Frank

G.

Shellock,

PhD

MR Imaging Materials,

Julie

Swengros

#{149}

ferromagnetic metallic immaterials, and devices are reas contraindications for magnetic resonance imaging, primarily because of the risks associated with their movement or dislodgment. More than 40 publications have reported the ferromagnetic qualities of 261 different metallic objects (aneurysm and hemostatic clips, 32; carotid artery vascular clamps, five; dental devices or materials, 16; heart valve prostheses, 29; intravascular coils, filters, and stents, 14; ocular implants, 12; orthopedic implants, materials, and devices, 15; otologic implants, 56; pellets and bullets, 23; penile implants, nine; vascular access ports, 33; and miscellaneous, 17) on the basis of measurements of defieclion forces or attraction during exposure to static magnetic fields at strengths of 0.147-4.7 T. The results of these studies are listed with respect to the specific object tested, the material used to construct the object (if known), whether or not the object was deflected or moved during exposure to the static magnetic field, and the highest static magnetic field strength used for testing the object. plants, garded

term:

Radiology

Magnetic 1991;

resonance

(MR),

safety

180:541-550

M

Resonance

Implants, Updated

Review’

resonance (MR) imaging may be contrarndicated in a patient with a ferromagnetic metallic implant, material, or device primarily because of the risk associated with movement and/or dislodgment of the object as well as other possible hazards, including the induction of electrical current, excessive heating, and misinterpretation of an artifact, produced by the presence of the object, as an abnormality (1-58). The potential for MR imaging to injure patients by inducing electric currents in conductive metallic materials or devices such as gating leads, unused surface coils, halo vests, or improperly used physiologic monitors has been previously discussed (15,49,54), and recommendations to protect the patient during MR imaging have been presented (49). Temperature elevations associated with MR imaging of metallic implants, materials, and devices (with the exception of monitoring equipment, surface coils, or other externally applied equipment) have been studied, and there appears to be no significant hazard related to the temperature changes that have been measured (7,16,17). The type and extent of various artifacts caused by metaffic implants, materials, and devices have also been described and are typically well recognized on MR images AGNETIC

(9,10,13,18-21,38,40,46,52).

I

From the Tower

Center, Department Cedars-Sinai Medical

Musculoskeletal

Imaging

of Diagnostic Radiology, Center, 8700 Beverly Blvd.

Los Angeles, CA 90048 (F.G.S.,J.S.C.); and Department of Diagnostic Radiology, University of California, Los Angeles, School of Medicine, Los Angeles u.S.C.). Received February 21, 1991; revision requested March 25; revision received April

5; accepted

April

8. Supported

in part

by

PHS grant 1 RO1 CA44014-03 from the National Cancer Institute, National Institutes of Health. Address

reprint

©RSNA,1991

requests

to F.G.S.

Imaging

MD

and Biomedical and Devices: An

Certain

Index

Curtis,

Magnetic

Numerous studies have assessed the ferromagnetic qualities of various metallic implants, materials, or devices by measuring deflection forces or movements associated with the static magnetic fields used for MR imaging (1-14,17,21-30,33,35-43,47,51, 53,55; Becker RD. written communication, 1989). In general, these investigations have demonstrated that MR imaging may be performed safely in patients with metaffic implants, matenals, or devices if the object is nonferromagnetic or is only minimally attracted by the static magnetic field in relation to its in vivo application (ie,

the associated deflection force or attraction is insufficient to move or dislodge the implant or material in situ). Since prior knowledge of the relative degree of ferromagnetism that a specific type of metallic implant, material,

or device

possesses

is essential

for proper screening of patients before MR imaging (15,44,45,54), the articles pertaining to this topic have been reviewed and summarized. The Table lists data on 261 different implants, materials, and devices that have been tested for ferromagnetism, whether or not the objects were deflected or attracted by static magnetic fields, and the highest static magnetic field strength (range, 0.147-4.7 T) at which the objects were evaluated. Unless specifically

otherwise

stated,

this

article

pertains to the safety aspects of performing MR imaging in a patient with respect to the ferromagnetic qualities of a metallic implant, material, or device (ie, its attraction to a magnetic field). Other issues related to electrical conductivity, artifact production, and the like are not discussed in this article.

DISCUSSION Various

factors

influence

the

risk

of

performing MR imaging in a patient with a ferromagnetic implant, material, or device, including the strength of the static and gradient magnetic fields, the relative degree of ferromagnetism of the object, the mass of the object, the configuration of the object, the location and orientation of the object in situ, and the length of time the object has been in place (9,11,15, 33,44,45,49,54). These factors should be carefully considered before subjecting a patient with a ferromagnetic object to MR imaging, particularly if the object is in a potentially dangerous area of the body such as near a vital neural, vascular, or soft-tissue structure where movement or dis541

Metallic to Static

Implants,

Materials,

Magnetic

Fields

Metallic

Implant, or Device

MateriaL

and Devices Moveznent/ Deflection

An.iuysm

and henstatic Downs multipositional(17-7PH); Sims Surgical,

Keene, NH

Highest Strength

Field (F)

for Movement/Deflection

Forces Metallic

Reference

Drake

Gastrointestinal tomosis clip, Suture SCIA United States cal, Norwalk, Heifetz (17-7PH);

1.44

9

Poppen-Blaylock

Yes

1.44

9,29

Yes

0.147

9

Yes

1.5

11,29

American

Surgi-

No

1.5

11

Yes

1.89

4,42

No

1.89

4,29,42

No

1.5

11

No

Ed-

(Tantalum);

Edward

Weck

Housepian implant I(app (405 SS); V. Mueller Kapp curved (404 SS); V. Mueller Kapp straight (404 55); V. Mueller Ligadlip, no. 6 (316L SS); Ethicon, Born-

