1、Designation: F2119 07 (Reapproved 2013)Standard Test Method forEvaluation of MR Image Artifacts from Passive Implants1This standard is issued under the fixed designation F2119; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method characterizes the distortion and signalloss artifacts produced in a magnetic resonance (MR) ima
3、ge bya passive implant (implant that functions without the supply ofelectrical or external power). Anything not established to beMR-Safe or MR-Conditional is excluded.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.2. Refere
4、nced Documents2.1 ASTM Standards:2F2052 Test Method for Measurement of Magnetically In-duced Displacement Force on Medical Devices in theMagnetic Resonance EnvironmentF2182 Test Method for Measurement of Radio FrequencyInduced Heating On or Near Passive Implants DuringMagnetic Resonance ImagingF2213
5、 Test Method for Measurement of Magnetically In-duced Torque on Medical Devices in the Magnetic Reso-nance EnvironmentF2503 Practice for Marking Medical Devices and OtherItems for Safety in the Magnetic Resonance Environment3. Terminology3.1 Definitions:3.1.1 artifact width, nthe maximum distance (m
6、m) fromthe edge of the implant to the fringe of the resulting imageartifact found in the entire set of images acquired using this testmethod.3.1.2 image artifact, na pixel in an image is considered tobe part of an image artifact if the intensity is changed by atleast 30 % when the device is present
7、compared to a referenceimage in which the device is absent.3.1.3 magnetic resonance (MR) environment, nvolumewithin the 0.50 mT (5 gauss (G) line of an MR system, whichincludes the entire three dimensional volume of space sur-rounding the MR scanner. For cases where the 0.50 mT line iscontained with
8、in the Faraday shielded volume, the entire roomshall be considered the MR environment.3.1.4 magnetic resonance imaging (MRI), nimaging tech-nique that uses static and time varying magnetic fields toprovide images of tissue by the magnetic resonance of nuclei.3.1.5 MR-Conditional, adjan item that has
9、 been demon-strated to pose no known hazards in a specified MR environ-ment with specified conditions of use. Field conditions thatdefine the specified MR environment include field strength,spatial gradient, dB/dt (time rate of change of the magneticfield), radio frequency (RF) fields, and specific
10、absorption rate(SAR).Additional conditions, including specific configurationsof the item, may be required.3.1.6 MR-Safe, adjan item that poses no known hazards inall MR environments.NOTE 1MR-Safe items include nonconducting, nonmagnetic itemssuch as a plastic petri dish.An item may be determined to
11、be MR-Safe byproviding a scientifically based rationale rather than test data.3.1.7 MR-Unsafe, adjan item that is known to posehazards in all MR environments.NOTE 2MR-Unsafe items include magnetic items such as a pair offerromagnetic scissors.3.1.8 tesla (T), nthe SI unit of magnetic induction equal
12、 to104G.4. Summary of Test Method4.1 Pairs of spin echo images are generated both with andwithout the implant in the field of view. Image artifacts areassessed by computing differences outside the region corre-sponding to the implant between reference and implant images.Once the worst case condition
13、s using the spin echo pulsesequence are ascertained, a pair of gradient echo images areacquired under the same conditions.5. Significance and Use5.1 This test method provides a quantified measure of theimage artifact produced under a standard set of scanningconditions.1This test method is under the
14、jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved March 1, 2013. Published March 2013. Originallyapproved in 2001. Last previous edition approved in 2007 as F2119 07.
