MRI4ALL: A Week-Long Hackathon for the Development of an Open-Source Ultra-Low-Field MRI System

The goal of the MRI4ALL hackathon, which took place in October 2023, was to develop a functional low-field MRI scanner in just one week and to release all created source code and resources as open-source packages. The event was attended by 52 participants from 16 institutions who assembled the scanner on the last day of the hackathon. The scanner's magnetic B₀ field with a strength of 43 mT and a target field-of-view size of 11 cm³ was created with a Halbach array made from 990 N40UH permanent magnets, held in place using 3D printed ring formers. Gradient coils were fabricated by gluing enameled copper wire onto 3D printed holders with imprinted wire patterns. A solenoid coil for RF transmission and reception was built by winding 20 turns of Litz wire around a 3D printed cylinder. A Red Pitaya FPGA prototyping board running the MaRCoS framework was used to control the scanner components, and a GPA-FHDO amplifier board was used to drive the gradients. To simplify the scanner's operation, console software with an intuitive graphical user interface was developed in Python using the PyPulseq package for sequence calculations. Furthermore, the scanner was equipped with a cooling system, as well as options for passive and active shimming. After resolving several technical issues that arose during the assembly, the scanner is now able to acquire MR images with different sequences. While not suitable for real-world clinical applications, it can be utilized for educational purposes or as a low-cost prototyping platform. Moreover, it may serve as a reference design for future MRI development projects. All source code and resources are available on the project website mri4all.org, allowing other groups to replicate the scanner. EVIDENCE LEVEL: n/a TECHNICAL EFFICACY: Stage 1.