Abstract
We report the use of wavelet transformation for quantitative analysis of cerebral circulation, visualized as the Doppler flow velocity signal. One full-term and two preterm neonates without intracranial lesions were examined as normal subjects, and two neonates with asphyxia and one with viral myocarditis were examined as subjects with pathological conditions. All were treated in the NICU at Yamaguchi University Hospital.
We sampled the Doppler signal at the anterior cerebral artery (ACA) and the basilar artery (BA) using a color Doppler unit (Aloka SSD 2200) with a 5-MHz sector probe. Color Flow Doppler images and Pulsed Doppler images were recorded on videotape. The Doppler sound on the videotape was uploaded into a personal computer as a digital signal and subjected to wavelet analysis with the Gabor 8 function φ(x) = exp(−x2/σ2)exp(ix) as the mother wavelet.
In the normal neonates, wavelet analysis revealed strong components at levels 7 and 8 on the ACA; these components could not be disclosed on the BA. Two of the neonates with pathological conditions did not show any components at levels 7 and 8 on either the ACA or the BA; the remaining one showed very strong components on both the ACA and BA.
The components at levels 7 and 8 in wavelet analysis with the Gabor 8 function may be useful markers of effective cerebral perfusion.
