Same-Day Stroke MRI in a Patient with an Unverified Cardiac Device
An inpatient stroke team calls the MRI suite at 06:40 about a 74-year-old man with sudden left-arm weakness and slurred speech that began 2 hours ago; NIHSS is 9. The order is an urgent brain MRI with diffusion-weighted imaging to guide thrombolysis, and the team wants the patient on the table within 25 minutes. The scanner is a 1.5 T system. While screening, the patient's nurse reports a 'pacemaker' implanted in 2011, but the chart has no device card, no manufacturer, and no MRI-conditional documentation. The device clinic is closed until 08:00. The patient is confused and cannot reliably answer questions; he keeps saying 'I think it's fine.' A portable chest radiograph shows a left pectoral generator and two leads, but no model number. The stroke team asks you to 'just scan the brain without contrast' because time is critical. Another inpatient is waiting for a 30-minute spine study.
1. What immediate screening and device-verification steps must occur before this patient enters the scan room, and who should make the final decision?
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Do not allow the patient into the scan room until the device is identified or a formal risk decision is made. 'Brain only' is not a mitigation: the RF field is whole-body and can heat leads, induce currents, inhibit pacing, or reprogram the generator.
Immediate steps:
- Search all records, prior imaging, and operative notes for the exact manufacturer, model, and lead information.
- Call the device clinic, on-call cardiology, and the manufacturer's MRI support line.
- Obtain device interrogation if it can be done without delaying emergency care.
- Confirm whether the system is MR-conditional at 1.5 T, whether all leads are MR-conditional, and whether any abandoned leads are present.
- Treat an unidentified device as MR-unsafe.
The final decision belongs to the radiologist in consultation with cardiology or the device service, not to the technologist alone and not to the referring stroke team. Because thrombolysis is time-critical, immediately notify the radiologist and offer CT/CTA as the alternative to exclude hemorrhage and assess for large-vessel occlusion. Document every query, contact, time, and decision.
2. The stroke team pushes to proceed because the device is old and probably not MRI-conditional anyway. How do you respond, and what alternatives do you propose?
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Acknowledge the urgency but challenge the reasoning directly: an old device is not a known-safe device. Scanning an unverified pacemaker can cause lead heating, arrhythmia, pacing failure, or death, and the risk is not confined to the brain.
Respond with a clear safety statement: 'I cannot scan an unidentified pacemaker. The risk is serious and not justified by the urgency.' Offer concrete alternatives rather than simply refusing:
- CT head without contrast to exclude hemorrhage, with CTA if large-vessel occlusion is suspected.
- Immediate discussion with the on-call radiologist about the stroke pathway.
- If MRI is truly essential, arrange urgent device interrogation before scanning; the device clinic opens at 08:00.
- If the patient is transferred, send the device information request with the patient.
Ask the stroke team to document their request and your safety concern. If they insist, escalate to the radiologist and risk management. Do not accept verbal reassurance or 'the patient says it is fine.' Reassure the team that you are redirecting care to a safe pathway, not delaying it.
3. If the device is later identified as MR-conditional at 1.5 T, what conditions and monitoring must be in place?
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Verify the exact generator and all leads against the manufacturer's conditions; a conditional generator with non-conditional or abandoned leads may still be unsafe. Confirm that the field strength is 1.5 T and that SAR, gradient, and scan-time limits are respected.
Before scanning:
- Obtain informed consent after explaining the residual risks.
- Reprogram the device as required by the manufacturer, often to an asynchronous or monitored mode.
- Ensure ECG, SpO2, and voice contact are maintained throughout.
- Have trained staff, external pacing/defibrillation capability, and a plan to remove the patient quickly.
- Confirm no contraindicated implants or lead adapters.
During scanning: use the lowest SAR that answers the clinical question, monitor for heating, palpitations, or change in symptoms, and stop if anything is abnormal.
After scanning: interrogate the device before the patient leaves the department and document the pre- and post-scan settings. Follow the manufacturer's conditions exactly rather than assuming that 'MR-conditional' means unconditional scanning.