Yes

1.5 0.147

11 9

Yes

1.89

4,29

merville, NJ Ligaclip (tantalum); Ethicon

No

1.5

11

No

1.5

11

Mayfleld Codman, Mass Mayfield

(304

gle (17-7PH); Surgical

1.5

11

Yes

1.89

4

Yes No

1.5 1.44

11,29 9

Yes

1.89

4

Yes

1.89

4,29

No

0.15

2

No

1.89

4,29

Yes

1.5

11,29

1.89

4,29

No

15

11

1.89

4

Yes*

1.5

22

Yes*

1.5

22

Yes

1.5

22

Yes*

1.5

22

Yes*

1.5

22

No

1.5

11

Yes*

1.5

11

Yes*

1.5

55

Yes* No

1.5 1.44

55 9

Yes

13

55

Yes

1.5

9,55

Yes*

1.5

55

Yes

1.5

37

Yes

1.5

37

Yest

1.5

37

No

1.5

11

Yes

1.5

37

Yes*

1.5

37

No

1.5

11

Yes

1.5

37

Yes

2.35

12

No

1.5

11 11

of

clad mag-

Parkell

Products

Palladium/palladium keeper; Parkell Products PalladiunVplatinum casting alloy; Parkell Products Permanent crown (amalgam); Ormco 55 clad magnet; Parkell Products 55 keeper; Parkell Products Silver point; Union Broach, New York

Titanium

clad magnet; Products

valve prostheses Beall; Coratomic, Indiana, Penn

No

Yes

1.89

0.15

Irvine,

(convexo/ Shiley,

Calif

Bjork-Shiley saVspherical);

(univerShiley

Yes

1.5

4,29

Bjork-Shiley, model MBC; Shiley

Yes*

2.35

5

2,29

Bjork-Shiley, model 25 MBRC 11030; Shiley

Yes*

2.35

5

Yes*

2.35

5

Yes

0.15

2,29

No

1.89

4

No

1.89

4,29

Burlingame,

Radiology

large indirect keeper; Dental Ventures America, Yorba Linda, Calif

Bjork-Shiley concave);

(17-

SS); Codman (316 SS); Aes-

Reference

Heart

Yes

Spring

ucts

Parkell

McFadden

Calif Yasargil (Phynox); Aesculap

#{149}

Yes

(17-7PH);

Van-angle

(T)

Magna-Dent,

Yes

(MP35N); Codman Van-angle Micro (177PM SS); Codman

542

9

Downs

Codman

culap,

1.44

sil-

Auto Suture (SS); United Surgical

Van-angle

7PM Yasargil

Yes

Dc-

Sugita (Elgiloy); Downs Surgical Sundt-Kees (301 SS); Downs Surgical Sundt-Kees Multi-An-

States Van-angle

9

(301 SS);

ver alloy)

M-93

1.44

SS);

Pivot (17-7PH); V. Mueller Scoville (EN58J); Downs SurgicaL cater, Ga Stevens (50-4190,

Field

Strength

Dental,

Keeper, preformed post; Parkell Products, Farmingdale, NY

net;

Codman

Highest

Deflection

and materials (55);

MissoWa, Mont Brace wire (chrome alloy); Ormco, San Marcos, Calif Castable alloy; Golden Dental Products, Golden, Cob Cement-in keeper; Solid State Innovations, Mt Airy, NC Dental amalgam GDP Direct Keeper, preformed post; Golden Dental Prod-

Palladium

Olivecrona

Surgidlip,

Yes

(301 SS); Randolph,

Codman McFadden

devices

Brace band

anas-

Heifetz

Hemoclip

Salibi (55); Codman Selverstone (55); Cod-

man

Auto (SS);

ward Weck (Elgiloy); Edward Weck Hemodip no. 10 (316L SS); Edward Weck

Movement/

(SS);

Codman

Dental

Corns

or Device

man Kindt (55); V. Mueller

(301 SS); Ed-

ward Weck

Exposure

Implant,

Material,

Drake

Weck

during

Carotid artery vascular damps Crutchfield (55); Cod-

clips

Yes

(DM4, DR24); Edward Weck, TnangLe Park, NJ Drake (DR16); Edward

Tested

Carpentier-Edwards, model 2650; Amencan Edwards Laboratones, Santa Ma, Calif

Continued

August

1991

Implants,

Metaffic to Static

Materials, Fields

Magnetic

Metaffic Material,

Implant, or Device

and

Devices

Tested

for Movement/Deflection

Movement/ Deflection

Highest Field Strength (F)

Referewe

American

Edwards

Laborato-

ties

Yes*

Hall-Kaster,

2.35

5

model

Yes*

1.5

11

Yes*

1.5

11

Hancock I(porcine); Johnson and Johnson, Anaheim, H (porcine); Yes*

1.5

11

extracorpo-

Johnson

242R;

and

Johnson

3005; Grove Minn 5009;

2.35

5

Yes*

2.35

5

Mobin-Uddin P/C/ umbrella ifiter; American Edwards Palmaz endovascular

Yes*

2.35

12

Yes*

2.35

5

Hall;

Medtronic

Yes*

model Medical

3523T029;

6522; Medical

5

Yes*

2.35

5

Yes*

Starr-Edwards, 2320; American

2.35

5

Yes*

2.35

11

Yes*

2.35

12

Yes*

2.35

12

No

1.5

11

Edmodel

Pre 6000; American Edwards Laboratoties Starr-Edwards,

Yes

2.35

12

model

American

Ed-

wards Laboratories St. Jude; St. Jude Medical, St. Paul St.Jude, modelA 101; St. Jude Medical St.Jude, modelM 101; St.Jude Medical

Yes*

2.35

5

No

1.5

11

Yes*

2.35

5

Yes*

2.35

5

coils, filters, and stents

plant;

