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Real‐time adaptive methods for treatment of mobile organs by MRI‐controlled high‐intensity focused ultrasound
Author(s) -
de Senneville Baudouin Denis,
Mougenot Charles,
Moonen Chrit T.W.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21124
Subject(s) - displacement (psychology) , tracking (education) , focal point , computer science , transducer , ultrasound , computer vision , intensity (physics) , visualization , match moving , motion (physics) , artificial intelligence , acoustics , biomedical engineering , cardinal point , physics , optics , medicine , psychology , pedagogy , psychotherapist
Focused ultrasound (US) is a unique and noninvasive technique for local deposition of thermal energy deep inside the body. MRI guidance offers the additional benefits of excellent target visualization and continuous temperature mapping. However, treating a moving target poses severe problems because 1) motion‐related thermometry artifacts must be corrected, 2) the US focal point must be relocated according to the target displacement. In this paper a complete MRI‐compatible, high‐intensity focused US (HIFU) system is described together with adaptive methods that allow continuous MR thermometry and therapeutic US with real‐time tracking of a moving target, online motion correction of the thermometry maps, and regional temperature control based on the proportional, integral, and derivative method. The hardware is based on a 256‐element phased‐array transducer with rapid electronic displacement of the focal point. The exact location of the target during US firing is anticipated using automatic analysis of periodic motions. The methods were tested with moving phantoms undergoing either rigid body or elastic periodical motions. The results show accurate tracking of the focal point. Focal and regional temperature control is demonstrated with a performance similar to that obtained with stationary phantoms. Magn Reson Med 57:319–330, 2007. © 2007 Wiley‐Liss, Inc.