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T1 Thermometry for Deep Brain Stimulation Applications: A Comparison Between Rapid Gradient Echo Sequences Publisher



Zarrinimonfared Z1 ; Parvaresh M2 ; Mirbagheri MM1, 3
Authors
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Authors Affiliations
  1. 1. Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  2. 2. Department of Neurosurgery, Hazrat Rasool Hospital, Iran University of Medical Sciences, Tehran, Iran
  3. 3. Department of Physical Medicine and Rehabilitation, Northwestern University, United States

Source: Journal of Biomedical Physics and Engineering Published:2024


Abstract

Background: T1 thermometry is considered a straight method for the safety monitoring of patients with deep brain stimulation (DBS) electrodes against radiofrequen-cy-induced heating during Magnetic Resonance Imaging (MRI), requiring different sequences and methods. Objective: This study aimed to compare two T1 thermometry methods and two low specific absorption rate (SAR) imaging sequences in terms of the output image quality. Material and Methods: In this experimental study, a gel phantom was pre-pared, resembling the brain tissue properties with a copper wire inside. Two types of rapid gradient echo sequences, namely radiofrequency-spoiled and balanced steady-state free precession (bSSFP) sequences, were used. T1 thermometry was performed by either T1-weighted images with a high SAR sequence to increase heating around the wire or T1 mapping methods. Results: The balanced steady-state free precession (bSSFP) sequence provided higher image quality in terms of spatial resolution (1×1×1.5 mm3 compared with 1×1×3 mm3) at a shorter acquisition time. The susceptibility artifact was also less pro-nounced for the bSSFP sequence compared with the radiofrequency-spoiled sequence. A temperature increase, of up to 8 ℃, was estimated using a high SAR sequence. The estimated change in temperature was reduced when using the T1 mapping method. Conclusion: Heating induced during MRI of implanted electrodes could be estimated using high-resolution T1 maps obtained from inversion recovery bSSFP sequence. Such a method gives a direct estimation of heating during the imaging sequence, which is highly desirable for safe MRI of DBS patients. © Journal of Biomedical Physics and Engineering.