- Email: [email protected]
Scientific Session 8 Vascular Stents
difference between patients with patent or non-patent arteries in myometrial enhancement, uterine size, or dominant fibroid size.
PURPOSE: To determine the safety and effectiveness of uterine embolization for leiomyomata using Embospheres Microspheres when compared to hysterectomy.
CONCLUSION: In spite ofembolization ofthe uterine arteries with permanent agents, most patients show no change in myometrial enhancement, suggesting minimal ischemic effects on the myometrium.
MATERIALS AND METHODS: This is a multi-center prospective parallel cohort study comparing uterine artery embolization with hysterectomy for the treatment of patients with menorrhagia. Each patient completed a baseline symptom severity questionnaire, a menorrhagia questionnaire, and a SF-12 health survey. Each UAE patient had baseline imaging. Bilateral uterine embolization was performed in the standard fashion using Embosphere Microspheres. Hysterectomy was performed using standard surgical techniques. Clinical followup occurred during the first month, at 3 months, 6 months and 12 months after treatment, with imaging at 3 and 6 months.
1:36PM
Abstract o. 55
MR Imaging Outcome after Uterine Artery Embolization for Leiomyomata Using Tris-Acryl Gelatin Microspheres. F. Banovac, Georgetown University, Washington DC, USA' S.M. Ascher· D.A. Jones' M. D. Black· 1. C. Smith' 1.B. Spies PURPOSE: To determine the frequency and extent of leiomyomata infarction and shrinkage after uterine artery embolization (UAE) using tris-acryl gelatin microsphercs (Embospheres). MATERIALS AND METHODS: A retrospective analysis of MR images of the pelvis was performed comparing studies completed approximately 3-4 months after UAE to those obtained before UAE. Twenty three (23) patients with a total of 61 leiomyomata were examined (up to 3 fibroids per patient). Orthogonal T2 HASTE, axial TlW fat saturated spoiled gradient echo, sagittal T2 FSE, and dynamic T IW sagittal images post-gadoliniuJl1 were analyzed Two abdominal imaging specialists characterized each leiomyoma and the uterus for total volume using equation for prolate ellipse. They also examined perfusion by assessing enhancement relative to myometrium. Total fibroid volume perfused before and after UAE was calculated. Readers were blinded and disagreements in interpretation were resolved by consensus. Paired Student-t test was used for inferences in uterine and leiomyoma size difference, percent infarction, and volume of fibroid tissue perfused before and after UAE. RESULTS: Mean volume ofall leiomyomata (n=61) decreased from 91 ± 143 cc to 52 ± 106 cc (p<0.001) with mean 49% decrease in volume. When dominant fibroids were considered alone (n=23) a mean 53% volume decrease (p<0.001) was noted. Uterine volume decreased from 651 ± 423 cc to 469 ± 344 cc (p<0.00 I) with mean 32% decrease in volume. Perfused volume of all fibroids (n=61) decreased from 84 ± 138 cc to 3 ± 8 cc (p<0.001) with mean 93% decrease in volume, and 117 ± 190 cc to 4 ± 9 cc (p<0.001) with mean 95% decrease in perfused volume for dominant fibroids alone (n=23). Average percent of infarcted tissue volume for all leiomyomata increased from 8% to 89% after treatment, and 9% to 92% for dominant leiomyomata. Fifty-two (52) out of all 61 fibroids (85%), and 20 of 23 dominant fibroids (87%) were completely devascularized by UAE using Embospheres. One fibroid disappeared completely after treatment. There was no myometrial ischemia or injury identified. CONCLUSION: Tris-acryl gelatin microspheres (Embospheres) are an effective embolic agent for UAE, causing infarction and significant decrease in leiomyoma volume.
1:47PM
Abstract No. 56
FEAI UREIlARSTR \CT Commcntahll': I{ichard Shlansl{) -Goldberg. M D
820
Uterine Artery Embolization (UAE) Using Embospheres: Initial Results of a Phase II Comparative Study. 1.B. Spies, Georgetown University Hospital, Washington DC, USA· 1.M. Cooper' R.L. Worthington-Kirsch' 1. C. Lipman· J.F. Benenati· B. McLucas
RESULTS: To date, 67 patients have been treated with UAE and 20 with the hysterectomy. Among the patients treated with UAE available for 3 month imaging follow-up (N=27), there was a mean reduction of29% (SD 29) in uterine volume and the dominant leiomyoma 42% (SD 36). In those patients available for 3 month clinical follow-up (N=29), 83% of patients had improved menstrual bleeding 3 months posttreatment. At baseline, 61 % of UAE patients rated their bleeding as extremely heavy, while only 7% similarly rated their bleeding 3 months after treatment. The menstrual bleeding score reduced on average 60% (p less than 0.0001). For the UAE patients, the SF-12 physical score increased from 45 to 52 (p=0.0006) and the SF-12 mental score mean increased from 45 to 53 (p=0.0004). Only 7 hysterectomy patients were available for follow-up. Among these, the SF-12 physical scores increased from 35 to 52 (p=O.0119) willIe the SF-12 mental scores did not change (pre 41, post 42, p=0.7099). Among the UAE patients, there were no major complications. Minor complications occurred in 12 patients (17%). Hysterectomy was performed in one patient who developed pelvic inflammatory disease 9 weeks after UAE, which was unrelated directly to UAE. Complications occurred in 4 of20 hysterectomy patients. CONCLUSION: Initial results suggest that UAE using Embospheres is safe and effective when compared to hysterectomy.
Scientific Session 8 Vascular Stents Monday, April 8, 2002 12:30 PM - 2:00 PM Moderator(s): Klemens H. Barth, MD 12:30 PM
Abstract No. 57
Vascular Stent Surface Composition Differs Significantly from the Bulk Material. C. Fuss, UTHSC San Antonio, San Antonio, TX, USA· 1. C. Palmaz • S.R. Bailey· E.A. Sprague· D. Marton PURPOSE: To determine the surface chemical composition ofstents, currently available and widely used in the US, using X-ray Photoelectron Spectroscopy (XPS). MATERIALS AND METHODS: Nine coronary and three peripheral stent brands were examined in groups of 3 each. The sterile devices were handled in compliance with proper surface-sensitive analytical techniques. The bulk stent material was stainless steel (88) in eight, Nitinol in three and goldcoated SS in one. A five-point analysis pattern per stent was evaluated for eminent atomic peaks and quantitative acquisition was targeted accordingly. Quantitative analysis
data ofeach selected element was analyzed from an n=15 per stent for mean and standard error, for total and fractional data. Selected elements were C, 0, Si, Fe, Cr, Ni, Ti, Na, K, CI and Au.
work pertaining to WS placement in anatomic regions ofvessel strain has been published. The purpose of this study was to perform a radiographic and histologic assessment ofWS subject to strain force (SF).
