EPI proton resonant frequency temperature mapping at 0.5T in the brain: Comparison to single‐echo gradient recalled echo

• Published in: Magnetic resonance in medicine Vol. 93; no. 4; pp. 1733 - 1740
• Main Authors: Martinez, Diego F., Wiens, Curtis N., Harris, Chad T., Handler, William B., Chronik, Blaine A.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.04.2025; John Wiley and Sons Inc
• Subjects: Algorithms; Body Temperature - physiology; Brain; Brain - diagnostic imaging; Brain - physiology; Control stability; Echo planar imaging; Echo-Planar Imaging - methods; gradient recalled Echo; Humans; Image Processing, Computer-Assisted - methods; Imaging Methodology; In vivo methods and tests; magnetic resonance imaging; Magnetic Resonance Imaging - methods; MRI phantom; Optical fibers; Optical scanners; Phantoms, Imaging; Protocol; Protons; Reproducibility of Results; Resonant frequencies; Technical Note; Temperature; Temperature control; temperature mapping; Temperature measurement; Thermography - methods; Thermometry; Thermometry - methods; Tracking; temperature mapping; magnetic resonance imaging; MRI phantom; Echo planar imaging; gradient recalled Echo; thermometry
• ISSN: 0740-3194; 1522-2594; 1522-2594
• DOI: 10.1002/mrm.30373

Purpose Evaluate the use of both single‐echo gradient recalled echo (SE‐GRE) and EPI approaches to creating temperature maps on a mid‐field head‐only scanner, both in vivo and on a tissue mimicking gel. Methods Three 2D protocols were investigated (an SE‐GRE, single‐shot EPI, and an averaged single‐shot EPI). The protocols used either a gradient recalled acquisition or an echo planar acquisition, with EPI parameters optimized for the longer T2*$$ {\mathrm{T}}_2^{\ast } $$ at lower field‐strengths. Phantom experiments were conducted to evaluate temperature tracking while cooling, comparing protocol to measurements from an optical fiber thermometer. Studies were performed on a 0.5T head only MR scanner. Temperature stability maps were produced in vivo for the various protocols to evaluate precision. Results The use of an EPI protocol for thermometry improved temperature precision in a temperature control phantom and provided an 18% improvement in temperature measurement precision in vivo. Temperature tracking using a fast (<2 s) update rate EPI thermometry sequence provided a similar precision to the slower SE‐GRE protocol. Conclusion While SE‐GRE PRF thermometry shows good performance, EPI methods offer improved tracking precision or update rate, making them a better option for thermometry in the brain at mid‐field.