Journal of clinical ultrasound : JCU
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Four-dimensional (4D) analysis of atherosclerotic plaque and wall motion, the application of 4D ultrasound to the study of atherogenesis, and the incorporation of ultrasound data into flow models for simulation of cerebrovascular hemodynamics are new frontiers in diagnostic ultrasound that use computer vision and optical flow techniques to exploit the full potential of real-time imaging and Doppler studies. New approaches to improve blood vessel delineation with ultrasound include application of contrast agents, harmonic imaging, and red blood cell density imaging. ⋯ Likewise, the value of ultrasound techniques for the measurement of blood flow to evaluate cerebrovascular hemodynamics must be compared to related methods in magnetic resonance, such as dynamic MR inflow tracking. This article addresses several new and future developments in cerebrovascular ultrasound and discusses their relative merits in terms of ongoing research in the field of magnetic resonance angiography, imaging, and related techniques.
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Transcranial color-coded duplex sonography (TCCD), magnetic resonance angiography (MRA), and computed tomography angiography (CTA) are novel noninvasive or minimally invasive techniques for the study of the intracranial circulation. TCCD is relatively inexpensive and permits bedside examination. It improves the accuracy and reliability of conventional transcranial Doppler studies. ⋯ CTA relies on spiral CT technology and intravenous contrast injection. To date, intracranial use has been predominantly for the diagnosis of aneurysms. The role of CTA for the detection of nonaneurysmal intracranial vascular disease has yet to be established.
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Various methods were developed for the quantification of the degree of stenosis: B-mode imaging, CW Doppler with spectral analysis, PW-duplex, and color-flow imaging. The degree of stenosis can be evaluated using transverse views of the carotid in conventional B-mode imaging. The diameters of the residual lumen (Ds) and the external diameter (De) of the artery at the same level are measured and the degree of stenosis (in area) is calculated. ⋯ Such a quantitative assessment of carotid lesions for a long period of time may be very helpful in evaluating the beneficial effects of medical treatment or in detecting any significant increase of the stenosis that could lead to surgical treatment. A new method for the plaque volume assessment has been recently validated. The plaque volume index expressed in mm3 is calculated from longitudinal and transversal B mode views of the bifurcation.