Here we discuss broadly applicable principles for ultrasound imaging of arterial stents, emphasizing recognition of the most common and serious complications.

1. ARRS 2016 Making
Waves:
Pearls and Pitfalls in the
Ultrasound Evaluation of
Arterial Stent Complications
AY Mian, G Gunabushanam, J Pellerito, L
Scoutt, MV Revzin
Yale University School of Medicine
New Haven, CT

2. We have no disclosures...

3. Background
• Arterial stenting is a proven and ubiquitous
treatment for arterial insufficiency; the list of
medical applications continues to grow.
• To date, there has been no generalized
radiological review of ultrasound findings
common to the various types of arterial stents.
• Here we discuss broadly applicable principles for
ultrasound imaging of arterial stents,
emphasizing recognition of the most common
and serious complications.

4. Indications for Arterial
Stents in Modern
Medical Practice• Peripheral vascular disease
• Carotid artery stenosis
• Renal artery stenosis
• Celiac/SMA
• Extremities
• Hepatic stenting,TIPS
• Cardiac
• Vasculitis, stricture

5. Types of Stents
Stent types (images used courtesy of
various industry websites) : Clockwise
from top left, a. drug eluting stent, b.
various designs for metallic stents
used in peripheral vascular disease, c.
covered stent0graft and d. metallic
expandable aortoiliac stent. These are
generally similar in appearance by
ultrasound. (Boston Scientific,
www.unmc.edu, Biotextiles 2012,
Stable Microsystems.)
a. b. c.
d.

6. Ultrasound Protocol
• Grayscale images through the stent are
obtained in sagittal and transverse plane to
look for luminal plaque, aneurysm, collections
and stent integrity.
• Color Doppler is obtained to assess stent
patency and possible stenosis (look for
aliasing).
• Spectral Doppler is obtained for peak systolic
velocities and waveforms proximal, within
and distal to the stent.

7. General US features
of Arterial Stent
Evaluation• Both greyscale and duplex evaluation
is needed
• Assess for:
• Patency: velocity/turbulence
• Location:
placement/expansion/migration
• Integrity: kinking/rupture
• Collections:
infection/leak/pseudoaneurysm

8. Dissection
Restenosis
Post-stenosis
Rupture/pseudoaneurysm
Kink
Infection
Waveforms for Common Arterial Stent
Complications

9. Complications
within the
native vessel
Complication of
the stent itself
Complications
within the stent
lumen
• dissection
• distal occlusion
• pseudoaneurysm
• stenosis distal to stent
• infection
• stent fracture
• fragmentation
• kinking
• migration
• in-stent restenosis
• juxta-stent stenosis
• in-stent occlusion
• leak
• embolus
ee Categories of Arterial Stent Complicati

10. Dissection in native
vessel proximal to stent.
History: 69yo F with
dissection proximal to
the femoral to popliteal
artery stent
Findings: Dissection flap
is seen on greyscale cine
loop (arrow) and false
lumen is noted on color
Doppler cine (arrow).
Note the distal stent (S)
is intact on the greyscale
image. Aliasing (A) on
the color Doppler image
indicates turbulent flow.
S
A

11. Occlusion distal to the
aortoiliac stent History: 72yo M with leg
pain, history of
aortobiiliac stent graft
repair of AAA
Findings: Greyscale
and power Doppler
images show no flow in
the distal SFA (arrow).
Spectral Doppler shows
no appreciable
waveform (arrow),
findings compatible
with complete SFA
occlusion.Aortobiiliac
stent-graft is seen on
coronal CT spanning a
7cm AAA (arrow) and
on a fluoroscopic image
(arrow).

