High-Tc SQUID based ultra-low field MRI

High-Tc SQUID based ultra-low field MRI

Doctors cannot perform potentially life-saving medical MRIs on more than 15% of the population because of a lack of access, safety or claustrophobia issues, or simply because the subject cannot fit in a standard system. MedTech West is developing a new MRI modality that can potentially lead to cheaper, simpler, and, for some medical applications, better imaging capabilities.

We perform MR imaging with advanced high-Tc SQUIDs at a magnetic field strength that is roughly equal to that of the earth's magnetic field. Our method therefore does not require giant and expensive superconducting MRI coils. While such standard coils generate magnetic fields strong enough that metal objects become dangerous projectiles or heating centers, our system does not pose these threats to clinicians or their patients. Furthermore, our capability to record MRIs at extremely weak fields enables a new type of imaging contrast. In the future, hospitals will be able to perform life-saving contrast agent-free imaging of notoriously difficult-to-image diseases like prostate cancer. Portable ultra-low field MRI systems could also be used for bedside or even in-home imaging of patients with limited mobility.

Our approach

Magnetic resonance imagers (MRIs) are the tools of choice for clinical imaging of the body’s soft tissues. Since the technique was invented, the trend has been to build systems with increasingly strong measurement (B0 ~ Teslas) fields to improve the spatial resolution and signal-to-noise ratios of MR images. More recently, however, researchers have begun to explore the possibility of employing ultra-sensitive SQUID sensors in order to perform ultra-low field MR imaging (ulf-MRI, with B0 ~ 10s or 100s of microTeslas). Safety benefits aside, ulf-MR offers improved spectroscopic resolution with relaxed field-homogeneity requirements that simplifies system construction and reduces cost. Furthermore, T1-weighted imaging contrast is enhanced in comparison with standard MRI systems. Our goal is to develop a clinical imager based on ulf-MR with our high-Tc SQUIDs.

Current developments

We have constructed a high-Tc SQUID-based ulf-MRI system for imaging at ~100 microTesla and obtained single-shot NMR peaks with signal-to-noise ratios on the order of 100. Proof-of-principle images of water phantoms with an imaging volume of several cubic centimeters and resolution of a few millimeters have also been recorded. These capabilities demonstrate that, despite higher noise levels when compared to their low-Tc counterparts, high-Tc SQUIDs are a feasible technology for ulf-MRI. The relaxed thermal insulation requirement of high-Tc technology adds another level of improvement in overall system complexity. The instrument as it is serves as a platform for exploring and developing ways of exploiting the T1-weighted contrast and spectroscopic resolution enhancements available at ultra-low fields. The imaging demonstrations pave the way to larger sample volumes that will enable e.g. imaging of appendages or the entire head.

Outlook

Future systems will be catered to a variety of applications suited to the advantages of ulf-MRI. The simplicity and low-cost nature of the hardware (in comparison to standard MRI systems) lend themselves to development of portable and/or bedside MR imagers. Clinicians may then be able to bring the MR camera to their patients, improve diagnostics and monitoring with enhanced imaging capabilities, as well as safely image patients with metal and/or magnetic implants.

Research team

MedTech West partner

Dr. Justin F. Schneiderman, Department of Clinical Neuroscience and Rehabilitation, University of Gothenburg.

Clinical partners

Prof. Dag Winkler, Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology.

Contact

For more information on this project, contact Henrik Mindedal at henrik.mindedal@medtechwest.se