SCREENING PATIENTS FOR MR PROCEDURES AND
INDIVIDUALS FOR THE MR ENVIRONMENT
Frank G. Shellock, Ph.D.
Institute for Magnetic Resonance
Safety, Education, and Research
Article excerpted from
DiagnosticImaging.com with permission of Frank G. Shellock, Ph.D.
The establishment of thorough and effective screening
procedures for patients and other individuals is one of the most critical
components of a program that guards the safety of all those preparing to
undergo MR procedures or to enter the MR environment. An important aspect of
protecting patients and individuals from MR system-related accidents and
injuries involves an understanding of the risks associated with the various
implants, devices, accessories, and other objects that may cause problems in this
setting. This requires constant attention and diligence to obtain information
and documentation about these objects in order to provide the safest MR setting
possible. In addition, because most MR-related incidents have been due to
deficiencies in screening methods and/or a lack of properly controlling access
to the MR environment (especially with regard to preventing personal items and
other potentially problematic objects into the MR system room), it is crucial
to set up procedures and guidelines to prevent such incidents from occurring.
Magnetic Resonance (MR) Procedure
Screening for Patients
Certain
aspects of screening patients for MR procedures may take place during the
scheduling process. This should be conducted by a healthcare worker that is
specially trained in MR safety (i.e., this person should be trained to
understand the potential hazards and issues associated with the MR environment
and MR procedures and be familiar with all of the information contained on the
screening forms for patients and individuals). During this time, it may be
ascertained if the patient has any implant that may be contraindicated for the
MR procedure (e.g., a ferromagnetic aneurysm clip, pacemaker, etc.) or if there
is any condition that needs careful consideration (e.g., the patient is
pregnant, has a disability, etc.). Preliminary screening helps to prevent
scheduling patients that may be inappropriate candidates for MR examinations.
After preliminary screening, every patient must undergo
comprehensive screening in preparation for a magnetic resonance (MR) procedure
(i.e., MR imaging, MR angiography, functional MRI, MR spectroscopy).
Comprehensive patient screening involves the use of a printed form to document
the screening procedure, a review of the information on the screening form, and
a verbal interview to verify the information on the form and to allow
discussion of any question or concern that the patient may have. An MR-safety
trained healthcare worker must conduct this aspect of patient screening.
A screening form for patients developed by Sawyer-Glover
and Shellock (2000) was recently revised in consideration of new information in
the peer-reviewed literature. This two-page form entitled, Magnetic Resonance (MR) Procedure
Screening Form for Patients (Table 1), was also created in conjunction with the
Medical, Scientific, and Technology Advisory Board and the Corporate Advisory
Board of the Institute for Magnetic Resonance Safety, Education, and Research
(IMRSER).
Page one of this
screening form requests general patient-related information (name, age, sex,
height, weight, etc.) as well as information regarding the reason for the MR
procedure and/or symptoms that may be present. Pertinent information about the
patient is required not only to ensure that the medical records are up-to-date,
but also in the event that the MR facility needs to contact the referring
physician for additional information regarding the examination or to verify the
patient’s medical condition.
The form
requests information regarding a prior surgery or operation to help determine
if there may be an implant or device present that could create a problem for
the patient. Information is also requested pertaining to prior diagnostic
imaging studies that may be helpful to review for assessment of the patient’s
condition.
Next, important
questions are posed in an effort to determine if there are possible problems or
issues that should be discussed with the patient prior to permitting entry to
the MR environment. For example, information is requested regarding any problem
with a previous MR examination, an injury to the eye involving a metallic
object, or any injury from a metallic object or foreign body. Questions are
posed to obtain information about current or recently taken medications as well
as the presence of drug allergies. There are also questions asked to assess
past and present medical conditions that may affect the MR procedure or the use
of an MRI contrast agent in the patient.
At the
bottom of page one, there is a section for female patients that poses questions
that may impact MR procedures. For example, questions regarding the date of the
last menstrual period, pregnancy or late menstrual period are included. A
definite or possible pregnancy must be identified prior to permitting the
patient into the MR environment so that the risks vs. the benefits of the MR
procedure can be considered and discussed with the patient. MR procedures
should only be performed in pregnant patients to address important clinical
questions. MR facilities should have a clearly defined procedure to follow in
the event that the patient has a confirmed or possible pregnancy.
Questions
pertaining to the date of the last menstrual period, use of oral contraceptives
or hormonal therapy, and fertility medication are necessary for female patients
undergoing MR procedures that are performed to evaluate breast disease or for
OB/GYN applications, as these may alter the tissue appearance on MR imaging. An
inquiry about breastfeeding is included in case the administration of MRI
contrast media is being considered for nursing mothers.
The second
page of the form has a statement at the top that indicates: “WARNING: Certain implants,
devices, or objects may be hazardous to you and/or may interfere with the MR
procedure (i.e., MRI, MR angiography, functional MRI, MR spectroscopy). Do
not enter the MR system room or MR environment if you have any question or
concern regarding an implant, device, or object. Consult the MRI Technologist
or Radiologist BEFORE entering the MR system room. The MR system magnet is
ALWAYS on.”