RESULTS: The predominant surface elements were C, mean = 52.7 ± 0.84% (17.4% to 87.7%) and 0, mean = 30.0 ± 0.68% (8.6 to 58.6%). SS bulk elements like Fe, Cr, and Ni were not as abundant as expected. Fe averaged 3.5 ± 0.27% (0 to 21.1%). Cr averaged 2.8 ± 0.21% (0 to 11.6%) and Ni averaged 0.9 ± 0.1 % (0 to 8.75%). Ti, a major component ofNitinol stents, averaged 5.8 ± 0.69 %. On goldcoated stents, Au averaged 18 ± 1.9%. Besides C and 0, the next most abundant element on all stents was Si, from surface lubricants. Si averaged 6.8 ± 0.49% (0 to 22.7%), representing 30% in total polydimethylsiloxane.
MATERIALS AND METHODS: WS (Wallstent™, Boston Scientific Corp.) were placed in arteries subject to flexion SF (groin and neck) and in arteries protected from SF (pelvis and chest). WS were centered at the point of maximum flexion within the distal common iliac artery (CIA) of dogs (n=5) in the groin. Control WS were placed in the contralateral proximal CIA, in the pelvis. WS were also centered at the point of maximum flexion within the distal common carotid artery (CCA) in the neck. Control WS were placed in the contralateral proximal CCA in the chest. Standard radiography, digital angiography, intravascular ultrasound, and standard histology were used to assess conformational change, stenosis, and neointimal hyperplastic response ofWS placed in regions of SF compared to WS protected from SF over a 4-month period.
CONCLUSION: Chemical surface composition of current stents does not reflect the bulk composition. Large variability is present between and within stent brands. Surface contaminants such as Si lubricants, are present in significant amounts. 12:41 PM
Abstract No. 58
In Vitro Evaluation of Thrombogenicity of Various Endovascular Stent Types. G. Tepe, Dep. ofDiagnostic Radiology, University of Tuebingen, Tuebingen, Germany· H.P. Wendel· J. Wiskirchen • CD. Claussen· S.H. Duda
PURPOSE: The aim of this study was to evaluate the thrombogenicity of different peripheral stent types in a standardized model. MATERIALS AND METHODS: Different stents (total number: 104; eacb group with n = 8) were placed in a modified ChandlerLoop. Tbe platelet count, beta-thromboglobulin, and the TAT (thrombin-antithrombin-lIl complex) was assessed at 0 and after 2 hours. RESULTS: After two hours significant differences were seen. TAT [~glll ranged between 31 ± 18 (control, no stent), 328 ± 187 (Bard peripheral) and 5897 ± 2203 lomed SelfX without electropolishing (-ep). The ranking was: Saxx < Smart < Palmaz Corinthian (+ep) < lomed peripheral (+ep) < Palmaz Schatz < Palmaz Schatz Re 188 < Palmaz Schatz Re 186 < MegaLink < Bridge peripheral < Palmaz Corinthian (-ep) < Jomed peripheral (-ep) < lomed SelfX (+ep) < lomed SelfX (-ep). CONCLUSION: This standardized study showed a wide range of platelet activation following stcnt implantation. Electropolishing (+ep) clearly reduced the thrombogenicity of the stents. Altering the stent surface for local delivery (Re 186/ Re 188) did not increase platelet activation. Thrombogenicity is an important parameter ofan endovascular prosthesis besides physical properties like hoop strength, total mass, and flexibility. This may influence the rate ofacute thrombosis and restenosis. 12:52 PM
Abstract No. 59
Radiographic and Histologic Assessment of Flexible-SelfExpanding-Endovascular Stents under Strain Conditions. B.Z. Cooper, Hackensack University Medical Center, Hackensack, NJ, USA· T.F. Panetta· J. G. Najjar· S B. Blattman • SJ. Sclafani· F.M. Weinreb, et al.
PURPOSE: The use of flexible-self-expanding-endovascu (ar stents (WS) to treat peripheral arterial occlusive disease is becoming increasingly prevalent. Little clinical and investigative
RESULTS: All stents (n=20) were properly placed and dogs did well as evidenced by weight gain and resumption ofnorrnal activity. Radiographic and microscopic analysis did not demonstrate stent fractures. High grade stenosis (>80%) occurred more frequently in WS subject to SF compared to WS protected from SF. The diameter ofWS that were located in strain positions increased (+ 12.2%, ±0.26) while the diameter ofstents protected from SF decreased (-8.3%, ±0.19) (P=0.005). The mean neointimal thickness (0.88 ±1.04 mm vs. 0.49 ±0.70 mm, P
Abstract No. 60
Radiopacity ofEndovascular Stents. EvaJuation of Balloon and Selfexpandable Stents in an Experimental Setting. J Wiskirchen, Dept ofDiagnostic Radiology, University of Tuebingen, Tuebingen, Germany· B. Pusich • U. Kramer· J Truebenbach • C Koenig· SH. Duda
PURPOSE: To evaluate the radiopacity of endovascular stents depending on tbe fluoroscopy mode using a phantom of the human pelvis. MATERIALS AND METHODS: The following stents were included in the study: Bridge (BR), Bridge X (BRX), Cordis Covered Nitinol (CV), Dynalink (DY), Memotherm Luminexx (LX), Megalink (MK), Memotherm Flexx (MF), Palmaz Medium (PM), Palmaz-Schatz Long-Medium (PS), Palmaz Corinthian 29 mm (PC29) and 39 rum (PC39) version, SelfX (SLF), SMART without markers (SM), SMART with radiopaque markers (SMR), Wallstent (WA). To evaluate radiopacity, images of the stents placed on four different positions (lumbosacral junction left and right, ileosacral joint left and right) ofa pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, l5 pulses per second, 7.5 pulses per second, and 3 pulses per second. Images were presented at random to four independent readers and a rad.iopaci~ score (RS) - from 0= invisible, I=poor, 2=average, 3=good, and 4=very good - was assessed. RESULTS: At spotfilm mode the following three stents performed best: LX > CV and WA (RS 3.9 to 3.94), at continuous fluoro CV > LX > BRX (RS 2.94 to 3.4), at 15
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pulses per second CV > BRX > WA (RS 2.6 to 3.25), at 7.5 pulses per second CV > LX > WA and BRX (2.4 to 2.9), and at 3 pulses per second CV > BRX > LX (RS 1.9 to 2.6).
