MRI Monitoring of Focused Ultrasound Sonications Near Metallic Hardware

We previously developed a method for imaging temperature changes in tissue near metal hardware; here we evaluate its use to monitor MR-guided focused ultrasound treatments. Thermometry measurements are typically made based on the shift in resonance frequency that is caused by a change in temperature; however, metallic hardware creates additional off-resonance that interferes with this shift and therefore the measured temperature change. 2D multispectral imaging (2DMSI) reduces the image artifacts caused by metallic hardware to create cleaner images and can instead rely on changes in the T1 parameter to monitor temperature. The goal of this work was to determine the feasibility of 2DMSI-based thermometry for monitoring temperature changes caused by focused ultrasound sonications near metallic hardware.

Weber H, Ghanouni P, Pascal-Tenorio A, Pauly KB, Hargreaves BA. MRI monitoring of focused ultrasound sonications near metallic hardware. Magn Reson Med. 2017 Dec 7. doi: 10.1002/mrm.27034.

Online Journal Article

2DMSI signal change relates to temperature change after sonication. Black lines indicate the location of a metal implant in the leg of a pig; green regions near the implant show that the signal changes near the implant due to the sonication, and thus 2DMSI can give information about temperature change near metal implants.

Assistant Professor of Radiology (General Radiology) and, by courtesy, of Neurosurgery and of Urology at the Stanford University Medical Center
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Basic Life Res Scientist, Rad/Radiological Sciences Laboratory
Professor of Radiology (Radiological Sciences Lab) and, by courtesy, of Electrical Engineering
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Professor of Radiology (Radiological Sciences Laboratory) and, by courtesy, of Electrical Engineering
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Hans Weber is an alumnus of the BMR group