Persistent Microembolic Signals in the Cerebral Circulation on Transcranial Doppler after Intravenous Sulfur Hexafluoride Microbubble Infusion

Abstract

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.

Cerebral Emboli Monitoring Using Transcranial Doppler Ultrasonography in Adults and Children: A Review of the Current Technology and Clinical Applications in the Perioperative and Intensive Care Setting

“…Monitoring with the TCD-X system for 3.5 hours found that sulfur hexafluoride microbubbles (SonoVue, Milan, Italy) persisted for 12-77 minutes (median 40.5 minutes), leading the authors to conclude that MES detection for the identification of stroke-related microemboli should wait at least 77 minutes following the administration of SF6. 117 Further evaluation and validation of the TCD-X is still warranted.…”

Biodegradable Defined Shaped Printed Polymer Microcapsules for Drug Delivery

“…Previously, printed microparticles and nanoparticles with cargo mixed into the bulk polymer have been reported by Rolland et al 25 and later by Key et al 26 Independently Tao and Desai, 27 Guan et al, 28 and Abid et al 29 10 μm, which are too large for intravenous administration, as they can potentially block pulmonary and sinusoidal capillaries. 30 Nonetheless, intravenous injection of particles of a few microns in size has been widely reported as clinically relevant and previously applied for microbubble as ultrasound markers, 31 Alzheimer disease treatment, 32 and for in vivo studies of radiolabeled PLA microparticles biodistribution and biodegradation. 33 In this work, we propose a method for the fabrication of printed polymer capsules based on soft lithography, which exploits microwell arrays.…”