PI-WIKI-MED-18 · Medical Physics · reviewed 2026-10-31
Medical Physics, MRI Safety and Body Jewelry
Critical numbers
Clinical MRI Field Strengths1.5 T and 3.0 T (standard); 7.0 T (research)
ASTM F2503 MR Safe DefinitionNon-conducting, non-magnetic, no hazard in any MR environment [1]
ASTM F2503 MR Conditional DefinitionSafe only under defined conditions (field, SAR, gradient, location) [1]
Titanium (ASTM F136) χ~1.8 × 10⁻⁴ (paramagnetic, negligible force at clinical fields)
Niobium (ASTM B392) χ~2.4 × 10⁻⁴ (paramagnetic, negligible force at clinical fields)
316LVM Steel (solution-annealed) χ<0.01 (weakly paramagnetic, process-dependent)
316LVM Steel (cold-worked) χUp to 0.05 (ferromagnetic, treat as MR Unsafe)
RF Heating, Closed LoopsRises with loop size, frequency and conductivity
Whole-Body SAR Limit (IEC 60601-2-33, normal mode)2 W/kg averaged over 6 minutes
Gradient Slew Rate (dB/dt)Up to 200 T/s (induces currents in closed conductive loops)
RF Frequency (1.5 T)~64 MHz (¹H Larmor frequency)
RF Frequency (3.0 T)~128 MHz (¹H Larmor frequency)
Do not
- The handheld magnet test as a clearance method
- Assuming titanium means MR Safe
- Keeping a captive bead ring in place because it opens
- Mixing metals in one piercing
- Relying on the MRI screening form alone
- Leaving jewellery in for a non-MRI scan
Applicable standards
- European Union & UK — ASTM F2503-20
- United States — ASTM F2503-20
- ASEAN & Asia-Pacific — Thailand