15、 DOI:10.1520/F2119-07R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Ba
16、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 This test method applies only to passive implants thathave been established to be MR-Safe or MR-Conditional.6. Apparatus6.1 An MR imaging system with a static field strength of 1.5T or 3.0 T is recommended. The MRI sys
17、tem must have theability to swap readout and phase-encode directions.6.2 A reference object made from a nondistorting medium,such as 0.5-in. diameter nylon rod.7. Test Specimen7.1 The implant for which image artifact is to be measuredshall serve as the test specimen.7.2 For the purposes of device qu
18、alification, the deviceevaluated according to this test method should be a finishedsterilized device.NOTE 3The device does not have to be sterile at the time of testing;however, it should have been subjected to all processing, packaging, andsterilization steps before testing because any of these ste
19、ps may affect themagnetic properties of the device.7.3 This test method may be used on prototype devices atany stage of production during product development. A justi-fication for using a prototype instead of the finished devicemust be provided.8. Procedure8.1 MR Imaging Parameters for Testing Artif
20、acts:8.1.1 The recommended MR imaging test environment forevaluation of artifacts are given as follows.An alternative maybe used if an adequate case can be made for relevance to thespecific device. Field of view, slice thickness, and matrix sizeshall be adjusted to achieve pixel dimensions to accura
21、telymeasure the artifact. Two example situations are described, onefor small implants, such as a coronary stent, and one for largerimplants such as an artificial hip joint.Static field strength: 1.5T (see 6.1)Bandwidth: 32 kHz (required)Field of view: sufficient to encompass the entire implantand th
22、e artifactSmall implant (for example, coronary stent):Matrix size: 256 256Slice thickness: 3 mmLarge implant (for example, hip implant):Matrix size: 256 128Slice thickness: 5 mmTwo different pulse sequences will be used:Pulse sequence: spin echoTR: 500 msTE: 20 msPulse sequence: gradient echoTR: 100
23、 500 msTE: 15 msFlip angle: 308.1.2 The device should be immersed in a solution. Forexample, a copper sulfate (CuSO4) solution (12 g/L) may beused to reduce T1and keep TR at a reasonable level. Thedevice may be suspended in nylon netting. If a copper sulfatesolution is inappropriate for a particular
24、 device, a substitutemay be used but a justification must be provided. Nickelchloride (NiCl2) and manganese chloride (MnCl2) are possiblesubstitutes. To achieve adequate field homogeneity, thereshould be at least 4 cm of clearance between the device andeach side of the container holding the solution
25、 and the implant.8.1.3 Each image must contain a reference object, (made ofnylon or some other material, which does not cause distortion),so that the position of the device may be accurately assessed.For example, a section of 0.5-in. diameter nylon rod positionedso that it appears as a circle in the
26、 image could serve as thereference object. Each image must also contain a physical sizescale, generally displayed on MR images, so that distances maybe measured.8.2 Set of Images To Be Acquired:8.2.1 A complete set of spin echo image pairs, as describedin 8.2.2-8.2.4, shall be acquired.8.2.2 An indi
27、vidual test image pair shall consist of an imageof the reference object only, and an image containing both thereference object and the device being tested. The device mustbe tested in three mutually orthogonal orientations relative tothe static field. Orientations for which the implant will not fit
28、inthe bore may be omitted. Cylindrically symmetric devices maybe tested parallel to the static field and in just one directionperpendicular to the static field. Sagittal, relative to static fielddirection, images should be acquired in all cases.8.2.3 For images containing both the device being teste
29、dand the reference object, for each orientation two sets ofimages must be acquired using both possibilities for designa-tion of readout and phase-encode directions. For imagescontaining the reference object only, one image is acquiredusing either possibility for designation of readout and phase-enco
30、de direction. The reference object is oriented along theright-left axis so that it extends beyond the length of the devicebeing tested so that the reference object will appear in eachimage containing the tested device.8.2.4 For each image pair and each orientation and eachreadout/phase-encode direct
31、ion designation, a sufficient num-ber of contiguous slices to span the entire device must beacquired. So, for example, a device that is completely con-tained within one slice will require three orientations times tworeadout/phase-encode designations = six images containing thedevice being tested + t
32、hree images containing the referenceobject only.8.2.5 For the worst case (largest artifact size) set of condi-tions (orientation, readout/phase-encode designation, and slicenumber) from the set of spin echo images, an image pair (see8.2.2) using the gradient echo pulse sequence must be ac-quired. It
