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Persistent Microembolic Signals in the Cerebral Circulation on Transcranial Doppler after Intravenous Sulfur
Sander Johan Aarli1,2, Vojtech Novotny1,2, Lars Thomassen1,2
1Department of Neurology, Haukeland University Hospital, Bergen, Norway.
Background And Purpose:
Microembolic signals (MES) are detectable by transcranial Doppler monitoring and associated with increased risk of first or recurrent ischemic stroke. MES detection can also illuminate stroke etiology and the effect of prophylactic treatment. MES detection cannot accurately distinguish between stroke-related microemboli and ultrasound contrast agents. These agents contain microbubbles and are frequently used in neuro- and cardiovascular diagnostics. We aimed to assess how long after contrast infusion microbubbles are detectable by transcranial Doppler monitoring.
Methods:
Ten healthy volunteers received an intravenous infusion of stabilized sulfur hexafluoride microbubbles (SonoVue®) for 30 minutes. The infusion was followed by continuous unilateral Doppler monitoring (TCD-X, Atys Medical, Soucieu-en-Jarrest, France) for 3.5 hours.
Results:
MES persisted for 12 to 77 minutes (median 40.5 minutes), and the frequency tended to decrease gradually until cessation.
Conclusions:
None of the subjects had detectable MES for more than 77 minutes after ultrasound contrast infusion. MES detection with the intent to detect stroke-related microemboli should wait for at least this long after completed infusion.
Insights
Microembolic signals (MES) from ultrasound contrast agents are detectable for up to 77 minutes after infusion. This finding is crucial for distinguishing between stroke-related microemboli and contrast agents during transcranial Doppler monitoring.
Area of Science:
- Neuroscience
- Medical Imaging
- Cardiovascular Science
Background:
- Microembolic signals (MES) detected via transcranial Doppler monitoring are linked to ischemic stroke risk and can aid in stroke etiology assessment.
- Distinguishing stroke-related microemboli from ultrasound contrast agents, which contain microbubbles, is a diagnostic challenge.
Purpose of the Study:
- To determine the duration of microbubble detectability by transcranial Doppler monitoring after contrast agent infusion.
- To establish a timeframe for differentiating between naturally occurring microemboli and those introduced by contrast agents.
Main Methods:
- Ten healthy volunteers received a 30-minute intravenous infusion of stabilized sulfur hexafluoride microbubbles (SonoVue®).
- Continuous unilateral Doppler monitoring was performed for 3.5 hours post-infusion using TCD-X equipment.
Main Results:
- Microembolic signals (MES) were detectable in subjects for 12 to 77 minutes after contrast infusion, with a median duration of 40.5 minutes.
- The frequency of detected MES generally decreased gradually until they were no longer observed.
Conclusions:
- Microbubbles from ultrasound contrast agents are not detectable by transcranial Doppler monitoring beyond 77 minutes post-infusion.
- When using MES detection for stroke-related microemboli, a waiting period of at least 77 minutes after contrast infusion is recommended.
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