How to evaluate the safety of cobalt chromium nickel alloy implants.(Hy-industry encyclopaedia)
What are the contraindications of MRI?
The following patients are strictly prohibited from undergoing MRI examination:
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Pacemaker
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Equipped with automatic electrical cardioverter defibrillator
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Equipped with functional nerve stimulator
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The body has an insulin pump and other infusion pumps
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After aneurysm clipping
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Those suspected of having metal objects in the eyeball and by the large blood vessels
The following patients are not suitable for MRI examination:
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Pregnant women within 3 months of pregnancy
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Mentally ill
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Emergency and critically ill patients with multiple life monitoring instruments
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Patients who can’t stay in position for a long time
The following patients should obtain the consent of the surgeon and the MRI room doctor before undergoing MRI examination:
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After the operation, there are metal objects, metal implants or metal prostheses (such as various catheters, guide wires and internal stents) left in the patient’s body.
It is strictly prohibited to bring the following objects into the MR scanning room:
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Walking stick (crutch), wheelchair
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Removable hospital bed
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Oxygen cylinders and other metal objects
How to evaluate the safety of implants before MRI examination?
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Try to understand the manufacturer, type, manufacturing materials, batch number, serial number and other information of the implant, especially the manufacturing materials, you can consult the surgeon. Only patients with aneurysm clips and intravascular stents treated with non-ferromagnetic or weakly ferromagnetic materials can undergo MRI.
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Aneurysm clip and intravascular stent with original packaging, if made of cobalt chromium nickel alloy (including Phynox and Elgiloy products), nickel cobalt chromium molybdenum alloy (such as MP35N), titanium alloy, pure titanium, or other known For non-ferromagnetic or weakly ferromagnetic materials, 1.5T or lower field strength MRI is feasible.
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Patients with any bio-medical electronic implants (such as cardiac pacemakers, various defibrillators, hearing aids) should not be exposed to strong magnetic fields, and do not enter the MRI scanning room.
Can MRI examination be accepted if there is any metal foreign body on the head?
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Metallic foreign objects (including fragments or debris) are ferromagnetic substances. No matter where they are located in the body, electrothermal effects may occur in the magnetic field and burn local tissues.
If the foreign body is pulled and moved by the magnetic force, it will cut the adjacent tissue or blood vessel, destroy the function of the organ, and seriously endanger the patient’s life.
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How to avoid such things:a:Carefully ask about the medical history, whether there is any occupational exposure related to metal work, and whether it has been hit by metal fragments.b:Suspicious or uncertain need to do X-ray plain film or CT examination of the corresponding part before MRI examination.c:X-ray plain film shows that the threshold of metal foreign objects is 0.12mm × 0.12mm × 0.12mm, CT is 0.12mm × 0.12mm × 0.12mm.
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Patients who have received eyelid makeup, hair coloring, eyebrow dyeing, eyelash dyeing, and tattoo decoration should remove the accessories as much as possible before the MRI examination. Because artificial dyes usually contain iron oxides, some subjects who have dyed their hair may make the MRI system unable to find the resonance frequency. If you examine it, it will not only produce artifacts, but also may cause irritation and damage local skin tissue.
What preparation does the patient need to do before MRI examination?
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Fasting 4 hours before pelvic examination
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Fasting before magnetic resonance cholangiopancreatography (MRCP)
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Urinary tract magnetic resonance examination (MRU) and pelvic MRI examination before holding urine properly
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Before entering the scanning room, carefully read the MRI examination instructions to eliminate nervousness and fear, and actively cooperate with the examination.
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Do not bring magnetically sensitive items and electronic devices such as magnetic cards, credit cards, mobile phones, and watches into the scanning room.
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Actively remove all metal objects from the body and clothing, such as: dentures, hairpins, keys, knives, pens, coins, etc.
