Understanding the Importance of MRI Exams

Pregnant patients

It is advisable to avoid doing examination by MRI in the first trimester unless you have justification by the benefit balance risk.However, it is not prudent clinically.

Lactating mothers

Excretion of even one Gadolinium-based agent into breast milk is always minimal, and therefore they are always avoided on the prudence grounds. Therefore, the gadolium is not indicated totally, and breast milk doesn’t need to be discarded. After gadolinium injection, ceasing of breast feeding should be temporary as an added minimal value precaution.

A discussion should be done with the patient about the matter for her to make a choice that is informed. It is advisable to have a record of it in an informed consent document which is formal.

Warning of patient

IMMEDIATELY warn the patient to make a report of any warmth sensation.

K.2 Precautions of Cable

• Remove all conductors that are unnecessary from the bore

• Check lead condition before scan
• Keep cable off the patient where possible the fiber optic cables pads
• In necessary conductors, avoid loops especially large, with no leads that are crossing or diagonal.
• Check conductors or cables lying on unconscious patients regularly for heating evidence.

K.3 Padding and positioning for patient

• Instruction must be given to the patients not to cross their legs or to clasp their hands in the bore of the magnet
• Pads lying between patients arms and body, thighs and the ankles, and between other tissues that can potentially fold the skin (appose) may decrease the risk of burn
• Pads lying between magnet bore and the body may particularly be of great importance at fields of high. (Look at the recommendations of the manufacturer).
• Conductors that are necessary should be possibly be padded, and coiled (wet cloth);they must lie centrally in magnetic bore and parallel to the z axis
• Patients, particularly the unconscious ones must be under monitoring for any signs of more heat around the conductors around.

K.4 Metal Skin Precautions

Possible staples of the skin heating, eye shadow and also some tattoos containing iron oxide warning should be given to the patient. If needed, pads for cooling can be used in the areas relevant.

• Anecdotal reports exist of bleeding of tattoo dye linked to performed scans within a period of 48 hours of injection of ink of tattoo.

K.5 Internal metal precautions

• All patient reported of internal metals, specifically imaging by clinicians must be identified (where relevant the serial no/model/make).
• If conductive inserts, risk benefit assessments are required to be placed on the RF field(some Foley catheters, Swan-Ganz catheters with electrical leads etc)
• Non ferromagnetic prostheses that are large may undergo heating
• Before marketing, testing of endo-coils should be done.

K.6 RF Delivery Patches for Heating- Drug

health to ensure the safety of prescribed drugs. This paper discuss the recall of tetrazepam Drug delivery patches put cutaneously and has metal mesh that is conductive. It is appropriate clinically those patches that contain metals during the scan should be removed, after consulting a doctor who prescribed it, and replacement of the patches done following the scan.

K.7 RF Heating-SAR

At low field it is less likelihood of becoming an issue.

K.7 (a) Environmental Conditions Influence

The criteria for regulation make an assumption of 24^oC room temperature and <60% humidity monitor system of SAR may not make a correction for the differences from those values (look the instruction of the manufacturer).

K.7 (b) Greater Risks Patients

Make a consideration of monitoring the temperature, heat rate and blood pressure, and restricting operations of system of MRI to uncontrolled/normal conditions, or temperatures restricted rises to less than 0.5^oC. Those who are at a greater risk of thermo- stress are:

• The patients on medications such as calcium blockers, beta blockers, diuretics and vasodilators
• The patients with retained wires and others with large implants of non-ferromagnetic.

Hearing protection

The fetus potential risk in utero hearing, thus it is a recommendation that exposure to noise to be minimized to the pregnant patients.

Kidney disease risk factors

All the patients whom an application of MRI contrast agent that is gadolinium based is being considered should be screened for the kidney disease presence. The screening includes available records reviewing and questioning the patient. (Acquaintances or relatives in cases where the patient is unable to appropriately respond).the indicators to be sought that are relevant include:

• Previous laboratory tests (eGFR, serum creatinine, GFR)
• Known kidney disease or dialysis history
• Known history of the family in renal disease
• Age above 60 years
• Torres Strait Islander or Aboriginal (ATSI) ethnicity
• Diabetes history
• Vascular disease history- previous stroke or AMI
• Hypertension
• Smoking history
• BMI>30

 Reliability of eGFR Measurements

In scenarios where eGFR is a marker of GFR that is unreliable include AKI (Acute Kidney Injury) (Note that the serum creatinine cannot become stable up to 7-10 days following an insult that is acute). Peri-operative liver transplant patients,  hepato-renal syndrome patients, and chronic liver disease patients where eGFR may sometimes overestimate the true GFR. The patients are at high NSF risk, but the risk size remain quantified poorly at the moment

Contrast agent safety

The ACR approves the material that is contrasted injection or radiopharmaceuticals diagnostic level by licensed or the radiologic technologists that is certified and certified nurse under the instruction of a radiologist or a designee physician of him or her, who is immediately or personally available, if the practice complies with the state or regulations of the institution. There must also be an approval which is written before by the director of the medical radiology services or the department of such kind of individuals.