12. Pseudoaneurysm
History: 45yo M without
h/o trauma presents
with a 3d h/o swelling
and left hand numbness
4 days after L subclavian
artery stent grafting
Findings: Color Doppler
images shows the stent (S)
with a focal leak just distal to
the stent margin, within the
native vessel (arrow), known
as a type 1B endoleak, and
the classic “yin-yang”
pattern (Y) within the
pseudoaneurysm from to-
and-fro flow. Angiogram
shows pseudoaneurysm
(arrow). Coronal CT shows
partial thrombosis of the
pseudoaneurysm (arrow).
S
Y

13. Pseudoaneurys
m (con’t)
3 month followup
Findings: Color Doppler image
in the same patient 3 months
later shows the patent stent (S)
with complete
pseudoaneurysm thrombosis
(arrow). Angiogram shows
resolution of the
pseudoaneurysm (arrow).
Axial and coronal CT shows the
stent (S) is patent, slightly
angulated at the distal vessel,
with complete thrombosis of
the pseudoaneurysm (arrow).
S
S

14. Stenosis Distal to the
Stent.
Findings: Long segment stenosis of
the native SFA/popliteal artery distal
to stent due to atherosclerotic
plaque (arrow). Elevated PSV in the
SFA (357cm/s) and aliasing (arrow)
seen on color and spectral Doppler.
History: 92yo F with leg pain, remote
history of SFA stent

15. Stent Infection.
Findings: The stent (S)
and an adjacent area of
heterogeneous soft
tissue without flow by
grayscale (arrows), color
Doppler (arrow) and MRI
(arrow). WBC
scintigraphy shows
uptake around the aorta,
compatible with
infection (arrow). (Note
the normal splenic
uptake.)
History: 89yo M s/p
aorto-bifemoral stent-
graft and celiac stent
presents with fever.
S
S

16. Stent Infection
(Companion case)
Findings: The stent (S) and an
adjacent area of
heterogeneous soft tissue by
grayscale (arrow), without flow
by spectral Doppler. Coronal
CT shows wall thickening and
adjacent fluid (arrow). WBC
scintigraphy shows focal
uptake in the left groin,
compatible with infection
(arrows).
History: 70yo F with
Left SFA stent
complicated by
infection/peri-stent
phlegmon
S

17. Stent Fracture and
Pseudoaneurysm
Findings: Grayscale
US shows a fracture
of the carotid stent
(arrow) . Biphasic flow
(Yin Yang) is seen
outside of the carotid
lumen on Color
Doppler (arrow) with
biphasic flow at the
neck on spectral
Doppler (B).
Radiograph shows
the stent fracture
(arrow), and a
pseudoaneurym is
seen on neck CTA
(arrow).
History: 68yo F with 2
days of neck swelling
B
B

18. Stent Fracture (companion)
Findings: Angulation of the
proximal fracture fragment
seen on grayscale (circle and
arrows) with pseudoaneurysm
(Yin-Yang) on color Doppler
(arrow).
History: 81yo M with bruit , h/o
carotid stent

19. Renal Stent Fragmentation
History: 60yo F with renal artery
stenosis presents with HTN
Findings: No abnormalities of the stent
are seen on grayscale images, color
Doppler shows only partial filling of the
lumen with color Doppler (arrow), and
elevated PSV on spectral Doppler (=324
cm/s) in the proximal stent (arrow). IR
images show fragmentation of the
proximal stent resulting in stenosis (see
next slide).

20. Renal Stent
Fragmentation (con’t)
History: 60yo F with renal artery stenosis
presents with HTN
Findings: Color Doppler shows only
partial filling of the lumen with color
Doppler (arrow). Fluoroscopic
images show fragmentation of the
proximal stent resulting in stenosis
(arrow). Subtracted angiogram
shows stenosis at the RRA origin.

21. Stent Fracture
History: 47yo F with
history of AV fistula in the
forearm presents with
swelling and pain.
Findings: Grayscale images
show a fractured loopAV
fistula in the right forearm in
sagittal (arrow) and axial
(arrow) planes . Color
Doppler shows flow in the
lumen and no
pseudoaneurysm (arrow).

22. Stent Kink
History: 61 yo M with a
kinked R SFA stent
Findings: Grayscale images
show angulation of the
kinked area with turbulent
flow (arrow). Velocities and
waveforms were normal
(arrow). Color Doppler
shows the kinked area with
turbulent flow in the lumen
(arrow) .

