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



Zarrinimonfared Z¹ ; Parvaresh M² ; Mirbagheri MM^{1, 3}
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.