180

Scientific

Yes*S

1.5

13

Yes*S

1.5

13

Yes*$

1.5

13,40

No

13

13

Yes*t

1.5

13

No

4.7

13

No

4.7

13

No

4.7

13

Yes*f

1.5

13

Yes*S

1.5

13

No

1.5

25,34

Yes

1.5

23

No

1.5

3

No

1.0

3

No

1.0

3

No

1.0

3

No

1.5

27

No

1.5

27,41

No

1.5

27

No

1.5

41

No

1.5

27

No

1.5

27

im-

Binkhorst, lens;

loop lens insplant; Binkhorst, iridocapsular lens; loop ins-

plant; Binkhorst, iridocapsular lens; titanium loop Intraocularlens implant; Worst, platinum clip lens Retinal tack (303 55); Bascom Palmer Eye

Institute Retinal tack (titanium alloy); Coopervision, Irvine, Calif Retinal tack(303 SS); Duke University Retinal tack (cobalt/ Grieshaber,

Fallsington, staple

tack,

NC ifiter; Bloomington,

No

4.7

13

No

4.7

13

Penn Norton

(platinum/ Norton

rhodium); Retinal tack

md

Volume

13,24

(tanta-

wire iztraocularlens

nickel);

Infravascular

Cragg nitinol ifiter

1.5

Ocular implants Fatio eyelid spring/

Retinal

Amplatz Cook,

Yes*$

Medi-teclt/

platinum Intraocularlens

Laboratories

Starr-Edwards,

Reference

Intraocular

model Ed-

American

lum);

(‘F)

ifiter;

iridocapsular platinum-fridium

wards Laboratories Starr-Edwards, model

6520;

2.35

Cutter

Laboratories, Berkeley, Calif Starr-Edwards, model 1260; American Edwards Laboratories

wards

Yes*

model

Smeloff-Cutter;

2400;

5

stent

Boston

Medtronic

Omniscience,

2.35

model

NC

Thomas Jefferson University, Philadelphia Strecker

Medtronic Hall, A7700-D-16;

Ethicon

Retrievable

Medical

Omnicarbon,

ifiter (titanium alby); Medi-tech/Boston Scientific Gunther NC ifiter; William Cook, Europe Maas helical endovascular stent; Medinvent

stent;

Field

Strength

cava

No

model

Medtronic

vena

Maas helical NC ifiter; Medinvent, Lausanne, Switzerland

Inver

Lifiehi-Kaster,

stent; Cook Greenfleld vena cava ifiter (55); Meditech/Boston Scientific, Watertown, Mass

5

Heights,

Highest

zig-zag

2.35

model

Medical,

tion coil; Cook

Yes*

Urn-

versallSM Lillehi-Kaster,

Deflection

5

Vascor,

lonescu-Shiley;

Movement/

or Device

2.35

extracorporeal model M 436533; Johnson and

model 505; Johnson and Johnson

Exposure

Implant,

Yes*

Hancock

Johnson Hancock

Metallic Material,

Greenfleld

and

real, model

.+

Gianturco

A7700; Medtronic, Minneapolis

Calif Hancock Johnson Johnson Hancock

during

Gianturco Bird’s Nest NC ifiter; Cook Gianturco emboliza-

Carpentier-Edwards

(porcine);

Forces

(Continued)

(alumi-

num textraoxide); Ruby

spiral

Number

#{149}

2

Continued

Radiology

#{149} 543

Implants, Magnetic

Metallic to Static

Metallic MateriaL

Materials,

Fields

Implant,

or Device

Retinal tack (SS-martensitic); Western European Orthopedic implants, materials, and devices AML femoral component bipolar hip prosthesis; Zimmer, Warsaw, md Cervical wire, 20 gauge (316L SS) Cotrel rods with hooks (316L 55)

Druninsond wire (316L SS) Drr,

device

and

Devices

Tested

for Movement/Deflection

Movement!

Highest

Field

Deflection

Strength

(1’)

Yes

1.5

Metallic Reference

27

No

1.5

11

No

0.3

35

No

0.3

35

No

0.3

35

Zimmer

Jewett nail; Zimmer Kirschner intermedullar)r rod; Kirschner Medical, Timonium,

Md

ss

mesh;

0.3

35

Zinsmer

SS plate; Zimmer SS screw; Zimmer SS wire; Zinsmer Zielke rod with screw, washer, and nut

(316L SS)

No

0.3

35

No

0.3

35

No

1.5

11

No

1.5

11

No No No No

1.5 1.5

11 11

1.5

11

1.5

11

No

1.5

11

No

0.3

35

gelwood, Cody

Cob

tack

1.5

26

2 SS); Storz,

St. Louis

House single loop (tantalum); Storz House double loop (tantalum); Storz House double loop (ASTM-318-76 grade

2 SS); Storz

544

Radiology

#{149}

Highest

Field

Strength

(‘1’)

Reference

loop

(316L SS); Richards Medical House-type SS piston

No

1.5

26,53

No

1.5

26

No

0.5

36

No

0.5

36

No

1.5

26,53

No

1.5

26,53

Yes

1.5

53

No

1.5

26

No

1.5

26,53

No

1.5

26

No

1.5

26

No

1.5

26,53

No

1.5

53

No

1.5

53

Richards Medical Richards shepherd’s crook (platinum); Richards Medical Richards Teflon piston (Teflon); Richards

No

1.5

26

No

0.5

36

Medical Robinson-Moon-Lippy offset stapes prosthesis (ASTM-318-76 grade 2 SS); Storz Robinson-Moon offset

No

1.5

53

No

1.5

26

No

1.5

26

wire

(ASTM-

2SS); (Bris-

tol-Myers, Squibb) House wire (tantalum); Otomed House wire (SS); Otomed piston

prosthesis Richards McGee

stapes

(316L SS); Medical

piston

stapes

prosthesis (platinum/316L 55); Richards Medical

num/Cr1Ni4 55); Richards Medical (recalled by manufacturer) McGee shepherd’s crook thesis

stapes pros(316L 55); Richards Medical Plasti-pore piston (316L SS/plasti-pore

material); Richards Medical Platinum ribbon loop stapes prosthesis (platinum); Medical Reuter bObbin

