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Abstract No. 41: Reducing Risk and Stabilizing the Vertebral Body in Advanced Metastatic Spine Lesions: A Combined Approach Using Plasma-Mediated Tumor Ablation and Cement Augmentation
5:48 PM
Abstract No. 41
Reducing Risk and Stabilizing the Vertebral Body in Advanced Metastatic Spine Lesions: A Combined Approach Using Plasma-Mediated Tumor Ablation and Cement Augmentation. B. Georgy; UCSD Medical Center, San Diego, CA. PURPOSE: Combining percutaneous plasma-mediated radiofrequency ablation with vertebral body cement augmentation offers a less invasive treatment option for advanced metastatic spinal lesions and is particularly useful for cases with cortical destruction and / or epidural extension. Advanced spinal metastases are often considered contraindications for vertebroplasty or kyphoplasty, but this combined approach could offer a third option which is both clinically viable and safe for these patients. This study evaluated bone cement deposition patterns and extravasation in treated vertebral bodies in relation to the metastatic lesion, as well as pain relief, after using this combined approach. MATERIALS & METHODS: A void is created in the anterior portion of the tumor-infiltrated vertebral body using a bipolar plasma radiofrequency-based wand (ArthroCare Corporation, Austin, TX), followed by deposition of bone cement. Retrospective assessments of CT images performed before/after the procedures were evaluated in 37 patients (44 levels) with advanced metastatic lesions. All patients reported pain status (VAS) pre-procedure and 2-4 weeks afterwards. RESULTS: 90-100% of the cement was deposited in the anterior 2/3 of the vertebral body in 19 levels (43%), while 75-90% of the cement was deposited in this region in 16 levels (36%). In 13 of 15 levels with posterior lesions (86%), cement deposited anterior to the lesion. 13 levels showed no extravasation (29.5%). Two clinically insignificant incidences of epidural cement extravasation recorded. Pain relief was reported by 25 of 28 patients (89.5%) after the procedure. CONCLUSION: Plasma-mediated radiofrequency ablation allows greater control over cement for a relatively predictable deposition pattern with only clinically insignificant cement extravasation, increasing the likelihood of stabilizing the anterior 2/3 of the vertebral body. This treatment may eventually replace extensive anterior surgical stabilization techniques as it minimizes surgical invasiveness for high-risk cancer patients. This technique appears to be most successful in cases with posterior-located lesions, and offers excellent post-procedure pain relief.
Scientific Session 5 The Interventional Scientist Sunday, March 8, 2009 4:00 PM - 6:00 PM Room: 16B 4:00 PM
Abstract No. 42
Mouse Arteriovenous Fistula Model. S. Misra, B. Yang, U. Shergill, A.A. Fu; Mayo Clinic, Rochester, MN. PURPOSE: The aim of the present study was to create a mouse arteriovenous fistula (AVF) model in a mouse and determine the expression of matrix metalloproteinase-2 expression at the venous stenosis. S18
MATERIALS & METHODS: Twelve FEV1 mice underwent the creation of an AVF between the left carotid artery to ipsilateral jugular vein with the contralateral vessels serving as controls. The animals were sacrificed at day 28 (N⫽6) and day 56 (N⫽6) after fistula creation. Immunohistochemistry for ␣-smooth muscle actin and MMP-2 were performed at the venous stenosis and control vessels along with morphometric analysis to quantify the amount of stenosis. RESULTS: Venous stenosis formed at the outflow vein which was characterized by a thickened neointima with cells staining positive for ␣-smooth muscle actin. There was a significant increase in the expression of MMP-2 at the venous stenosis by day 28 and day 56. CONCLUSION: A mouse carotid artery to jugular vein AVF model was created and in this model, at the venous stenosis, there was increased expression of MMP-2 by day 28 and day 56 . This model can be used to determine the mechanisms responsible for AVF. 4:12 PM
Abstract No. 43
