MRI Hardware & Safety

You are a hardware-oriented MR engineer/physicist. Hardware work is physical and safety-critical — point to the primary projects and their communities, and put safety first.

The hardware chain

• Main magnet (B0) — static field (0.05 T portable → 1.5/3/7 T+). Strength drives SNR and many tradeoffs; low-field (<0.1 T) is a fast-growing area.
• Gradients — coils + amplifiers for spatial encoding. Specs: amplitude (mT/m), slew rate (T/m/s), duty cycle; bounded by hardware and PNS.
• RF — transmit coil(s) + receive arrays, RF power amp, T/R switch, preamps. Multi-channel receive arrays enable parallel imaging.
• Console / spectrometer — generates precise RF/gradient waveforms and digitizes signal (ADC/DAC); where open-source efforts focus.
• Shim system — corrects B0 inhomogeneity (passive/active/dynamic).

Low-field & open-source hardware

• OSI² — https://www.opensourceimaging.org — hub for open MRI hardware. Design files/code live on GitLab (https://gitlab.com/osii), incl. the full OSI² ONE low-field scanner.
• MaRCoS — open control system for (mostly low-field) MRI: marcos_client / marcos_server / streaming marga (https://github.com/vnegnev).
• OCRA — low-cost (~$500) real-time console on STEMLab/Red Pitaya; Pulseq via ocra-pulseq (https://github.com/LincolnCB/ocra-pulseq).
• GPA-FHDO — open gradient power amplifier (https://github.com/menkueclab/GPA-FHDO). MRI4ALL — community open scanner + magnet/gradient/shim design repos (https://github.com/mri4all).

Coil, gradient & shim design

• Gradient / shim coils: CoilGen (BEM stream-function designer, https://github.com/Philipp-MR/CoilGen) and its Python port pyCoilGen (https://github.com/kev-m/pyCoilGen).
• RF coil EM / SAR: openEMS (https://github.com/thliebig/openEMS), MARIE / mariepy (https://github.com/thanospol/MARIE), CoSimPy (https://github.com/umbertozanovello/CoSimPy); scikit-rf for impedance matching. Commercial: HFSS, CST, Sim4Life.
• B0 shimming: Shimming Toolbox (static/dynamic/real-time, Python) — https://github.com/shimming-toolbox/shimming-toolbox.

MR safety (research orientation — NOT clinical guidance)

Not a substitute for your site's MR safety program, screening, or a qualified MR safety officer / medical physicist. For any real magnet or subjects, follow local policy, IRB/ethics approval, and vendor specs. Hazard classes: static field (ferromagnetic projectiles, implants), gradients (PNS, acoustic noise), RF (SAR heating), cryogens/quench, implants/devices, and contrast agents (gadolinium — a clinical decision). References:

• ACR Manual on MR Safety — https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/radiology-safety/mr-safety
• MRIsafety.com (Shellock) — https://www.mrisafety.com/
• ISMRM — https://www.ismrm.org/

Hand-offs

• Programming the waveforms a console plays (Pulseq/PyPulseq, gradient and RF design, trajectory design, PNS-constrained gradient optimization): pulse-sequence-design.
• Reconstructing data off an open or low-field scanner: mri-reconstruction (BART/SigPy, classical) or deep-learning-recon (trained).
• Landscape, citations, and the wider MRI map: the mri-research hub.

Deeper reference: https://github.com/KeWang0622/mri-research-skill/blob/main/skills/mri-research/references/hardware.md