• Proceedings of the Korean Fiber Society Conference
• /
• 2003.10b
• /
• pp.104-107
• /
• 2003

Poly(vinyl alcohol) (PVA) obtained by the saponification of poly(vinyl ester) like poly(vinyl acetate) o. poly(vinyl pivalate) is a linear semicrystalline polymer, which has been widely used as fibers for clothes and industries, films, membranes, medicines for drug delivery system, and cancer cell-killing embolic materials[1-3]. PVA fibers and films have high tensile and compressive strengths, high tensile modulus, and good abrasion resistance due to its highest crystalline lattice modulus. (omitted)

• Polymer(Korea)
• /
• v.37 no.5
• /
• pp.563-570
• /
• 2013

Poly(vinyl pivalate) (PVPi) was bulk polymerized to make poly(vinyl alcohol) (PVA) microfibrils to apply for polymeric embolization coils replacing metalic coils. Then, syndiotactic PVA (s-PVA) microfibrils having number-average degree of polymerization of 1100 and s-diad content of 60.4% were prepared via saponification of the PVPi with no separate spinning process. To make s-PVA microfibrils with radiopacity, zirconium dioxide ($ZrO_2$) and barium sulfate ($BaSO_4$) were added into s-PVA microfibrils during saponification. The computed tomography (CT) value indicating radiopacity reached up to over 1000 when the amount of $ZrO_2$ and $BaSO_4$ were 12 and 6 wt%, respectively.

• Polymer(Korea)
• /
• v.37 no.4
• /
• pp.486-493
• /
• 2013

The structure, morphology, and physical properties of syndiotatic poly(vinyl alcohol) (s-PVA) gel spun fibers were investigated to prepare polymeric embolization coils. S-PVA was prepared by saponification of the poly(vinyl acetate)/poly(vinyl pivalate)(PVAc/PVPi) copolymer. The viscosity of s-PVA solutions showed shear thinning behavior and the solution formed a homogeneous phase. Based on shear viscosity change with concentration, the optimum dope concentration was selected as 13 wt%, after which s-PVA fibers were spun and the solvent was removed. The fibers were then drawn with a maximum draw ratio of 15. A polymeric embolization coil was made of the s-PVA gel-spun fibers. The fibers were wound densely onto rigid rod and then annealed at different annealing temperatures. The polymeric embolization coil annealed at $200^{\circ}C$ was similar to metallic coils and its shape was maintained well after extension. Overall, gel-spun PVA fibers performed well for the preparation of primary and secondary coils to replace metallic coils.

• Journal of Korean Neurosurgical Society
• /
• v.30 no.1
• /
• pp.12-19
• /
• 2001

Objective : Albumin is a very useful drug for the improving of cerebral blood volume and the oncotic effect in cerebral ischemia or cerebral vasospasm. The purpose of this study was to examine the morphological and neurological effect of albumin therapy on reperfusion injury following transient focal cerebral ischemia. Materials and Methods : 18 Male Sprague-Dawley rats weighing 270-320g were used. The ischemia model was produced by 2-hour period of transient middle cerebral artery occlusion with a poly-L-lysin coated intraluminal suture. The agent(20% human serum albumin[HSA]) or control solution(NaCl 0.9%) was administered intravenously at a dosage of 1% of body weight immediate after reperfusion following a 2-hour period occlusion. Neurological function was evaluated by the postural reflex and the forlimb placing test during occlusion(at 60 min) and daily for 3 days thereafter. The brain was perfusion-fixed, and infarct volumes and brain edema were measured. Results : The HSA significantly improved the neurological score in treated group. The rats of albumin treatment group showed significantly reduced total infarct volume(by 34%) and brain edema(by 81%) compared with salinetreated rats. Conclusion : HSA showed a substantial effect on the transient focal cerebral ischemia and reperfusion injury model. These results may indicate its usefulness in treating reperfusion injury patients after thrombolysis treatment for the thrombo-embolic major cerebral artery occlusions.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.1
• /
• pp.17-25
• /
• 2016