CONCLUSION: I) Stcnt radiopacity dircctly depends on the fluoroscopy mode. By decreasing the pulse frequency detecting the stcnts became more difficult. 2) SteDt mass correlates with stent radiopacity (e.g. Cordis Covered Nitinol, Bridge X). 3) Radiopaque markers may improve stem radiopacity dramatically. 1:14PM
Abstract No. 61
Comparison of BiocompatibUity and Performance between \Vallstent and Three Slenl-Grafts. M. Cejna, Interv. Dep.l Vienna Med School, Vienna, Austria • R. Virmani· R. Jones· C. wewe • M. Grgun"n .1. Lammer PURPOSE: Most recently developed slenl-grafts were compared directly in an animal model in regard of perfonnancc and biocompatibility.
MATERIALS AND METHODS: Threc stent-grafts, Hemobahn (polytetrafluorocthylene (ePTFE)1 nitinol, W.L. Gore, Flagstaff, USA), Wallgraft (polyesterlNi-Co-Ti-steclalloy, Boston Scientific Inc, Meditech, Natick, MA, USA) and Jostent peripheral stentgraft (ballon' cxpandable ePTFEI stainless steel, JOMED Inc., Switzerland) and WaJlstent(NiCO-Ti-steel-alloy, Boston Scientific Inc), n=8 each, were implanted in sheep iliac arteries (0=8 animals). Angiography, IVUS, histomorphometry, histology and scanning electron microscopy (SEM) were performed at 3 months.
RESULTS: Early Iwnen gain, late lumen loss and patent vessel diameter at angiography were not significantly different. Two stcntgrafts had significantly more neointima formation (Hemobahn 9.88 ± 0.94nun' and Wallgraft (14.98 ± 0.90nun') than the Jostent (6.52 ± 0.46nun') and the Wallstent (5.24 ± 0.62mm 2 ), p-Anova <0.0 I. Patent lumen arca was not significantly differcnt (Hemobahn 42.57 ± 1.41 nun', Jostcnt 39.76 ± 2.04nun', Wallgraft 40.22 ± 1.00nun' and Wallstent 41.64 ± 1.59 mm', p-Anova~0.57). The Hemobahn had significantly more innammative vessel wall reaction (inflammation score of 0.83 ± 0.03) than Jostent (0.58 ± 0.03), Wallgrafl (0.55 ± 0.04) and WaUstent (0.16 ± 0.01). Angiography and rvus demonstrated absence ofanastomotic neointima formation. Endothelializati~n was incomplete for all prosthcses, yet there was no significant differcnce between the stents (p-Anova=0.22). Predominantly mature endothelium was found for the Wallstent, the Hemobahn had predominantly immature endothelium. CONCLUSION: The stent-grafts caused a greater degree of neointima formation and inflarruriative vessel wall reaction than the bare stent. Yet these changes did not interfere with comparable patent lumen areas and occured in the absence of anastomotic neointima formation. 1:25 PM
Abstract No. 62
Stent Struts and Articulations. Their Impact on Hoop Strength, Pushability, and Radiopacity. J. Wiskirchen, Dept ojDiagnostiC Radiology, University Hospital Tuebingen, Tuebingen, Germany· B. Pusich • U. Kramer· G. Tepe • CD. Claussen· s.H. Duda
PURPOSE: To evaluate the hoop strength, the pushability, and the radiopacity ofendovascular stents depending on their design.
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MATERiALS AND METHODS: The Palmaz Mcdium (PM) (rectangular stent struts, no articulation), thc Palmaz-Schatz Long-Medium (PS) (rectangular stent struts, central articulation), and the 29 nun (PC29) and 39 nun (PC39) version of the Palmaz Corinthian Stent (archlike stent struts, multiple artic':llations) were included in the study. Stent hoop strength was assessed in a special pressure chamber, and pushability was analyzed in a plexiglass iliac model. To evaluate radiopacity, images of the four stents placed on a pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, and at 7.S pulses per second. Images were presented at random to two independent readcrs and a radiopacity score (RS) - from 0= invisible, I =poor, 2=average, 3=good, and 4=very good - was assessed.
RESULTS: The absolute hoop strength ofthe PC39 exceeded those of the other stents significantly. Mass adjusted hoop strength was nearly the same for the PC39 and the PC29. (PC29 156.5 N/g'cm, PC39 159.2 N/g·cm). Their hoop strengtbs per unit mass significantly exceeded that of a PM (125 N/g'cm) by 27%, and that ofa PS (75.3 N/g' cm). The most pushable stent was the PC29 (0.54 lIN) followed by tbe PC39 (0.47 lIN) and the PS (0.169). Due to multiplestent dislocations the PM was considered non flexible. At spotfilm mode the PM was the most visible stent (RS 3.5) followed by the PC39 (RS 3.25), the PS (RS 3.12) and the PC29 (RS 1.9). At continuous fluoroscopy the PC39 (RS 1.8) was better than the PM (RS 1.12), the PS (RS 1.0), and the PC29 (RS 0.6). At 7.5 pulses per second thc PM (RS 1.3) perfonned slightly better than the PC39 (RS 1.25), and clearly bener than the PS (RS 0.8), and the PC29 (RS 0.3). CONCLUSION: Overall, the idcal stent having high hoop strength, a low profile, good pushability, and good radiopacity still does not exist. However, by changing strut design (from rectangular to archlike struts) and by inserting articulations hoop strength and pushability can be improved without reducing radiopacity. 1:36 PM
Abstract No. 63
Re-186 for Prevention of Resteoosis in a Rabbit ModelHistologic Effec[S of Stent-Based Radiation Therapy. G. Tepe, Department ofRadiology, University ofTuebingen, Tuebingen, Germany· L.M. Dinkelborg • T. Dietrich· A. Greschniok • P. Muschick • s.H. Duda
PURPOSE: We could recently show that Re-186 stents are capable to reduce neointima fonnation in a dose-dependent fashion in rabbits 7 weeks after implantation with a total inhibition of neointima fonnation in the high-dose groups and no edge-effect. The aim of this study was to evaluate the histologic effects of stent-based radiation therapy.
