Ultrasound Contrast Agents for Brain Perfusion Imaging and Ischemic Stroke Therapy

Abstract

Stroke is one of the major causes of death and disabilities in industrialized countries. Ultrasound imaging is a largely wide spread bedside technique that is easily accessible and valuable in case of emergency but suffers from the fact that the ultrasound wave has to cross the skull for brain imaging. However, ultrasound contrast agents and new contrast-specific imaging modalities have helped to improve the diagnostic quality of transcranial ultrasonography. This review article surveys and discusses the current state of microbubbles technology and the use of contrast-enhanced transcranial ultrasound for the assessment of brain perfusion. Future aspects and expectations in contrast agent functionality, such as targeting and drug or gene delivery, acceleration of thrombolysis, and imaging technology, are also discussed.

Ultrasound Perfusion Imaging: Determination of Thresholds for the Identification of Critically Disturbed Perfusion in Acute Ischemic Stroke—A Pilot Study

“…By using ultrasound harmonic imaging of perfusion after ultrasound contrast agent (UCA) bolus injection (BHI), it is possible to track a UCA bolus within the human cerebral microcirculation (della Martina et al 2005;Postert et al 1998;Seidel et al 2000). BHI provides a qualitative impression of cerebral perfusion and may be useful in assessing pathologic brain perfusion in acute ischemic stroke (Federlein et al 2000;Seidel et al 2003Seidel et al , 2004Eyding et al 2005), as well as brain tumors (Harrer et al 2004).…”

Transcranial color coded duplex sonography in the intensive care unit

“…Based on their biochemical properties [4], the UCA generates an increase of the acoustic signal which results in quantitative and qualitative improvements in TCCS examinations [2]. In addition, the use of UCAs permits the minimally invasive study of the cerebral perfusion using ultrasound perfusion imaging techniques in patients with neurological disorders, especially those with ischemic cerebrovascular disease [12]. In our patient, we used the bolus kinetic approach, evaluating different regions of interest (ROIs) in which we studied the TICs.…”

“…The peak intensity, peak width, and time to peak intensity have been correlated with cerebral perfusion. A delay in the time to peak intensity has been suggested to constitute the most accurate parameter for studying cerebral perfusion in cerebrovascular disease because its value shows low intraindividual variability and is not influenced by the depth of the insonation plane [6,12]. A delay of close to 4 s compared with the unaffected hemisphere may identify hypoperfused areas [6].…”

“…In our patient, we used the bolus kinetic approach, evaluating different regions of interest (ROIs) in which we studied the TICs. Different derived parameters after infusion of UCAs have been studied [12]. The peak intensity, peak width, and time to peak intensity have been correlated with cerebral perfusion.…”

Changes of Contrast-Specific Ultrasonic Cerebral Perfusion Patterns in the Course of Stroke; Reliability of Region-Wise and Parametric Imaging Analysis

“…The latest research results imply the ability of semiquantitative differentiation between the core of the infarction and the surrounding, still salvageable penumbra in acute stroke (Eyding et al 2006). However, different protocols by the involved research groups use different ultrasound techniques (for an overview, see Della Martina et al 2005) and, more crucial, different time windows in the examination of patients presenting with acute stroke. Federlein et al (2000) examined 25 stroke patients within 24 h after symptom onset and 14 controls using the bolus-kinetic approach; Seidel et al (2004) examined 23 patients within 40 h after symptom onset in their study; Wiesmann et al (2004) examined 30 patients within 12 h after onset; Kern et al (2004) examined 15 patients within 24 h after onset using a destructive technique; in our study, we included 34 patients within 12 h after onset using the bolus-kinetic approach (Eyding et al 2006).…”