Richards ventila-

tion tube (316L 55);

Medical Richards Teflon

platinum

No

1.5

26

Yes

0.6

8

Yes

0.6

8

num); Medical Richards

0.6

piston,

mm (Teflon,

plati-

Richards platinum

Teflon piston, 0.8 mm (Teflon, platinum); Richards Medical

Yes No

1.5 0.6

53 8

Ehmke hook stapes prosthesis (platinum); Richards Medical Fisch piston (Teflon, 55); Richards Medical House single loop (ASTM-318-76 grade

Movement/ Deflection

(316L SS); Richards No

Berger “V” bobbin ventilation tube (titanium); Richards Medical, Memphis Cochlear implant; 3M/ House Cochlear implant; 3M/ Vienna Cochlear implant, Nucleus Mini 22-channel Cochlear, En-

prosthesis

Richards Medical Richards bucket handie stapes prosthesis

Otologic

Implants Austin Tytan piston (titanium); Treace Medical, Nashville

Exposure

McGee piston stapes prosthesis (plati-

distraction

hooks (316L SS) Harris hip prosthesis;

wire

stapes

McGee

No

Harrington rod with

House-type

Xomed-Treace

compres-

sion rod with hooks and nuts (316L SS)

Implant, or Device

Material,

and

for trans-

SS)

during

318-76 grade

verse traction (316L Harrington

Forces

(Continued)

No

1.5

26

No

1.5

53

No

1.5

26

No

1.5

26

No

1.5

26

Richards piston stapes prosthesis (platinuni/fluoroplastic);

stapes

No

1.5

26

prosthesis

(ASTM-318-76 2 55); Storz

grade

Continued

August

1991

Metallic to Static

Implants, Magnetic

Metallic Material, Robinson

placement

Materials, Fields

Implant,

Movement!

or Device

Deflection

Devices

Tested

for

Movement/Deflection

Highest

Field

Strength

(1)

No

1.5

26

No

1.5

26

No

13

26

No

1.5

26,53

Scheer

piston

ards Scheer

Medical piston

No

1.5

53

1.5

No

1.5

1.5

53

No

1.5

26

No

1.5

26

No

1.5

26

Yes Yes

15 1.5

15 15

No

1.5

33

No

13

33

Yes

1.5

33

No

1.5

33

No

1.5

33

No

1.5

33

No

1.5

33

Geco Bullet, 0.357 inch copper,

Yes

1.5

33

lead); Winchester

No

1.5

33

No

15

33

Yes

1.5

33

per,lead); Fiocchi Bullet, 0.357 inch (cop-

No

1.5

33

per,lead); Hornady BUllet, 9 mm (copper, lead); Norma

No

1.5

33

Yes

1.5

33

No

15

33

No

13

33

No

15

33

No

13

loop

stapes prosthesis (platinum); Richards Medical Williams microclip

Xomed stapes (ASTM318-76 grade 2 SS; Xomed-Treace

Bullet, No

6

1.5

Bullet, (lead);

No

1.5

26

No

15

2 SS); Storz

No

26,53

1.5

Schuknecht Teflon wire piston, 0.6 mm

316L SS);

Richards

Medical

bullets

bronze);

North

ordnance 7.62 x 39mm steel);

0.357 inch (coplead); Cascade 0.357 inch

Remington

BUllet, 0.357 inch (alulead); Winchester Bullet, 9 nun (copper,

lead); Remington

Tef-wire malleus attachment (ASTM-318-76 grade

(Teflon,

and

BUllet, (copper, Norinco

2 SS); Storz

26,53

BUllet, 0.380 inch (coplead);

BUllet,

.

0.357

lon,lead);

inch

(ny. Smith and

Wesson No

Schuknecht Teflon wire piston, 0.8 mm (Teflon, 316L SS); Richards Medical Sheehy incus replace-

No

(ASTM-318-76 2 SS); Storz

No

1.5

1.5

1.5

53

53

26

strut

(316L SS); Richards

BUllet, i (steel, lead); Evansville Ordnance BUllet, 0.357 inch (cop.

Bullet,

No

Medical

1.5

53

incus

0.357

(bronze,

inch plastic);

Patton-Morgan

strut

BUI1et

0.357

inch

(cop.

316L SS); No

Richards Medical Silverstein malleus clip ventilation tube (Teflon, 316L SS); Richards Medical bObbin

1.5

26

No

1.5

53

No

15

26

ventila-

Medical

#{149} Number

per,lead); Morgan BUllet, 0.45

lion tube (316L SS);

180

1.5

Medical

ribbon

53

Schuknecht

Volume

No

(316L SS);

Richards

ion,

Richards Medical Schuknecht Tel-wire incus attachment (ASTM-318-76 grade

Richards

26

BUllet, 0.44 Inch (ref.

tic);

Spoon

1.5

26

prosthesis

(Teflon,

Reference

No

BB’s; Crosman Bullet, 0.380 inch (cop, plastic, lead); Glaser

Gelfoam prosthesis, style

Sheehy.type replacement

(‘F)

26,53

BB’s; Daisy

(Teflon,

No

incus

Field

Strength

1.5

53

(316L SS/fluoroplas-

grade Sheehy

Highest

Deflection

No

Pellets No

(316L SS); Richards Medical Schuknecht piston

ment

Movement/

(Tel-

316L 55); RichardS

stapes

Exposure

(316L SS); Richards

stapes prosthesis (316L 55/ fluoroplastic); Rich-

Medical Schuknecht and wire Armstrong

(tantalum); Richards MediCal Id-platinum piston (platinum); XomedTreace Total ossicular replacement prosthesis

Medical

ion, 316 L 55); RichMedical

Implant, or Device

Material,

Trapeze

ment piston (TefIon); Richards Medical Schea SS and Teflon

ards

#{149}

(TORY)

prosthesis

prosthesis

during

Tantalum wire loop stapes prosthesis

(platinunVfluoroplastic); Richards Medical Schea malleus attach-

wire

Forces

Metallic Referen

incus reprosthe-

515 (ASTM-318.76 grade 2 55); Storz Robinson stapes prosthesis (ASTM-318-76 grade 2 SS); Storz Ronis piston stapes prosthesis (316L SS/ fluoroplastic); Richards Medical Schea cup piston

stapes

and

(Continued)

2

Pattoninch

(cop.

