EP- 104 EVALUATION OF VISUAL

CONTROL DURING FLUOROSCOPIC ONYX® (EVOH)

INJECTIONS USING A NOVEL CALIBRATED VASCULAR MODEL

 James Ryan Mason, DO, MPH 1, Guyla Gal, MD2, Goetz Benndorf, MD, PhD 2

1 Swedish Medical Center, Seattle, Washington2 University of Southern Denmark, Odense

Disclosures:

JRM: None

GB: None

Gal: Consultant - Balt Extrusion

Consultant - Penumbra

Purpose:Onyx® is a well established non-adhesive liquid embolic agent for the

endovascular treatment (EVT) of brain arteriovenous malformations (AVMs).

• Comprised of Ethylene-Vinyl Alcohol copolymer (EVOH), tantalum powder for radiopacity in Dimethyl sulfoxide (DMSO) solvent, it offers some advantages over traditional adhesive liquids such as NBCA (acrylic glue) and has improved feasibility and safety of EVT of cerebral arteriovenous (AV) shunting lesions.

• Nevertheless, complications may occur, potentially attributable in part to its inferior radiographic visibility when compared to standard iodine-based vascular contrast medium.

Purpose:• We hypothesize that some of

these complications may be the result of loss of visual control during therapeutic Onyx® injections under fluoroscopy with subsequent “silent migration” or invisible reflux into small terminal arteries or via “dangerous anastomoses” causing inadvertent occlusion of normal territories.

• The purpose of this study was to evaluate the radiographic visualization of Onyx® in comparison to iodine-based contrast medium using a newly developed calibrated vascular model and state-of-the-art angiographic equipment.

Thalamoperforators

Thalamoperforators

Thalamoperforators (Rr. diencephalici inf.post.) may arise from the P1 segment, basilar artery or superior cerebellar

artery an can measure between 0.1 and 1.0 mm. They give off mammillary branches measuring between 0.12 and

0.37mm (120-370 micron) after Lang and Brunner, 1978. Drawing modified after J. Lang (Lanz & Wachsmuth,

Springer 1985)

Purpose:Many essential perforating cerebral vessels are known to have diameters as small as 120 microns and average in outer diameters ranging from 330 to 520 microns.

Given these known vessel sizes, we devised a model to test visualization of onyx between 100 and 500 microns.

Clival branches - “dangerous

anastomoses” from ECA to ICA

Thalamoperforators

This stepwise reduced diameter model was then connected to a microcatheter which allow for injections very similar to clinical

scenarios

Microcatheter

Microcatheter

500μ

350μ 250μ 175μ 100μ

Methods: A vascular model was built using tubing of stepwise reduced calibrated inside diameters: 500 microns, 380 microns, 250 microns, 175 microns

and 100 microns.

Methods:

The Model had identical outside diameters.

Small Gaps between different sections allows for easy visual identification that radiopaque material has passed through preceding section.

500μ

380μ 250μ 175μ 100μMicrocatheter Microcatheter

Methods: Philips Allura system under the following settings: • Cerebral 2 f/sec • Unsubtracted DSA• “Blank” Roadmap in• “Embo”- Mode 3 (high dose) • FD size = 6 inch• SID = 90 • Table Height = +5

Microcatheter Microcatheter

500μ

380μ 250μ 175μ 100μ

Injections performed with the following:

• Contrast - Standard vascular Iodine contrast medium (non-diluted Omnipaque® 300)

• Onyx – Onyx®-18, Ethylene-Vinyl Alcohol copolymer (EVOH), tantalum powder for radiopacity in Dimethyl sulfoxide (DMSO) solvent

Microcatheter

Microcatheter

Model

Model

Results: Model injected with contrast, unsubtracted DSA

Contrast in tubing

Results: Model injected with contrast, unsubtracted DSA

Model

Model

Results: Model injected with contrast, unsubtracted DSA

Microcatheter Microcatheter

Results: Model injected with contrast, unsubtracted DSA

Contrast entering

Contrast leaving

MicrocatheterMicrocatheter

Results: Model injected with contrast, unsubtracted DSA

Contrast in gaps between tubing

Small Gaps between different sections allows for easy visual identification that radiopaque material has passed through preceding section.

Results: Model injected with contrast, unsubtracted DSA

500μ

380μ 250μ 175μ 100μ

Contrast in tubing

500μ

380μ 250μ 175μ 100μ

The Model had identical outside diameters.

