MRI Policies - Safety and Contraindications
Metallic fragments, clips or devices in the brain, eye, spinal canal, etc.:
Movement in the bore of the magnet may damage sensitive tissues. Plain radiography
is sufficient for screening. Some intracranial clips may be safe, but these
must have been tested in the OR just prior to implantation.
Magnetically activated implanted devices:
Cardiac pacemakers, insulin pumps,
neurostimulators, cochlear implants, etc. may be de-programmed.
Non-graphite spinal cord tongs: Graphite tongs are compatible.
Thermodilution Swan-Ganz catheter: Local heating can result.
Metal outside the brain and eye is NOT a contraindication: Magnetic deflection is minimal compared to normal physiologic forces. Cardiac valves), inferior vena cava filters, biliary and vascular stents, IUD's and metallic prostheses are safe, unless there is doubt as to positional stability.
Decreased renal function is Not a contraindication: Gadolinium contrast agents are not nephrotoxic at doses used as per our protocols, although excretion is primarily renal.
Signed consent is not needed unless a patient is identified as high risk for gadolinium.
Risk of nephrogenic systemic fibrosis (NSF) in patients with severe renal failure (stage 4 or 5; GFR < 30 mL/min/1.73 m2) :
1. Benefit/risk and indication for gadolinium contrast agent should be reevaluated by a radiologist.
2. If unenhanced MRI is likely to provide sufficient information, gadolinium should not be administered to these patients.
3. If, after review of clinical indications, gadolinium enhancement is judged to be important for diagnosis, the lowest effective dose of contrast agent should be used. Gadavist is a highly stable macrocyclic agent; Eovist and MultiHance both have in vivo stability similar to that of Magnevist, but Eovist is used at lower gadolinium doses. Neither Gadavist, MultiHance or Eovist have a single reported associated case of NSF when used at standard recommended doses, so these agents as per our dosing policy pose negligible risk of NSF. Most NSF has occurred using more than 30 mL of gadolinium contrast agent, and most have been following Omniscan (gadodiamide), which is a much less stable linear ionic contrast agent.
4. For patients treated with hemodialysis, a hemodialysis session within a few hours following gadolinium contrast injection is likely to further reduce NSF risk.
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Below are the recommended doses and contrast types for dosing administration
in MRI:
Standard MRI
Gadavist: 0.1 mmol/kg
MultiHance: 0.1 mmol/kg
Abdomen/Pelvis or Single-Station MRA
MultiHance: 0.1 mmol/kg
MRV or Bolus Chase MRA (runoff)
MultiHance: 0.15 mmol/kg
Exams routinely getting MultiHance:
1. In patient with reduced renal function, as an alternative to Magnevist in sites that do not use Gadavist, use MultiHance (0.07 mmol/kg)
2. MR Urography (0.07 mmol/kg) and MR Enterography (0.1 mmol/kg)
exams to include patients with normal renal function.
3. MRA Single station exam at (0.1 mmol/kg)
4. MRA Runoff and MRV exams at (0.15 mmol/kg)
The following exam types listed below would be a consideration for Eovist based
on prior exam history and at the discretion of the Body radiologist.
All patients
with NORMAL RENAL FUNCTION will receive a dose of at least 10 mL.
Patients weighing more than 200 lbs. receive 20 mL.
Patients with a
history of COMPROMISED RENAL FUNCTION will receive Eovist via the weight
based dosing chart at (0.025 mmol/kg = 0.1mL/kg). See dosing chart number six.
1. FNH (focal nodular hyperplasia) or liver adenoma characterization
2. Malignant liver mass: improved delineation of tumor margins.
3. Bile ducts improved delineation, or functional evaluation.
4. Suspected gallbladder obstruction.
For #s 3 and 4 above, a radiologist should check the images before the patient leaves the imaging suite
to assure biliary and gallbladder opacification
*Any dose higher than the above list requires explicit instructions by an Attending
Radiologist and must be documented in ImageCast (RIS).
**Pediatrics – contrast administration must be approved by a radiologist. If approved,
the contrast dose is based on weight at 0.1 mmol/kg.
Dosing for all Pediatric exams will follow Dosing
Chart number 7.
***Exam exceptions to the weight base dosing charts
1. Neuro Dynamic MRA of Arch/Carotids-Vertebrals 35 mL.
2. MR Brain Perfusion exams 30 mL.
3. Sella/pituitary -- weight based dosing up to a maximum dose of 15mL
(150 lbs or 68 kg).
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Steroid pretreatment policy: There is no routine pretreatment of patients with prior reaction to either iodinated or gadolinium contrast agents, since there has been no evidence that this is beneficial. Decisions to pretreat, or not to use contrast agent, may be made on an individual basis. If a prep is administered, it is identical to the prep for iodinated contrast: Medrol 32 mg po (or its equivalent) 12 and 2 hours prior to contrast administration.
MRI is not contraindicated, but... Prudence is urged, although there is no evidence that MRI is harmful to the fetus during any trimester.
Documented benefit. The risk is minimal at most, but the benefit must be finite. Ask: "Would CT be performed if MRI were not available." If "No", MRI should not be performed.
Only essential sequences should be performed.
Informed consent. Verbal and signed consent should be obtained, and the referring physician must be informed that bioeffects cannot be excluded with certainty. The dictation should mention the informed consent.
Pregnant women who are not being scanned should not enter the magnet room to accompany the patient. The benefit/risk ratio of the medical indication covers the patient, not friends or family.
Do not use gadolinium unless essential for diagnosis and management. Although there is no documented harm, it is known that gadolinium crosses the placenta into the amniotic fluid and is then swallowed and urinated back into the amniotic fluid. It's stability during this path, and the half life in the fetus, have not been determined.
1. Shellock FG. Pocket Guide to MR Procedures and Metallic Objects. Lippincott Williams & Wilkins.
2. Shellock FG. Reference Manual for Magnetic Resonance Safety: Amirys, Inc.