33、 is probably most time efficient to acquire theseimages while the object is in position for acquiring the spinecho images.8.3 Measurement of Artifact Size:8.3.1 The distance (in mm) from the device boundary to thefringe of the artifact (630 % zone, see 3.1.2) should bemeasured. To compute the distan
34、ce in mm, take the distance inpixels and multiply by the ratio of the field of view (FOV)expressed in mm to the matrix dimension (m) also measured inmm. Distance (mm) = Distance (pixels) FOV/m. Thisdistance may be evaluated quantitatively at the system consoleF2119 07 (2013)2using software, commonly
35、 included with MRI scanners, to plotintensity profiles. Alternatively, if necessary, the distance maybe evaluated visually at the console or on film but in this casea conservative definition of the artifact fringe location shouldbe adopted to ensure that artifact size is not underestimated.For each
36、image, the artifact must be characterized by the worstcase (maximum) distance as the boundary of the device iscompletely circumscribed. The worst case (maximum) distancefound in the entire set of images acquired (as prescribed above)must be used to characterize the artifact.8.3.2 Difficulty may aris
37、e if the MRI image consists of avoid corresponding to the implant surrounded by a voidcorresponding to the artifact. The boundary of the implant maynot be visible. In this case, the border of the implant, measuredwithout MRI, for example, using a ruler or calipers, may besuperimposed in the center o
38、f the void so that distances fromimplant boundary to the artifact fringe can be measured. Thesuperimposed implant border should be scaled to match theMRI image distance scale.9. Report9.1 The report shall include the following for each specimentested:9.1.1 Device product description.9.1.2 Device pro
39、duct number and lot number.9.1.3 Device size (physical dimensions).9.1.4 The gradient echo image pair and a representative setof spin echo images, including those that exhibit the worstartifacts.9.1.5 MRI system make, model, and static field strength.9.1.6 MRI parameters including TR, TE, bandwidth,
40、receiver, field of view, matrix size, and coil used.9.1.7 The method used for measuring artifact.9.1.8 Spin echo artifact width and gradient echo artifactwidth, (see 3.1.1).9.1.9 Solution (and solution concentration) used to immersethe device. If a CuSO4solution is not used, include ajustification f
41、or the solution used.10. Precision and Bias10.1 The precision and bias of this test method have notbeen established.11. Keywords11.1 image artifact; implant; metals for surgical implants;MRI (magnetic resonance imaging); MR compatibility; MRsafetyAPPENDIX(Nonmandatory Information)X1. RATIONALE FOR D
42、EVELOPMENT OF THE TEST METHODX1.1 This test method characterizes the artifact produced bya passive implant, which has been determined to be MR-Safeor MR-Conditional. Test Methods F2052 and F2213 can beused to determine magnetically induced displacement forceand torque, respectively, on a medical dev
43、ice in the MRenvironment, and Test Method F2182 can be used to measureradio frequency induced heating during MRI. Although acommercial 1.5 T MR system currently produces the condi-tions that are most commonly encountered, 3 T MR systemshave been cleared for market and are becoming more commonin clin
44、ical situations.X1.2 The size of an artifact induced by a passive implant ina given MR environment has a complex relationship to implantsize, shape, and composition. Acceptability of an artifact willdepend on implant type and location in addition to which partof the body is being imaged. The protoco
45、l described in this testmethod provides an objective basis for quantifying the extentof an artifact associated with an implant. This information maybe used to compare potential artifact sizes for many implantsand may be useful for health care professionals in selectingimplants for various applicatio
46、ns.X1.3 For most applications, image artifacts are smaller forfast spin echo pulse sequences than conventional spin echo andgradient echo pulse sequences; however, the combined use ofspin echo and gradient echo pulse sequences in the test methodprovides a valid method for ranking implants with regar
47、d totendency to produce artifacts under controlled conditions.X1.4 This test method was revised in 2007 to reference theMR safety terminology in Practice F2503 and the MR TestMethods F2182, F2213, and F2052. The historical definitionsfor MR safe and MR compatible were removed and thedefinitions of M
48、R-Safe, MR-Conditional, and MR-Unsafewere inserted. The definition for MR environment was revisedto be in agreement with the definitions in Practice F2503.F2119 07 (2013)3BIBLIOGRAPHY(1) Schenck, J. F., “The Role of Magnetic Susceptibility in MagneticResonance Imaging: MRI Magnetic Compatibility of
49、the First andSecond Kinds,” Med. Phys., 23 (6), June 1996, pp. 815850.(2) Shellock, F. G., and Kanal E., Magnetic Resonance: Bioeffects,Safety, and Patient Management, Second edition, Lippincott -Raven, Philadelphia, PA, 1996 .ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.Th