Pert lead); Samson Shot, 12-gauge, size: 00 (copper, lead); Federal

33 Continued

Radiology

#{149} 545

Metallic to Static

Implants,

Materials,

Magnetic

Fields

Metaffic

Implant, or Device

Material,

Movement,1 Deflection

Shot, 71,4 (lead) Shot, 4 (lead) Shot,

Tested

for Movement/Deflection

Highest Field Strength (F)

No No

1.5 1.5

33 33

No

1.5

33

implants

Systems, Mmnetonka, Minn AMS 700 CX Inflat-

able; American ical Systems Flexi-Flate

No

1.5

10

No

1.5

10

Mcd-

fone);

cal

Engineering Jonas; Dacomed, Mmneapolis Mentor Flexible; Mentor, Minneapolis Mentor Inflatable; Mentor Omniphase; Dacomed

No

1.5

10

No

1.5

10

No

1.5

10

No Yes

1.5 1.5

10 10

access

No

1.5

1.5

10

1.5

21

of

13

21

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

15

21

No

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

13

21

No

1.5

21

No

1.5

21

No

1.5

21

Yes*

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

1.5

21

No

1.5

11

No

1.5

11

Pharmatitanium (titanium);

Port-a-cath,

21

(316L SS); Pharmada Deltec Q-port (316L 55); Quinton Instrument,

Infu-

1.5

Deltec

21

polyNo

venous

Seattle Yes*

No

1.5

1.5

21

21

S.E.A. (titanium); Harbor MediCal Devices, Boston Snap-lock (titanium, polysulfone polymer, silicone); Infusaid Synchromed, model 8500-1 (titanium,

Bethle-

No

1.5

21

No

1.5

21

No

1.5

21

6013

thermoplastic, sificone); Medtronic Vasport

(titanium/flu-

oropolymer); Biomedical, Ana,

Gish Santa

Calif

plastic); Medical,

Radiology

#{149}

15

low-profile

(titanium); ciaDeltec Port-a-cath, Pharmada

No

Bev-

erly, Mass Lifeport, model 1013 (titanium); Strato Medical Macroport (polysulfone polymer, sillcone); Infusaid Microport (polysulfone polymer, sillcone); Infusaid

546

No

titanium

venous

Infu-

hem, Penn Infusaid, model 400 (titanium); Infusaid Infusaid, model 600 (titanium); Infusaid

Strato

Reference

Pharmacia

venous

poly-

model

(1)

rubber,

Deltec

Port-a.cath,

(316L 55); Davol/Subsidiary of C R Bard Hickman, pediatric (titanium); DavoV Subsidiary of C R Bard Implantofix II (polysulfone); Bur-

(Deirin

Field

Strength

titanium

nium); No

said

Lifeport,

Highest

peritoneal(tita-

Hickman

Medical,

silicone

Dacron); Norfolk Medical PeriPort (polysulfone, titanium); Infusaid Port-a-cath, P.A.S. port (titanium); Pharmacia Deltec, St Paul Port-a-cath, titanium dual lumen (titamum); Pharmacia Deltec

Macroport

ron

Movement/ Deflection

(tita-

Port-a-cath,

No

mer, silicone);

Exposure

Mcdi-

mum); Norfolk Mcdical Norport-SP (polysul.

C R Bard, Cranston,

(polysulfone

Norfolk

Norport-PT

ports

mer, silicone); said

Ill

10

fone,

Button (polysulfone polymer, silicone); Infusaid, Norwood, Mass Dome (titanium); Davol/Subsidiary RI Dual Microport (polysulfone

Skokie,

Norport-DL (316L SS); Norfolk Medical Norport-LS (titanium); Norfolk Medical Norport-LS (316L SS); Norfolk Medical Norport-LS (polysul-

Surgitek; No

Dual

MRI (Delrin plastic, silicone); Davol/Subsidiary of C R Bard Norport-AC (titamum); Norfolk Mcd-

Engineer-

ing, Racine, Wis Flexi-Rod (standard) Surgitek; Medical Engineering Flexi-Rod II (firm) Surgitelc Medical

Vascular

during

Implant, or Device

Material,

ical,

Malleable 600; American Medical

AMS

Medical

Forces Metallic

Reference

00 buckshot

(lead) Penile

and Devices (Continued)

No

1.5

21

Miscellaneous Artificial

urinary

sphincter, American No

No

No

1.5

1.5

1.5

21

21

21

Systems Cerebral

AMS 800; Medical

ventricular tube connec-

shunt tor, Accu-flow, straight; Codman

Continued

August

1991

Metaffic

Implants,

to Static

Magnetic

Metallic

Materials, and Devices Fields (Continued)

Implant,

Movement!