MATERiALS AND METHODS: Control Slents (n ~ 7) were compared with Re-186 stenlS (2.6 MBq [n ~ 6], 8.1 MBq [n ~ 5], 16.0 [n ~ 6], and 25.3 MBq [n ~ 8]. Thc segments were analyzed for fibrin (location [a] near the stent struts, in the [b] neointima, [c] media, [d] adventitia), necrosis (location b-d), edema (location a-d), inflammation (location a-d), and endothel ial ization. RESULTS: With higher radiation doses the degree of fibrosis, necrosis, and edema increased in a dose-dependent reaction. Inflammation was mainly seen near the stent struts (dosedependent) with only small numbers of granulocytes and monocytes in the neointima, media and adventitia which were independent of the amount of exposure to radiation. Fibrinrich, acellular regions were especially found near the stent struts. The adventitia was a-actin negative in the control group and turned a-actin positive in the high-dose groups. Reendothelialization after stent implantation was found in
the control group whereas in mid- and high-dose stents the endothelium was absent. CONCLUSION: Histologic changes seen after Re-186 stent impantation were mild to moderate. Whether the changes of the vascular wall will cause late side-effects has still to be investigated.
Scientific Session 9 Biliary/GU Monday, April 8, 2002 12:30 PM - 2:00 PM Moderator(s): Ziv Haskal, MD
1:47 PM
Abstract No. 64
Hepar.in-Coated Balloon-Expandable Stent Reduces Intimal Hyperplasia in the Iliac Artery in Baboons. PH. Lin, Baylor College ofMedicine, Bellaire, TX· M.M. Marijianowski· NA. Chronos • C. Chen· A.B. Lumsden· S.R. Hanson PURPOSE: Intimal hyperplasia represents a major cause of failure following endovascular intervention. The effect of heparin on reducing thrombogenicity and intimal hyperplasia following vascular reconstruction has been recognized. In this study, we examined the effect of heparin-coated balJoonexpandable iliac stent on intimal hyperplasia in a baboon model. MA TERlALS AND METHODS: Balloon-expandable (PalmazSchatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated (HC) iliac stent was placed on one side while the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at I month (n=IO) and 3 months (n=IO). Arteriography was perfonned to assess iliac patency, and intravascular ultrasound (IVUS) was used to determine neointimal and luminal areas. Histological, morphometric analysis, and scanning electron microscopy were perfonned in the stented iliac arteries. RESULTS: One animal was excluded in the I-month group due to premature death. In the remaining 9 surviving animals, seven control stents (78%) and nine HC stents (100%) remained patent. Morphometric analysis showed the HC stented iliac arteries had larger luminal areas (20%, p=0.04), less neointimal areas (34%, p=O.02), less neointimallmedia ratios (35%, p=0.05), and equivalent medial areas (p=0.92) when compared to the control group. In contrast, all control and HC stents were patent (100%) in the 3-month group. No differences in the luminal area, neointimal areas, medial areas, or neointimal/media ratios were noted between the control or He stented iliac arteries in the 3-month group by either morphometric or IVUS evaluation (p>0.05). CONCLUSION: Our data demonstrated that heparin-coated balloon-expandable stents reduce intimal hyperplasia following iliac artery placement. This approach may represent a useful strategy for prolonging luminal patency following iliac stent placement.
12:30 PM
Abstract No. 65
Radiologic Diagnosis and Management of Biliary Complications in Liver Transplants: Whole Livers vs. Donated Segments. S. Kwon, Mt Sinai Medical Center, New York, NY, USA· A. Falk • R. Lookstein • J Guller • F.s. Nowakowski' H. Milty, etal. PURPOSE: To evaluate the radiologic diagnosis and management ofbiliary complic:itions in liver transplants: whole standard livers (STD) versus segments from living related donors (LRD). MATERIALS AND METHODS: From August 1998 - April 2001, 439 liver transplants were performed: 342 STD and 97 LRD. The radiologic diagnosis of biliary complications was made by PTC, MRCP, ERCP and nuclear hepatobiliary scans. Radiologic intervention was performed when needed. RESULTS: 49 biliary complications were found in 45 STD transplants: 32 anastomotic strictures, 7 anastomotic leaks, 5 intrahepatic strictures, 4 intrahepatic bile lakes and I intrahepatic abscess. 25 biliary complications were found in 25 LRD transplants: 10 anastomotic strictures, II anastomotic leaks, I intrahepatic stricture, 2 intrahepatic bile lakes and I intrahepatic abscess. The difference in biliary complications between the STD and LRD transplants was statistically significant (P<.OI). The difference in anastomotic leaks between STD and LRD transplants was also statistically significant (P<.O I). 18 interventions were perfonned in the STD group: II biliary drainage and 7 extrahepatic drainage. 8 interventions were performed in the LRD group: 3 biliary drainage and 5 extrahepatic drainage. CONCLUSION: The radiologic diagnosis of biliary complications following liver transplants is greater in segmental LRD as compared to whole STD liver transplants. Biliary anastomotic leaks are significantly greater in segmental LRD transplants as compared to whole STD transplants. This may be related to the surgical difference between these two types of liver transplants. In STD the donor bile duct is connected to the recipient bile duct whereas in LRD the donor bile duct is connected to the recipient small bowel. Radiologic intervention is useful in managing these patients and insuring continuing function of the transplanted liver.
12:41 PM
Abstract No. 66
Biliary Complications after Pediatric Liver Transplantation Revisited. D. Redd, Department ofRadiology, Emory University Hospital, Atlanta, GA, USA· R. Romero· T Heffron PURPOSE: Biliary complications in pediatric liver transplantation (PLT) are associated with increased morbidity and mortality. In PLT, reduced size grafts have been associated with an increased incidence of biliary complications when compared to whole liver transplantation. The purpose of this review is to report our incidence of biliary complications in PLT based upon graft type, age/weight of recipient, surgical technique and intervention following bile duct complication.
