ASTM F2119-01

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Designation:F2119–01
Standard Test Method for
Evaluation of MR Image Artifacts from Passive Implants
This standard is issued under the fixed designation F 2119; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.1.7 tesla(T),n—theSIunitofmagneticinductionequalto
10 G.
1.1 This test method characterizes the distortion and signal
loss artifacts produced in a magnetic resonance (MR) image by
3. Summary of Test Method
a passive implant (implant that functions without the supply of
3.1 Pairs of spin echo images are generated both with and
electrical or external power). Anything not established to be
without the implant in the field of view. Image artifacts are
MR-safe is excluded.
assessed by computing differences outside the region corre-
2. Terminology spondingtotheimplantbetweenreferenceandimplantimages.
Once the worst case conditions using the spin echo pulse
2.1 Definitions
sequence are ascertained, a pair of gradient echo images are
2.1.1 artifact width, n—the maximum distance (mm) from
acquired under the same conditions.
the edge of the implant to the fringe of the resulting image
artifactfoundintheentiresetofimagesacquiredusingthistest
4. Significance and Use
method.
4.1 This test method may be used to evaluate degree of MR
2.1.2 image artifact, n—a pixel in an image is considered to
compatibility for passive implants by providing a quantified
be part of an image artifact if the intensity is changed by at
measure of the image artifact produced under a standard set of
least 30 % when the device is present compared to a reference
scanning conditions.
image in which the device is absent.
4.2 This test method applies only to passive implants that
2.1.3 magnetic resonance (MR) environment, n—refers to
have been established to be MR-safe.
the electromagnetic environment present in the vicinity of an
MR system within the 5-G line.
5. Apparatus
2.1.4 magnetic resonance imaging (MRI), n—imaging tech-
5.1 AnMRimagingsystemwithastaticfieldstrengthof1.5
nique that uses static and time varying magnetic fields to
T is recommended. Alternatively, a different static field
provide images of tissue by the magnetic resonance of nuclei.
strength may be used and the measurements may be extrapo-
2.1.5 MR-safe, adj—the device, when used in the MR
lated to what would occur in a 1.5 T system, if a valid
environment, has been demonstrated to present no additional
extrapolationmethodisknown.TheMRIsystemmusthavethe
risk to the patient or other individuals, but may affect the
ability to swap readout and phase-encode directions.
quality of the diagnostic information. The MR conditions in
5.2 A reference object made from a nondistorting medium,
which the device was tested should be specified in conjunction
such as 0.5-in. diameter nylon rod.
with the term MR safe since a device which is safe under one
setofconditionsmaynotbefoundtobesoundermoreextreme
6. Test Specimen
MR conditions.
6.1 The implant for which image artifact is to be measured
2.1.6 MR-compatible, adj—the device, when used in the
shall serve as the test specimen.
MR environment, is MR-safe and has been demonstrated to
6.2 For the purposes of device qualification, the device
neither significantly affect the quality of the diagnostic infor-
evaluated according to this test method should be a finished
mation nor have its operations affected by the MR device. The
sterilized device.
MR conditions in which the device was tested should be
specified in conjunction with the term MR-compatible since a NOTE 1—The device does not have to be sterile at the time of testing;
however, it should have been subjected to all processing, packaging, and
devicewhichiscompatibleunderonesetofconditionsmaynot
sterilization steps before testing because any of these steps may affect the
be found to be so under more extreme MR conditions.
magnetic properties of the device.
6.3 This test method may be used on prototype devices at
This test method is under the jurisdiction ofASTM Committee F04 on Medical
any stage of production during product development. A justi-
and Surgical Materials and Devices and is the direct responsibility of subcommittee
fication for using a prototype instead of the finished device
F04.15 on Material Test Methods.
must be provided.
Current edition approved June 10, 2001. Published September 2001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2119–01
7. Procedure 7.2.3 For images containing both the device being tested
and the reference object, for each orientation two sets of
7.1 MR Imaging Parameters for Testing Artifacts:
images must be acquired using both possibilities for designa-
7.1.1 The recommended MR imaging test environment for
tion of readout and phase-encode directions. For images
evaluation of artifacts are given as follows.An alternative may
containing the reference object only, one image is acquired
be used if an adequate case can be made for relevance to the
using either possibility for designation of readout and phase-
specific device. Field of view, slice thickness, and matrix size
encode direction. The reference object is oriented along the
shall be adjusted to achieve pixel dimensions to accurately
right-left axis so that it extends beyond the length of the device
measuretheartifact.Twoexamplesituationsaredescribed,one
being tested so that the reference object will appear in each
for small implants, such as a coronary stent, and one for larger
image containing the tested device.
implants such as an artificial hip joint.
7.2.4 For each image pair and each orientation and each
Static field strength: 1.5T (see 5.1)
readout/phase-encode direction designation, a sufficient num-
Bandwidth: 32 kHz (required)
ber of contiguous slices to span the entire device must be
Field of view: sufficient to encompass the entire implant
and the artifact acquired. So, for example, a device that is completely con-
tained within one slice will require three orientations times two
Small implant (for example, coronary stent):
readout/phase-encode designations = six images containing the
Matrix size: 256 3 256
device being tested + three images containing the reference
Slice thickness: 3 mm
object only.
Large implant (for example, hip implant):
7.2.5 For the worst case (largest artifact size) set of condi-
Matrix size: 256 3 128
tions (orientation, readout/phase-encode designation, and slice
Slice thickness: 5 mm
number) from the set of spin echo images, an image pair (see
Two different pulse sequences will be used:
7.2.2) using the gradient echo pulse sequence must be ac-
Pulse sequence: spin echo quired. It is probably most time efficient to acquire these
TR: 500 ms
images while the object is in position for acquiring the spin
TE: 20 ms
echo images.
Pulse sequence: gradient echo 7.3 Measurement of Artifact Size
TR: 100 − 500 ms
7.3.1 The distance (in mm) from the device boundary to the
TE: 15 ms
fringe of the artifact (630 % zone, see 2.1.2) should be
Flip angle: 30°
measured. To compute the distance in mm, take the distance in
7.1.2 The device should be immersed in a solution. For
pixels and multiply by the ratio of the field of view (FOV)
example, a CuSO solution (1–2 g/L) may be used to reduceT
4 1 expressed in mm to the matrix dim
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