Objective : Treatment of intracranial dural arteriovenous fistulas (dAVFs) remains a challenge. However, after introduction of Onyx, transarterial approach is the preferred treatment option in many centers. We report our experience of dAVFs embolization with special emphasis on transarterial approach. Methods : Seventeen embolization procedures were performed in 13 patients with dAVFs between Jan 2009 and Oct 2014. Clinical symptoms, location and type of fistulas, embolization methods, complications, radiological and clinical outcomes were evaluated using charts and PACS images. Results : All 13 patients had symptomatic lesions. The locations of fistulas were transverse-sigmoid sinus in 6, middle fossa dura in 4, cavernous sinus in 2, and superior sagittal sinus in 1 patient. Cognard types were as follows : I in 4, IIa in 2, IIa+IIb in 5, and IV in 2. Embolization procedures were performed ${\geq}2$ times in 3 patients. Nine patients were treated with transarterial Onyx embolization alone. One of these required direct surgical puncture of middle meningeal artery. Complete obliteration of fistulas was achieved in 11/13 (85%) patients. There were no complications except for 1 case of Onyx migration in cavernous dAVF. Modified Rankin scale score at post-operative 3 months were 0 in 11, and 3 in 2 patients. Conclusion : Transarterial Onyx embolization can be a first line therapeutic option in patients with dAVFs. However, transvenous approach should be tried first in cavernous sinus dAVF because of the risk of intracranial migration of liquid embolic materials. Furthermore, combined surgical endovascular approach can be considered as a useful option in inaccessible route.

• Korean Journal of Radiology
• /
• v.22 no.11
• /
• pp.1834-1840
• /
• 2021

Objective: To analyze the computational fluid dynamics (CFD) of femoral artery pseudoaneurysm (FAP), identify a suitable location and timing for percutaneous thrombin injection (PTI) based on this analysis, and report our clinical experience with the procedure. Materials and Methods: CFD can be used to analyze the hemodynamics of the human body. An analysis using CFD recommended that the suitable location of the needle tip for PTI is at the center of the aneurysm sac and the optimal timing for starting PTI is during the early inflow phase of blood into the sac. Since 2011, seven patients (three male and four female; median age, 60 years [range, 43-75 years]) with FAP were treated with PTI based on the devised suitable location and time. Prior to the procedure, color Doppler ultrasonography was performed to determine the location and timing of the thrombin injection. Results: The technical success rate of the PTI was 100%. The amount of thrombin used for the procedure ranged from 200 IU to 1000 IU (median, 500 IU). None of the patients experienced any symptoms or signs of embolic complications during the procedure. Follow-up CT images did not reveal any embolism in the lower extremities and showed complete thrombosis of the pseudoaneurysm. Conclusion: Based on our study of CFD, PTI administered centrally in the FAP during early inflow, as seen on color Doppler, can be an effective technique.

• Korean Journal of Radiology
• /
• v.24 no.6
• /
• pp.512-521
• /
• 2023

Objective: There is increasing recognition that left atrial (LA) strain can be a prognostic marker of various cardiac diseases. However, its prognostic value in acute myocarditis remains unclear. Therefore, this study aimed to evaluate whether cardiovascular magnetic resonance (CMR)-derived parameters of LA strain can predict outcomes in patients with acute myocarditis. Materials and Methods: We retrospectively analyzed the data of 47 consecutive patients (44.2 ± 18.3 years; 29 males) with acute myocarditis who underwent CMR in 13.5 ± 9.7 days (range, 0-31 days) of symptom onset. Various parameters, including feature-tracked CMR-derived LA strain, were measured using CMR. The composite endpoints included cardiac death, heart transplantation, implantable cardioverter-defibrillator or pacemaker implantation, rehospitalization following a cardiac event, atrial fibrillation, or embolic stroke. The Cox regression analysis was performed to identify associations between the variables derived from CMR and the composite endpoints. Results: After a median follow-up of 37 months, 20 of the 47 (42.6%) patients experienced the composite events. In the multivariable Cox regression analysis, LA reservoir and conduit strains were independent predictors of the composite endpoints, with an adjusted hazard ratio per 1% increase of 0.90 (95% confidence interval [CI], 0.84-0.96; P = 0.002) and 0.91 (95% CI, 0.84-0.98; P = 0.013), respectively. Conclusion: LA reservoir and conduit strains derived from CMR are independent predictors of adverse clinical outcomes in patients with acute myocarditis.