or Device

Material,

Cerebral

Deflection

Highest Strength

tube

No

1.5

11

No

1.5

11

Yes

0.147

10

Field

fl

Reference

device,

Cop-

per 1; Searle

Phar-

maceuticals,

Chicago

No

13

7

Yes*

1.5

38

Penn

No

1.5

38

No No

1.5 1.44

59 9

Yes

15

30

Yes*

1.5

thermodi-

lution catheter; American-Edwards Laboratories, Irvine,

Yes*

1.5

11 Tantalum

Yes*

1.5

Koroflex; Drug ProdNJ

11

(titanium) valve and

1.5

11

Yes* No

1.44

10

No

1.44

10

powder

Tissue expander with magnetic port; McGhan Medical, Santa Barbara, Calif Vascular marker, 0-ring washer (302 SS); PlC Design,

dia-

Piscataway,

Highest Strength

contra-

Bridgeport,

cal

Young

Movement/ Deflection

Implant, or Device

Swan-Ganz

Pharmaceuti-

Contraceptive phragm,

Exposure

valve, Hottertype; Holter, Bridgeport, Penn Shunt valve, HolterHausner type; Holter-Hausner,

flat spring

Ortho

during

Shunt

dia-

phragm,

Hakim pump

Metallic Material,

Reference

connec-

Contraceptive

Forces

Intrauterine ceptive

tor, Accu-flow right angle; Codman Cerebral ventricular shunt tube connector, Accu-flow, T-connector; Codman Cerebral ventricular shunt tube connector (type unknown) Contraceptive diaphragm, All Flex; Ortho Pharmaceutical, Raritan, NJ

Forceps

Field (‘F)

for Movement/Deflection

ventricular

shunt

ucts,

Tested

Middlebury,

Becker,

Conn

1989

Note.-”Highest field strength” refers to the highest intensity of static magnetic field in teds that was used for the evaluation of movement or deflection forces of the various implants, materials, and devices tested. NC = inferior vena cava, SS = stainless steeL Material or materials used to construct the object are indicated, if known. Manufacturer information is provided, if known. * These metallic implants, materials, or devices were considered to be safe for MR imaging despite being moved/deflected by the static magnetic fields. For example, certain heart-valve prostheses were moved/deflected by the static magnetic fields but the forces were considered to be less than that exerted on the valves by the beating heart. Ferromagnetic coils, filters, and stents typically become firmly incorporated into the vessel wall several weeks following placement, and therefore, it is highly unlikely that they will be moved or dislodged by magnetic forces. t While there is no magnetic deflection associated with the triple-lumen thermodilution Swan-Ganz catheter, there has been a report of a catheter “melting” in a patient. Therefore, this catheter would be considered a relative contraindication for MR imaging.

t

lodgment

could

injure

the

patient

(9,11,15,33,44,45,49,54).

All biomedical implants, materials, and devices, particularly those made from unknown materials, should be evaluated with ex vivo techniques before MR imaging is performed in patients with them (11). This procedure allows for the determination of the presence and amount of ferromagnetism so that a competent decision can be made concerning the potential associated risks. Aneurysm

and

Hemostatic

Clips

Nineteen of the 26 aneurysm clips tested displayed ferromagnetic qualities and, therefore, contraindicate MR imaging (4,9,11,29,32,38,42). Laboratory studies have demonstrated that subjecting ferromagnetic aneurysm clips to static magnetic fields is hazardous insofar as these clips may be displaced and result in serious consequences (4,38,42). Because of this hazard, we recommend that patients be examined with MR imaging only if

Volume

180

Number

#{149}

2

the type of aneurysm clip is emphatically known to be nonferromagnetic. Four patients with nonferromagnetic or weakly ferromagnetic aneurysm clips have undergone MR imaging without

incident

(29).

None of the six hemostatic vascular clips evaluated were attracted by static magnetic fields used for MR imaging up to field strengths of 1.5 T (11). These hemostatic clips are made from nonferromagnetic materials and, therefore, do not present a risk to patients during MR imaging. Patients with each of the hemostatic vascular clips listed have undergone imaging safely with a 1.5-T MR imager at our institution. Carotid

Artery

Vascular

Clamps

Each of the five carotid artery vascular clamps tested displayed magnetic deflection in the presence of a 1.5-T static magnetic field (22). However, only the Poppen-Blaylock carotid artery vascular clamp was believed to be contraindicated in

patients undergoing MR imaging because of the tremendous ferromagnetism of this device (22). The others were believed to be safe because of the existence of only mild ferromagnetism (22). Patients with metallic carotid artery vascular clamps have undergone imaging with MR systems with static magnetic fields of 0.35-0.60 T without experiencing any discomfort or neurologic sequelae (22). Dental

Devices

and

Materials

Of the 16 different dental devices and materials tested, 12 had measurable deflection forces but only three of these represent a potential problem for patients during MR imaging because they are magnetically activated devices (see subsequent section, Magnetically Activated Implants and Devices) (9,11,37,55). Heart

Valve

Prostheses

Twenty-nine different heart prostheses have been evaluated

Radiology

valve for

547

#{149}

magnetic deflection related to exposure to a 1.5- or 2.35-T static magnetic field (5,11,12). Of these, four were nonferromagnetic and 25 had measurable deflection forces. However, because the magnetic deflection of these heart valves is minimal compared with the force exerted by the beating

heart,

MR

imaging

is not

con-

sidered to be hazardous for patients with these prostheses (5,11,12) (with the possible exception of performing MR imaging with an MR system

Orthopedic and Devices

Implants,

going MR imaging artifacts (34).

Materials,

Each of the 15 different orthopedic materials and devices tested are made from nonferromagnetic materials and are safe for MR imaging (11,35). An additional concern of subjecting these typically

large

metallic

implants

to

MR imaging is the potential heating that may develop as a result of exposure to the gradient and/or radio-frequency

electromagnetic

fields.

How-

has a Starr-Edwards Pre 6000 valve when there is concern regarding the integrity of the anulus or presence of valvular dehiscence [12J).

ever, studies have demonstrated that heating of these implants is relatively insignificant (17). Patients with each of these orthopedic materials and devices have undergone imaging safely with a 1.5-T MR imager at our institution.