H.4 Sedation

• Groups at risk (Main diseases of the organs, children, the previous adverse reaction, allergies, medications, diabetes, liver diseases, cardiac and respirator) need special considerations and may need supervision of an anesthetic.
• Preparation of the patient-provide information that is appropriate
• Patient to have fasted for 6 hours from solid and from liquid 2 hours.
• The sites should give definition to the standard sedative regime of doses agents that are appropriate
• Administration of sedation supervision, and sequential monitoring of the patient sedated must be done by personnel appropriately and well trained (observe RANZCR Standards section T.6.1, ref. 5)

H.5 Anesthesia Generally

Look at RANZCR Accreditation Standard T.6.2 (ref.5). Area of preparation should if possible out of zone 3. There must be some precautions, if not, to minimize objects being taken inadvertently into zone 4.

ACR sedation and monitoring issues

The guidelines need the following provisions:

1. Pre procedural each patient examination and medical history
2. Fating guidelines that are suitable for age
3. Training uniformly and sedation providers with credentials
4. Post procedural and an intra procedural monitors that has appropriate sized adaptors for the children (compatibility with the magnetic field).
5. Method of observing the patient (Camera, window)
6. Equipment for resuscitation, including oxygen suction and delivery
7. Uniform charting system and record keeping (With assessment that is continuous and vital signs recordings.)
8. Protocol and location for discharge and recovery
9. Program of quality assurance that follows morbidity and complications

F.1 documentation of presence of foreign body/implant

In situations where history portrays any presence doubt as to the potential significant foreign body or an implant, these are recommended:

• Look for a documentation that is written (product ID form, notes of operation) of implant nature and any performed pre plant testing at the site of implanting.
• If any documentation that is written cannot be gotten, former imaging of implant made after will at least make a confirmation or make an exclusion of the metallic implant presence (to identify it specificallyis unlikely).
• If the entire above are not available, limited radiography that is appropriate (sometimes CT) of anatomical sites that are relevant should be asked. However, this will rarely identify specifically any detected implant

F.2 documentation of MR compatibility status of foreign body/implant

MR safe: Has no hazard that is known in all the environments of MR

MR conditional: its demonstration shows to no hazard known in the MR environment specified with conditions of use. Conditions of the field that give a definition to the MR environment that is specified include spatial gradient, , dB/dt(change of the magnetic field time rate) radio frequency (RF) fields, field strength and specific absorption rate (SAR).Other added conditions including the items configurations that is specific, may be needed.

MR unsafe: Has no hazards in all the environments of MR

NB.

Status of compatibility on conditions tested is contingent, including shielding, strength of field, and relative position to the magnetic bore, slew rate and gradient strength. May require re-test if modification is done in any of these. High fields strengths may be linked forms of hazards (e.g. moving conductors displacement because of the Lenz effect), that at fields up to 1.5 T are not appreciable. Thus, for the implant to undergo scanning at the high strength of the fields, must have been tested formerly at such strengths of the fields. Status of compatibility should be written down.

Information of the product: the requirements of US FDA is that all marketed implants for use in the US by human use to have available information for MR safety. There exists a possibility of the same requirements in future in Australia medium term.

Objects lacking written documentation on their MR status of compatibility in terms of the definitions that are current of ASTM should be unsafe by presumption, particularly if it has a metallic component that is obvious.

1. handheld screening magnet >(0.1T) for testing metal objects

• Optional
• Make sure that the objects will not be rendered/damaged broken down by magnet, for instance pacemakers.
• Use only as adjunct, known of low sensitivity

2. The Metal Detector

• It is optional
• Application that is limited as supplementary pacemakers screens, and other gross metals
• Be aware, if used, of the adverse potential effects of detector of electronic implants
• Device low sensitivity for small but significant foreign bodies that are metallic (e.g. clips of aneurysm)
• Being unable to distinguish between paramagnetic and ferromagnetic objects, resulting to false positive screens of high level.

