Neurointervention.  2017 Mar;12(1):3-10. 10.5469/neuroint.2017.12.1.3.

In Vitro Quantification of the Radiopacity of Onyx during Embolization

• Jiang YY
• Jo YE
• Woo JM
• Lim OK
• Hwang C
• Maeng JY
• Kim J
• Kim N
• Lee DH

• KMID: 2371753
• DOI: http://doi.org/10.5469/neuroint.2017.12.1.3

Abstract

PURPOSE
Onyx has been successfully applied in the treatment of various neurovascular lesions. However, some experience is required to get accustomed to its unpredictable fluoroscopic visibility during injection. This in vitro study aimed to evaluate the characteristics of radiopacity change in a simulated embolization procedure.
MATERIALS AND METHODS
Using a bench-top Onyx injection experiment simulating a typical brain arteriovenous malformation embolization, nine cycles of casting modes (continuous injection) and plugging modes (injection with intermittent pauses) were performed. Radiodensity of Onyx droplets collected from the microcatheter tip and the distal head portion of the microcatheter were measured as time lapsed. Distribution of droplet radiodensity (radiodensity) and distribution of radiographic grade (grade) were analyzed and compared by repeated measurements.
RESULTS
Within-group analysis revealed no significant radiodensity change with time (P>0.05). The radiodensity was significantly higher in the casting mode than in the plugging mode (P<0.01). The lateral radiograph of the microcatheter showed higher radiopacity (P<0.01) and better evenness (P<0.01) in the casting mode than in the plugging mode. A significant difference in microcatheter attenuation (both radiographic grade mean and SD; P<0.01) was noted between the two modes. Radiodensity had a significant influence on the radiopacity and radiopacity evenness of the microcatheter.
CONCLUSION
The radiopacity of the Onyx can vary significantly over time because of early precipitation of tantalum powder. Radiopacity decreased significantly during plugging modes, characterized by pauses between injections.

Keyword

Onyx; Liquid embolic material; Brain arteriovenous malformations; Embolization

MeSH Terms

Arteriovenous Malformations
Brain
Head
In Vitro Techniques*
Tantalum
Tantalum

Figure

• 

  Fig. 1 (A) The bench-top set up of the in vitro experiment simulating the head and body of a patient during a typical brain AVM embolization using Onyx. The microcatheter was adhered to the plate along the imaginary course of the main feeder of a medial parietal cortical brain AVM. Under the very tip of the injecting microcatheter a 48-well-cell-culture plate was placed to collect the Onyx droplets to be radiographed. (B, C, D) Collection of the Onyx droplets (B) Close-up image showing the 48-well-cell-culture plate placed under the injecting microcatheter tip. (C) Image of a 48-well-cell-culture plate filled with Onyx droplets in each well. (D) The radiograph of the same culture plate filled with Onyx droplets. This image was transferred to ImageJ for the measurement of the radiodensity of each droplet.

• 

  Fig. 2 Time-radiodensity curves of all nine Onyx injection cycles (upper row) and representative radiographic images of the distal head portion of the microcatheter in (A) casting mode (black solid line) and (B) plugging mode (black dash line) of the 5th cycle. An X-ray attenuation (radiodensity) curve for each droplet from all casting and plugging mode cycles demonstrating the dynamic change of X-ray units with time lapse and dramatic change of the radiodensity in the two modes. We graded all 12 segments of image A as grade 2. Image B segments were grade 0, except for segments 3, 8, and 11, which were grade 1.

• 

  Fig. 3 (A) Sequential change of droplet radiodensity with 95% confidence intervals (CIs) in casting mode and plugging mode (repeated measures). The unit of radiodensity is X-ray unit standing for X-ray attenuation. (B) Sequential change of the mean value of the microcatheter radiographic grade with 95% confidence intervals (CIs) in casting mode and plugging mode (repeated measures). (C) Sequential change of the standard deviation (SD) of the microcatheter radiographic grades with 95% confidential intervals (CIs) in casting mode and plugging mode (repeated measures). (D) Scatter plot of the droplet radiodensity and the mean of the microcatheter radiographic grades. (E) Scatter plot of the droplet radiodensity and the standard deviations (SDs) of the microcatheter radiographic grades.

Reference

1. Katsaridis V, Papagiannaki C, Aimar E. Curative embolization of cerebral arteriovenous malformations (AVMs) with Onyx in 101 patients. Neuroradiology. 2008; 50:589–597. PMID: 18408923.

2. Mounayer C, Hammami N, Piotin M, Spelle L, Benndorf G, Kessler I, et al. Nidal embolization of brain arteriovenous malformations using Onyx in 94 patients. AJNR Am J Neuroradiol. 2007; 28:518–523. PMID: 17353327.

3. van Rooij WJ, Jacobs S, Sluzewski M, van der Pol B, Beute GN, Sprengers ME. Curative embolization of brain arteriovenous malformations with onyx: patient selection, embolization technique, and results. AJNR Am J Neuroradiol. 2012; 33:1299–1304. PMID: 22383233.

4. Terada T, Nakamura Y, Nakai K, Tsuura M, Nishiguchi T, Hayashi S, et al. Embolization of arteriovenous malformations with peripheral aneurysms using ethylene vinyl alcohol copolymer. Report of three cases. J Neurosurg. 1991; 75:655–666. PMID: 1885987.

5. Yamashita K, Taki W, Iwata H, Nakahara I, Nishi S, Sadato A, et al. Characteristics of ethylene vinyl alcohol copolymer (EVAL) mixtures. AJNR Am J Neuroradiol. 1994; 15:1103–1105. PMID: 8073979.

6. Siekmann R. Basics and Principles in the Application of Onyx LD Liquid Embolic System in the Endovascular Treatment of Cerebral Arteriovenous Malformations. Interv Neuroradiol. 2005; 11(Suppl 1):131–140.

7. van Rooij WJ, Sluzewski M, Beute GN. Brain AVM embolization with Onyx. AJNR Am J Neuroradiol. 2007; 28:172–177. PMID: 17213451.

8. Lv X, Wu Z, Li Y. Arteriovenous malformation in the brain: a theoretical study explaining the behavior of liquid embolic agents during endovascular treatment. Neuroradiol J. 2013; 26:661–668. PMID: 24355185.

9. Weber W, Kis B, Siekmann R, Kuehne D. Endovascular treatment of intracranial arteriovenous malformations with onyx: technical aspects. AJNR Am J Neuroradiol. 2007; 28:371–377. PMID: 17297015.

10. Chaloupka JC, Huddle DC, Alderman J, Fink S, Hammond R, Vinters HV. A reexamination of the angiotoxicity of superselective injection of DMSO in the swine rete embolization model. AJNR Am J Neuroradiol. 1999; 20:401–410. PMID: 10219404.

11. Murayama Y, Vinuela F, Ulhoa A, Akiba Y, Duckwiler GR, Gobin YP, et al. Nonadhesive liquid embolic agent for cerebral arteriovenous malformations: preliminary histopathological studies in swine rete mirabile. Neurosurgery. 1998; 43:1164–1175. PMID: 9802860.

12. van Beijnum J, van der Worp HB, Buis DR, Al-Shahi Salman R, Kappelle LJ, Rinkel GJ, et al. Treatment of brain arteriovenous malformations: a systematic review and meta-analysis. JAMA. 2011; 306:2011–2019. PMID: 22068993.

13. Durst CR, Starke RM, Gaughen J, Evans AJ. A method for complete angiographic obliteration of a brain arteriovenous malformation in a single session through a single pedicle. J Clin Neurosci. 2015; 22:391–395. PMID: 25439751.