Ultrasound contrast enhancing agents in neurosonology: principles, methods, future possibilities

Objectives - Ultrasound of the brain supplying arteries is a standard diagn ostic procedure in patients with suspected and definite acute and chronic c erebrovascular occlusive disease. Anatomical and pathological limitations l ed to the development of echocontrast agents which are able to survive pulm onary and capillary transit and improve the echogenicity of the flowing blo od. Material and Methods - This article reviews present and future applicat ions of echocontrast agents in conjunction with personal experiences. Resul ts - Currently, echocontrast is used for the differentiation of internal ca rotid artery occlusion and pseudoocclusion, better delineation of the maxim al narrowing in high-grade stenoses, and better visualization of the extrac ranial vertebral artery and its collaterals. Transcranial applications incl ude the insufficient foraminal or temporal window, assessment of arterioven ous malformations, thrombosis of cerebral veins and sinuses, and intracrani al aneurysms. The use of echocontrast can have direct diagnostic and therap eutic consequences. Harmonic imaging, perfusion imaging, stimulated acousti c emission, and drug delivery are possible future domains of the technique. Discussion Besides the support of conventional neurovascular ultrasound in poor examination conditions due to the patients' anatomy or pathology, ech ocontrast agents may allow for novel applications in the diagnosis and trea tment of cerebrovascular patients.