Document Detail

Numerical prediction of frequency dependent 3D maps of mechanical index thresholds in ultrasonic brain therapy.
MedLine Citation:
PMID:  22225316     Owner:  NLM     Status:  In-Data-Review    
Purpose: Therapeutic ultrasound has been used in the brain for thrombolysis and high intensity focused ultrasound (HIFU) therapy. A low-frequency clinical study of sonothrombolysis, called the transcranial low-frequency ultrasound-mediated thrombolysis in brain ischemia (TRUMBI), has revealed an increased incidence of hemorrhage, which may have been caused by cavitation. The goal of this study is to determine if there is a comparable risk of generating cavitation during HIFU brain therapy at different frequencies.Methods: Two approaches are used to transmit acoustic energy through the skull to the brain: low-frequency ultrasound, with a wavelength that is larger than the skull thickness, and high frequency ultrasound, that is sensitive to aberrations and must use corrective techniques. At high frequency, the mechanical index (MI) is lower, which translates to a higher cavitation threshold. In addition to the nonfocused geometry of the 300 kHz sonothrombolysis treatment device, two types of focused therapeutic transducers were modeled: a low frequency 220 kHz transducer and a 1 MHz transducer that required aberration correction with a time-reversal approach, representing the lowest and highest frequencies currently used. The acoustic field was modeled with a finite difference fullwave acoustic code developed for large scale computations, that is, capable of simulating the entire brain volume. Various MI thresholds and device geometries were considered to determine the regions of the brain that have an increased probability of cavitation events.Results: For an equivalent energy deposition rate, it is shown that at a low frequency there is a significant volume of the brain that is above the MI thresholds. At a high frequency, the volume is over 3 orders of magnitude smaller, and it is entirely confined to a compact focal spot.Conclusions: The significant frequency dependence of the volumes with an increased probability of cavitation can be attributed to two factors: First, the volume encompassed by the focal region depends on the cube of the frequency. Second, the heat deposition increases with frequency. In conclusion, according to these simulations, the acoustic environment during HIFU brain therapy at 1 MHz is not conducive to a high probability of cavitation in extended regions of the brain.
Gianmarco Pinton; Jean-Francois Aubry; Mathias Fink; Mickael Tanter
Related Documents :
633876 - Analysis of abnormal articulatory dynamics in two dysarthric patients.
10503606 - Electromyographic study relating to shoulder motion: control of shoulder joint by funct...
15646006 - Electromyographic and mechanomyographic estimation of motor unit activation strategy in...
11102846 - Intensity analysis in time-frequency space of surface myoelectric signals by wavelets o...
10852236 - Differential effects of vestibular stimulation on walking and running.
7773436 - Block of c-fos and junb expression by antisense oligonucleotides inhibits light-induced...
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Medical physics     Volume:  39     ISSN:  0094-2405     ISO Abbreviation:  Med Phys     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-09     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0425746     Medline TA:  Med Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  455     Citation Subset:  IM    
Institut Langevin, CNRS UMR 7587, ESPCI, 75005 Paris, France.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms

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

Previous Document:  An efficient inverse radiotherapy planning method for VMAT using quadratic programming optimization.
Next Document:  High-quality multiple T(2)(?) contrast MR images from low-quality multi-echo images using temporal-d...