23. Proximal Stent
Migration
History: 81yo M with left
arm pain and swelling, h/o
of left subclavian stenosis
s/p stent in mid subclavian
artery.
Findings: Grayscale images
show left subclavian stent
has migrated proximally into
the aortic arch (arrow). Color
Doppler shows mild
retrograde flow into arch in
diastole, turbulent flow in
systole (arrows). Spectral
doppler shows an area of
stenosis and biphasic flow
(arrow). CTA shows the stent
has migrated into the aortic
arch (arrow) .Systole
Diastole

24. In-Stent Re-stenosis
Findings: Grayscale image
showing a stent (S) and in-stent
stenosis at the origin of the left
renal artery. Color Doppler
shows luminal narrowing and
turbulent flow (arrow). Spectral
Doppler shows elevated velocity
= 567cm/s (arrow) at the stenosis
and distal tardus parvus
waveforms in the left renal
parenchyma due to proximal
stenosis (arrow) .
History: 65-year-old F s/p partial
right nephrectomy with left renal
artery stenosis at the ostium,
status post stent placement,
presenting with hypertension.
S

25. In-Stent Re-stenosis
(Companion case)
Findings: Grayscale image
showing a stent (S) and in-
stent stenosis in the L SCA
(arrow) . Spectral Doppler
shows elevated velocity (= 375)
cm/s (circle) and high
resistance waveforms (arrow).
Angiogram shows the area of
focal re-stenosis (arrow).
History: 55-year-old F with
subclavian stent placed for
stenosis presents with recurrent
arm painS

26. In-Stent Occlusion
with collateral
Findings: Power Doppler shows
luminal occlusion (arrow) with
collateral formation (arrow) .
Color Doppler image shows
distal reconstitution (arrow)
History: 70yo M with left distal
CFA stent presents with pain.
S

27. Progressive Stent
Thrombosis/Emb
olism
History: 60yo M with high grade
carotid stenosis,TIA 1 day after
LCCA stent.
Findings: Color Doppler shows
severe luminal narrowing and
turbulent flow (arrow) within the
stent (s) . Angiogram shows
filling defects consistent with
foci of severe in-stent stenosis
(arrow). Spectral Doppler shows
elevated velocity (=273 cm/s)
(circle) and compensatory low
diastolic resistance (arrow) at the
stenosis
s

28. (Con’t) Now
complete stent
thrombosis/dista
nt embolism
Findings: Color Doppler
now shows complete
occlusion (arrow). CTA
shows thrombosed lumen
(arrow). Acute infarcts in
the brain are now seen with
restricted diffusion on
DWI/ADC (arrows).
History: 60yo M with
high grade carotid
stenosis,TIA 1 day
after LCCA stent,
now with aphasia.

29. Stent Malposition with
Pseudoaneurysm
Findings: Color Doppler
shows a malpositioned
carotid stent (S) and a
retained catheter fragment
(arrow), and a
pseudoaneurysm is seen
(arrow). Biphasic flow (Yin
Yang) is seen outside of the
carotid lumen on Color
Doppler. RCCA angiogram
shows wide-necked,
contained pseudoaneurysm
(arrow).
History: 72yo M with
neck pain and
swelling, s/p carotid
stent
S

30. History: 62yo male
with bruit, h/o RCCA
stent 4 years ago.
Candy wrapper re-
stenosis distal to the
stent
Findings: Color
Doppler shows
luminal narrowing
and turbulent flow
(arrow). Spectral
Doppler shows
elevated velocity
(arrow) at the
stenosis.
Angiogram shows
RCCA re-stenosis at
the distal edge of
the stent (arrow).

