Choosing The Right Size Particle. Gary Siskin, MD FSIR Professor and Chairman Department of Radiology Albany Medical Center Albany, New York

Transcription

1 Choosing The Right Size Particle Gary Siskin, MD FSIR Professor and Chairman Department of Radiology Albany Medical Center Albany, New York

2 Gary Siskin, M.D. Consultant/Advisory Board: Boston Scientific, Embomedics, Biocompatibles, Medtronic Research Grants: Boston Scientific, Embomedics, Biocompatibles, Medtronic

3 Introduction Imagine this

4 Introduction Imagine this For every clinical condition that warrants the use of particulate embolization for treatment, there is a correct particle size. This means that the correct particle will get to the correct place and result in the best clinical outcome possible.

5 Introduction The problem... In some situations, we know what particle to use and in others, we probably do not. There is no universal table or chart that can be prepared to answer this question for every conceivable clinical situation.

6 Introduction However... I believe that there is a thought process that should be followed to help you determine the right size particle.

7 Pathologic Findings Clinical Data Material Characteristics Particle Selection

8 Pathologic Findings Clinical Data Material Characteristics Particle Selection

9 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same.

10 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Important Characteristics Size Distribution Aggregation Compressibility & Elastic Recovery Visibility Pelage JP. Interventional News 2009; 11:32

11 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Particles vs. Microspheres In general, irregularly shaped particles aggregate more than microspheres and can therefore cause a more proximal occlusion than microspheres. Consider the use of smaller particles compared to microspheres.

12 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Microspheres vs. Microspheres The different microspheres on the market differ primarily in the packaged size ranges, compressibility, and elastic recovery.

13 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Microspheres vs. Microspheres The different microspheres on the market differ primarily in the packaged size ranges, compressibility, and elastic recovery. Size (Narrow vs. Broad Size Ranges): Consider a smaller particle size to treat a more distal target.

14 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Microspheres vs. Microspheres The different microspheres on the market differ primarily in the packaged size ranges, compressibility, and elastic recovery Compressibility: More compressible agents can potentially travel further in the target vascular bed, causing a more distal occlusion. Consider a larger particle when using a compressible particle.

15 Material Characteristics It should be apparent to everyone here that all particulate embolic agents are not the same. Microspheres vs. Microspheres The different microspheres on the market differ primarily in the packaged size ranges, compressibility, and elastic recovery Elastic Recovery: Less elastic recovery means that the agent will not be restored to its baseline size after being compressed. Consider a larger particle when using a particle with diminished elastic recovery.

16 Pathologic Findings Clinical Data Material Characteristics Particle Selection

17 Pathologic Findings Clinical Data Material Characteristics Particle Selection

18 Uterine Fibroid Embolization This is a great example of how to apply this algorithm because we have a lot of well-documented clinical experience as well as a good understanding of the pathology being treated.

19 Uterine Fibroid Embolization Pathology Information to Know Fibroid Vasculature The perifibroid plexus is composed of enlarged arterial branches measuring microns in diameter. This is our target for uterine fibroid embolization. Holmgren B. Acta Obstet Gynecol Scand 1938; 18:

20 Uterine Fibroid Embolization Pathology Information to Know Ovarian Anastomoses The diameter of the uteroovarian anastomosis in women with fibroids is usually <500 microns in diameter. These are the vessels we want to avoid during uterine fibroid embolization. Pelage JP, et al. J Vasc interv Radiol 2003; 14:15-20

21 Uterine Fibroid Embolization Pathology The pathology information supports the use of microspheres that are >500 microns in diameter.

22 Uterine Fibroid Embolization Pathology The pathology information supports the use of microspheres that are >500 microns in diameter. Does the clinical data support this recommendation?