• Korean Journal of Veterinary Research
• /
• v.41 no.3
• /
• pp.429-436
• /
• 2001

The present study was performed to investigate the effect of iohexol-ethanol mixture and barium-ethanol mixture on the induction of transcatheter renal artery embolization in healthy 18 dogs, which were divided into two groups of 9 dogs and the 9 dogs were divided into 3 subgroups of 3 dogs. The renal artery embolization was undertaken unilaterally with the dose of 1.5, 2.0, and 3.0 ml/kg iohexol-ehtanol mixture and with the dose of 0.2, 0.4, and 0.8 ml/kg barium-ethanol mixture. And serum chemistry on 0, 1,3, 7, and 14 days, intravenous pyelography on 7days, angiography on 14 days, and histopathology on 14 days were evaluated. Serum BUN and creatinine concentration of two groups with iohexol-ethanol mixture and barium-ethanol mixture administration were mildly increased a t 1 day after injection of embolic materials and then returned to baseline. No significant changes in BUN and creatinine levels occurred in any of dogs. In all dogs with the dose of 1.5 ml/kg iohexol-ethanol mixture, the renal arteries were not embolized. All dogs with the dose of 3.0 ml/kg died. In all dogs with the dose of 2.10 ml/kg, the treated arteries were completely occluded. In barium-ethanol mixture administered group, the renal artery in one dog with the dose of 0.2 ml/kg was not embolized. In all dogs with the dose of 0.8 ml/kg, the renal arteries were completely embolized, but loac overembolization occured in two dogs. All animals with the dose of 0.4 ml/kg had effective embolization and no evidence of radiopaque barium opacity in systemic arteries distal to the renal-artery was found. All embolized kidneys were shrunk and decreased in size in gross examination and were shown diffuse necrosis in histopathologic examination. In the present study, renal arteries were embolized with the dose of 2.0 ml/kg iohexol-ethanol mixture or 0.4 ml/kg barium-ethanol mixture. And it is considered that the dose had a satisfactory embolic effect.

• Investigative Magnetic Resonance Imaging
• /
• v.6 no.2
• /
• pp.158-165
• /
• 2002

Purpose : To evaluate the effect of Gd-DTPA on signal intensity of diffusion-weighted magnetic resonance(MR) image and apparent diffuse coefficient (ADC) in dog brain with hype racute stroke. Materials and methods : Experimental canine model of hyperacute cerebral infarction was made by selective intraarterial embolization with particulate embolic material. Diffusion-weighted MR imaging was performed in five dogs at 1 hour after the embolization of internal carotid artery. After intravenous bolus injection of Gd- DTPA, additional 11 diffusion-weighted MR images were serially obtained from 2 minutes to 90 minutes after injection in each dog. The author evaluated findings of hyperacute cerebral infarction on diffusion-weighted MR imaging, and calculated mean signal intensity and mean ADC in infarcted region and contralateral normal region. Statistical analysis of mean signal intensity, mean ADC and contrast-noise ratio before and after Gd-DTPA injection was performed. Results : Hyperacute cerebral infarction developed in all five dogs on diffusion-weighted MR images obtained 1 hour after embolization. The area of hyperacute infarction had steady increase in signal intensity on diffusion-weighted MR image and decrease in ADC. In normal perfusion area, decrease in signal intensity was observed at 2 minutes the Gd-DTPA injection, whereas ADC did not changed. Conclusion : Intravenous injection of Gd-DTPA had no influence on ADC in both hyperacute infarction and normally perfused are a, but caused initial transient signal reduction in normally perfused area on diffusion-weighted MR image due to susceptibility effect of Gd-DTPA. It is important to calculate ADC in evaluating the effect of diffusion after injection of Gd-DTPA.

• Journal of the Korean Society of Radiology
• /
• v.79 no.6
• /
• pp.315-322
• /
• 2018

Purpose: To analyze the clinical and angiographic features with outcome of transcatheter arterial embolization in patients with secondary postpartum hemorrhage. Materials and Methods: Clinical details and angiographic features with assessment of arterial embolization were reviewed in total 38 patients underwent arterial embolization at single tertiary referral center. Results: Twenty patients (53%) had Cesarean section. The major causes of bleeding were iatrogenic vascular injury, and retained placenta (55%). The patterns of vaginal bleeding were recorded as intermittent (50%), or as persistent (50%). Seven patients (18%) were hemodynamically unstable at presentation. Positive angiographic findings appeared in eighteen patients (47.3%). The frequency of pseudoaneurysm was statistically high in the Cesarean section (p < 0.001). The used embolic agents except gelfoam were N-butyl cyanoacrylate (n = 7), and microcoil (n = 7). Unilateral selective embolization (26.3%) was shown effective in superselective embolization of bleeding focus. Technical and clinical success rate were 100% and 97.4%, respectively with no complication. Sixteen resumed regular menstruation, and one pregnancy were observed in patients with available follow-up of over 6 months. Conclusion: Considerable rate of hemodynamically unstable patients was observed with high rate of positive angiography findings. Given high successful rate and few complications, early angiographic assessment with embolization should be considered.