31. • Tortuosity branch versus stenosis,
• Poorly selected angle: false versus elevated
velocities,
• Occlusion – use of power doppler/lower
scale,
• Kinking versus breakage,
• Junction of stents versus rupture,
• High velocities/turbulence versus bruit
artifact.
Pitfalls in Diagnosis

32. Pitfall: tortuous vessel
causing elevated velocity

33. Findings: Grayscale and
color Doppler show
narrowing of the lumen due
to external compression
from the plaque that was
there when stent was
placed, it didn’t fully expand
the lumen (arrow) .
History: 50yo M with
no symptoms,
carotid stenosis s/p
stent.
Pitfall: pre-existing plaque
mistaken for re-stenosis

34. Stent pitfall- no flow due
to post-operative air
History: 64yo M s/p R axillary
pseudoaneurysm repair with
thrombin injection, presents with
pain and cold digits. IR performed
the procedure on the same day and
found the stent was patent .
Findings: Grayscale image shows
the stent (s) but deeper structures are
not well seen (arrow) due to dirty
shadowing. Color Doppler shows flow
on either side of the dirty shadowing
(arrow). Power Doppler shows flow
throughout the stent (arrow).
Spectral Doppler initially shows no
flow (arrow) in the stent, but once an
appropriate angle is chose without
intervening air, normal flow is seen
(F).
s
F

35. Pitfall: Bulging portion of stent
in carotid, can mimic pseudoaneurysm,
cause turbulent flow.

36. Summary Points
• Ultrasound is a reliable, powerful and cost-effective means
of evaluating arterial stents.
• By keeping in mind basic protocol methods and avoiding pitfalls that
lead to erroneous findings, ultrasound proves vital for assessing arterial
stents.
• Complications are common in arterial stents, and will become more
common as their uses expand.
• In-stent stenosis, occlusion, fracture and fragmentation are readily
diagnosed by ultrasound, and have characteristic imaging features.
Pseudoaneurysm, and infection are important complications that
warrant a high index of suspicion.
• Further investigation into the imaging appearance of the newer stents
on the market may prove useful as these effective devices continue to
find new applications.

37. References
1. Sohgawa E, SakaiY, Nango M, Cho H, Jogo A, Hamamoto S,Yamamoto A, MikiY. Mid-term Results of EndovascularTreatment for
InfrarenalAortic Stenosis and Occlusion. Osaka City Med J. 2015 Jun;61(1):1-8. PubMed PMID: 26434100.
2. Salsamendi J, Pereira K, Baker R, Bhatia SS, Narayanan G. Successful technical and clinical outcome using a second generation
balloon expandable coronary stent for transplant renal artery stenosis: Our experience. J RadiolCase Rep. 2015 Oct 31;9(10):9-17.
doi: 10.3941/jrcr.v9i10.2535. eCollection 2015 Oct. PubMed PMID: 26629289; PubMed Central PMCID: PMC4638400.
3. LiW, Dai Z,Yao L, Luo J,Yan Z. Chemoembolization and stenting combined with iodine-125 seed strands for the treatment of
hepatocellular carcinoma with inferior vena cava obstruction. ExpTher Med. 2015 Sep;10(3):973-977. Epub 2015 Jun 18. PubMed
PMID: 26622424; PubMed Central PMCID: PMC4533169.
4. Ching KC, Santos E, McCluskey KM, Orons PD, Bandi R, FriendCJ, Xing M, ZureikatAH,Zeh HJ. Covered Stents and Coil
Embolization forTreatment of PostpancreatectomyArterial Hemorrhage. JVasc Interv Radiol. 2015 Nov 20. pii: S1051-
0443(15)00968-9. doi: 10.1016/j.jvir.2015.09.024. [Epub ahead of print] PubMed PMID: 26611883.
5. Adigopula S, Nsair A. Images in Clinical Medicine. Left Main CoronaryArteryStent Migration. N Engl J Med. 2015 Nov
12;373(20):1957. doi: 10.1056/NEJMicm1500200. PubMed PMID: 26559574.
6. Wang DS,Ganaha F, Kao EY, Lee J, Elkins CJ, Waugh JM, Dake MD. Local Stent-Based Release ofTransforming Growth Factor-β1
Limits Arterial In-Stent Restenosis. J Lab Autom. 2015 Oct 13. pii: 2211068215611040. [Epub ahead of print] PubMed PMID:
26464421.
7. Bourdon E, Schüller K, Diehl S.The role of clinical evidence in emergent therapies: an empirical study on femoropopliteal stent-
angioplasty in Europe. J Eval Clin Pract. 2015 Oct 8. doi: 10.1111/jep.12461. [Epub ahead of print] PubMed PMID: 26446576.