23 Uterine Fibroid Embolization Clinical Data Embosphere Microspheres Several studies demonstrate that the micron size microspheres are effective for UFE. Spies JB, et al. J Vasc Interv Radiol 2001; 12: Banovac F, et al. J Vasc Interv Radiol 2002; 13: Pelage JP, et al. J Vasc Interv Radiol 2003; 14:15-20 Spies JB, et al. Am J Obstet Gynecol 2004; 191:22-31 Spies JB, et al. J Vasc Interv Radiol 2005; 16: Lohle PN, et al. J Vasc Interv Radiol 2006; 17: Siskin GP, et al. J Vasc Interv Radiol 2008; 19:58-65 Scheurig-Muenkler C, et al. J Vasc Interv Radiol 2010; 21: Yu SCH, et al. J Vasc Interv Radiol 2011; 22:

24 Uterine Fibroid Embolization Clinical Data PVA Particles Several studies demonstrate that nonspherical PVA microns in diameter are effective for UFE Ravina JH, et al. Lancet 1995; 346: Goodwin SC, et al. J Vasc Interv Radiol 1997; 8: Worthington-Kirsch RL, et al. Radiology 1998; 208: Spies JB, et al. J Vasc Interv Radiol 1999; 10: Siskin GP, et al. J Vasc Interv Radiol 2000; 11: Spies JB, et al. Obstet Gynecol 2001; 98:29-34 Pelage JP, et al. Radiology 2004; 230:

25 Uterine Fibroid Embolization Clinical Data PVA Particles It has been well-established that PVA particles can aggregate and therefore result in an embolization that is more proximal than intended. Given this fact, the use of PVA particles measuring microns in diameter has been studied and is effective as well. Siskin GP, et al. J Vasc Interv Radiol 2000; 11: Pron G, et al. Fertil Steril 2003; 79: Das R, et al. Cardiovasc Intervent Radiol 2013; 36:

26 Uterine Fibroid Embolization Recommendation Given the fact that the pathologic findings suggest the use of particles >500 microns in diameter and the clinical data supports the use of particles measuring >500 microns in diameter, this has become the correct particle size to use for UFE (modifications can be made based on the characteristics of the embolic agent).

27 Bronchial Artery Embolization Pathologic Findings Clinical Data Material Characteristics Particle Selection

28 Bronchial Artery Embolization Pathology Information to Know Bronchopulmonary arterial anastomoses exist in the lungs. These occur between the pulmonary and bronchial arteries located on the bronchi. The diameters of the bronchial arteries involved in this type of anastomosis range from μin diameter. Pump KK. Chest 1972; 62:

29 Bronchial Artery Embolization Pathology Information to Know Anastomoses may also be present between the bronchial arteries and pulmonary veins, primarily in the pleura and within the bronchial walls. Hayek Hv. The Human Lung. New York. Hafner Publishing Co., Inc. 1960

30 Bronchial Artery Embolization Pathology Information to Know Bronchial arteries also supply the middle 1/3 of the esophagus, the diaphragmatic and mediastinal visceral pleura, and vasa vasorum of the aorta and pulmonary artery. Marshall TJ & Jackson JE. Eur Radiol 1997; 7:

31 Bronchial Artery Embolization Pathology These pathologic findings support the use of particles that are greater in size than 350μ in diameter. This can help to reduce (or eliminate) the risk of pulmonary infarction via bronchial artery-pulmonary artery shunts, systemic embolization via bronchial artery-pulmonary vein shunts, or nontarget embolization to the esophagus or aortic wall. Yoon W, et al. Radiographics 2002; 22:

32 Bronchial Artery Embolization Pathology There is no data to support the use of particles larger than 500μin diameter for the purpose of minimizing the risk of spinal cord infarction although that is a commonly held belief. Lorenz J, et al. Semin Intervent Radiol 2012; 29:

33 Bronchial Artery Embolization Clinical Data & Material Characteristics Clinical studies have reported the effectiveness of bronchial artery embolization with particles greater in size than 350 microns in diameter. Spherical agents greater in size than 500 microns in diameter have been used successfully as well. Yoon W, et al. Radiographics 2002; 22:

34 Bronchial Artery Embolization Recommendation Based on this review, the correct particle size is one that is at least 350 microns in diameter. Yoon W, et al. Radiographics 2002; 22:

35 Conclusion I believe that there is a correct particle size for each of the clinical indications being treated today with particulate embolization. Thinking about this question in this manner will help you determine the appropriate size (and appropriate agent) for different clinical conditions.