for CM subjects (p=0.02). Conclusions: Using AVERAGE even subtle differences between flow spectra of subjects with CM and those with normal MRI. The method needs further evaluation in different settings, but it might be helpful in identifying patients who suffer from or are at risk for CM.