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PURPOSE: To determine the safety and effectiveness of uterine embolization for leiomyomata using Embospheres Microspheres when compared to hysterectomy.
CONCLUSION: In spite ofembolization ofthe uterine arteries with permanent agents, most patients show no change in myometrial enhancement, suggesting minimal ischemic effects on the myometrium.
MATERIALS AND METHODS: This is a multi-center prospective parallel cohort study comparing uterine artery embolization with hysterectomy for the treatment of patients with menorrhagia. Each patient completed a baseline symptom severity questionnaire, a menorrhagia questionnaire, and a SF-12 health survey. Each UAE patient had baseline imaging. Bilateral uterine embolization was performed in the standard fashion using Embosphere Microspheres. Hysterectomy was performed using standard surgical techniques. Clinical followup occurred during the first month, at 3 months, 6 months and 12 months after treatment, with imaging at 3 and 6 months.
1:36PM
Abstract o. 55
MR Imaging Outcome after Uterine Artery Embolization for Leiomyomata Using Tris-Acryl Gelatin Microspheres. F. Banovac, Georgetown University, Washington DC, USA' S.M. Ascher· D.A. Jones' M. D. Black· 1. C. Smith' 1.B. Spies PURPOSE: To determine the frequency and extent of leiomyomata infarction and shrinkage after uterine artery embolization (UAE) using tris-acryl gelatin microsphercs (Embospheres). MATERIALS AND METHODS: A retrospective analysis of MR images of the pelvis was performed comparing studies completed approximately 3-4 months after UAE to those obtained before UAE. Twenty three (23) patients with a total of 61 leiomyomata were examined (up to 3 fibroids per patient). Orthogonal T2 HASTE, axial TlW fat saturated spoiled gradient echo, sagittal T2 FSE, and dynamic T IW sagittal images post-gadoliniuJl1 were analyzed Two abdominal imaging specialists characterized each leiomyoma and the uterus for total volume using equation for prolate ellipse. They also examined perfusion by assessing enhancement relative to myometrium. Total fibroid volume perfused before and after UAE was calculated. Readers were blinded and disagreements in interpretation were resolved by consensus. Paired Student-t test was used for inferences in uterine and leiomyoma size difference, percent infarction, and volume of fibroid tissue perfused before and after UAE. RESULTS: Mean volume ofall leiomyomata (n=61) decreased from 91 ± 143 cc to 52 ± 106 cc (p<0.001) with mean 49% decrease in volume. When dominant fibroids were considered alone (n=23) a mean 53% volume decrease (p<0.001) was noted. Uterine volume decreased from 651 ± 423 cc to 469 ± 344 cc (p<0.00 I) with mean 32% decrease in volume. Perfused volume of all fibroids (n=61) decreased from 84 ± 138 cc to 3 ± 8 cc (p<0.001) with mean 93% decrease in volume, and 117 ± 190 cc to 4 ± 9 cc (p<0.001) with mean 95% decrease in perfused volume for dominant fibroids alone (n=23). Average percent of infarcted tissue volume for all leiomyomata increased from 8% to 89% after treatment, and 9% to 92% for dominant leiomyomata. Fifty-two (52) out of all 61 fibroids (85%), and 20 of 23 dominant fibroids (87%) were completely devascularized by UAE using Embospheres. One fibroid disappeared completely after treatment. There was no myometrial ischemia or injury identified. CONCLUSION: Tris-acryl gelatin microspheres (Embospheres) are an effective embolic agent for UAE, causing infarction and significant decrease in leiomyoma volume.
1:47PM
Abstract No. 56
FEAI UREIlARSTR \CT Commcntahll': I{ichard Shlansl{) -Goldberg. M D
820
Uterine Artery Embolization (UAE) Using Embospheres: Initial Results of a Phase II Comparative Study. 1.B. Spies, Georgetown University Hospital, Washington DC, USA· 1.M. Cooper' R.L. Worthington-Kirsch' 1. C. Lipman· J.F. Benenati· B. McLucas
RESULTS: To date, 67 patients have been treated with UAE and 20 with the hysterectomy. Among the patients treated with UAE available for 3 month imaging follow-up (N=27), there was a mean reduction of29% (SD 29) in uterine volume and the dominant leiomyoma 42% (SD 36). In those patients available for 3 month clinical follow-up (N=29), 83% of patients had improved menstrual bleeding 3 months posttreatment. At baseline, 61 % of UAE patients rated their bleeding as extremely heavy, while only 7% similarly rated their bleeding 3 months after treatment. The menstrual bleeding score reduced on average 60% (p less than 0.0001). For the UAE patients, the SF-12 physical score increased from 45 to 52 (p=0.0006) and the SF-12 mental score mean increased from 45 to 53 (p=0.0004). Only 7 hysterectomy patients were available for follow-up. Among these, the SF-12 physical scores increased from 35 to 52 (p=O.0119) willIe the SF-12 mental scores did not change (pre 41, post 42, p=0.7099). Among the UAE patients, there were no major complications. Minor complications occurred in 12 patients (17%). Hysterectomy was performed in one patient who developed pelvic inflammatory disease 9 weeks after UAE, which was unrelated directly to UAE. Complications occurred in 4 of20 hysterectomy patients. CONCLUSION: Initial results suggest that UAE using Embospheres is safe and effective when compared to hysterectomy.
Scientific Session 8 Vascular Stents Monday, April 8, 2002 12:30 PM - 2:00 PM Moderator(s): Klemens H. Barth, MD 12:30 PM
Abstract No. 57
Vascular Stent Surface Composition Differs Significantly from the Bulk Material. C. Fuss, UTHSC San Antonio, San Antonio, TX, USA· 1. C. Palmaz • S.R. Bailey· E.A. Sprague· D. Marton PURPOSE: To determine the surface chemical composition ofstents, currently available and widely used in the US, using X-ray Photoelectron Spectroscopy (XPS). MATERIALS AND METHODS: Nine coronary and three peripheral stent brands were examined in groups of 3 each. The sterile devices were handled in compliance with proper surface-sensitive analytical techniques. The bulk stent material was stainless steel (88) in eight, Nitinol in three and goldcoated SS in one. A five-point analysis pattern per stent was evaluated for eminent atomic peaks and quantitative acquisition was targeted accordingly. Quantitative analysis
data ofeach selected element was analyzed from an n=15 per stent for mean and standard error, for total and fractional data. Selected elements were C, 0, Si, Fe, Cr, Ni, Ti, Na, K, CI and Au.
work pertaining to WS placement in anatomic regions ofvessel strain has been published. The purpose of this study was to perform a radiographic and histologic assessment ofWS subject to strain force (SF).
