Devices and implants
| Item | Status | Notes |
|---|---|---|
| MR-conditional pacemaker or ICD | Scan within the labelled conditions | Whole system (generator and every lead) must be conditional; field strength, SAR mode, exclusion zone and programming per the label; device check before and after; monitoring throughout |
| Non-conditional (legacy) pacemaker or ICD | Scan under an institutional protocol when clinically justified | HRS 2017 consensus: acceptable with device interrogation, reprogramming, monitoring and a physician present; risk is higher with abandoned or fractured leads, epicardial leads and pacing dependence |
| Abandoned, epicardial or fractured leads | Relative contraindication | Lead-tip heating cannot be controlled by programming; case-by-case |
| Temporary transvenous pacing wire with external generator | Do not scan | Unshielded lead and external hardware |
| Prosthetic heart valves and annuloplasty rings | Safe at 1.5T and 3T | All currently marketed prostheses; susceptibility artefact only |
| Coronary and peripheral stents | Safe at 1.5T and 3T, at any time after implantation | AHA 2007 statement; no waiting period |
| Sternal wires, vascular clips, surgical staples | Safe | Non-ferromagnetic; local artefact |
| Intracranial aneurysm clip | Only with documented MR-conditional labelling | Ferromagnetic clips can torque; unknown clip is a contraindication |
| Cochlear implant | Per label | Many current models are conditional at 1.5T with the magnet in place; older models need magnet removal or are excluded |
| Neurostimulator, drug pump, loop recorder | Per label | Often conditional with specific scan and programming limits; loop recorders are conditional at 1.5T and 3T |
| Metallic intraorbital foreign body | Exclude before scanning if the history suggests one | Orbital radiograph or CT |
| Retained bullets, shrapnel, welding history | Assess individually | Radiograph the region; position relative to vital structures matters |
Gadolinium-based contrast agents
| ACR group | Agents | Structure | NSF association |
|---|---|---|---|
| Group I | Gadodiamide (Omniscan), gadopentetate (Magnevist), gadoversetamide (OptiMARK) | Linear | Highest; the majority of unconfounded NSF cases |
| Group II | Gadobutrol (Gadovist), gadoterate (Dotarem, Clariscan), gadoteridol (ProHance), gadobenate (MultiHance), gadopiclenol (Elucirem, Vueway) | Macrocyclic (gadobenate linear) | Few, if any, unconfounded cases |
| Group III | Gadoxetate (Primovist, Eovist) | Linear | Limited data; hepatobiliary agent, not used in CMR |
NSF risk and eGFR
| eGFR (mL/min/1.73 m²) | Group II agent | Group I agent |
|---|---|---|
| ≥ 30 | Standard dose | Standard dose; avoid where a group II agent is available |
| < 30, not on dialysis | Standard dose when the study is indicated; risk of NSF is very low (ACR-NKF 2021). ESUR: lowest dose that answers the question, at least 7 days between doses | Contraindicated |
| Dialysis | Standard dose when indicated; dialyse afterwards if already scheduled, not as a precaution | Contraindicated |
| Acute kidney injury | Weigh the indication; eGFR does not reflect function | Contraindicated |
ACR-NKF 2021: renal function screening before a group II agent is optional. eGFR calculator on the calculators page.
Dosing
| Use | Dose | Injection |
|---|---|---|
| LGE | 0.1 to 0.2 mmol/kg total | Any rate; image 10 to 15 minutes after the last injection (mapping-based ECV needs the same total) |
| Stress and rest perfusion | 0.05 to 0.1 mmol/kg per pass | 3 to 7 mL/s followed by a 20 to 30 mL saline flush at the same rate |
| Contrast-enhanced MRA | 0.1 to 0.2 mmol/kg | Bolus timed to the vessel of interest, saline flush |
| Volume for 0.5 mmol/mL agents | 0.2 mL/kg per 0.1 mmol/kg | Gadobutrol is 1.0 mmol/mL: 0.1 mL/kg per 0.1 mmol/kg |
Ranges from the SCMR 2020 protocol update; agent labels give the licensed dose. Dose calculator.
Pregnancy and breastfeeding
| Situation | MRI | Gadolinium |
|---|---|---|
| Pregnancy, any trimester | No demonstrated harm at 1.5T or 3T; scan when the result will change management during the pregnancy | Only when essential to the mother’s care and no alternative exists; gadolinium crosses the placenta and remains in the amniotic fluid |
| Breastfeeding | No restriction | No interruption needed: less than 0.04% of the dose reaches breast milk and less than 1% of that is absorbed by the infant |
- Indik JH, Gimbel JR, Abe H, et al. 2017 HRS expert consensus statement on magnetic resonance imaging and radiation exposure in patients with cardiovascular implantable electronic devices. Heart Rhythm 2017;14(7):e97-e153. doi:10.1016/j.hrthm.2017.04.025
- Levine GN, Gomes AS, Arai AE, et al. Safety of magnetic resonance imaging in patients with cardiovascular devices: an American Heart Association scientific statement. Circulation 2007;116(24):2878-2891. doi:10.1161/CIRCULATIONAHA.107.187256
- Weinreb JC, Rodby RA, Yee J, et al. Use of intravenous gadolinium-based contrast media in patients with kidney disease: consensus statements from the American College of Radiology and the National Kidney Foundation. Radiology 2021;298(1):28-35. doi:10.1148/radiol.2020202903
- American College of Radiology Committee on Drugs and Contrast Media. ACR Manual on Contrast Media. 2024. acr.org/Clinical-Resources/Contrast-Manual
- European Society of Urogenital Radiology. ESUR Guidelines on Contrast Agents, version 10.0. esur.org/esur-guidelines-on-contrast-agents
- Kramer CM, Barkhausen J, Bucciarelli-Ducci C, Flamm SD, Kim RJ, Nagel E. Standardized cardiovascular magnetic resonance imaging (CMR) protocols: 2020 update. J Cardiovasc Magn Reson 2020;22(1):17. doi:10.1186/s12968-020-00607-1
- Shellock FG. MRISafety.com: the list. mrisafety.com