title: Acute stroke: perfusion imaging.
abstract: Ultrasound perfusion imaging of the human brain is a bedside technique based on the detection of ultrasound contrast agent (UCA) in the cerebral microcirculation. In the last decade, ultrasound technology improved from single-pulse harmonic imaging to multiple-pulse technologies (pulse inversion or power modulation harmonic imaging as well as contrast pulse sequencing), with a further dramatic increase of the contrast-agent-to-tissue ratio. Different kinetic models for the qualitative assessment of brain perfusion have been evaluated so far in healthy subjects as well as in patients suffering from acute ischemic stroke. The analysis of the contrast bolus kinetics yields robust time-intensity curve parameters, which qualitatively describe regional brain perfusion. In the acute phase of ischemic stroke, the peak signal increase and the time-to-peak intensity are the most valuable curve parameters to predict the area of definite infarction and the outcome of the patient. Color-coded parametric imaging of these parameters facilitates the interpretation of contrast kinetics in analyzing brain perfusion. UCA-specific kinetic models, such as replenishment and diminution kinetics, are new modalities for the qualitative visualization of brain perfusion. The latter is more promising for acute ischemic stroke patients because of the faster imaging and processing time, leading to a lower vulnerability to movement artifacts.
authors.affiliation: Neurologische Universitätsklinik, Lübeck, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Seidel
authors.forename: Karsten
authors.initials: K
authors.lastname: Meyer-Wiethe
mesh_terms: D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D002536:Cerebral Arteries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D003287:Contrast Media / Q000493:pharmacokinetics; D006801:Humans; D002537:Intracranial Arteriosclerosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008833:Microcirculation / Q000502:physiology; D010599:Pharmacokinetics; D011237:Predictive Value of Tests; D020521:Stroke / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014463:Ultrasonography / Q000379:methods* / Q000592:standards / Q000639:trends
chemical_list: D003287:Contrast Media