RESULTS: The predominant surface elements were C, mean = 52.7 ± 0.84% (17.4% to 87.7%) and 0, mean = 30.0 ± 0.68% (8.6 to 58.6%). SS bulk elements like Fe, Cr, and Ni were not as abundant as expected. Fe averaged 3.5 ± 0.27% (0 to 21.1%). Cr averaged 2.8 ± 0.21% (0 to 11.6%) and Ni averaged 0.9 ± 0.1 % (0 to 8.75%). Ti, a major component ofNitinol stents, averaged 5.8 ± 0.69 %. On goldcoated stents, Au averaged 18 ± 1.9%. Besides C and 0, the next most abundant element on all stents was Si, from surface lubricants. Si averaged 6.8 ± 0.49% (0 to 22.7%), representing 30% in total polydimethylsiloxane.
MATERIALS AND METHODS: WS (Wallstent™, Boston Scientific Corp.) were placed in arteries subject to flexion SF (groin and neck) and in arteries protected from SF (pelvis and chest). WS were centered at the point of maximum flexion within the distal common iliac artery (CIA) of dogs (n=5) in the groin. Control WS were placed in the contralateral proximal CIA, in the pelvis. WS were also centered at the point of maximum flexion within the distal common carotid artery (CCA) in the neck. Control WS were placed in the contralateral proximal CCA in the chest. Standard radiography, digital angiography, intravascular ultrasound, and standard histology were used to assess conformational change, stenosis, and neointimal hyperplastic response ofWS placed in regions of SF compared to WS protected from SF over a 4-month period.
CONCLUSION: Chemical surface composition of current stents does not reflect the bulk composition. Large variability is present between and within stent brands. Surface contaminants such as Si lubricants, are present in significant amounts. 12:41 PM
Abstract No. 58
In Vitro Evaluation of Thrombogenicity of Various Endovascular Stent Types. G. Tepe, Dep. ofDiagnostic Radiology, University of Tuebingen, Tuebingen, Germany· H.P. Wendel· J. Wiskirchen • CD. Claussen· S.H. Duda
PURPOSE: The aim of this study was to evaluate the thrombogenicity of different peripheral stent types in a standardized model. MATERIALS AND METHODS: Different stents (total number: 104; eacb group with n = 8) were placed in a modified ChandlerLoop. Tbe platelet count, beta-thromboglobulin, and the TAT (thrombin-antithrombin-lIl complex) was assessed at 0 and after 2 hours. RESULTS: After two hours significant differences were seen. TAT [~glll ranged between 31 ± 18 (control, no stent), 328 ± 187 (Bard peripheral) and 5897 ± 2203 lomed SelfX without electropolishing (-ep). The ranking was: Saxx < Smart < Palmaz Corinthian (+ep) < lomed peripheral (+ep) < Palmaz Schatz < Palmaz Schatz Re 188 < Palmaz Schatz Re 186 < MegaLink < Bridge peripheral < Palmaz Corinthian (-ep) < Jomed peripheral (-ep) < lomed SelfX (+ep) < lomed SelfX (-ep). CONCLUSION: This standardized study showed a wide range of platelet activation following stcnt implantation. Electropolishing (+ep) clearly reduced the thrombogenicity of the stents. Altering the stent surface for local delivery (Re 186/ Re 188) did not increase platelet activation. Thrombogenicity is an important parameter ofan endovascular prosthesis besides physical properties like hoop strength, total mass, and flexibility. This may influence the rate ofacute thrombosis and restenosis. 12:52 PM
Abstract No. 59
Radiographic and Histologic Assessment of Flexible-SelfExpanding-Endovascular Stents under Strain Conditions. B.Z. Cooper, Hackensack University Medical Center, Hackensack, NJ, USA· T.F. Panetta· J. G. Najjar· S B. Blattman • SJ. Sclafani· F.M. Weinreb, et al.
PURPOSE: The use of flexible-self-expanding-endovascu (ar stents (WS) to treat peripheral arterial occlusive disease is becoming increasingly prevalent. Little clinical and investigative
RESULTS: All stents (n=20) were properly placed and dogs did well as evidenced by weight gain and resumption ofnorrnal activity. Radiographic and microscopic analysis did not demonstrate stent fractures. High grade stenosis (>80%) occurred more frequently in WS subject to SF compared to WS protected from SF. The diameter ofWS that were located in strain positions increased (+ 12.2%, ±0.26) while the diameter ofstents protected from SF decreased (-8.3%, ±0.19) (P=0.005). The mean neointimal thickness (0.88 ±1.04 mm vs. 0.49 ±0.70 mm, P
Abstract No. 60
Radiopacity ofEndovascular Stents. EvaJuation of Balloon and Selfexpandable Stents in an Experimental Setting. J Wiskirchen, Dept ofDiagnostic Radiology, University of Tuebingen, Tuebingen, Germany· B. Pusich • U. Kramer· J Truebenbach • C Koenig· SH. Duda
PURPOSE: To evaluate the radiopacity of endovascular stents depending on tbe fluoroscopy mode using a phantom of the human pelvis. MATERIALS AND METHODS: The following stents were included in the study: Bridge (BR), Bridge X (BRX), Cordis Covered Nitinol (CV), Dynalink (DY), Memotherm Luminexx (LX), Megalink (MK), Memotherm Flexx (MF), Palmaz Medium (PM), Palmaz-Schatz Long-Medium (PS), Palmaz Corinthian 29 mm (PC29) and 39 rum (PC39) version, SelfX (SLF), SMART without markers (SM), SMART with radiopaque markers (SMR), Wallstent (WA). To evaluate radiopacity, images of the stents placed on four different positions (lumbosacral junction left and right, ileosacral joint left and right) ofa pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, l5 pulses per second, 7.5 pulses per second, and 3 pulses per second. Images were presented at random to four independent readers and a rad.iopaci~ score (RS) - from 0= invisible, I=poor, 2=average, 3=good, and 4=very good - was assessed. RESULTS: At spotfilm mode the following three stents performed best: LX > CV and WA (RS 3.9 to 3.94), at continuous fluoro CV > LX > BRX (RS 2.94 to 3.4), at 15
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pulses per second CV > BRX > WA (RS 2.6 to 3.25), at 7.5 pulses per second CV > LX > WA and BRX (2.4 to 2.9), and at 3 pulses per second CV > BRX > LX (RS 1.9 to 2.6).
