This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3 T
M.C. Mabraya,*, A. Uzelaca, J.F. Talbotta, S.C. Linb, and A.D. Geana,c,d
appears to be safe for MRI at 1.5 and 3 T, and does not produce significant susceptibility
artefact to adversely affect diagnostic interpretation of routine brain MRI.
Acknowledgments
M.C.M. was supported by an NIH T32 training grant (5T32EB001631-10) while working on this project.
References
1. Weinreb RN, Aung T, Medeiros FA. The pathophysiology and treatment of glaucoma: a review. JAMA. 2014; 311:1901–11. [PubMed: 24825645]
2. Boland MV, Ervin AM, Friedman DS, et al. Comparative effectiveness of treatments for open-angle glaucoma: a systematic review for the U.S. Preventive Services Task Force. Ann Intern Med. 2013; 158:271–9. [PubMed: 23420235]
3. de Jong L, Lafuma A, Aguade AS, et al. Five-year extension of a clinical trial comparing the EX-PRESS glaucoma filtration device and trabeculectomy in primary open-angle glaucoma. Clin Ophthalmol. 2011; 5:527–33. [PubMed: 21607021]
4. Brandao LM, Grieshaber MC. Update on minimally invasive glaucoma surgery (MIGS) and new implants. J Ophthalmol. 2013; 2013:705915. [PubMed: 24369494]
5. Buys YM. Trabeculectomy with ExPRESS: weighing the benefits and cost. Curr Opin Ophthalmol. 2013; 24:111–8. [PubMed: 23443055]
6. Salim S. Ex-PRESS glaucoma filtration device—surgical technique and outcomes. Int Ophthalmol Clin. 2011; 51:83–94. [PubMed: 21633240]
8. Geffen N, Trope GE, Alasbali T, et al. Is the Ex-PRESS glaucoma shunt magnetic resonance imaging safe? J Glaucoma. 2010; 19:116–8. [PubMed: 19661826]
9. De Feo F, Roccatagliata L, Bonzano L, et al. Magnetic resonance imaging in patients implanted with Ex-PRESS stainless steel glaucoma drainage microdevice. Am J Ophthalmol. 2009; 147:907–11. [PubMed: 19232564]
10. Freedman J. What is new after 40 years of glaucoma implants. J Glaucoma. 2010; 19:504–8. [PubMed: 20179631]
Mabray et al. Page 6
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Highlights
• The Ex-PRESS glaucoma filtration device is a tiny metallic orbital implant.
• It can simulate a metallic orbital foreign body on imaging.
• There is little information in the literature about it’s MRI safety.
• We report 18 MRIs performed on 7 patients including the first at 3 T.
• Imaging appears to be safe at 1.5 and 3 T in patients with this device.
Mabray et al. Page 7
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 1. The Ex-PRESS glaucoma filtration device (Alcon Laboratories) placed on a penny for
reference. This device is approximately 3 mm in length. For reference a penny is 19.05 mm
in diameter (United States Mint). Photo by S.C.L.
Mabray et al. Page 8
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 2. An example of the Ex-PRESS glaucoma filtration device (Alcon Laboratories) within a
patient’s eye (arrow). This device is inserted into the anterior chamber at the limbus under a
small conjunctival or scleral flap and provides drainage of aqueous humour into the
subconjunctiva. Photo by S.C.L.
Mabray et al. Page 9
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 3. Diagram showing the method of action of the Ex-PRESS glaucoma filtration device.
Original figure from De Feo et al., Am J Ophthalmol.9 Reprinted with permission from
Elsevier Copyright Clearance Center.
Mabray et al. Page 10
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 4. (a) Non-contrast axial CT image showing the high-attenuation implants within the surface of
the globes along the anterior chamber. A small amount of metallic streak artefact is present.
(b–c) Contiguous axial T2-weighted MRI images at 1.5 T demonstrating a small amount of
magnetic susceptibility artefact associated with the implants.
Mabray et al. Page 11
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 5. Left-sided Ex-PRESS glaucoma filtration device in a patient imaged at 3 T. Note the
minimal susceptibility artefact with conventional fast spin-echo technique on this axial T2
fluid attenuated inversion recovery (FLAIR) image (a). Even with susceptibility-weighted
sequences, minimal local phase dispersion and signal loss is seen in the region of the device
on the phase map (b) and susceptibility-weighted image.
Mabray et al. Page 12
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Figure 6. Traditional larger glaucoma tube shunt on (a) axial and (b) coronal T2-weighted MRI
images. Note the large sub-scleral implanted plate along the superior-lateral globe and
associated overlying sub-scleral bleb.
Mabray et al. Page 13
Clin Radiol. Author manuscript; available in PMC 2016 May 01.
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Author M
anuscriptA
uthor Manuscript
Mabray et al. Page 14
Tab
le 1
Patie
nt c
hara
cter
istic
s an
d M
RI
exam
inat
ions
.
Age
at
firs
t M
RI
(yea
rs)
Gen
der
Lat
eral
ity
of E
x-P
RE
SSM
RI
even
tF
ield
str
engt
h (T
)In
divi
dual
MR
I ex
amin
atio
nsM
onth
s fr
om O
R
to M
RI
Mon
ths
to f
irst
eye
ex
amin
atio
nM
onth
s to
late
st
eye
exam
inat
ion
65Fe
mal
eB
ilate
ral
11.
5B
rain
172
4
62Fe
mal
eL
eft
11.
5Pe
lvis
32N
AN
A
21.
5B
rain
32N
AN
A
81Fe
mal
eL
eft
13
Bra
in a
nd n
eck
NA
NA
NA
MR
A(2
)
23
C/T
/L s
pine
3N
AN
AN
A
70M
ale
Lef
t1
3T
/L s
pine
217
28
23
L s
pine
172
8
33
T/L
spi
ne2
181
7
41.
5B
rain
230.
52
88Fe
mal
eL
eft
13
Bra
in3
0.5
11
84M
ale
Rig
ht2
1.5
Bra
in11
0.25
3
61Fe
mal
eR
ight
33
Bra
in a
nd C
spi
ne2
50.
510
Mea
n 73
5:2
1 B
ilate
ral
127a
t 3 T
18 E
xam
inat
ions
Mea
n 17
.5M
ean
1.1
Mea
n 6.
6
SD
11.
2Fe
mal
e:4
Lef
tT
otal
5 at
1.5
TSD
9.8
SD 0
.8SD
3.3
Mal
e2
Rig
ht
No
imm
edia
te o
r de
laye
d co
mpl
icat
ions
wer
e no
ted
on o
phth
alm
olog
ical
exa
min
atio
n.
SD=
Stan
dard
Dev
iatio
n. C
Spi
ne=
Cer
vica
l Spi
ne. T
Spi
ne=
Tho
raci
c Sp
ine.
L S
pine
=L
umba
r Sp
ine.
MR
A=
MR
Ang
iogr
am. T
=T
esla
. OR
=O
pera
ting
Roo
m. E
x-PR
ESS
(ex
cess
ive
pres
sure
reg
ulat
ing
shun
t sy
stem
).
Clin Radiol. Author manuscript; available in PMC 2016 May 01.