arXiv subjects

Umberto Zanovello

Publications and source records attributed to Umberto Zanovello.

5 recordsLinked to original sources

arXiv2026

A Reference System for Open Source Portable Low-Field MRI

Despite its renewed attention, the pathway to point-of-care portable low-field MRI systems remains challenging, limiting adoption across research groups. Incomplete documentation limits reproducibility, causing redesign and complicating cross-system comparison. Moreover, non-standardized testing and characterization complicates ethical approval for clinical studies. We present an open-source reference system for portable low-field MRI designed to support replication, reproducibility, benchmarking, and quantitative comparison. The system is fully open source, based on a ~50 mT permanent magnet, and integrated with a cloud-native acquisition platform. Pulseq-based calibration, characterization, and imaging sequences assessed noise level, eddy currents, image-based SNR, and geometric accuracy. Quantitative T1, T2, and B0 mapping sequences were developed and evaluated against reference values. Initial results from independent replications at two sites were compared. The system reached a noise level of 1.4 relative to the thermal noise floor and short eddy-current decay constants of 27-32 us across all gradient channels. Geometric deviations were below 2 mm over the field of view. Image-based SNR were consistent between the independent replications. Measured T1 values closely matched specified values, with an average absolute error of 3.1(1.8)%, while T2 values were overestimated by 10.4(5.8)%. Simulations showed only marginal errors for both quantities, suggesting experimental error sources for T2 mapping. The reference system combines openly documented hardware, software, calibration procedures, phantoms, quantitative MRI, and simulation tools in a reproducible ecosystem, aiming to support cross-site comparability, reproducible research, and collaborative development of future portable low-field MRI technologies.

physics.med-ph↗

arXiv2026

Birth of the Coil: another Milestone towards a fully reproducible low-field MRI scanner for head-imaging

Low-field magnetic resonance imaging (MRI) provides an accessible, portable, and low-cost alternative to high-field scanners, expanding diagnostic imaging to point-of-care settings. However, widespread adoption is fundamentally hindered by a severely reduced signal-to-noise ratio (SNR). At low frequencies, radiofrequency (RF) coil conductor losses - rather than tissue sample losses - predominantly govern the system's total noise, making meticulous RF coil optimization critical to recovering image quality. This work presents an open-source, optimized solenoid head coil tailored for the 50 mT open-source scanner (OSII ONE v2.1). The paper validates production reproducibility across three independent international institutions and introduce an open-source connector with integrated digital circuitry for coil identification and DC or logic signals. Comprehensive benchtop measurements, Electromagnetic Interference (EMI) coupling analysis, Specific Absorption Rate (SAR) safety simulations, and phantom and human volunteer imaging confirm the design's efficacy, safety, and reproducibility. The results of the paper, when combined with the material provided in the open-source dedicated repositories, set the basis for a fully reliable and reproducible component for the open-source OSII ONE MRI scanner. In addition, the same optimization strategy and design material can be exploited for designing other RF coils for imaging of other body parts.

physics.med-ph↗

arXiv2026

Lenz effect in conductive nonmagnetic objects moved in MRI environments

Purpose: To model and predict the dynamics of conductive nonmagnetic objects moved within the MRI room under the influence of Lenz effect. High frequency motions, like vibrations induced by gradient eddy currents are not taken into account. Methods: The dynamics are described by an ordinary differential equation and the Lenz effect approximated under the assumption of negligible skin effect. This allows to separate the Lenz effect dependency on the object position and velocity, leading to a simple numerical procedure for objects of any shape. Results: The proposed model and numerical procedure were validated with experimental data recording the rotation of an aluminium plate falling inside a 1.5 T MRI scanner. The model was also applied for studying the translation of an aluminium plate pushed with constant force towards the MRI bore through the fringe field. Conclusion: The collected results showed that it is possible to obtain accurate predictions of motion in the presence of Lenz effect by neglecting the skin effect while determining the motional eddy currents induced in the metallic object.

cs.CE↗

arXiv2025

Very-low-field MRI scanners: from the ideal to the real permanent magnet array

Very-low-field MRIs are becoming increasingly popular due to their portability and adaptability to different environments. They are being successfully used for various clinical applications, leading to a paradigm shift in the way imaging care is typically performed. The development of low-cost MRI scanner prototypes began a few years ago, with some interesting and promising open-source projects emerging in both hardware and software design. Using permanent magnets (PMs) to generate the static magnetic field B0 can substantially reduce the manufacturing cost while achieving satisfactory homogeneity. This article aims to explore the reasons behind discrepancies between magnet design and prototype performance in terms of magnetic field homogeneity. Understanding the impact of the practical implementation of magnet design could inform the development of more tolerant designs in future, simplifying subsequent B0 shimming procedures or even making them unnecessary. This work also evidences the impact of using different numerical model approximations in the modelling phase, proving how they also impact the quality of the design outcomes.

cs.CE↗

arXiv2025

3D-1D modelling of cranial mesh heating induced by low or medium frequency magnetic fields

Safety assessment of patients with one-dimensionally structured passive implants, like cranial meshes or stents, exposed to low or medium frequency magnetic fields, like those generated in magnetic resonance imaging or magnetic hyperthermia, can be challenging, because of the different length scales of the implant and the human body. Most of the methods used to estimate the heating induced near such implants neglect the presence of the metallic materials within the body, modeling the metal as thermal seeds. To overcome this limitation, a novel numerical approach that solves three-dimensional and one-dimensional coupled problems is proposed. The proposed method is compared with measurements performed on a cranial mesh exposed to the magnetic field generated by a gradient coil system for magnetic resonance imaging. Then, it is applied to a magnetic hyperthermia case study in which a patient with a cranial mesh is exposed to the magnetic field generated by a collar-type magnetic hyperthermia applicator for neck tumour treatment. The experimental comparison of the proposed method predictions and the measurement data shows an improved accuracy near the maximum temperature increase up to 25% with respect to the method based on thermal seeds. The application of the proposed method applied to the magnetic hyperthermia case study leads to a prediction of the maximum temperature increase that is 10% lower than the one overestimated by relying on thermal seeds. At the same time, the proposed method corrects the underestimation of the thermal seeds in the regions where the electromagnetic power is not directly deposited and the temperature increase is only due to heat transfer. The proposed method leads to improved results with respect to previous approximations by modelling the thermal diffusion through the highly conductive metallic implants.

cs.CE↗