CONCLUSION: I) Stcnt radiopacity dircctly depends on the fluoroscopy mode. By decreasing the pulse frequency detecting the stcnts became more difficult. 2) SteDt mass correlates with stent radiopacity (e.g. Cordis Covered Nitinol, Bridge X). 3) Radiopaque markers may improve stem radiopacity dramatically. 1:14PM
Abstract No. 61
Comparison of BiocompatibUity and Performance between \Vallstent and Three Slenl-Grafts. M. Cejna, Interv. Dep.l Vienna Med School, Vienna, Austria • R. Virmani· R. Jones· C. wewe • M. Grgun"n .1. Lammer PURPOSE: Most recently developed slenl-grafts were compared directly in an animal model in regard of perfonnancc and biocompatibility.
MATERIALS AND METHODS: Threc stent-grafts, Hemobahn (polytetrafluorocthylene (ePTFE)1 nitinol, W.L. Gore, Flagstaff, USA), Wallgraft (polyesterlNi-Co-Ti-steclalloy, Boston Scientific Inc, Meditech, Natick, MA, USA) and Jostent peripheral stentgraft (ballon' cxpandable ePTFEI stainless steel, JOMED Inc., Switzerland) and WaJlstent(NiCO-Ti-steel-alloy, Boston Scientific Inc), n=8 each, were implanted in sheep iliac arteries (0=8 animals). Angiography, IVUS, histomorphometry, histology and scanning electron microscopy (SEM) were performed at 3 months.
RESULTS: Early Iwnen gain, late lumen loss and patent vessel diameter at angiography were not significantly different. Two stcntgrafts had significantly more neointima formation (Hemobahn 9.88 ± 0.94nun' and Wallgraft (14.98 ± 0.90nun') than the Jostent (6.52 ± 0.46nun') and the Wallstent (5.24 ± 0.62mm 2 ), p-Anova <0.0 I. Patent lumen arca was not significantly differcnt (Hemobahn 42.57 ± 1.41 nun', Jostcnt 39.76 ± 2.04nun', Wallgraft 40.22 ± 1.00nun' and Wallstent 41.64 ± 1.59 mm', p-Anova~0.57). The Hemobahn had significantly more innammative vessel wall reaction (inflammation score of 0.83 ± 0.03) than Jostent (0.58 ± 0.03), Wallgrafl (0.55 ± 0.04) and WaUstent (0.16 ± 0.01). Angiography and rvus demonstrated absence ofanastomotic neointima formation. Endothelializati~n was incomplete for all prosthcses, yet there was no significant differcnce between the stents (p-Anova=0.22). Predominantly mature endothelium was found for the Wallstent, the Hemobahn had predominantly immature endothelium. CONCLUSION: The stent-grafts caused a greater degree of neointima formation and inflarruriative vessel wall reaction than the bare stent. Yet these changes did not interfere with comparable patent lumen areas and occured in the absence of anastomotic neointima formation. 1:25 PM
Abstract No. 62
Stent Struts and Articulations. Their Impact on Hoop Strength, Pushability, and Radiopacity. J. Wiskirchen, Dept ojDiagnostiC Radiology, University Hospital Tuebingen, Tuebingen, Germany· B. Pusich • U. Kramer· G. Tepe • CD. Claussen· s.H. Duda
PURPOSE: To evaluate the hoop strength, the pushability, and the radiopacity ofendovascular stents depending on their design.
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MATERiALS AND METHODS: The Palmaz Mcdium (PM) (rectangular stent struts, no articulation), thc Palmaz-Schatz Long-Medium (PS) (rectangular stent struts, central articulation), and the 29 nun (PC29) and 39 nun (PC39) version of the Palmaz Corinthian Stent (archlike stent struts, multiple artic':llations) were included in the study. Stent hoop strength was assessed in a special pressure chamber, and pushability was analyzed in a plexiglass iliac model. To evaluate radiopacity, images of the four stents placed on a pelvic phantom were taken at the following modes: spotfilm, continuous fluoroscopy, and at 7.S pulses per second. Images were presented at random to two independent readcrs and a radiopacity score (RS) - from 0= invisible, I =poor, 2=average, 3=good, and 4=very good - was assessed.
RESULTS: The absolute hoop strength ofthe PC39 exceeded those of the other stents significantly. Mass adjusted hoop strength was nearly the same for the PC39 and the PC29. (PC29 156.5 N/g'cm, PC39 159.2 N/g·cm). Their hoop strengtbs per unit mass significantly exceeded that of a PM (125 N/g'cm) by 27%, and that ofa PS (75.3 N/g' cm). The most pushable stent was the PC29 (0.54 lIN) followed by tbe PC39 (0.47 lIN) and the PS (0.169). Due to multiplestent dislocations the PM was considered non flexible. At spotfilm mode the PM was the most visible stent (RS 3.5) followed by the PC39 (RS 3.25), the PS (RS 3.12) and the PC29 (RS 1.9). At continuous fluoroscopy the PC39 (RS 1.8) was better than the PM (RS 1.12), the PS (RS 1.0), and the PC29 (RS 0.6). At 7.5 pulses per second thc PM (RS 1.3) perfonned slightly better than the PC39 (RS 1.25), and clearly bener than the PS (RS 0.8), and the PC29 (RS 0.3). CONCLUSION: Overall, the idcal stent having high hoop strength, a low profile, good pushability, and good radiopacity still does not exist. However, by changing strut design (from rectangular to archlike struts) and by inserting articulations hoop strength and pushability can be improved without reducing radiopacity. 1:36 PM
Abstract No. 63
Re-186 for Prevention of Resteoosis in a Rabbit ModelHistologic Effec[S of Stent-Based Radiation Therapy. G. Tepe, Department ofRadiology, University ofTuebingen, Tuebingen, Germany· L.M. Dinkelborg • T. Dietrich· A. Greschniok • P. Muschick • s.H. Duda
PURPOSE: We could recently show that Re-186 stents are capable to reduce neointima fonnation in a dose-dependent fashion in rabbits 7 weeks after implantation with a total inhibition of neointima fonnation in the high-dose groups and no edge-effect. The aim of this study was to evaluate the histologic effects of stent-based radiation therapy.
