A nonmagnetic micropositioner for displacement measurement validation in the MRI environment
Year: 2026
Type: article
Abstract: Objective The purpose of this study was to implement a nonmagnetic micropositioner in the MRI environment to validate displacement estimates of magnetic resonance acoustic radiation force imaging (MR-ARFI). Methods The micropositioner consisted of a stage driven by a piezoelectric stepper motor in closed-loop operation with an optical quadrature encoder. A 100-gram agar gel phantom was prepared, and three MR-ARFI pulse sequences were used to generate displacement maps. MR-ARFI measured displacements were compared to ground truth data from the optical encoder. Results The micropositioner demonstrated consistent performance with positioning times of $$1.6 \pm 0.4$$ 1.6 ± 0.4 ms for extension and $$2.2 \pm 0.2$$ 2.2 ± 0.2 ms for return to baseline position. The micropositioner decreased the signal-to-noise ratio of magnitude images due to increased electronic noise. Linear regression analysis showed that displacement measurements were highly linear with $$R^2 \ge 0.98$$ R 2 ≥ 0.98 but exhibited scaling biases that may have been due to the experimental setup. Conclusion The proposed instrument can potentially improve the accuracy and precision of MR-ARFI-based applications, including focused ultrasound dosimetry and mechanical biomarker imaging.
Authors: William Ryan Willoughby, Mark Bolding
Institutions: University of Alabama at Birmingham, UAB Medicine
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $5,090
OpenAlex ID: W7155103647