Evaluation of Novel Biodegradable Sclerosing Liquid Embolics for the Treatment of Arteriovenous Malformations: Pilot Study in Rabbits. O. Jordan1, A. Uske2, F. Laurence3, E. Doelker1; 1University of Geneva, University of Lausanne, Geneva, Switzerland; 2Universite´ de Lausanne, Lausanne, Switzerland; 3Institut Pasteur, Paris, France. PURPOSE: To evaluate in vivo the performances of new liquid embolics designed for the sclerosis of AVMs. Some of the formulations possess novel properties, such as material biodegradability. MATERIALS & METHODS: The liquid embolics tested formed in situ semisolid implants through solvent exchange and precipitation, similarly to Onyx™. Five formulations contained 30% ethanol as a sclerosing agent and either a biodegradable polymer (poly(lactic acid), poly(lactic-coglycolic acid) or chitosan) or a non-degradable acrylic polymer for comparison. Another formulation contained acetic acid 40% as a sclerosing agent and a cellulose acetate polymer. Onyx 18™ and cyanoacrylate were used as controls. Micronized tantalum 20% w/w was added as a radiopacifier. Each formulation was injected in the kidney of a New Zealand rabbit through femoral access by selective catheterization of the renal artery, with 0.018 inch microcatheter under radioscopic guidance. Animals were sacrificed after 1 week and explanted kidneys submitted to radioscopic and histopathologic analysis. RESULTS: Viscosities ranging from 40 to 180 mPas allowed an easy injection of all the formulations and an adequate radiopacity. More distal embolization could be obtained using lower embolic viscosity and/or higher sclerosing agent concentration. Ethanol-based formulations could embolize the renal artery, leading to acute and diffuse necrosis of the renal parenchyma. Chitosan formulation led to the most complete effect, embolizing glomeruli and small capillaries. Polymers with different biodegradation kinetics could thus be combined with ethanol, producing adequate in situ precipitation patterns. The acetic acid-containing embolic induced the strongest effect, resulting in kidney atrophy and massive sclerosis extending to glomeruli.
Abstract No. 41
Reducing Risk and Stabilizing the Vertebral Body in Advanced Metastatic Spine Lesions: A Combined Approach Using Plasma-Mediated Tumor Ablation and Cement Augmentation. B. Georgy; UCSD Medical Center, San Diego, CA. PURPOSE: Combining percutaneous plasma-mediated radiofrequency ablation with vertebral body cement augmentation offers a less invasive treatment option for advanced metastatic spinal lesions and is particularly useful for cases with cortical destruction and / or epidural extension. Advanced spinal metastases are often considered contraindications for vertebroplasty or kyphoplasty, but this combined approach could offer a third option which is both clinically viable and safe for these patients. This study evaluated bone cement deposition patterns and extravasation in treated vertebral bodies in relation to the metastatic lesion, as well as pain relief, after using this combined approach. MATERIALS & METHODS: A void is created in the anterior portion of the tumor-infiltrated vertebral body using a bipolar plasma radiofrequency-based wand (ArthroCare Corporation, Austin, TX), followed by deposition of bone cement. Retrospective assessments of CT images performed before/after the procedures were evaluated in 37 patients (44 levels) with advanced metastatic lesions. All patients reported pain status (VAS) pre-procedure and 2-4 weeks afterwards. RESULTS: 90-100% of the cement was deposited in the anterior 2/3 of the vertebral body in 19 levels (43%), while 75-90% of the cement was deposited in this region in 16 levels (36%). In 13 of 15 levels with posterior lesions (86%), cement deposited anterior to the lesion. 13 levels showed no extravasation (29.5%). Two clinically insignificant incidences of epidural cement extravasation recorded. Pain relief was reported by 25 of 28 patients (89.5%) after the procedure. CONCLUSION: Plasma-mediated radiofrequency ablation allows greater control over cement for a relatively predictable deposition pattern with only clinically insignificant cement extravasation, increasing the likelihood of stabilizing the anterior 2/3 of the vertebral body. This treatment may eventually replace extensive anterior surgical stabilization techniques as it minimizes surgical invasiveness for high-risk cancer patients. This technique appears to be most successful in cases with posterior-located lesions, and offers excellent post-procedure pain relief.
