Focused Ultrasound Ablation of an Arteriovenous Malformation Model.
Authors: Jones J, Bolding M, Ullman H, Kaneko N, Tateshima S
Brain AVMs are rare but serious vascular lesions that often pose a management dilemma between the risk of various treatment modalities and uncertain natural history during observation. We describe preliminary data on the use of focused ultrasound as a novel therapeutic strategy. In an AVM model, one session of ultrasound gradually reduced flow through the lesion without inducing rupture. Due to its non-invasive yet immediate ablative effects, focused ultrasound may allow safer treatment of AVMs. However, further studies are needed to clarify its efficacy and side effect profile.
Introduction
Purpose
Thermal ablation
Study Objective
To assess the feasibility of high-intensity focused ultrasound (HIFU) ablation as a treatment for brain arteriovenous malformations in a swine model.
Animal model / Human subject
Porcine (Yucatan swine), juvenile, female
Disease model
Brain arteriovenous malformation (AVM)
MRI or image guidance method
MRI guidance on a 3T scanner using anatomical MRI (T1W MPRAGE, T2 FSE) and contrast-enhanced time-resolved MRA (CE-MRA); MR thermography was attempted but non-diagnostic; HIFU trajectory was planned from MRI-identified acoustic window and ablation was monitored with interleaved CE-MRA.
Targeted brain region(s)
Rete Mirabile
Outcomes and Safety
Summary of Outcomes
In a swine AVM model, MRg HIFU produced a progressive reduction in AVM shunt flow, increasing mean transit time and decreasing CE-MRA signal intensity, with a final 27% reduction in blood flow relative to baseline. Complete nidus obliateration was not achieved.
Safety-related matter
Post-ablation T2 MRI and necropsy demonstrated thermal injury to facial soft tissues along the ultrasound trajectory; however the treatment did not induce rupture. The authors warn that ultrasonic heat deposition could cause tissue damage along the beam path and potentially serious complications if vital vessels are inadvertently damaged, and call for further studies to define the side-effect profile.
Brain Region
Ultrasound Parameters
Ultrasound instrument
1.0 MHz HIFU system with 128-element phased array transducer (model LF-LAS-128, Image Guided Therapy, Pessac, France); transducer aperture/diameter: None
FUS Frequency
1.0 MHz
Focal Characteristics
focal depth: None; focal length: None; aperture size: None
Treatment frequency
single session
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