A magneto-motive ultrasound platform designed for pre-clinical and clinical applications

Abstract

Introduction: Magneto-motive ultrasound (MMUS) combines magnetism and ultrasound (US) to detect magnetic nanoparticles in soft tissues. One type of MMUS called shear-wave dispersion magneto-motive ultrasound (SDMMUS) analyzes magnetically induced shear waves (SW) to quantify the elasticity and viscosity of the medium. The lack of an established presets or protocols for pre-clinical and clinical studies currently limits the use of MMUS techniques in the clinical setting. Methods: This paper proposes a platform to acquire, process, and analyze MMUS and SDMMUS data integrated with a clinical ultrasound equipment. For this purpose, we developed an easy-to-use graphical user interface, written in C++/Qt4, to create an MMUS pulse sequence and collect the ultrasonic data. We designed a graphic interface written in MATLAB to process, display, and analyze the MMUS images. To exemplify how useful the platform is, we conducted two experiments, namely (i) MMUS imaging to detect magnetic particles in the stomach of a rat, and (ii) SDMMUS to estimate the viscoelasticity of a tissue-mimicking phantom containing a spherical target of ferrite. Results: The developed software proved to be an easy-to-use platform to automate the acquisition of MMUS/SDMMUS data and image processing. In an in vivo experiment, the MMUS technique detected an area of 6.32 ± 1.32 mm 2 where magnetic particles were heterogeneously distributed in the stomach of the rat. The SDMMUS method gave elasticity and viscosity values of 5.05 ± 0.18 kPa and 2.01 ± 0.09 Pa.s, respectively, for a tissue-mimicking phantom. Conclusion: Implementation of an MMUS platform with addressed presets and protocols provides a step toward the clinical implementation of MMUS imaging equipment. This platform may help to localize magnetic particles and quantify the elasticity and viscosity of soft tissues, paving a way for its use in pre-clinical and clinical studies.

Magnetic particles in motion: magneto-motive imaging and sensing

“…Magneto-motive ultrasound encompasses the benefits of conventional ultrasound with the added ability to capture molecular-level, functional information in real-time at clinically-relevant penetration depths. Thus far, MMUS has been demonstrated in phantom 40 , 49 , 78 , 79 , 104 , cell 40 , and animal studies 80 , 102 .…”

“…In general, SDMMUS systems are more expensive due to more advanced hardware requirements to track shear waves. As a more cost-effective alternative, researchers are developing platforms to integrate MMUS and SDMMUS imaging with existing clinical systems 49 , 102 .…”

Magnetic mediators for ultrasound theranostics

“…B. Localization of MNPs inside the body by MMUS. Adapted with permission from 145 , copyright 2016 Springer. C. B-mode image of a tissue-mimicking phantom with MNPs (left), common MMUS evaluation of raw US data (center), and evaluation according to the inverse MMUS algorithm (right).…”

Nanopartículas de magnetita dopadas com zinco para fins teranósticos: magnetoacustografia e hipertermia magnética

“…From the cross-correlation output and using the sampling frequency information, the time-delay between the pair of echoes was estimated and then converted into displacement. For more details about the MMUS platform used in this experiment and the algorithm used to estimate displacement, the reader is referred to [180].…”

“…A speckle tracking strategy was used to estimate the induced displacements within the phantom, hence, generating the MMUS images. In this method, the time shift between the RF data of a reference frame and the subsequent frames, collected during the applied pulsed magnetic field, was estimated using an axial 1-D normalized cross-correlation algorithm [180,339]. This algorithm was applied to 0.8 mm windows with 70% overlap.…”