Extra- and Intracranial Waveform Analysis Algorithm, Descriptions, Classifications, and Differential Diagnosis

Abstract

Waveform recognition is an essential step in the interpretation of vascular ultrasound studies. Waveforms can vary widely as the result of systemic and focal hemodynamic changes in the precerebral and particularly intracranial vessels. Waveform pattern recognition can aid or refine the application of strict velocity criteria, and this review will focus on typical normal and abnormal waveforms. Algorithms for waveform analysis and interpretation of extra- and intracranial waveforms are discussed along with correlative imaging and clinical findings. Waveform descriptions and classifications based on prediction of vessel patency, systemic versus local circulatory conditions, and resistance to flow are provided for specific clinical conditions. Interpretation of waveforms rests on our ability to integrate systemic and cerebral hemodynamics across a wide spectrum of conditions. Intracranial vasculature poses unique challenges yet may yield new knowledge if our technologies are able to quantify blood flow beyond just velocities in the future.