Low-Cost High-Performance MRI

TLDR

MRI uniquely visualizes anatomy and function non‑invasively, yet its low sensitivity requires superconducting magnets at 1.5–3 T, which are large, costly (≈$1 M per tesla) and limit deployment. The study aims to demonstrate a simple, non‑cryogenic method for high‑performance human MRI at ultra‑low magnetic field. The method uses under‑sampling and fully‑refocused dynamic spin control via steady‑state free precession in an open‑geometry electromagnet. At 6.5 mT the system achieves 2.5 × 3.5 × 8.5 mm³ brain imaging in 6 min, and the authors argue that sub‑10 mT MRI can complement conventional scanners, offering clinically relevant images with devices under $50 k.

Abstract

Abstract Magnetic Resonance Imaging (MRI) is unparalleled in its ability to visualize anatomical structure and function non-invasively with high spatial and temporal resolution. Yet to overcome the low sensitivity inherent in inductive detection of weakly polarized nuclear spins, the vast majority of clinical MRI scanners employ superconducting magnets producing very high magnetic fields. Commonly found at 1.5–3 tesla (T), these powerful magnets are massive and have very strict infrastructure demands that preclude operation in many environments. MRI scanners are costly to purchase, site and maintain, with the purchase price approaching $1 M per tesla (T) of magnetic field. We present here a remarkably simple, non-cryogenic approach to high-performance human MRI at ultra-low magnetic field, whereby modern under-sampling strategies are combined with fully-refocused dynamic spin control using steady-state free precession techniques. At 6.5 mT (more than 450 times lower than clinical MRI scanners) we demonstrate (2.5 × 3.5 × 8.5) mm 3 imaging resolution in the living human brain using a simple, open-geometry electromagnet, with 3D image acquisition over the entire brain in 6 minutes. We contend that these practical ultra-low magnetic field implementations of MRI (<10 mT) will complement traditional MRI, providing clinically relevant images and setting new standards for affordable (<$50,000) and robust portable devices.