title: [Introduction to the study of the Willis circle with transcranial color Doppler: methodological notes and preliminary experience].
abstract: To date, adult intracranial circulation has been studied only with pulsed-wave Doppler US, which is a useful diagnostic tool even though several technical and practical limitations are related to the difficult location of intracranial vessels. Recently, dedicated color-Doppler transducers have been proposed, which can pass through the skull which makes a physiologic barrier for the US beam: this technique has been called transcranial color-Doppler (TCD). We report on our personal experience with TCD in 30 healthy volunteers (12 men and 18 women, age range: 17-75 years) submitted to TCD for Willis circle imaging. We used an ATL Ultramark 9HDI unit with a phased array transducer (3.5 MHz) and 2 MHz Doppler frequency; the PRF was 3000 Hz, with 80% color gain. 100 Hz wall filters were used. The middle cerebral artery was always shown correctly in all subjects, while the posterior one was depicted only in 7 cases (23.3%); in contrast, the anterior cerebral artery was demonstrated in 3 cases only (10%). Nowadays, TCD is mostly applied to normal intracranial circle studies, to assess normal blood speed values more accurately. To this purpose, both the direct visualization of blood vessels and the flowmetric values obtained measuring the incidence angle are useful pieces of information. TCD permits a more accurate study of intracranial local blood flow in the Willis circle and of its changes in pathologic conditions. In contrast, TCD yield is poor in characterizing intracranial tumor tissue.
authors.affiliation: Instituto di Radiologia P. Cignolin, Policlinico Universitario, Palermo.
authors.forename: R
authors.initials: R
authors.lastname: Lagalla
authors.forename: G
authors.initials: G
authors.lastname: Caruso
authors.forename: S
authors.initials: S
authors.lastname: Pappalardo
authors.forename: M
authors.initials: M
authors.lastname: Brancato
authors.forename: L
authors.initials: L
authors.lastname: Manfrè
authors.forename: M
authors.initials: M
authors.lastname: De Maria
mesh_terms: D000328:Adult; D000368:Aged; D002941:Circle of Willis / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018615:Ultrasonography, Doppler, Color; D017585:Ultrasonography, Doppler, Transcranial
vernacular_title: Introduzione allo studio con color Doppler transcranico del poligono di willis: note metodologiche ed esperienza preliminare.