Intravascular and Stents

Otologic

greater

than

0.35

T in a patient

Coils,

that

Filters,

Fourteen different intravascular coils, filters, and stents have been assessed for ferromagnetic qualities (13,25,28,31,40). Five of these are ferromagnetic. However, these devices typically become firmly incorporated into the vessel wall after several weeks,

and

therefore,

it is unlikely

that any of them would become dislodged by magnetic forces (13,58). Patients with most of the intravascular coils, filters, and stents listed in the Table have undergone imaging with 1.5-T MR imagers without incident (13,24,25,31,40,58).

Therefore,

it is con-

sidered to be safe to perform MR imaging in patients with any of the intravascular coils, filters, and stents listed after a suitable period has elapsed to ensure stable positioning of the device. MR imaging should not be performed if there is any possibility that an intravascular coil, ifiter, or stent is not held firmly in place.

Ocular

Implants

Of the 12 ocular implants tested, the Fatio eyelid spring (23) and the retinal tack made from martensitic stainless steel (27) were deflected by a 1.5-T static magnetic field. These may be uncomfortable (ie, the Fatio eyelid spring)

retinal

or injure

tack)

imaging.

The

(ie,

the case

patient

the

martensitic

during

MR

of a ferromagnetic

object damaging the eye of a patient undergoing MR imaging has been previously described (50), which underscores the need for special diiigence when subjecting a patient with any type of ferromagnetic material located near the eye to this imaging procedure (49). 548

#{149} Radiology

and

Bullets

Most of the pellets and bullets tested are composed of nonferromagnetic materials (15,33). Ammunition that proved to be ferromagnetic tended to be manufactured in foreign countries and/or was of a military vanety (33). Shrapnel typically contains steel and, therefore, presents a potential hazard for MR imaging (33). Because pellets, bullets, and schrapnel may be contaminated with ferromagnetic

cause

severe

Implants

Only one of the nine penile implants, the Dacomed Omniphase, had a significant deflection force measured when exposed to a 1.5-T static magnetic field (10). While it is unlikely that this implant would Severely injure a patient undergoing MR imaging because of the manner in which it is utilized, it would undoubtedly be uncomfortable for the patient, and therefore, imaging in a patient with this implant is inadvisable. Patients with each of the nonferromagnetic penile implants have undergone imaging safely with a 1.5-T MR imager at our institution.

Implants

The three cochlear implants tested contraindicate MR imaging because, in addition to being attracted by static magnetic fields, they are also electronically and/or magnetically activated (8,53). Of the remaining otologic implants, only one of them displayed magnetic deflection during testing with a 1.5-T static magnetic field (6,8,26,53). This implant, the McGee stapedectomy piston prosthesis, made from platinum and Cr17Ni4 stainless steel (manufactured during mid1987), has been recalled by the manufacturer (53). In addition, patients who received this implant have been identified and issued cards warning them not to undergo MR imaging (53).

Pellets

Penile

and

materials,

the

risk

versus

bene-

fits of performing MR imaging should be carefully considered whether or not the pellet, bullet, or schrapnel is located near a vital structure (33,34). Of further note is that, in an effort to reduce lead poisoning in puddle-type ducks, the federal government requires, in much of the eastern United States, the use of steel shotgun pellets instead of lead, which would present a potential hazard to patients under-

Vascular

Access

Ports

Two of the 33 impiantable vascular access ports tested had measurable deflection forces, but the forces were believed to be unimportant relative to the in vivo application of these implants (21). Therefore, it is safe to perform MR imaging in a patient that may have one of these implants. Miscellaneous Of the miscellaneous metallic implants, materials, and devices tested, the cerebral ventricular shunt tube connector (type unknown) (10) and tissue expander with magnetic port (30) had strong deflection forces that may be hazardous to patients undergoing MR imaging. Another ferromagnetic implant, the 0-ring washer vascular marker, displayed only slight ferromagnetic qualities and, therefore, does not represent a risk to patients examined with MR imaging (Becker RD, personal communication, 1989). Contraceptive diaphragms were attracted strongly by the 1.5-T static magnetic field, but we have performed

imaging

in patients

with

these

devices who did not complain of any sensation related to movement of these objects. Accordingly, the presence of a diaphragm is not believed to pose a hazard to a patient during MR imaging. There is, however, a remote possibility that the contraceptive properties of the diaphragm may be hindered if it is inadvertantly moved during an MR imaging examination. Although

modilution constructed terials, the

the

triple-lumen

Swan-Ganz

ther-

catheter

of nonferromagnetic presence of this

is ma-

device August

1991

may be injurious to the patient during MR imaging. A report indicated that a portion of a thermodilution SwanGanz catheter that was outside the patient melted as a result of MR imaging (59). It was postulated that the high-frequency electromagnetic fields generated by the MR imaging system caused eddy current heating of either the wires within the thermodilution catheter or the radiopaque material inside the catheter. This incident suggests that MR imaging has the potential to injure patients with triple-lumen, thermodilution Swan-Ganz catheters or other similar devices.

Magnetically and Devices

Activated

structures

net-containing removed (55).

after

portion

the

of the

device

LeonjA, Gabriele thesis: significance imaging. 406.

Magn

Reson

Imaging

1987;

24.

Mattucd KF, Setzen M, Hyman R, Chaturvedi C. The effect of nuclear magnetic resonance imaging on metaffic middle ear prostheses. Otolaryngnol Head Neck Surg 1986; 94:441-443. New PFJ, Rosen BR, Brady TJ, et aL Po-

25.

1987; 162:311-314.

9.

10.

tential hazards and artifacts netic and nonferromagnetic dental materials and devices magnetic resonance imaging. 1983; 147:139-148. Shellock FG, Crues N Sacks

12.

13.

14.

of ferromag-

27.

surgical and in nudear Radiology

28.

32.

with

of magnetic

intraorbital

metallic

and

nal reattachment

objects

or trauma

and

33.

Magn

Davis

J

safety

Kaufman

resonance imaging. Q 1989; 5:243-261.

