Characteristics of sonographic modalities used for imaging cerebrovascular circulation

StudyLocationFrequencyCommon Usage
Transcranial DopplerExtracranial (extravascular)Multiples of 2 MHzMeasures velocity of blood through intracranial vessels
Carotid duplex ultrasonographyExtracranial (extravascular)5–10 MHzDuplex procedure: brightness mode (B-mode) allows imaging and Doppler imaging enables color-flow volume and directional information; spectral analysis measures blood flow velocity; measures intimal medial thickness and evaluates stenosis
Intravascular ultrasoundIntracranial, extracranial (intravascular)20–40 MHzDetermination of morphology and composition of atherosclerotic plaque within the extracranial and intracranial circulation; allows evaluation of correct stent diameter and the amount of balloon inflation pressure needed during angioplasty; enables visualization of stent apposition and expansion, mural thrombus, plaque ulceration, and aneurysm and vessel dissection