Next,
there is a section that lists various implants, devices, and objects to
identify anything that could be hazardous to the patient undergoing the MR
procedure or that may produce an artifact that could interfere with the
interpretation of the MR procedure. In general, these items are arranged on the
checklist in order of the relative safety hazard (e.g., aneurysm clip, cardiac
pacemaker, implantable cardioverter defibrillator, electronic implant, etc.), followed
by items that may simply produce imaging artifacts that could be problematic
for the interpretation of the MR procedure. Additionally, questions are posed
to determine if the patient has a breathing problem, movement disorder, or
claustrophobia because these are known to present difficulties for MR
procedures.
Figures of the human body are included on the second page of the screening form
for the patient as a means of showing the location of any object inside of or
on the body. This information is particularly useful so that the patient may
indicate the approximate position of any object that may be hazardous or that
could interfere with the interpretation of the MR procedure as a result of
producing an artifact.
Page 2 of the screening form also has an Important
Instructions section that states: “Before entering the MR environment or MR
system room, you must remove all metallic objects including hearing
aids, dentures, partial plates, keys, beeper, cell phone, eyeglasses, hair
pins, barrettes, jewelry, body piercing jewelry, watch, safety pins,
paperclips, money clip, credit cards, bank cards, magnetic strip cards, coins,
pens, pocket knife, nail clipper, tools, clothing with metal fasteners, &
clothing with metallic threads. Please consult the MRI
Technologist or Radiologist if you have any [DJT1] question
or concern BEFORE you enter the MR system room.”
Finally, there is a statement on the Magnetic
Resonance (MR) Procedure Screening Form for Patients that indicates hearing
protection is “advised or required” to prevent possible problems or hazards
related to acoustic noise. In general, this should not be an option for a
patient undergoing an MR procedure on a high-field-strength MR system. By
comparison, it may not be necessary for the use of hearing protection by
patients undergoing MR procedures on low-field-strength MR systems.
It should be noted that undergoing previous MR procedures
without incidents does not guarantee a safe subsequent MR examination. Various
factors (e.g., the static magnetic field strength of the MR system, the
orientation of the patient, the orientation of a metallic implant or object,
etc.) can substantially change the scenario. Thus, a written screening form
must be completed each time a patient prepares to undergo an MR procedure. This
is not an inconsequential matter because a surgical intervention or accident
involving a metallic foreign body may have occurred that could impact the
safety an MR procedure or of entering the MR environment.
With the
use of any type of written questionnaire, limitations exist related to
incomplete or incorrect answers provided by the patient. For example, there may
be difficulties associated with patients that are impaired with respect to
their vision, language fluency, or level of literacy. Therefore, an appropriate
accompanying family member or other individual (e.g., referring physician)
should be involved in the screening process to verify any information that may
impact patient safety. Versions of this form should also be available in other
languages, as needed (i.e., specific to the demographics of the MR facility).
In the event that the patient is comatose or unable to communicate, the written
screening form should be completed by the most qualified individual (e.g.,
physician, family member, etc.) that has knowledge about the patient’s medical
history and present condition. If the screening information is inadequate, it
is advisable to look for surgical scars on the patient and/or to obtain plain
films of the skull and/or chest to search for implants that are known to be
particularly hazardous in the MR environment (e.g., aneurysm clips, cardiac
pacemakers, etc.).
Following completion of the Magnetic
Resonance (MR) Procedure Screening Form for Patients, an MR-safety trained
healthcare worker should review the form’s content. Next, a verbal interview
should be conducted by the MR-safety trained healthcare worker to verify the
information on the form and to allow discussion of any question or concern that
the patient may have before undergoing the MR procedure. This allows a
mechanism for clarification or confirmation of the answers to the questions
posed to the patient so that there is no miscommunication regarding important
MR safety issues. In addition, because the patient may not be fully aware of
the medical terminology used for a particular implant or device, it is
imperative that this particular information on the form be discussed during the
verbal interview.
After the comprehensive screening procedure is completed,
any patient that is transferred by a stretcher, gurney, or wheelchair to the MR
system room should be checked thoroughly and systematically for metal objects
under the sheets or blankets such as ferromagnetic oxygen tanks, monitors, or
other objects that could pose a hazard.
Magnetic Resonance (MR) Environment
Screening for Individuals
Before any “non-patient”
individual (e.g., MRI technologist, MR support person, patients, family member,
visitor, allied health professional, physician, maintenance worker, custodial
worker, fire fighter, security officer, etc.) is allowed into the MR
environment, he or she must be screened by a MR-safety trained healthcare
worker. Proper screening for individuals involves the use of a printed form to
document the screening procedure, a review of the information on the form, and
a verbal interview to verify the information on the form and to allow
discussion of any question or concern that the individual may have before
permitting entry to the MR environment.
