Document Detail

Evaluation of a 1 MHz transducer for transcranial Doppler ultrasound including embolic signal detection.
MedLine Citation:
PMID:  11516539     Owner:  NLM     Status:  MEDLINE    
A 1 MHz transducer for use with transcranial Doppler ultrasound may improve the intensity and therefore the detection of embolic signals (ES) and may also reduce the number of absent acoustic windows. A series of studies was performed to investigate its potential benefits. Firstly, ES were detected using a 1 MHz and a 2 MHz transducer both in vitro and in vivo. Secondly, the time taken to identify 100 middle cerebral arteries (MCA) was recorded for both transducers and the best Doppler signal obtained was reviewed off-line and graded for quality. ES were more intense when detected with the 1 MHz compared with the 2 MHz transducer, both in vitro (p <.0001) and in vivo (p <.0001). Of the 100 MCAs studied, 81 had acoustic windows identified with both transducers. The number of acoustic windows detected with one transducer but not the other was the same for both transducers (n = 3). The time taken to identify the MCA was longer with the 1 MHz transducer (p <.0001) and the quality of the signal achieved was poorer (p <.0001). In conclusion, the 1 MHz transducer improved embolic signal intensity but the overall quality of the flow spectrum obtained was poorer with the 1 MHz than with the 2 MHz transducer. A lower frequency transducer of 1 MHz or possibly 1.5 MHz with transcranial Doppler ultrasound may improve the application of embolic signal detection but may not improve the signal for routine measurement of flow velocities.
M Cullinane; H S Markus
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Publication Detail:
Type:  Comparative Study; Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ultrasound in medicine & biology     Volume:  27     ISSN:  0301-5629     ISO Abbreviation:  Ultrasound Med Biol     Publication Date:  2001 Jun 
Date Detail:
Created Date:  2001-08-22     Completed Date:  2001-09-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0410553     Medline TA:  Ultrasound Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  795-800     Citation Subset:  IM    
Department of Clinical Neuroscience, St George's Hospital Medical School, London, UK.
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MeSH Terms
Endarterectomy, Carotid / adverse effects
Heart Valve Prosthesis / adverse effects
Intracranial Embolism / etiology,  ultrasonography*
Middle Aged
Middle Cerebral Artery / ultrasonography
Models, Cardiovascular
Phantoms, Imaging
Ultrasonography, Doppler, Transcranial / instrumentation*,  methods

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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