Reson PL, Crooks

L, Arakawa L, Margulls AR.

ards in NMR imaging:

effects

and temperature

large

prostheses 165(P):150.

(abstr).

changes

induced

Radiology

1.

19.

Applebaum magnetic pedectomy

2.

3.

4.

EL, Valvassori GE. Effects of resonance imaging fields on staprostheses.

Arch

Otolaryngol

1985; 11:820-821. Barrafato D, Henkelman RM. Magnetic resonance imaging and surgical clips. Can J Surg 1984; 27:509-512. de Keizer RJ, Te Strake L. Intraocular lens implants (pseudophakoi) and steelwire sutures: a contraindication for MRI? Doc Ophthalmol 1986; 61:281-284. Dujovny

M, Kossovsky

al. Aneurysm netic resonance

Volume

180

N, Kossowsky

2

21.

22.

1988;

in patients magnetic

Ann Thorac

Teitelbaum

undergoing resonance

Surg 1989; 48:643-

GP, Yee CA, Van-Horn

GP. imaging

35.

36.

DD,

MR

Metallic

ballistic fragand artifacts

safety

Radiology

1990; 177:883. RR, Mesgarzadeh M, Revesz G, Bonakdarpour A, Clancy M. The effect of magnetic resonance imaging on metal spine implants. Spine 1989; 14:670-672. White DW. Interaction between magnetic CJ, Beta

fields and metallic

ossicular

prostheses.

Am

J Otol 1987; 8:290-292. 37.

in

1987;

Bellon EM, Haacke EM, Coleman PE, Sacco DC, Steiger DA, Gangarosa RE. MR artifacts: a review. Magn Reson Imaging 1984; Pusey E, Lufkin RB, Brown RKJ, Solomon MA, et aL Magnetic resonance imaging artifacts: mechanism and clinical significance. RadioGraphics 1986; 6:891-911. Yamanashi WS, Wheatley KK, Lester PD, Anderson DW. Technical artifacts in mag-

imaging. Physiol Chem Phys Med NMR 1984; 16:237-250. Shellock FG, Meeks T. Ex vivo evaluation of ferromagnetism and artifacts for implantable vascular access ports exposed to a 1.5 ‘F MR scanner (abstr). JMRI 1991; 1:243. Teitelbaum GP, Un MCW, Watanabe Norfray JF, Young TI, Bradley WG.

clips

ments: (letter). Lyons

38.

Shellock flection

FG. forces

Ex vivo assessment of deand artifacts associated with

high-field strength MRI of “mini-magnet” dental prostheses. Magn Reson Imaging 1989; 7(suppl 1):P38. Go KG, Kamman RL, Mooyaart EL. Interaction of metallic neurosurgical implants with

magnetic

resonance

Tesla as a cause

39.

of image

imaging

1.5

and of

of the implant.

Clin

movement

Neurosurg

1989; 91:109-115. AH, Teitelbaum

Matsumoto

at

distortion

hazardous

GP, Barth

KB,

Strecker EP. Tantalum vascular stents: in vivo evaluation with MR imaging. Radiology 1989; 170: 753-755. Carvlin

netic resonance

R, et

clip motion during magimaging: in vivo experi-

#{149} Number

20.

AJR

Teitelbaum CP, Ortega HV, Vinitski 5, et al. Low artifact intravascular devices: MR imaging evaluation. Radiology 1988; 168:713719. GoldJP, Puisinelli W, Winchester P, Brifi PW,Jacewicz M, Isom OW. Safety of me-

Teitelbaum

2:41-52.

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U

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6.

Implants

Certain ferromagnetic implants and devices such as cochlear implants, tissue expanders, ocular prostheses, and dental implants are magnetically activated (8,30,37,55,56,60). Most of these are considered to be potentially hazardous to patients undergoing MR imaging (49,54). Besides dislodging these particular types of implants and devices, MR imaging may also alter or damage the operation of the magnetic components (49,54), possibly necessitating surgery for replacement. Furthermore, if the portion of the prosthesis that the magnet attracts is implanted in soft tissue (eg, with certam ocular prostheses, the magnet is contained in the prosthesis and a ferromagnetic “keeper” is placed in the soft tissue), it is inadvisable to perform MR imaging in a patient with this type of device because of potential adverse effects associated with displacement of the keeper (60). MR imaging may be performed safely in patients with dental magnet appliances that are properly attached to supporting

5.

mental study with metallurgical factor analysis. Neurosurgery 1985; 17:543-548. Hassler M, Le Bas JF, WolfJE, Contamin C, Waksmann B, Coulomb M. Effects of magnetic fields used in MRI on 15 prosthetic heart valves.J Radiol 1986; 67:661-

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Dental

et al.

of postoperative

tallic implants. AJR 1984; 143:1281-1284. Shellock FC, Kanal E, SMRJ Safety Committee. Policies, guidelines, and recommendations for MR imaging safety and patient management. JMRI 1991; 1:97-101. Kelly WM, Paglan PC, PearsonjA, San Diego AG, Solomon MA. Ferromagnetism of intraocular foreign body causes unilateral

60.

Rehabil 1990; 17:403-410. Power W, Collum LMT. Magnetic resonance imaging and magnetic eye implants (letter). Lancet 1988; 2:227. Kanal E, Shellock FG, Sonnenblick D. MRI clinical site safety survey: phase I results and preliminary data (abstr). Magn Reson Imaging 1988; 7(suppl 1):106. Teitelbaum GP, Ortega HV, Vinitski S, et Optimization of gradient-echo imaging parameters for intracaval filters and trapped thromboemboli. Radiology 1990; 174:1013-1019. ECRI, Health Devices Alert. A new MRI

complication? May 27, 1988; 1. Yuh WTC, Hanigan MT, NeradjA, et al. Extrusion of a magnetic eye implant after MR imaging

examination:

ard to the enudeated

a potential haz(in press).

eye. AJNR

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August1991

aL