MATERiALS AND METHODS: Control Slents (n ~ 7) were compared with Re-186 stenlS (2.6 MBq [n ~ 6], 8.1 MBq [n ~ 5], 16.0 [n ~ 6], and 25.3 MBq [n ~ 8]. Thc segments were analyzed for fibrin (location [a] near the stent struts, in the [b] neointima, [c] media, [d] adventitia), necrosis (location b-d), edema (location a-d), inflammation (location a-d), and endothel ial ization. RESULTS: With higher radiation doses the degree of fibrosis, necrosis, and edema increased in a dose-dependent reaction. Inflammation was mainly seen near the stent struts (dosedependent) with only small numbers of granulocytes and monocytes in the neointima, media and adventitia which were independent of the amount of exposure to radiation. Fibrinrich, acellular regions were especially found near the stent struts. The adventitia was a-actin negative in the control group and turned a-actin positive in the high-dose groups. Reendothelialization after stent implantation was found in
the control group whereas in mid- and high-dose stents the endothelium was absent. CONCLUSION: Histologic changes seen after Re-186 stent impantation were mild to moderate. Whether the changes of the vascular wall will cause late side-effects has still to be investigated.
Scientific Session 9 Biliary/GU Monday, April 8, 2002 12:30 PM - 2:00 PM Moderator(s): Ziv Haskal, MD
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Abstract No. 64
Hepar.in-Coated Balloon-Expandable Stent Reduces Intimal Hyperplasia in the Iliac Artery in Baboons. PH. Lin, Baylor College ofMedicine, Bellaire, TX· M.M. Marijianowski· NA. Chronos • C. Chen· A.B. Lumsden· S.R. Hanson PURPOSE: Intimal hyperplasia represents a major cause of failure following endovascular intervention. The effect of heparin on reducing thrombogenicity and intimal hyperplasia following vascular reconstruction has been recognized. In this study, we examined the effect of heparin-coated balJoonexpandable iliac stent on intimal hyperplasia in a baboon model. MA TERlALS AND METHODS: Balloon-expandable (PalmazSchatz) stents were placed in bilateral common iliac arteries in 20 male baboons (mean weight: 8.8 kg). In each animal, a heparin-coated (HC) iliac stent was placed on one side while the contralateral iliac artery received an uncoated stent that served as a control. The iliac artery stents were harvested at I month (n=IO) and 3 months (n=IO). Arteriography was perfonned to assess iliac patency, and intravascular ultrasound (IVUS) was used to determine neointimal and luminal areas. Histological, morphometric analysis, and scanning electron microscopy were perfonned in the stented iliac arteries. RESULTS: One animal was excluded in the I-month group due to premature death. In the remaining 9 surviving animals, seven control stents (78%) and nine HC stents (100%) remained patent. Morphometric analysis showed the HC stented iliac arteries had larger luminal areas (20%, p=0.04), less neointimal areas (34%, p=O.02), less neointimallmedia ratios (35%, p=0.05), and equivalent medial areas (p=0.92) when compared to the control group. In contrast, all control and HC stents were patent (100%) in the 3-month group. No differences in the luminal area, neointimal areas, medial areas, or neointimal/media ratios were noted between the control or He stented iliac arteries in the 3-month group by either morphometric or IVUS evaluation (p>0.05). CONCLUSION: Our data demonstrated that heparin-coated balloon-expandable stents reduce intimal hyperplasia following iliac artery placement. This approach may represent a useful strategy for prolonging luminal patency following iliac stent placement.
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Abstract No. 65
Radiologic Diagnosis and Management of Biliary Complications in Liver Transplants: Whole Livers vs. Donated Segments. S. Kwon, Mt Sinai Medical Center, New York, NY, USA· A. Falk • R. Lookstein • J Guller • F.s. Nowakowski' H. Milty, etal. PURPOSE: To evaluate the radiologic diagnosis and management ofbiliary complic:itions in liver transplants: whole standard livers (STD) versus segments from living related donors (LRD). MATERIALS AND METHODS: From August 1998 - April 2001, 439 liver transplants were performed: 342 STD and 97 LRD. The radiologic diagnosis of biliary complications was made by PTC, MRCP, ERCP and nuclear hepatobiliary scans. Radiologic intervention was performed when needed. RESULTS: 49 biliary complications were found in 45 STD transplants: 32 anastomotic strictures, 7 anastomotic leaks, 5 intrahepatic strictures, 4 intrahepatic bile lakes and I intrahepatic abscess. 25 biliary complications were found in 25 LRD transplants: 10 anastomotic strictures, II anastomotic leaks, I intrahepatic stricture, 2 intrahepatic bile lakes and I intrahepatic abscess. The difference in biliary complications between the STD and LRD transplants was statistically significant (P<.OI). The difference in anastomotic leaks between STD and LRD transplants was also statistically significant (P<.O I). 18 interventions were perfonned in the STD group: II biliary drainage and 7 extrahepatic drainage. 8 interventions were performed in the LRD group: 3 biliary drainage and 5 extrahepatic drainage. CONCLUSION: The radiologic diagnosis of biliary complications following liver transplants is greater in segmental LRD as compared to whole STD liver transplants. Biliary anastomotic leaks are significantly greater in segmental LRD transplants as compared to whole STD transplants. This may be related to the surgical difference between these two types of liver transplants. In STD the donor bile duct is connected to the recipient bile duct whereas in LRD the donor bile duct is connected to the recipient small bowel. Radiologic intervention is useful in managing these patients and insuring continuing function of the transplanted liver.
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Abstract No. 66
Biliary Complications after Pediatric Liver Transplantation Revisited. D. Redd, Department ofRadiology, Emory University Hospital, Atlanta, GA, USA· R. Romero· T Heffron PURPOSE: Biliary complications in pediatric liver transplantation (PLT) are associated with increased morbidity and mortality. In PLT, reduced size grafts have been associated with an increased incidence of biliary complications when compared to whole liver transplantation. The purpose of this review is to report our incidence of biliary complications in PLT based upon graft type, age/weight of recipient, surgical technique and intervention following bile duct complication.
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