A novel compact pneumatic turbine-driven transducer for MR Elastography

TY - JOUR

T1 - A novel compact pneumatic turbine-driven transducer for MR Elastography

AU - Kiss, Lorenz

AU - Gnanago, Jean Lynce

AU - Wampl, Stefan

AU - Wolf, Marcos

AU - Breitenfelder, Christopher

AU - Hodul, Andreas

AU - Nguyen, Quang

AU - Königshofer, Markus

AU - Frass-Kriegl, Roberta

AU - Meyerspeer, Martin

AU - Schmid, Albrecht Ingo

N1 - Publisher Copyright: © 1963-2012 IEEE.

PY - 2026

Y1 - 2026

N2 - Magnetic Resonance Elastography (MRE) can be used to estimate biomechanical parameters, e.g., shear stiffness of human tissue. As such, it is an imaging-based extension of palpation. To perform MRE, mechanical waves are induced into the tissue by transducers or actuators. The resulting periodic microscopic tissue displacements are recorded using phase-contrast magnetic resonance imaging (MRI). Good transducers need sufficient vibration amplitudes and frequency stability with little contributions of higher order harmonics. For clinical use, it needs to be compact for comfort as well as interference with RF coil placement. Safe operation in strong electromagnetic fields is a must. Setup procedures should be simple and quick. Here, a new compact pneumatically driven gravitational transducer (CPT) for MR elastography is presented. It consists of rotating unbalances stacked on either side of a turbine. Additional insertable masses allow adjustment of the vibration amplitude at a set frequency. Additive manufacturing and milling were combined to produce the transducer. The flat design of the CPT allows for placement between body and receiver coil with minimal sensitivity loss in most relevant targets. PID control is used to precisely control vibration frequency, based on optical detection of rotation cycles. It adjusts a valve in the air supply of the turbine. It is constructed using non-magnetic, non-conducting materials, which makes it inherently MRI-safe. The electronics, fittings and valves are placed in a control unit (CU) outside the magnet room. A hose and two optical fibres connect the transducer and the CU. The performance of the transducer was thoroughly bench tested and phantom experiments in the MRI scanner demonstrated the feasibility and robustness of the system. The frequency control was excellent for a pneumatic system (FWHM 0.04-0.20 Hz) across a wide range (50-130 Hz), while amplitudes of higher harmonics are very low (1.9-8.1 % 1st, 0.2-4.6 % 2nd order). Imaging data confirm that the CPT generated displacements which could be recorded with MR elastography pulse sequences. In conclusion, we present a new MRE pneumatically driven gravitational transducer, Its advantages are the combination of the following features: It requires no electrical components in the vicinity of the MR scanner. It performs equally well as electromechanically driven systems while it outperforms pneumatic designs in terms of frequency stability. Its compact design allows for flexibility in placement with a variety of RF coils and target tissues in the body. It consists of low-cost components and is easily used. We conclude that the combination of the CPT’s features constitute a substantial improvement in MRE transducer design.

AB - Magnetic Resonance Elastography (MRE) can be used to estimate biomechanical parameters, e.g., shear stiffness of human tissue. As such, it is an imaging-based extension of palpation. To perform MRE, mechanical waves are induced into the tissue by transducers or actuators. The resulting periodic microscopic tissue displacements are recorded using phase-contrast magnetic resonance imaging (MRI). Good transducers need sufficient vibration amplitudes and frequency stability with little contributions of higher order harmonics. For clinical use, it needs to be compact for comfort as well as interference with RF coil placement. Safe operation in strong electromagnetic fields is a must. Setup procedures should be simple and quick. Here, a new compact pneumatically driven gravitational transducer (CPT) for MR elastography is presented. It consists of rotating unbalances stacked on either side of a turbine. Additional insertable masses allow adjustment of the vibration amplitude at a set frequency. Additive manufacturing and milling were combined to produce the transducer. The flat design of the CPT allows for placement between body and receiver coil with minimal sensitivity loss in most relevant targets. PID control is used to precisely control vibration frequency, based on optical detection of rotation cycles. It adjusts a valve in the air supply of the turbine. It is constructed using non-magnetic, non-conducting materials, which makes it inherently MRI-safe. The electronics, fittings and valves are placed in a control unit (CU) outside the magnet room. A hose and two optical fibres connect the transducer and the CU. The performance of the transducer was thoroughly bench tested and phantom experiments in the MRI scanner demonstrated the feasibility and robustness of the system. The frequency control was excellent for a pneumatic system (FWHM 0.04-0.20 Hz) across a wide range (50-130 Hz), while amplitudes of higher harmonics are very low (1.9-8.1 % 1st, 0.2-4.6 % 2nd order). Imaging data confirm that the CPT generated displacements which could be recorded with MR elastography pulse sequences. In conclusion, we present a new MRE pneumatically driven gravitational transducer, Its advantages are the combination of the following features: It requires no electrical components in the vicinity of the MR scanner. It performs equally well as electromechanically driven systems while it outperforms pneumatic designs in terms of frequency stability. Its compact design allows for flexibility in placement with a variety of RF coils and target tissues in the body. It consists of low-cost components and is easily used. We conclude that the combination of the CPT’s features constitute a substantial improvement in MRE transducer design.

KW - elastography

KW - hardware

KW - pipeline

KW - transducer

UR - https://www.scopus.com/pages/publications/105041495202

U2 - 10.1109/TIM.2026.3701175

DO - 10.1109/TIM.2026.3701175

M3 - Article

AN - SCOPUS:105041495202

SN - 0018-9456

JO - IEEE Transactions on Instrumentation and Measurement

JF - IEEE Transactions on Instrumentation and Measurement

ER -