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When blood flow in these arteries is occluded, impaired oxygen supply can cause rapid brain tissue death, and permanent neurological dysfunction. In the context of acute ischemic stroke, the leading cause of long-term disability in the United States, TCD is commonly used to detect occluded and stenosed cerebral arteries. The pulsatile CBFV waveform can provide information concerning numerous cerebrovascular pathologies, including stroke, intracranial hypertension, sickle cell disease, and mild Traumatic Brain Injury. Transcranial Doppler ultrasound (TCD) is a noninvasive methodology for measuring Cerebral Blood Flow Velocity (CBFV) through the large arteries of the brain. This research was also supported in part by NINDS-1R43NS105340. Our commercial affiliation does not alter our adherence to PLOS ONE policies on sharing data and materials. The funding institution, Neural Analytics, Inc., holds numerous patents related to transcranial doppler technology from which the authors do not directly stand to benefit. All authors either hold stock or stock options in the company. This research was also supported in part by National Institute of Neurological Disorders and Stroke (US), 1R43NS105340.Ĭompeting interests: At the time this research was conducted, authors ST, CT, KJ, AD, NC, SW, and RH were salaried employees of Neural Analytics, Inc., and TD was a paid consultant. The specific roles of these authors are articulated in the ‘author contributions’ section. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All data underlying the results presented in the study are shared publicly on the Figshare Data Repository and are available at: įunding: The primary funding Institution, Neural Analytics, Inc., provided support in the form of salaries for authors ST, CT, KJ, AD, NC, SW, and RH, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Received: SeptemAccepted: JanuPublished: February 6, 2020Ĭopyright: © 2020 Thorpe et al. PLoS ONE 15(2):Įditor: Johannes Boltze, University of Warwick, UNITED KINGDOM (2020) Toward automated classification of pathological transcranial Doppler waveform morphology via spectral clustering. We conclude that important morphological variability exists beyond that currently quantified by TIBI in populations experiencing or at-risk for acute ischemic stroke, and posit that the observed flow-types provide the foundation for objective methods of real-time automated flow type classification.Ĭitation: Thorpe SG, Thibeault CM, Canac N, Jalaleddini K, Dorn A, Wilk SJ, et al. Types II and III represented commonly observed flow-types not delineated by TIBI, which nonetheless deviate from normal and blunted flows. Cluster morphologies for types I and IV aligned clearly with Normal and Blunted TIBI flows, respectively. Types I and II were primarily composed of control subject waveforms, whereas types III and IV derived mainly from LVO patients. We found that gap statistic disparity was maximized at four clusters, referred to as flow types I, II, III, and IV. Spectral clustering identified groups implicit in the resultant three-dimensional feature space, with gap statistic criteria establishing the optimal cluster number. From each waveform, three morphological features were extracted, quantifying onset of maximal velocity, systolic canopy length, and the number/prominence of peaks/troughs. TCD beat waveforms were recorded at multiple depths from the Middle Cerebral Arteries of 106 subjects 33 with Large Vessel Occlusion (LVO). In this work we seek to determine whether TCD morphology can be objectively assessed using an unsupervised machine learning approach to waveform categorization. Thrombolysis in Brain Ischemia (TIBI) flow grades are widely used for this purpose, but require subjective assessment by expert evaluators to be reliable. Cerebral Blood Flow Velocity waveforms acquired via Transcranial Doppler (TCD) can provide evidence for cerebrovascular occlusion and stenosis.