Scientific Session 5 The Interventional Scientist Sunday, March 8, 2009 4:00 PM - 6:00 PM Room: 16B 4:00 PM
Abstract No. 42
Mouse Arteriovenous Fistula Model. S. Misra, B. Yang, U. Shergill, A.A. Fu; Mayo Clinic, Rochester, MN. PURPOSE: The aim of the present study was to create a mouse arteriovenous fistula (AVF) model in a mouse and determine the expression of matrix metalloproteinase-2 expression at the venous stenosis. S18
MATERIALS & METHODS: Twelve FEV1 mice underwent the creation of an AVF between the left carotid artery to ipsilateral jugular vein with the contralateral vessels serving as controls. The animals were sacrificed at day 28 (N⫽6) and day 56 (N⫽6) after fistula creation. Immunohistochemistry for ␣-smooth muscle actin and MMP-2 were performed at the venous stenosis and control vessels along with morphometric analysis to quantify the amount of stenosis. RESULTS: Venous stenosis formed at the outflow vein which was characterized by a thickened neointima with cells staining positive for ␣-smooth muscle actin. There was a significant increase in the expression of MMP-2 at the venous stenosis by day 28 and day 56. CONCLUSION: A mouse carotid artery to jugular vein AVF model was created and in this model, at the venous stenosis, there was increased expression of MMP-2 by day 28 and day 56 . This model can be used to determine the mechanisms responsible for AVF. 4:12 PM
Abstract No. 43
Evaluation of Novel Biodegradable Sclerosing Liquid Embolics for the Treatment of Arteriovenous Malformations: Pilot Study in Rabbits. O. Jordan1, A. Uske2, F. Laurence3, E. Doelker1; 1University of Geneva, University of Lausanne, Geneva, Switzerland; 2Universite´ de Lausanne, Lausanne, Switzerland; 3Institut Pasteur, Paris, France. PURPOSE: To evaluate in vivo the performances of new liquid embolics designed for the sclerosis of AVMs. Some of the formulations possess novel properties, such as material biodegradability. MATERIALS & METHODS: The liquid embolics tested formed in situ semisolid implants through solvent exchange and precipitation, similarly to Onyx™. Five formulations contained 30% ethanol as a sclerosing agent and either a biodegradable polymer (poly(lactic acid), poly(lactic-coglycolic acid) or chitosan) or a non-degradable acrylic polymer for comparison. Another formulation contained acetic acid 40% as a sclerosing agent and a cellulose acetate polymer. Onyx 18™ and cyanoacrylate were used as controls. Micronized tantalum 20% w/w was added as a radiopacifier. Each formulation was injected in the kidney of a New Zealand rabbit through femoral access by selective catheterization of the renal artery, with 0.018 inch microcatheter under radioscopic guidance. Animals were sacrificed after 1 week and explanted kidneys submitted to radioscopic and histopathologic analysis. RESULTS: Viscosities ranging from 40 to 180 mPas allowed an easy injection of all the formulations and an adequate radiopacity. More distal embolization could be obtained using lower embolic viscosity and/or higher sclerosing agent concentration. Ethanol-based formulations could embolize the renal artery, leading to acute and diffuse necrosis of the renal parenchyma. Chitosan formulation led to the most complete effect, embolizing glomeruli and small capillaries. Polymers with different biodegradation kinetics could thus be combined with ethanol, producing adequate in situ precipitation patterns. The acetic acid-containing embolic induced the strongest effect, resulting in kidney atrophy and massive sclerosis extending to glomeruli.