Abstract 10764: Quantitative Improvements in Cerebral Blood Flow Using Transtemporal Ultrasound and Microbubbles in an Acute Ischemic Stroke Model With Multiple Cerebral Emboli
Background: Intravenous microbubbles (MB) and transcutaneous ultrasound alone have been utilized to recanalize intra-arterial thrombotic occlusions. In the setting of acute ischemic stroke, it is unclear whether attenuation would limit the ability of ultrasound to induce the inertial cavitation (IC) required to safely dissolve thrombi and improve cerebral blood flow (CBF).
Methods: In 24 pigs, bilateral internal carotid artery thrombotic occlusions were created by injection of four hour old thrombi into both ascending pharyngeal arteries (which supply the internal carotids through a collateral rete network). After confirmed occlusions, pigs were randomized to one of three treatment regimens: high mechanical index (MI=2.4) short pulse (5μs) transtemporal ultrasound (TTUS) alone, or a systemic MB infusion (3% Definity) with image-guided high MI (2.4) short pulse (5μs) or intermediate MI (1.7) long pulse (20μs) TTUS. Based on the angiographic results, quantitative analysis of CBF with perfusion magnetic resonance imaging (MRI) was performed before, immediately after, and at 24 hours after the 2.4 MI 5 us TTUS treatments (with and without microbubbles) in 14 pigs using T2* intensity versus time curves.
Results: Complete recanalization was achieved in 100% (8/8) pigs treated with image-guided high MI TTUS and microbubbles, but only 4/8 treated with high MI TUS alone or 3/8 pigs treated with image-guided intermediate MI TTUS and microbubbles (both p <0.05). At 24 hours post stroke, ipsilateral and contralateral CBF measured with perfusion MRI improved only following 2.4 MI 5 us pulse TTUS treatments in the presence of MB (p<0.005) while no change was noted with 2.4 MI 5 usec pulse treatments alone. Histologically, there was no evidence of microvascular or macrovascular hemorrhage with any treatment.
Conclusions: During a systemic commercially available microbubble infusion, guided high MI impulses from an ultrasound imaging system produce sustained improvements in ipsilateral and contralateral CBF following acute cerebral emboli.
- © 2013 by American Heart Association, Inc.