Results: Model injected with contrast, unsubtracted DSA

500μ

350μ 250μ 175μ 100μ

Stepwise reduced inside diameters

500μ

380μ 250μ 175μ 100μ

Mic

roca

thet

er

Mic

roca

thet

er

Results: Model injected with contrast, Roadmap

500μ

350μ 250μ 175μ 100μ

500μ

380μ 250μ 175μ 100μ

Stepwise reduced inside diameters

Mic

roca

thet

er

Mic

roca

thet

er

Results: Model injected with contrast, Roadmap

Microcatheter

Microcatheter

Contrast in gaps between tubing

Results: Onyx® vs. Contrast, unsubtracted DSA

Onyx

Contrast

Microcatheter

Microcatheter

Microcatheter

Microcatheter

Results: Onyx® vs. Contrast, unsubtracted DSA

Onyx

Contrast entering

Contrast leaving

Onyx entering

Oynx exiting

Contrast

Results: Onyx® vs. Contrast, unsubtracted DSA

Onyx seen in gaps between tubing

Contrast seen in gaps between tubing

Onyx

Contrast

Results: Onyx® vs. Contrast, unsubtracted DSA

500μ

380μ 250μ 175μ 100μ

Stepwise reduced inside diameters

Stepwise reduced inside diameters

350μ 250μ 175μ 100μ500μ

Onyx

Contrast

500μ

380μ 250μ 175μ 100μ

Mic

roca

thet

er

Mic

roca

thet

er

Results: Onyx® vs. Contrast, unsubtracted DSA

500μ

380μ 250μ 175μ

Beginning loss of visualization of contrast around 175 micron.

350μ 250μ 175μ 100μ500μ

Onyx

Contrast

500μ

380μ 250μ

Beginning loss of visualization of Onyx around 250 microns.

Mic

roca

thet

er

Mic

roca

thet

er

Results: Onyx® vs. Contrast, Roadmap

Onyx

500μ

380μ 250μ 175μ 100μ

Contrast

350μ 250μ 175μ 100μ500μ

500μ

380μ 250μ 175μ 100μ

Mic

roca

thet

er

Mic

roca

thet

er

Results: Onyx® vs. Contrast, Roadmap

Onyx seen entering gaps

Contrast seen entering gaps

Contrast

350μ 250μ 175μ 100μ500μ

Onyx

Mic

roca

thet

er

Mic

roca

thet

er

Results: Onyx® vs. Contrast, Roadmap

Beginning loss of visualization of contrast around 250 microns.

Contrast

500μ

380μ

500μ

380μ 250μ

350μ 250μ 175μ 100μ500μ

OnyxBeginning loss of visualization of Onyx® around 380 microns.

Mic

roca

thet

er

Mic

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er

Conclusions 1:

1. A newly designed calibrated vascular model allowed evaluation and

comparison of radiographic visualization of contrast medium and a

liquid embolic agent under standardized and reproducible

experimental conditions.

2. Visualization of both contrast and Onyx®-18 is under “blank” Road

Map is inferior compared to unsubtracted DSA.

3. Loss of visual control during therapeutic injections of liquid embolic

agents, such as Onyx®-18 may occur earlier than previously known,

and thus may be associated with the risk of “silent migration” into

small perforating arteries, “dangerous anastomoses” or reflux

channels with potentially serious clinical consequences.

Conclusions 2:

1. This is to our knowledge the first visualization test for a

liquid embolic using a vascular model with a stepwise

calibrated decreasing diameter to simulate flux

conditions comparable to human vasculature.

2. This model could also be used to help test and calibrate

fluoroscopy and angiographic machines, compare

visualization between different manufacturers, as well

as test visualization of various contrast and liquid

embolic agents.

References:

1. Loffroy R, Guiu B, Cercueil J, Krause D. Endovascular

therapeutic embolisation: An overview of occluding agents and

their effects on embolised tissues. Current vascular

pharmacology. 2009;7(2):250-263.

2. Lang J. Clinical anatomy of the head: Neurocranium, orbit,

craniocervical regions. Springer-Verlag; 1983.

3. Brunner FX: Über die Arterien des Hirnstammes. Vorkommen,

Zahl, Durchmesser und Variationen. Thesis 1978, University

Würzburg.