Application of Transcranial Color-Coded Duplex Sonography in Stroke Diagnosis

Cerebrovascular diagnostics are increasingly important in stroke therapy, especially in cases when the time window for IV rtPA has exceeded, in follow-up and secondary prevention of ischemic stroke. Transcranial color-coded duplex sonography (TCCS), a noninvasive and flexible method for vascular and parenchymal imaging of the adult brain, and is considered complementary to CT- and MR-Angio as the investigator depicts intracranial hemodynamics including occlusions, stenosis and the sufficiency of collateral flow. After an introduction to the general technical requirements of the ultrasound system and the defined transcranial image planes important for stroke diagnostics we focus on intracranial arterial vessel occlusions and stenosis important for cerebral ischemia work-up. UCA have had a tremendous impact on TCCS application and are used in cases of unfavorable acoustic bone windows resulting in superior signal-to-noise and yield high and fast diagnostic confidence. In addition, new developments in ultrasound signal processing and transducer technology, such as harmonic B-mode and contrast burst imaging amongst others, take advantage of microbubble specific properties which allow for increased signal retrieval as well as separation of linear and non-linear acoustic responses. Bedside ultrasound perfusion sonography has gained special attention and first encouraging results have visualized and quantified perfusion defects in acute stroke patients. This review is aimed to guide the unexperienced sonographer to valid and important findings in intracranial cerebrovascular disease.