Echo-enhanced ultrasound for diagnosis and management in stroke patients

Abstract

Early diagnosis of stroke and recognition of preceding transient ischemic attacks (TIAs) is important for clinical outcome. Better education of the signs and symptoms of TIA and stroke and improved diagnostic procedures will help to reduce the impact of stroke. Magnetic resonance imaging (MRI), computed tomography (CT) and single photon emission computed tomography (SPECT) are used to diagnose cerebral infarctions. MRI is the most effective diagnostic modality, however, MRI equipment is expensive and not always available. CT is therefore usually used but it has limitations, in detecting small infarctions, particularly in the posterior fossa. Ultrasound is a safe and inexpensive bedside diagnostic procedure. Ultrasound is often used in patients after TIA or stroke, however, it may be inadequate due to poor insonation conditions through the skull, or because the relevant vessel lies deep within the brain. Arteries with slow flowing blood are also difficult to image. The application of ultrasound has expanded with the development of two-dimensional transcranial color-coded sonography (TCCS) which provides both anatomical and functional information about the major cerebral vessels. In addition, the use of echo-enhancing agents now provides better images of vessels within the skull and enables ultrasound examinations to be performed even in patients with a poor transtemporal window. Echo-enhanced ultrasound can also provide images of vessels deep within the brain, which were previously non-evaluable. The echo-enhancing agent Levovist(R) has been extensively studied in patients undergoing ultrasound examination to detect cerebrovascular disease. Levovist improves diagnostic confidence without compromising safety. The improvement in images obtained of the cerebral vessels, including both arteries and veins, using echo-enhanced ultrasound may make this technique the future method of choice for patients with cerebrovascular disease.