In
general, magnetic resonance (MR) screening forms were developed with patients
in mind and, therefore, pose many questions that are inappropriate or confusing
to other individuals that may need to enter the MR environment. Therefore, a
screening form was recently created specifically for individuals that need to
enter the MR environment and/or MR system room. This form, entitled, Magnetic Resonance (MR) Environment
Screening Form for Individuals (Table 2), was developed in conjunction with
the Medical, Scientific, and Technology Advisory Board and the Corporate
Advisory Board of the Institute for Magnetic Resonance Safety, Education, and
Research (IMRSER).
At the top
of this form, the following statement is displayed: “The MR system has a very strong magnetic field that may be hazardous
to individuals entering the MR environment or MR system room if they have
certain metallic, electronic, magnetic, or mechanical implants, devices, or
objects. Therefore, all
individuals are required to fill out this form BEFORE entering the MR environment
or MR system room. Be advised, the MR system magnet is ALWAYS on.”
The Magnetic Resonance (MR) Environment
Screening Form for Individuals requests general information (name, age,
address, etc.) and poses important questions to determine if there are possible
problems or issues that should be discussed with the individual prior to
permitting entry to the MR environment. A warning statement is also provided on
the form, as follows: “WARNING: Certain
implants, devices, or objects may be hazardous to you in the MR environment or
MR system room. Do not enter the MR environment or MR system room if you
have any question or concern regarding an implant, device, or object.”
In addition, there is a section that lists various implants, devices, and
objects to identify the presence of anything that could be hazardous to an
individual in the MR environment (e.g., an aneurysm clip, cardiac pacemaker,
implantable cardioverter defibrillator (ICD), electronic or magnetically
activated device, metallic foreign body, etc).
Finally,
there is an Important Instructions
section on the form that states: Remove all
metallic objects before entering the MR environment or MR system room including
hearing aids, beeper, cell phone, keys, eyeglasses, hair pins, barrettes, jewelry
(including body piercing jewelry), watch, safety pins, paperclips, money clip,
credit cards, bank cards, magnetic strip cards, coins, pens, pocket knife, nail
clipper, steel-toed boots/shoes, and tools. Loose metallic objects are
especially prohibited in the MR system room and MR environment. Please consult
the MRI Technologist or Radiologist if you have any question
or concern BEFORE you enter the MR system room.
The proper
use of this written form along with thorough verbal screening of the individual
by an MR-safety trained healthcare worker should prevent accidents and injuries
in the MR environment.
[Portions of this text were adapted with permission from
Sawyer-Glover A, Shellock FG. Pre-Magnetic Resonance Procedure Screening, In:
Magnetic Resonance Procedures: Health Effects and Safety, FG Shellock, Editor,
CRC Press, LLC, Boca Raton, FL, 2001. The screening forms, Magnetic Resonance (MR) Procedure Screening Form For Patients and Magnetic Resonance (MR) Environment
Screening Form for Individuals were developed in conjunction with the
Medical, Scientific, and
Technology
Advisory Board and the Corporate Advisory Board of the Institute for Magnetic
Resonance Safety, Education, and Research (IMRSER), 2002.]
Pertinent References
http://www.MRIsafety.com
http://www.IMRSER.org
Kanal E, Borgstede JP, Barkovich AJ, Bell C, et al. American College of
Radiology White Paper on MR Safety. American Journal of Roentgenology
2002;178:1335-1347.
Sawyer-Glover A, Shellock
FG. Pre-Magnetic Resonance Procedure Screening, In: Magnetic Resonance Procedures: Health Effects and Safety, FG Shellock, Editor, CRC Press, LLC,
Boca Raton, FL, 2001.
Sawyer-Glover A, Shellock
FG. Pre-MRI procedure screening: recommendations and safety considerations for
biomedical implants and devices. J Magn Reson Imaging 2000;12: 92-106.
Shellock FG. Reference Manual for Magnetic Resonance Safety: 2002 Edition.
Amirsys, Salt Lake City, Utah, 2002.
Shellock FG. New recommendations for screening patients for suspected orbital foreign bodies.
Signals, No. 36, Issue 4, 2001, pp. 8-9,
Shellock FG. Biomedical implants and devices: assessment of
magnetic field interactions with a 3.0-Tesla MR system. J Magn Reson Imaging
(in press).
Shellock FG. MR safety update 2002: Implants and devices. J Magn Reson Imaging (in
press)
Shellock FG, Crues JV. Commentary. MR safety and the American College of
Radiology White Paper. American Journal of Roentgenology 2002;178:1349-1352.
Shellock FG, Kanal E. Policies, guidelines, and
recommendations for MR imaging safety and patient management. J Magn Reson
Imaging 1991;1:97-101.
Shellock FG, Kanal E. SMRI Report. Policies, guidelines and recommendations for MR imaging
safety and patient management. Questionnaire for screening patients before MR
procedures. J Magn Reson Imaging 1994;4:749-751, 1994.
Shellock FG, Kanal E. Policies,
guidelines, and recommendations for MR imaging safety and patient management. J
Magn Reson Imaging 1991;1: 97-101.
Shellock
FG, Kanal E. Magnetic Resonance: Bioeffects, Safety, and Patient Management.
Second Edition, Lippincott-Raven Press, New York, 1996.