Low‐cost and portable MRI

Abstract

Research in MRI technology has traditionally expanded diagnostic benefit by developing acquisition techniques and instrumentation to enable MRI scanners to "see more." This typically focuses on improving MRI's sensitivity and spatiotemporal resolution, or expanding its range of biological contrasts and targets. In complement to the clear benefits achieved in this direction, extending the reach of MRI by reducing its cost, siting, and operational burdens also directly benefits healthcare by increasing the number of patients with access to MRI examinations and tilting its cost–benefit equation to allow more frequent and varied use. The introduction of low‐cost, and/or truly portable scanners, could also enable new point‐of‐care and monitoring applications not feasible for today's scanners in centralized settings. While cost and accessibility have always been considered, we have seen tremendous advances in the speed and spatial‐temporal capabilities of general‐purpose MRI scanners and quantum leaps in patient comfort (such as magnet length and bore diameter), but only modest success in the reduction of cost and siting constraints. The introduction of specialty scanners (eg, extremity, brain‐only, or breast‐only scanners) have not been commercially successful enough to tilt the balance away from the prevailing model: a general‐purpose scanner in a centralized healthcare location. Portable MRI scanners equivalent to their counterparts in ultrasound or even computed tomography have not emerged and MR monitoring devices exist only in research laboratories. Nonetheless, recent advances in hardware and computational technology as well as burgeoning markets for MRI in the developing world has created a resurgence of interest in the topic of low‐cost and accessible MRI. This review examines the technical forces and trade‐offs that might facilitate a large step forward in the push to "jail‐break" MRI from its centralized location in healthcare and allow it to reach larger patient populations and achieve new uses.Level of Evidence: 5Technical Efficacy Stage: 6J. Magn. Reson. Imaging 2019. J. Magn. Reson. Imaging 2020;52:686–696.

High-sensitivity in vivo contrast for ultra-low field magnetic resonance imaging using superparamagnetic iron oxide nanoparticles

“…A key challenge to the implementation of ULF MRI remains simultaneously achieving signal-to-noise ratios (SNRs) adequate for imaging and contrast-to-noise ratios (CNRs) sufficient for diagnostic differentiation between tissues within a short imaging time ( 4 , 17 ). The traditionally low SNR of conventional (i.e., inductively detected) ULF MRI has been improved substantially through the use of high-efficiency sequences, such as balanced steady-state free precession (bSSFP), that can accommodate rapid signal averaging ( 18 ).…”

Development and validation of 3D MP‐SSFP to enable MRI in inhomogeneous magnetic fields

“…There is considerable research interest in creating MRI systems that are compact, cost-effective, and robust. [1][2][3][4][5][6][7][8] Most clinical MRI techniques presuppose a highly homogeneous magnetic field over the imaging volume, typically within ±10 ppm. Cost-effectively reducing magnet size can make MRI systems compact and lightweight; however, such size reduction will either reduce the magnetic field strength, magnetic field uniformity, or both compared with a clinical scanner.…”

Assessment of cardiac function, blood flow and myocardial tissue relaxation parameters at 0.35 T

“…Quantitative cardiac function and flow sequences commonly used at 1.5 and 3 T gave comparable results at 0.35 T. While the low‐field system used in our study is a hybrid radiation therapy + MRI system and not designed to reduce scanner costs or specifically intended for cardiac imaging, it provided a platform to explore the potential for cardiac MRI on a system that combines lower B0 field strength together with high end gradient performance. Magnet and cryostat costs alone can account for ~ 38% of MR equipment costs 12 ; lower magnet costs associated with lower field strength could increase affordability and thereby increase MR availability and accessibility to a broader range of patients. Our study results support the concept that basic cardiac MRI is feasible at lower field, thereby creating an opportunity to broaden access and improve the financial sustainability of cardiac MRI.…”

“…While not all cardiac MRI applications benefit from higher field, techniques that typically rely on spoiled gradient echo acquisitions (eg, flow quantification and late gadolinium enhancement), 9 and contrast‐enhanced applications (first‐pass myocardial perfusion, and contrast‐enhanced angiography) have demonstrated advantages at 3 T compared with 1.5 T 10,11 . However, the higher costs associated with higher field superconducting magnets, and concomitantly higher costs for installation, cryogens, and maintenance 12 in an era of downward pressure on imaging reimbursement rates, may be impediments to providing a financially viable cardiac MR service in clinical practice; the cost‐benefit ratio of increasing field strength must be carefully considered.…”