Quantitative evaluation of cerebrovascular reactivity in brain tissue by a refill kinetic method of transcranial ultrasonic perfusion imaging: a comparison with Doppler sonography.
To confirm the reliability of a refill kinetic method of ultrasonic harmonic perfusion imaging (HPI) capable of quantifying separate parameters of microvascular blood flow velocity and volume in brain tissue, we evaluated acetazolamide (ACZ) cerebrovascular reactivity by transcranial HPI in comparison with Doppler sonography (TCD). Methods. HPI during continuous Levovist infusion with changing pulsing intervals (t) and TCD time-averaged maximum velocity (TAMX) in the middle and posterior cerebral arteries were evaluated before and after ACZ administration in 12 patients, 8 without and 4 with a temporal skull defect. Plateau value (A) and rise rate (beta) of intensity (I) represented by HPI time-intensity curves of I(t) = A(1 - e(-beta*t)) were analyzed on the axial diencephalic plane.


RESULTS
1) A significantly decreased in proportion to the region of interest location depth only in the intact skull cases. 2) Despite inter- and intra-individual data scattering, in correspondence with TAMX increases after ACZ, significant beta increases were more frequently identified than increases of A.


CONCLUSIONS
Cerebral vasoreactivity analysis utilizing refill kinetics of transcranial HPI can potentially provide separate quantification based on microvascular blood velocity and volume (capillary patency) with consideration of depth-dependant ultrasound attenuation. This should be suitable for bedside evaluation of neurointensive care patients.
Shiogai
T
T
Department of Clinical Neurosciences, Kyoto Takeda Hospital, Kyoto, Japan. shiogait@pop11.odn.ne.jp
Morisaka
A
A
Takayasu
N
N
Yoshikawa
K
K
Mizuno
T
T
Nakagawa
M
M
Furuhata
H
H
D000086:Acetazolamide; D001921:Brain / Q000098:blood supply* / Q000187:drug effects; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging*; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007700:Kinetics; D008297:Male; D011134:Polysaccharides; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508; D000086:Acetazolamide