T. Shiogai 1, M. Yamamoto 1, M. Koyama 1, K. Yoshikawa 2, M. Nakagawa 3
1 Department of Clinical Neuroscience, Kyoto Takeda Hospital – Kyoto,
2 Department of Stroke Medicine, Hoshigaoka Kouseinenkin Hospital – Osaka,
3 Department of Neurology, Kyoto Prefectural University of Medicine – Kyoto, Japan
Objective: In order to evaluate cerebrovascular reserve capacity in the brain tissue, acetazolamide (ACZ) cerebrovascular reactivity (CVR) has been measured in major cerebral arteries by transcranial Doppler sonography. This has shown some correlation with CVR in the brain tissue, as measured by neuroradiological modalities. We have evaluated ACZ CVR in the brain tissue by transcranial power modulation imaging (PMI) and correlated with transcranial color duplex sonography (TCDS) observed CVR in the major arteries.
Material and Methods: Time-averaged maximum velocity (Vmax) in the middle/posterior cerebral arteries (MCA/PCA) was measured by TCDS before/after ACZ. After a bolus intravenous Levovist®, transcranial PMI was evaluated via temporal windows in 11 patients without and 10 patients with a transducer holder (Sonopod). Peak intensity (PI) and time to PI (TPI) before/ after ACZ were measured and CVR calculated on the basis of time-intensity curves in five regions of interest; bilateral basal ganglia (BG) and thalamus (Th), and contra-lateral temporal lobe (TL). Correlations between Vmax and PI/TPI in the corresponding vascular territories were evaluated before/after ACZ and in CVR.
Results: 1) Both before/after ACZ, Vmax in the ipsilateral MCA and PCA correlated closely with PI/TPI in the ipsilateral BG/TL and Th, respectively. 2) Easily disrupted PI/TPI CVR resulted in poor correlations with Vmax CVR. 3) Much closer CVR correlations were not always identifiable, despite utilization of the Sonopod.
Discussion: 1) Regardless of the use of time- or intensity- dependant parameters or a transducer holder, the tendency of close ACZ relationships between brain tissue perfusion and velocity changes in the major arteries remains unchanged. 2) Easily disrupted CVR in the brain tissue due to intraparenchymal lesions resulted in poor correlation with CVR in the major arteries.
Key words: acetazolamide vasoreactivity, color duplex sonography, power modulation imaging.