F.Time-Varying Magnetic Field Gradient Induced Voltages Related Issues

Patients’ types that need more caution:

Patients possessing retained or implanted wires within functionally or anatomically areas that are sensitive such as the epicedium or myocardium, electrodes implanted in the brain should be given a consideration as of risks that are higher, from sequences that are faster of MRI, like the imaging of echo-planar (that may be used in such sequences like weighted diffusion imaging, perfusion-weighted imaging, functional imaging, and imaging of MR angiographic among others).

The decision of limiting the dB/dt (change rate of magnetic field) and the magnetic maximum gradient strength subsystems when imaging such should be reviewed by MR personnel of level 2 designated and in attendance, a supervising radiologist of the patient or case.

Implant

The final decision of whether to do or not scanning on any patient with implant or foreign body, is decided by designated MR personnel of level 2 and in attendance MR radiologist, and the medical director of the MR, or specifically designated MR personnel of level 2 after criteria of acceptability that has been predetermined by the director of medical.

Pre-screening of the patients

• It is a requirement of the referrers to make a confirmation that no major contraindications of the MRI are present, ether by the specific use of request form of MRI, or by a generic form direct statement on of request.
• A specific request form of MRI listing the contra indications that are major will assist in facilitation of this
• All previous imaging is highly desirable to be available prior to examination

Structure

It is recommended that 3 safety screening to be done, with a minimum of two occurring at the site

• using referral form on booking acceptance-clerical
• On patient arrival using screening sheet -MR personnel,
• Immediately before patient enters the room for examination, MR personnel. Appropriate emphasis on the verbal to the understanding level of the patient should be put on the correct responses to the questions importance

Other people apart from the patients

• Companions of the patients
• Service person on the site including cleaners, security, policemen, fire
• Research subjects/volunteers

Any person with an intention of going to zone IV must be fully screened by personnel of MR. If there is the necessity of orbit radiography for a person apart from the patient, informed consent may be required for this. Anyone with an intention of going into zone III must be thoroughly screened at least for cardiac pacemaker. If the person is not thoroughly screened for any foreign bodies that are metallic, precautions should be laid to make sure the person does not go towards level of zone IV/ the controlled entrance areas of second level.

The staff of MRI should be screened annually t minimum with their records filed and retained Personnel of MRI must report any event or procedure where electronically activated device or ferromagnetic object must have been implanted within them soon as is practicable.

Screening information sought

• Verification of the ID of the patient, check weight
• Checklist:pacemakers ad clips, foreign bodies and metallic implants: the list now items more than thirty; (Examples can be found from ref 2and MRIsafety.com) renal disease,hypertension,diabetes,asthma,allergies,medication,seizures,breast feeding, pregnancy
• Preparation of the checklist should be done with comprehensiveness and on possibility of decreased compliance with extra long questionnaires
• Checklists to be reviewed with the patient by senior personnel of MR

Recommended procedure

• Utilize information from the carers/guardians, breast cancer. Ann has been a staunch Christian since childhood just like the rest of her family
• Perform physical examination that targets the implants
• Obtain SXR,CXR (or CT chest/head) if not already available
• Obtain other radiographs or examinations of CT that are appropriate to the clinical history and the findings of physical examination.

3. Personnel of Non-MR and patient screening

• All personnel that are non-MR desiring to go into zone III must first pass the process of safety screening of MR. Only personnel of MR are given authority to perform MR safety screening before allowing personnel that are non-MR into zone III
• The forms for screening forms and process of screening patients, personnel for MR and personnel for non-MR should be identical essentially. Particularly, one should make an assumption that non-MR personnel, MR personnel and practitioners of health care may enter MR imager bore during the process of MR imaging

NSF

Nephrogenic systemic fibrosis (NSF) is uncommon condition relatively in which plaques that are fibrous often grow in the dermis, especially in connective tissues that are deeper. Cases that are reported have almost occurred to patients exclusively with severe disease of the renal, almost all have been linked to with prior gadolium-containing agents for contrast of MRI use. The disease is always disabling, with no existing proven treatments, and may contribute to the demise of the patient.

Herman Bailey

With a student-centered approach, I create engaging and informative blog posts that tackle relevant topics for students. My content aims to equip students with the knowledge and tools they need to succeed academically and beyond.