Endovascular Embolization of the Swine Rete Mirabile with Eudragit-E 100 Polymer
H. Arakawaa,d,
Y. Murayamad,
C.R. Davisc,
D.L. Howarda,
W.L. Baumgardnera,
M.P. Marksa,b and
H.M. Doa,b
a Department of Radiology, Stanford University Medical Center, Stanford, Calif
b Department of Neurosurgery, Stanford University Medical Center, Stanford, Calif
c Department of Comparative Medicine, Stanford University Medical Center, Stanford, Calif
d Department of Neurosurgery, The Jikei University School of Medicine, Tokyo, Japan

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Fig 1. Anteroposterior view of the angiograms of swine retia injected with Eudragit mixture (pig 8). Left upper, Control angiogram before embolization shows the rete (arrow). Each rete is located between the ascending pharyngeal artery (arrowhead) and the internal carotid artery (white arrow). Right upper, Immediately after embolization of the rete with Eudragit mixture. Left lower, Angiogram 3 months after the embolization with Eudragit mixture shows complete obliteration of left rete. Right lower, Embolized Eudragit can be seen as radiopaque cast on the nonsubtracted image (white arrowhead).
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Fig 2. Anteroposterior view of the angiograms shows recanalization 1 month after embolization with Eudragit mixture (pig 4). Left upper, Before embolization. Right upper, Immediately after embolization of the rete with Eudragit mixture. Lower, One month after embolization. The rete shows complete recanalization.
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Fig 3. Histopathology of retia obtained at acute stages after embolization with 10% Eudragit mixture. Upper left, Embolized Eudragit polymer appears as intraluminal eosinophilic material accompanied by a thrombus. Empty spaces are shrinkage artifact due to processing. Upper right, Neutrophils and mononuclear cells infiltrate the vessel wall and adventitia. Lower, The internal elastic membrane is partially disrupted (arrow). Upper left, H&E, original magnification x100. Upper right, H&E, original magnification x400. Lower, Elastica-van Gieson, original magnification x400.
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Fig 4. Chronic response of vessels embolized with Eudragit mixture. Upper, One month after embolization. Arteritis and endarteritis consisting of lymphocytes, plasma cells, and macrophages. Lower, Three months after embolization. Embolized arteries show necrosis, loss of normal profiles, calcification, and fibrosis. Upper, H&E, original magnification x100. Lower, H&E, original magnification x100.
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Fig 5. Photomicrographs of recanalized retia after embolization with Eudragit mixture. Left, (pig 4) Note the patent lumen containing several erythrocytes (thin arrow) and the embolized lumen (thick arrow), both in the same embolized artery. The empty spaces in the embolized lumen are due to dissolution of the polymer during processing. This change may represent a step in recanalization. The patent lumen may be sequestered from the embolized vessel. Right, (pig 6) Small patent vessels are present within the embolus. This finding is also noted with n-BCA embolization. Left, H&E, original magnification x400. Right, H&E, original magnification x100.
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