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Poster: eP- 95
NO DISCLOUSURE
Comparison of Flat Detector Computed Tomography
Angiography (FD-CTA) Using Intravenous Contrast
Injection in Evaluation of Intracranial Stents and
Adjacent Arterial Segments with Digital Subtraction
Angiography (DSA) as Gold Standard
Patro, S. MD, Almansoori, T. MD, Lum, C, MD., Thornhill, R. PhD, Iancu, D. MD
Interventional Neuroradiology Section, Diagnostic Imaging Department, The Ottawa
Hospital, University of Ottawa, Ottawa, Canada
Purpose
• Intracranial stents are now commonly used in the treatment of
aneurysms.
• Future follow up is necessary to evaluate stent patency as in-stent
stenosis or residual stenosis are not uncommon.
• The standard imaging modality to follow up such intracranial stents
is by performing conventional digital subtraction angiography (DSA)
which is an invasive costly method and carries a low complication
rate which can be serious.
• A minimally invasive follow-up imaging technique is always
desirable.
• The aim of this study is to assess the intravenous IV FD-CTA
accuracy in patients with intracranial aneurysms treated with stent
assistance in comparison to DSA as gold standard.
Materials & Methods
• Protocol:
In our hospital, all patients with Flow Diverter stent (FD)
placement and Stent Assisted Coiling (SAC) for intracranial
aneurysms treatment had the following imaging:
A) Baseline DSA , IV FD-CTA and MRI/MRA Brain.
B) 3 Months follow up DSA, IV FD-CTA and MRI/MRA Brain.
C) 12 Months follow up DSA, IV FD-CTA and MRI/MRA Brain.
Materials & Methods
• Retrospective study approved by our institutional REB.
• Duration of study: July 2015 until April 2016.
• Inclusion criteria:
- Patients treated with intracranial stents (FD and SAC).
- Follow up DSA and IV FD-CTA.
Materials & Methods
• Both DSA and IV FD-CTA were performed on a biplane flat- detector
angiographic system (Siemens AG, Healthcare Sector, Forchheim,
Germany).
• Demographic data and aneurysm characteristic were collected.
• Random, independent and blinded evaluation of DSA and IV FD-CTA
data by 2 experienced readers using a modified visual scoring
system.
Materials & Methods
• A modified visual scoring system assessing 6 criteria listed below
was adopted from: Saake, M et al, Angiographic CT with
intravenous contrast agent application for monitoring of intracranial
flow diverting stents, Neuroradiology (2012) 54:727–735. The
following were assessed:
A) Stent deployment:
1 Complete deployment
2 Partial deployment
3 No lumen distinguishable
B) Wall apposition:
1 Circumferential direct wall contact
2 Partially missing direct wall contact
3 Stent freely floating
Materials & Methods
C) Parent vessel visible:
0 No change in parent vessel diameter.
1 Narrowing of the parent artery.
2 Occlusion.
3 Not assessable.
D) Neck coverage:
1 Complete neck coverage.
2 Short proximal or distal fixing of the stent.
3 Partial neck coverage.
4 No neck coverage.
Materials & Methods
E) Aneurysm Occlusion:
1 Class I.
2 Class II.
3 Class III.
4 Not assessable.
F) In-stent stenosis:
0 No change in diameter.
1 In stent stenosis.
2 Not assessable.
Materials & Methods
• Statistical Analysis: Inter-modality agreement was assessed via
weighted kappa statistics for all 6 criteria.
•
Kappa value of:
- 0-20 = poor agreement.
- 20-40 = fair agreement.
- 40-60 = moderate agreement.
- 60-80 = substantial agreement.
- 80-100 = very good agreement.
Case 1 - Flow Diverter
63 Year old man with slurred speech and left
sided weakness.
Unenhanced CT Head demonstrated acute SAH.
Case 1 - Flow Diverter
Blister aneurysm in the posterior aspect of
the basilar artery seen in the 2nd DSA.
Case 1 - Flow Diverter
In stent balloon angioplasty
Case 1 - Flow Diverter
IV FD- CTA
Stent well applied on the
BA wall
Persistent opacification of
the aneurysm
Case 2 - Flow Diverter with coils
• 52 year old woman
with 2 incidental
aneurysms in the Rt
MCA.
• Decision to treat
using Coils and Flow
Diverter stent
Case 2 - Flow Diverter
with coils
FD stent covering
both aneurysms
Coiling distal
aneurysm
Case 2 - Flow Diverter with coils
IV FD-CTA to assess proximal coverage of
the aneurysm neck
Case 3 – Stent Assisted Coiling
Y
stent
42 year old man with incidental AComm aneurysm
Case 3 – Stent Assisted Coiling
IV FD-CTA
AXIAL
CORONAL
SAGITTAL
IV FD - CTA to check adequate apposition of the
stents.
Case 4 – Stent Assisted Coiling
IV FD - CTA to check in-stent stenosis
Results
•
56 patients underwent FD or SAC between July 2015 until April 2016.
•
39 patients were included in the study as they had DSA and IV FD-CTA.
•
17 patients were excluded
–
–
8 patients were investigated for AVMs
9 patients had IA FD-CTA without IV FD-CTA
•
Study population:
10 males.
29 females.
•
Age ranges: 39 - 74 year old - mean (59 year old).
•
34 patients had a single aneurysm. 4 patients had 2 aneurysms and 1 patient had 3
aneurysms along the diseased arterial segment.
•
2 Blister type, 4 Multilobulated and 39 Saccular aneurysms were identified.
Results
• 19 patients underwent stent assisted coiling
– 1 Neuroform
– 5 solitaire
– 13 LVIS Jr.
• 20 patients underwent FD stent placement using SILK
– 9 patients FD was used with pre-existing coils
– 11 patients had Flow Diverter stent placement without coils
• From the 39 patients in our study
– 9 patients had a baseline and 3 months follow up DSA and IV Dyna CTA
– 30 patients had only baseline DSA and IV Dyna CTA
• Overall 57 sets of imaging have been identified and randomly
submitted to the blinded readers
Results
• There was VERY GOOD agreement in the reading of both DSA and
IV FD-CTA between both readers.
• For each reader there was good correlation when reading DSA and
IV FD-CTA for:
- SILK stents without coils
- SILK stents with coils
- Stent Assisted Coiling
Results
• Solitaire stents demonstrated more metallic artifacts from their distal
markers.
• The readers encountered difficulty assessing the degree of aneurysm
occlusion when reading IV FD-CTA if coils are present which will create
metallic artifacts.
• IV FD-CTA had a superior ability to demonstrate the inner side and wall
apposition of stents in different projections (Axial, Coronal and Sagittal).
Conclusion
• The assessment of intracranial stents using intravenous FD-CTA
compares favorably with DSA.
• IV FD-CTA is:
- Feasible.
- Non-invasive.
- Can assess intracranial stent deployment and wall
apposition in different projections.
• IV FD-CTA is a promising imaging technique to follow up patients
undergoing intracranial stent placement. However, further studies
are needed to validate these results.
References
1- Saake, M et al, Angiographic CT with intravenous contrast agent application
for monitoring of intracranial flow diverting stents, Neuroradiology (2012)
54:727–735.
2- Struffert, T et al, Effective dose to patient measurements in flat-detector and
multislice computed tomography: a comparison of applications in
neuroradiology, Eur Radiol (2014) 24:1257–1265.
3- Struffert, T et al, Intravenous flat detector CT angiography for non-invasive
visualisation of intracranial flow diverter: technical feasibility, Eur Radiol
(2011) 21:1797–1801.